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JUNE 2015 ISSN 1030-2662 06 9 771030 266001 9 PP255003/01272 $ 95* NZ $ 12 90 ü 100% Li-ion battery power q ü 100% performance q ü 100% exhilaration q INC GST INC GST At last! We experience the mighty Helping the blind to see Bionic Eyes Handy test gear! Signal Tracer & Injector BAD VIBES siliconchip.com.au INFRASOUND SNOOPER June 2015  1 KIT OF THE MONTH “Champion” Stereo/Dual Channel Preamplifier Kit NEW SILICON CHIP JUN ‘15 KC-5531 Use it as a general purpose stereo preamp or as a dual channel preamp. High input impedance for ceramic phono cartridge or piezoelectric pickup in musical instrument. Can be configured as single channel with fixed or variable gain, and works with Electret microphones. Powered from 6-9VDC (eg. 9V battery) or 12-20VDC. $ Kit supplied with PCB and on-board electronic components for 12-20VDC operation (Electret mic not included, use AM-4010). For 6-9VDC operation an LP2950-05 5V low dropout regulator is required (use ZV-1645). • PCB: 57 x 41mm 1695 Available mid-late June 2015 POWER KITS $ TEST EQUIPMENT KITS 1995 $ Improved Low Voltage Adaptor Kit 2495 Digital Multimeter Kit SILICON CHIP MAY ’08 KC-5463 KG-9250 Learn everything there is to know about component recognition and basic electronics with this comprehensive kit. From test leads to solder, everything you need for the construction of this meter is included. 9V battery included. This handy regulator will step down the voltage to run portable devices. It will supply either 3V, 5V, 6V, 9V, 12V or 15V and deliver up to 4A at the selected output voltage. Kit supplied with screen printed PCB and all specified components. • PCB: 108 x 37mm Kit includes DMM case, LCD, solder, battery, test leads, PCB, comprehensive 18 page learning manual and electronic components. • Meter size: 123 x 67 x 25mm $ 2995 Transistor Tester Kit ELECTRONICS AUSTRALIA SEP ’83 KA-1119 Have you ever unsoldered a suspect transistor only to find that it checks OK? Avoid these troubleshooting hassles with this kit - test drives WITHOUT the need to unsolder them from the circuit! Kit supplied with a jiffy box, battery and electronic components. • PCB: 70 x 57mm $ 3395 $ Battery Saver Kit SILICON CHIP SEP ’13 KC-5523 Ideal for lithium and SLA rechargeable batteries, this smart kit cuts off the power between the battery and load when the battery becomes flat to prevent the battery from over-discharging and becoming damaged. Suitable applications include cordless power tools, emergency lights, small to medium UPS (up to approx 300VA) and a wide variety of other devices. Cut-off voltage adjustable from 5.25 to 25.5V. Kit supplied with double sided, solder-masked and screen-printed PCB with SMDs pre-soldered, voltage setting diodes and resistors, and components. 3395 USB Port Voltage Checker Kit $ 5995 SILICON CHIP JUL ‘13 KC-5522 USB Power Monitor Kit Kit supplied with double sided, solder masked and screen-printed PCB with connectors for USB 2.0 & USB 3.0. Kit supplied with PCB with SMD components pre-soldered and LCD screen. An easy way to test a USB port to see if it is dead, faulty or incorrectly wired to help prevent damaging a valuable USB device you plan to connect. Voltage is indicated using three LEDs. • PCB: 44 x 17mm KC-5516 Plug this kit inline with a USB device to display the current that is drawn at any given time. Displays current, voltage or power and will read as low as a few microamps and up to over an amp. • PCB: 65 x 36mm AUTOMOTIVE KITS • PCB: 34 x 18.5mm $ 55 Soft Start Kit FOR POWER TOOLS SILICON CHIP JUL ’12 KC-5511 Stops that dangerous kick-back when you first power up an electric saw or other mains-powered hand tool to prevent damage to the job or yourself. Place it in line with the power tool’s mains power cord and when you squeeze the power tool’s trigger it will slowly spin up and be at full power after about a second. 240VAC, 10A max load. Kit supplied with PCB, silk screened case, 2m power cord and specified electronic components. • PCB: 81 x 59mm $ 2295 Courtesy Interior Light Delay Kit $ 3495 Threshold Voltage Switch Kit SILICON CHIP JUN ‘04 KC-5392 SILICON CHIP JUL ‘14 KC-5528 This kit provides a time delay in your vehicle’s interior light, for you to buckle up your seat belt and get organised before the light dims and fades out. It has a ‘soft’ fade-out after a set time has elapsed, and has universal wiring. 12-24VDC. A versatile device to switch a relay when its input voltage crosses a threshold. Use it to prevent a lead-acid battery from being overcharged, or to trigger an extra fuel pump under high boost or anti-lag waste-gate shutoff. Kit supplied with PCB and all electronics components. Kit supplied short-form with double sided, solder-masked and screen-printed PCB, onboard relay and electronic components. • PCB: 78 x 46mm To order phone 1800 022 888 or visit our new website www.jaycar.com.au • PCB: 107 x 61mm Catalogue Sale 24 May - 23 June, 2015 Contents Vol.28, No.6; June 2015 SILICON CHIP www.siliconchip.com.au Features   14  At Last . . . We Drive The Tesla Electric Car The Tesla is the only all-electric vehicle that really competes with highperformance luxury cars. We had one for a whole day! – by Ross Tester   23  Real “Hands-On”: Owning A Nissan Leaf Electric Car What’s it like to own an electric car? SILICON CHIP staff member Ross Tester bit the bullet and bought a Nissan LEAF. Here are his impressions . . . Bad Vibes Infrasonic Snooper – Page 36.   25  Tesla’s 7/10kWh Powerwall Battery: A Game Changer? Dreaming of going off-grid? Tesla’s new 7/10kWh Powerwall lithium-ion back-up battery is likely to be a game-changer – by Ross Tester   28  The Bionic Eye: Artificial Vision Is Becoming A Reality, Pt.1 New research is leading to promising advances in artificial vision. Pt.1 this month describes the problems and the challenges – by Dr David Maddison   78  SPIKE: Improved Software For The Signal Hound Audio Signal Injector & Tracer – Page 60. Enhanced software for the USB-SA44B mini spectrum analyser – by Jim Rowe Pro jects To Build   36  Bad Vibes Infrasound Snooper Got a problem with low-frequency vibrations? This Infrasound Snooper lets you listen directly to low-frequency sounds that would otherwise be inaudible – by Nicholas Vinen   60  Audio Signal Injector & Tracer Low-cost unit comprises a 1kHz oscillator & an in-built amplifier so that you can trace signals through an analog circuit to locate faults – by John Clarke   68  AM RF Demodulator Probe For Signal Tracers AM RF Demodulator Probe For Signal Tracers – Page 68. It uses just a handful of parts and will detect the amplitude-modulated RF signals that should be present in an AM radio circuit – by John Clarke   74  The Multi-Role Champion Preamplifier Use it as a general-purpose stereo preamp or as a dual-channel preamp, with a mic for one channel and guitar or other audio source in the other. It gives good performance & will work over a wide range of supply voltages – by Leo Simpson   81  WeatherDuino Pro2 Wireless Weather Station, Pt.4 Final article completes the Weather Station by building a handy little Wireless Display Unit (WDU) – by A. Caneira & Trevor Robinson Special Columns   53  Serviceman’s Log Diversifying – it’s not that easy – by Dave Thompson  71 Circuit Notebook (1) Wireless Door Chime Repeater; (2) High-side Mosfet Switch With Optocoupler Control; (3) Low Ohms Meter Has LCD The Multi-Role Champion Preamplifier – Page 74. Weather Station Wireless Display Unit – Page 81   84  Vintage Radio The Philips model 198 transistor radio – by Ian Batty Departments    2  Publisher’s Letter   4 Mailbag siliconchip.com.au  89 Product Showcase 90  Ask Silicon Chip 95 Market Centre 96 Advertising Index AJune pril 2015  1  SILICON CHIP www.siliconchip.com.au Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Production Manager Greg Swain, B.Sc. (Hons.) Technical Editor John Clarke, B.E.(Elec.) Technical Staff Ross Tester Jim Rowe, B.A., B.Sc Nicholas Vinen Photography Ross Tester Reader Services Ann Morris Advertising Enquiries Glyn Smith Phone (02) 9939 3295 Mobile 0431 792 293 glyn<at>siliconchip.com.au Regular Contributors Brendan Akhurst David Maddison B.App.Sc. (Hons 1), PhD, Grad.Dip.Entr.Innov. Kevin Poulter Dave Thompson SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. ACN 003 205 490. ABN 49 003 205 490. All material is copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Hannanprint, Warwick Farm, NSW. Distribution: Network Distribution Company. Subscription rates: $105.00 per year in Australia. For overseas rates, see our website or the subscriptions page in this issue. Editorial office: Unit 1, 234 Harbord Rd, Brookvale, NSW 2100. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9939 3295. E-mail: silicon<at>siliconchip.com.au ISSN 1030-2662 Recommended and maximum price only. 2  Silicon Chip Publisher’s Letter Anti-islanding in grid-tied inverters is a big drawback In the past, I have touched on the frustration of homeowners with solar panel installations who have no electricity during blackouts. They have this wonderful shiny panel installation which is prevented from generating power during black-outs by the “anti-islanding” feature of grid-tied inverters! This disadvantage was greatly magnified for many people in the aftermath of the severe weather in Sydney at the end of April. Many thousands of people were without power for more than a week. Just imagine that: no power at all for a whole week – nothing for light, cooking, heating, computers, TV and other entertainment or cordless phones – you could not even charge your mobile phone! And this was in Sydney suburbs, not somewhere out in the sticks! No-one was to blame for this situation as the storms downed many thousands of trees and the electricity linesmen were flat out reconnecting whole districts. Even as I write, the clean-up of felled trees is still going on and is likely to continue for another month or so. Now we all know why this “anti-islanding” feature is incorporated into grid-tied inverters. It is there to protect linesmen who may be working on the system when there is a power outage. On the face of it, this is a good idea. But is it really necessary to also prevent the home-owner from having any electricity at all when there is a blackout? There are other ways of protecting linesmen. The most obvious method would be to use the anti-islanding feature of the inverter to switch a contactor, so that the home-owner’s system was disconnected from the grid but still leave the inverter itself to generate power. Sure, the home-owner would not get any benefit from feeding power into the grid but at least he (or she) would still have power while the Sun was shining. While there would still be no power available at night, most home-owners would be happy to work around this, knowing that food in their refrigerators was not going to spoil and many other power-using tasks such as clothes washing could be done during the day. No doubt some people would argue that relying on a contactor to isolate the home-owner’s system could be a recipe for a fatality. But surely a contactor could be arranged to “fail-safe” so that if it did not work, the system would be isolated anyway. I am sure that it would possible to arrange for redundancy in the monitoring and switching to make sure it was always safe and reliable. Of course, it would be necessary for the grid-tied inverter to still be able to monitor for the presence of power on the grid, so that the system would automatically switch back when grid power was restored. If you concede that this idea has merit, then it is only a small step to allow solar systems which are grid-connected (no longer “grid-tied”) to have battery storage so that home-owners can generate their own power during blackouts at night. The release of the Tesla PowerWall lithium battery system (see article on page 25 in this issue) makes this a practical scheme. The solar panels would charge the PowerWall during hours of sunlight and feed the excess power into the grid. Then if there is blackout, the system automatically isolates itself from the grid and the home-owner can enjoy electricity as normal. The PowerWall would also have the benefit of smoothing the peaks in electricity demand from the grid, as it could supply at least some power after the Sun goes down. Of course, the Tesla PowerWall might also persuade some electricity customers to disconnect themselves entirely from the grid and thereby avoid paying daily service charges. Leo Simpson siliconchip.com.au “Rigol Offer Australia’s Best Value Test Instruments” Oscilloscopes RIGOL DS-1000E Series NEW RIGOL DS-1000Z Series 50MHz & 100MHz, 2 Ch 1GS/s Real Time Sampling USB Device, USB Host & PictBridge 439 FROM $ RIGOL DS-2000A Series 50MHz, 70MHz & 100MHz, 4 Ch 1GS/s Real Time Sampling 12Mpts Standard Memory Depth FROM $ ex GST 539 70MHz, 100MHz & 200MHz, 2 Ch 2GS/s Real Time Sampling 14Mpts Standard Memory Depth FROM $ ex GST 1,164 ex GST Function/Arbitrary Function Generators RIGOL DG-1022 RIGOL DG-4000 Series NEW RIGOL DG-1000Z Series 20MHz Maximum Output Frequency 2 Output Channels USB Device & USB Host ONLY $ 499 RIGOL DSA-800 Series 905 60MHz, 100MHz & 160MHz 2 Output Channels Large 7 inch Display RBW settable down to 10 Hz Optional Tracking Generator FROM $ ex GST Power Supply ex GST RIGOL DM-3058E Triple Output 30V/3A & 5V/3A 5 1/2 Digit Large 3.5 inch TFT Display USB Device, USB Host, LAN & RS232 ONLY $ ex GST 1,225 Multimeter RIGOL DP-832 9kHz to 1.5GHz, 3.2GHz & 7.5GHz 1,790 FROM $ ex GST Spectrum Analysers FROM $ 30MHz & 60MHz 2 Output Channels 160 In-Built Waveforms 599 9 Functions USB & RS232 629 ONLY $ ex GST ex GST Buy on-line at www.emona.com.au/rigol Sydney Tel 02 9519 3933 Fax 02 9550 1378 Melbourne Tel 03 9889 0427 Fax 03 9889 0715 email testinst<at>emona.com.au siliconchip.com.au Brisbane Tel 07 3275 2183 Fax 07 3275 2196 Adelaide Tel 08 8363 5733 Fax 08 83635799 Perth Tel 08 9361 4200 Fax 08 9361 4300 EMONA web www.emona.com.au June 2015  3 MAILBAG Letters and emails should contain complete name, address and daytime phone number. Letters to the Editor are submitted on the condition that Silicon Chip Publications Pty Ltd may edit and has the right to reproduce in electronic form and communicate these letters. This also applies to submissions to “Ask SILICON CHIP” and “Circuit Notebook”. Disagreement with topics of Publisher’s Letters I would like to again take issue with your April 2015 editorial (Publisher’s Letter). As before, I find the subject covered here has little to do with the magazine’s content as suggested by the front page. It is as if the author of this item is simply using the magazine as a platform to air his personal opinions. This seems somewhat inappropriate. Regarding the subject in the Publisher’s Letter, when I studied technical subjects at TAFE back in the 1960s we were often told we could assume the planet was infinitely large and could take whatever you threw at it. But this is wrong. Modern technology has already used much of the planet’s supply of rare earth metals to a point that they are now “rare”. Air-conditioning has not always been beneficial; it was the source of a new illness, namely, Legionnaires’ Disease. I have spent many years working in technical areas, including broadcasting, and have become very concerned about the introduction and use of technologies simply because you can and not because they fill an existing need. Mobile phones, for example, Climate change comments should not be dismissed It is with amusement that I again see the rise of intellectual arrogance in the Mailbag section (comments on the climate change debate, page 12, February 2015). To postulate that only specialists within the field of physics (or actually any field) can understand the details of climate change (or insert relevant topic: NBN, solar vehicles etc) and come to a “correct” conclusion is gross arrogance. I wonder what the other sciences think of the off-hand dismissal of their expertise and inputs. If the general readership, which obviously includes the Doctor, know what the Gaia hypothesis 4  Silicon Chip generate their own uses often based on the expectations of others. I don’t own one and yet am quite able to survive; why can’t others? In the end the Earth’s resources are finite and wearing “rose-coloured glasses”, no matter how strong, will not change that. Graeme Clinch, Willoughby, NSW. Comment: rare earths are still not actually rare. It is true that mining rare earths may be more expensive in the future but we are not going to run out. Legionnaires Disease occurs in poorly maintained air-conditioning systems with evaporative cooling towers. It is not a new illness, created by airconditioning. It is simply yet another variant of bacterial pneumonia. Rose-tinted glasses are ubiquitous Unusually, I found myself agreeing with the Publisher’s comments on the maintenance implications of roof-top solar in the May 2015 issue. I paused at the statement that DC is more dangerous than AC, since this is a contentious issue. However, it was his advice that solar advocates remove their rose-tinted is, then I would say this is a good place to commence discussion. To paraphrase, I don’t have to agree with what you say but I will defend your right to say it. Discussion is the first step towards understanding. As noted in that letter, “real experts are rarely complacent or absolutely certain of their conclusions”. How dare you identify anyone outside your area of expertise as not being a so-called “real expert”. History is littered with examples of where this constrained thinking has led to grievous errors in learning and development, even in physics! Secondly, if we are to wait for the statically “absolutely certain answer” we may be too late. The more glasses that completely bewildered me. I know of no one who more proudly wears rose-tinted glasses than the Publisher. The previous month’s editorial in the April issue was a classic example. His views on nuclear energy and the benign effects of climate change are just two examples. Nothing would suit me better than the Publisher’s optimistic views of the future playing out but surely prudence demands that we all remove our rosetinted glasses and start preparing for a more renewable future. Mark Baker, Perth, WA. Solar PV installation experience The Publisher’s Letter in the May 2015 issue highlighted some issues which may be of concern for those who have installed solar photovoltaic panels on their roof. The accompanying article in the same issue, detailing the experience of Dr Alan Wilson (“Home Solar Panel (PV) Electricity hypotheses that are aired, then the more informed are the discussions and the greater will be the know­ ledge of what is occurring. Experts and those with an indepth understanding are required to balance the arguments and provide know­ ledge and guidance in what will ultimately be a community/political decision. I n the final analysis, “the real experts” will only offer their “opinions” to the decision makers who, having other goals and agendas influencing their decisions, will set our environmental directions. To stifle discussion is a crime that future generations will pay for. Greg Budden, Woomera, SA. siliconchip.com.au Comments about true-RMS voltage measurement – is it worth it?”) also raised some points which deserve consideration. Despite these concerns I am of the opinion that it is still worth doing today but various state governments are hatching plans to create disincentives to limit the take-up of solar PV installations. I installed a solar PV off-grid system on my home in May 2009, when such systems were considerably more expensive than they are today. Prior to installing my system, I ensured that the roof area where it was to be installed was in prime condition. I have corrugated Colorbond roofing which had been in place for nearly 20 years but was still in very good condition. I made sure that all screws were replaced when fitting the solar panel mounting rails and that the roofing sheets were not likely to corrode in the foreseeable future. My home is located about 1.5km from the Indian Ocean so salt-laden air is not a real issue. However, I can see that those located right on the ocean may experience corrosion problems in the future. My household consists of only my wife and myself (both retired) and we are careful to minimise power usage, although going to the trouble of switching off at the GPO all devices which run on standby power is going a bit too far I feel. The house is powered solely by electricity, augmented by a solar hot water system. The HWS electric booster is on a timer circuit so that it only comes into operation during the colder months and only operates for about three hours during the daytime to moderately heat the water for showering. Why waste electricity to make the water really hot when you are going to mix it with cold water and cool it down again? My average power consumption prior to installing my system in 2009 was around 11kWh per day and my siliconchip.com.au FULL DUPLEX COMMUNICATION OVER WIRELESS LAN AND IP NETWORKS IP 100H See t reviewhe SILICON in Decem CHIP b (ask us er 2014 for a c o py!) Icom Australia has released a revolutionary new IP Advanced Radio System that works over both wireless LAN and IP networks. The IP Advanced Radio System is easy to set up and use, requiring no license fee or call charges. To find out more about Icom’s IP networking products email sales<at>icom.net.au WWW.ICOM.NET.AU ICOM5001 Thanks for the good article on the Appliance Earth Leakage Tester in the May 2015 issue but I have just one comment about “True RMS”. I think you should point out to the readers that the RMS you referred to in the article is AC RMS and does not take into account any DC level that may be present. This is a trap for the unwary as True RMS readings take into account any DC level that may be present. Remember the RMS value is equated to a DC level that would produce the same heating value in a resistor (power). So if you have a signal of 100V DC + 20VAC RMS you actually have 120V RMS! Most DMMs that I am aware of do not measure this DC level; not even a good Fluke DMM – which I use. You have to switch to DC, note that reading, then add it to the AC RMS reading to obtain the total voltage. Mike Abrams, Capalaba, Qld. Comment: measuring AC voltage when an accompanying DC voltage is present can cause problems for many multimeters. In those cases, it’s necessary to measure the AC via a suitably-rated blocking capacitor. Some older analog multimeters incorporated ranges with a blocking capacitor and some DMMs have an AC+DC mode. June 2015  5 Mailbag: continued Helping to put you in Control FRAM Breakout The KTB-299 is a Ferromagnetic RAM breakout board. FRAM is a non-volatile memory & it doesn’t wear out when read or written to. 64K memory space, accessible via I²C bus. 3.3 VDC powered. SKU: KTB-299 Price: $24.95 ea + GST 2-Button Pendant With ER Stop Industrial graded, IP66, 2-button control station pendant comes with ER stop pushbutton. It has contact rating up to 6A <at>250VAC. 4, 6 & 8 button models, with or without ER stop button, are also available. SKU: HNE-1022 Price: $74.95 ea + GST 125mm Siren IP55 rated, small rugged siren with 5 selectable sounds. It comes with a built-in adjustable volume controller from 95 dB to 105 dB. 24 VDC powered. SKU: QLL-3002 Price: $139.95 + GST Tri-colour LED Signal Light One small signal light that can transmit up to 3 colours: red, amber and green. High visibility is esured from a distance by housing the LED in a special reflector. Selectable steady or flashing mode. 24 VDC powered. SKU: QLL-1101 Price:$142.50 +GST Omega VLF tower has been demolished The former Omega VLF Tower near Woodside, in the Gippsland region of Victoria was felled on the 22nd April, 2015. The tower and the Omega Navigation System was the subject of my SILICON CHIP article in September 2014 and I mentioned the proposed demolition in Mailbag of March 2015 in which I suggested that concerned readers contact the relevant minister to oppose it. This is a sad moment because: (1) this was the last tower left in the world that was used for the historically significant Omega Navigation System and not currently used for another purpose; (2) it was the tallest structure in the Southern Hemisphere and (3) it was a significant local tourist attraction and landmark which was also used for navigation by commercial fishermen. Ostensibly, the reason given for demolishing the tower was that someone jumped off it, killing themselves. This seems to represent a new meme in government thinking. Does that mean that any other structure that someone illegally climbs and jumps off will also be destroyed? The implications of that are quite striking – no bridge, building or tower will be safe from the government wrecking ball. Whatever happened to the concept of individual responsibility? It’s too bad that no one in government seems to have understood the significance of the structure; nor cared. Everyone I know who has an interest in technology is appalled at the unnecessary and wanton destruction of the last tower standing that represented the navigation system that preceded GPS (former Station D in La Moure, North Dakota remains but was re-purposed). No attempt appears to have been made to find alternative uses for the tower nor does it appear that the opinions of the public were sought on the matter. A video of this destruction can be seen at https:// youtu.be/4YhZp4n1xys I am glad I got to write the SILICON CHIP article and make a YouTube video (https://youtu.be/S_T7hd0oXUE) before this vandalism occurred. Dr David Maddison, Toorak, Vic. Servo Trigger The servo trigger is a small robotics board that simplifies the control of hobby RC servo motors. 5 VDC powered with 3 control settings, configurable input polarity & response mode. SKU: SFC-018 Price: $28.97 ea + GST Switching Power Supply Universal AC input, powerfactor correcting, single output enclosed switching power supply with short circuit, overload and over voltage protection. 320 W, 24 VDC <at>13A output. SKU: PSM-026 Price: $114 ea + GST Wind Speed Sensor The anemometer measures wind speed between 0.5 to 50 m/s, which is scaled to a 0 to 5 VDC output. It features reverse polarity and over voltage protections. 12 to 30 VDC powered. SKU: FSS-002 Price: $170 ea + GST For OEM/Wholesale prices Contact Ocean Controls Ph: (03) 9782 5882 oceancontrols.com.au Prices are subjected to change without notice. 6  Silicon Chip decision to install solar PV was made in mid 2008 when it was mooted that electricity costs would rapidly increase within the next seven years. In 2008, WA was in election mode and Mr Barnett was proposing a solar rebate for exporting surplus electricity to the grid of around $0.60/kWh if he was elected. I quickly discarded this as blatant electioneering and it had no influence on how I voted. However, if this rebate did eventuate, it would have given some recompense against the high cost of installing a system at current prices, which in those days amounted to around $15,700 for a quality 1kW Sharp/Fronius package. As it came to pass, Mr Barnett was duly elected and as I had surmised, he reneged on the idea of a solar rebate. The only rebate paid for exported electricity was to be at the same rate as customers paid for any electricity consumed from the grid. The federal government offered a rebate of $8000 in those days and together with selling my RECs for around $1000, it ended up costing me about $6700 out of pocket to install my system. Today, you can install a 3kW system for about half this cost. As the price of solar PV products was dropping rapidly, the federal rebate of $8000 was cut since it was greater than the cost of purchase and would have just been a huge gift to home-owners. I had always considered that a 1kW system was a too small for my needs and in February 2010 I purchased the items necessary to increase my system to 1.5kW. This would entail extra roof mounting hardware, three additional panels and the necessary extension cables to reach the end of the panel string. Even though I was able to get these items at a discounted price from a wholesaler, it still cost around $2900 all up. siliconchip.com.au siliconchip.com.au June 2015  7 Mailbag: continued Sprague 500 receiver used to hunt interference I was just looking through the SILICON CHIP website and found the story on the Sprague 500 receiver in the September 2005 issue at www. siliconchip.com.au/Issue/2005/September/The+Sprague+500+multiband+receiver I used this receiver frequently from 1967 through 1974 when I was stationed with AF Security Service in Berlin, Sinop (Turkey) and Shu Linkou (Taiwan). At all three places we had one at our front gate. If an entering vehicle broke the squelch they’d be barred from the facility until they got their ignition system fixed. I frequently went off-site to hunt for RFI. Frankly, the Sprague 500 was a pretty good unit if you knew Because I performed the installation myself, I saved on that item but when all expenses were taken into account, my 1.5kW system ended up costing me a staggering $9600. As it eventuated, the WA government in 2011 decided to institute a nett feed-in tariff scheme which would mean existing owners would receive roughly 47 cents for each unit of solar electricity pumped into the grid. Not only this but the fee would apply for a period of 10 years. I quickly signed up for this offer. In 2013, Mr Barnett was starting to have second thoughts about his generous buyback scheme and sought to cancel the 10-year contracts and only how to operate it. We had a vehicle with an ignition suppression feature so we could be mobile. I found a lot of power-line interference, along with an occasional AM or FM station off frequency. In Taiwan, the ILS at Taipei airport often radiated past its limits. Thanks for the memories. Mike Dick, SMSgt, USAF, Ret. Knob Noster, MO. pay 27 cents for any excess put back into the grid. This sparked an immediate backlash – not the least of which came from voters who had helped put him in power at the last election. After some discussion and lobbying, Mr Barnett eventually decided to leave existing 10-year contract conditions alone for those who had installed prior to 19 May 2011 and to effectively reduce the buyback fee to 27 cents per unit for those installing solar after this date. Not satisfied that the revised energy buyback fees were sufficient to reduce the tariff being paid to solar PV owners, Mr Barnett was proposing to introduce at the budget this week a contrived “poles and wires rental charge”, similar to that proposed in 2013 by the Queensland Competition Authority where it was suggested that a fee of $210 per annum would apply for those who use the public utility infrastructure to export their electricity back into the grid. I see now that this idea has proved too difficult to implement immediately so it has been put on the back-burner for a while. No doubt it will come up at some time in the future. I find that my 1.5kW system contributes about 50% of my daily requirements year round so that with the feed-in tariff of 47 cents per kW I haven’t had to pay for electricity for the past few years and have actually ended up with a credit on my account. As far as my Fronius inverter is concerned, I have found it to be extremely efficient and reliable – up until about six months ago, just after the 5-year warranty period had expired. Since Fronius were now offering a 10-year warranty on current products, I imposed upon them to repair my inverter under warranty and they agreed. I had done some research and found that the main board in inverters of the same vintage as mine were prone to a flash-over failure after about five years service, due to dust combined with atmospheric moisture ingress. It took about two weeks for a new board to arrive from Sydney and the serviceman to come around to install it. The new board was now coated (both sides) with a semi-flexible epoxy to a thickness of about 6mm. This measure was obviously to counter any similar failure mode. tel: 08 8240 2244 Standard and modified diecast aluminium, metal and plastic enclosures www.hammondmfg.com 8  Silicon Chip siliconchip.com.au During the time it took for the repair I decided to see what was available on eBay in the way of a spare inverter to keep on hand should a similar failure occur in the future. I was surprised when I found that a solar company only a few kilometres away was auctioning unused Fronius inverters of the same vintage as mine (they had acquired stock from a company which had gone into receivership). I was successful in bidding on a slightly larger system (IG20) for around $430. This was about one-third what my original inverter had cost so I thought it was a good deal. When it arrived I removed the main board and masked off all connectors and components not requiring it, and gave it several coatings of acrylic conformal coating. The original IG15 which was repaired under warranty is now the spare. Ross Herbert, Carine, WA. Output transformer failures may be due to paper composition I have read with much interest the various comments regarding valve radio output transformer failures and I would like to put my view. Like John Hunter (Mailbag, March, 2015), I questioned Graham Parslow’s reasoning that excessive anode current was the usual cause of output transformer failure (Vintage Radio, November, 2014). Over the years, I have replaced many open-circuit output transformers. I usually “patch” a bench-test trans­ former and speaker across the output transformer to assess the overall oper­ating condition of the radio before proceeding to fit a replacement transformer. In most cases, the resulting audio has been pretty good. If the coupling capacitor to the output valve was leaky enough to cause excessive anode current, the sound is usually pretty distorted. My opinion on the causes of most failures parallels John’s comments, with the addition of the following thought: it is my belief that a significant problem behind output transformer failures lies in the chemical composition of the paper used; either between the layers of turns or between the winding and the paper bobbin. I don’t know the chemistry behind making paper but I believe that sulphur is (was?) used. An extension of this thought is fed by noting that people can buy “acid free” paper for archiving important documents. I also can’t help wondering if the wax might not have been as inert as the transformer designers believed it to be. A further comment: the Rola potted transformers that John refers to seem to have been prone to failure too, although maybe not as often as “open” transformers. I repair and restore valve radios myself and the Radio Corporation of New Zealand (RCNZ) which made Columbus and Courtenay (and other house brand) radios used “Isocore” wax impregnated transformers in cans. In their later model radios, Radio (1936) Ltd which made Ultimate (and also other house brands) used output transformers that were mounted on fibre washers to insulate them from the chassis and connected them to the B+ rail via a 470kΩ resistor. In both of these brands of radio, I note that output transformer failure seems to be about as “bad” as any other set I work on. I would also like to comment on IF transformer and RF coil failure. These all seem to either go high in resistance or open-circuit on their primaries, all having been connected to the B+ rails. This definitely seems to follow John’s reasoning on electrolysis but I still can’t help wondering if the chemical composition of the paper is still the primary culprit. Many years ago, I remember reading that a thought held by the engineers at the time was this: it was often women who wound the transformers and coils and they speculated that maybe their perspiration got more acidic as they approached “that time of the month”. There could also be some credence to their thoughts. It’s interesting to note that power transformers don’t suffer from the same rate of failures as do transformers (or coils) that are connected to a DC voltage. Further to John Hunter’s comments about his belief in fuses. When I repair or restore a valve radio, I always install a 250V 1A 32mm long “fast blow” glass fuse in the Active lead of the power cord inside the radio. I had the unfortunate experience many years ago when I had nearly completed an overhaul Five Instruments. One Device. Radically Practical. VirtualBench is an all-in-one instrument that combines essential benchtop equipment into one device and works with PCs or iPads. Convenient and compact, VirtualBench opens up new possibilities for how engineers interact with benchtop instruments. See how at ni.com/virtualbench or free call 1800 300 800. ©2015 National Instruments. All rights reserved. National Instruments, NI, ni.com, and VirtualBench are trademarks of National Instruments. Other product and company names listed are trademarks or trade names of their respective companies. 21173 siliconchip.com.au June 2015  9 21173_virtualbench_Ad_57x244.indd 1 3/27/15 9:05 AM Mailbag: continued Solar panel roof installations & nuclear power In the May 2015 issue, the Publisher’s Letter raised some very interesting points on the subject of solar panels. Even though at our home we have an ideal location for solar panels, we have resisted installation on the basis of cost per 10 years. Given that I am now into my 70s, there is unlikely to be any financial gain from going into such arrangement with our service provider. We did the sums and decided we would be better off to stay out of it (despite continuing calls from Mumbai around dinner time). However, last year we were travelling through France and Italy and we noted the prevalence of solar panels, particularly in Italy. With regard to your comments about roofing, and we didn’t have that incentive to get closer to the issue, but a lot of roofs in Italy are covered in solar panels and I am trying hard to recall but I think they were either the actual roof or very close to the roof so that any failure of the roof would be obviated. One area which I noted as being an obvious location were car parks, where the shade for the cars was provided by solar panels – acres of them. The idea seemed to be to make carport style parking and use the solar panels as the shade roof; what to a set that I had running well in my workshop as I went in to the house for my morning coffee. I went back out to the workshop about half an hour later to find the radio nearly on fire! The power transformer was extremely hot. A subsequent postmortem showed 10  Silicon Chip a good idea! Unfortunately, most of this was seen while travelling at 300km/h on their highly effective rail system. Not only are the Italians good at opera but now at solar panel arrangements. Strangely enough I didn’t see such in Singapore but the Marina Gardens have a very high-tech waste disposal masquerading as garden styling, another area of “green” technology that seems to work. I find the publisher’s support for nuclear energy refreshing. As I grow older, I am more and more convinced that we in Australia should move to nuclear power. We have the advantage of having much open space in which nuclear power stations could be built. We should also be building solar power stations like the La Florida one at Alvarado in Spain. Using lique­fied salt as a medium it produces 432MW. We have the climate in which we should build several such plants across the country, thus providing some flexibility when cloud happens to reduce output from one of the plants. However, I must say that I find an inconsistency in the publisher’s use of scientific opinion to show that nuclear is safe, and rightly so, but yet he “cherry-picks” the small minority of climate change opposers. There will always be legitimate scientists who challenge the orthodoxy (that is how science works) but it is undeniably the case that the vast majority of climate scientists now firmly agree that climate change is man-made. We must act now to reduce our carbon emissions and going nuclear and building the large solar plants is the way to achieve that end. Ken Anderson, Sale, Vic. that the phenolic rectifier socket had shorted (carbonised) across the HT pins (it would have had close to 750V across its adjacent pins, being a type 80 rectifier, if my memory is correct). I can only assume that the socket had absorbed some moisture hydro- scopically while the radio was in disuse and the stress of having about 750V applied was just too much for the poor socket to handle. I usually have a 200W lamp connected in series with the AC line to a radio while they’re soak-testing but I was a bit too cocky that day and I paid the ultimate price – $500 to have the transformer custom rewound! Peter Walsham, Pukekohe, New Zealand. Leo Simpson comments: I worked at Ducon Condenser Co in the mid-1960s and it was standard practice on the production line for polystyrene (Styroseal) capacitors (which had very high insulation resistance) for women who were menstruating to be taken off the winding machines and put on other duties – otherwise the wound capacitor elements were likely to have a high rate of rejection. Airborne radar story correction Your very interesting article on weather radar in the April 2015 issue refers to a company called ECKO. However, it should have been EKCO, as in Eric Kirkham Cole Ltd. John Leathley, Perth WA. Acer netbook charger problems Around 2010 I purchased a shiny new Acer netbook for my wife. It served her well for around 12 months but was soon made redundant by an iPad. The Acer sat in a cupboard for a little while before being passed on to my sister who had a need for it. During this year’s annual visit to my sister I noticed it seemed to be out of service again. On enquiry, my sister talked about her new iPad and fullsized laptop and said she didn’t need the netbook any longer. I decided to bring it home at which point she also explained it no longer worked on the battery, only the charger. Once home, there was no real need for a device with a dead battery and it didn’t seem worthwhile to purchase a new battery given all the other new devices that I’ve acquired since the departure of the netbook. Back in the cupboard it went. One day, when internet searching siliconchip.com.au siliconchip.com.au June 2015  11 Mailbag: continued Valve servicing I fix quite a lot of valve-based equipment. There are the usual dried up or leaky capacitors, resistors that have changed value or change as they warm up, dead valves and dodgy modifications. One fault is common to all devices that mount the valve sockets directly on a circuit board: one or more joints will have cracked where the socket pins meet the board. I am supposing this is due to differential expansion and contraction as the socket heats up and cools down. This is also probably why point-to-point wired amplifiers are popular with musicians as they seldom have this fault. I have devised a fix for the circuit board problem, which while a bit labour-intensive, does cure it for good. After carefully documenting the existing connections, I remove the socket and cut a circular hole in for something else, I came across a mention in a forum of a firmware update for battery failures in Acer netbooks. A quick check on the Acer website confirmed there was a new firmware update which was immediately downloaded and installed. After a reboot or two the system now identified the battery and began charging. I guess not all fixes are for a physical failure; it was only the long period of non use that had allowed the battery voltage to drop below a threshold the original firmware could not recharge the battery from. Anthony Vine, Tanilba Bay, NSW. Potentiometer testing tip I’ve been a bit of a train buff since I was young and the performance of the train I’m on is of special interest to me. To find out how fast the train I’m on is travelling, I usually take note of the time between the kilometre posts, although at higher speeds, it is sometimes hard to spot the posts. People have suggested to me that perhaps a GPS would do the job but I’m a bit unsure if it would be reliable 12  Silicon Chip the PCB, large enough for the valve socket pins to pass through but small enough to leave some “meat” around the hole to allow the socket to mount via its lugs, spacers, 3mm bolts and a pair of small holes for the bolts to pass through. I then carefully solder the valve socket pins to the appropriate tracks on the board, using small pieces of flexible hookup wire; different colours help with pin identification later on. Of course, this is made so much easier if the PCB is designed from scratch with the holes and some nice big square pads at the edge of the holes. A PCB offers huge advantages over point-to-point wiring for the passive components but falls down for the power valves in particular. This solution offers the best of both worlds. Derek Evans, Daintree, Qld. on a train. The windscreen in a car is swept back so a GPS attached to the windscreen would have good access to satellites fairly much overhead but on a train with windows that are vertical, it would mean that only satellites closer to the horizon could be used. In addition, many train windows are tinted and I understand that the tinting on the V’locity trains here in Victoria and the XPT in New South Wales is a metallic film-type tinting which may have an attenuating effect on the signals. So do you think it would work or would it be a bit unreliable? I suppose I should try to borrow one and go for a quick train trip and try it out but I’m not sure that any of my closer acquaintances have one. On a different matter, this little tip may be of use for your readers. I’m one of those electronics constructors who use salvaged components wherever possible. It can be a bit frustrating to find that a potentiometer which appeared to be OK when checked with a multimeter turns out to be noisy. So now before re-using a pot, I always do this simple test. I connect a bench DC supply across the outer terminals (the actual voltage is not particularly important; 5V or thereabouts is OK) and connect my oscilloscope between the wiper and one end. I then select AC-coupling and a fairly high sensitivity in the millivolt region and slowly rotate the shaft. Any “noisiness” which a multimeter would miss is very obvious on the trace. If it is minor, a squirt of contact cleaner usually fixes it but if there are noticeable drop-outs then it’s into the bin for the pot! Ray Chapman, Pakenham, Vic. Comment: we expect that a GPS SatNav could work but it would depend on reception conditions on the train and the GPS module’s sensitivity. It should certainly work on a train with wooden carriages. The only way to know is to try it. Thanks for your tip on testing suspect noisy pots. Vintage scopes for a good home I would like to place the following note in SILICON CHIP, if possible, as it just doesn’t sit right with me to have to throw this old equipment away without at least offering it to someone. I have been employed at a powergenerating company since the midseventies. Recently, I stumbled across these three oscilloscopes that were once used to service communications equipment of that era (see photo). I have not switched them on because I believe they should be thoroughly checked first. These units are now destined for the scrap-heap so if anyone would like them for free, they can either pick them up or be willing to pay the freight costs and I will send them. Please contact me at the following email address: big.penguin<at>bigpond. com T. Ives, SC Penguin, Tas. siliconchip.com.au And we raved about the Nissan LEAF! Now we drive a REAL electric car! by ROSS TESTER There are now several electric-only vehicles being sold in Australia but the only one which is real competition for high-performance luxury cars is the Tesla. That’s because the Tesla is a luxury, highperformance car in its own right. High-performance, though, is almost damning it with faint praise! T he first thing you notice about driving a Tesla is its acceleration. It quite literally pushes you back into the (very comfortable leather!) seat and you think WOOOOHAAAA! It’s been compared very favourably with that of a Porsche or Ferrari but having never quite got to own (or even driven!) one of those lofty marques I cannot comment. However, I can say (because Tesla told me!) that over 200m, the new two-motor all-wheel-drive Tesla P85D (not yet available here) will blow a very much more expensive Ferrari FF or the popular Porsche Panamera Turbo into the weeds! (The Ferrari FF starts at about $US300,000; the Porsche Panamera ranges from about $US78,000 to >$US200,000). The P85D will post a 0-160km/h time of just eight seconds and has been clocked at 3.2 seconds for 0-100km/h. I can, however, comment on the very next thing you notice: the speedo reading. In the blink of an eye (or two) you can easily be going FAR above the speed limit. (I was; fortunately there were no speed radars around . . .). Top speed of the S85 is a rather impressive 225km/h. And no, I didn’t try to prove it. 14  Silicon Chip Incidentally, that model number (70, 85, etc) refers to battery size - 85 is for the 85kWh model. It’s a true PEV Having come from a PEV environment (that’s Plug-In Electric Vehicle for the great unwashed, as distinct from PHEV, or Plug-in Hybrid Electric Vehicle. See the following column “Owning an Electric Car”) I was well-used to the almost total lack of sound when driving. OK, there is some road (tyre) noise; at speed there is a tiny amount of wind noise (more a whisper!) but most of the time there is no noticeable noise. The Tesla is little different in this regard. The much larger (18-inch or even the optional 21-inch) tyres are obviously partly responsible for slightly more road noise but it’s certainly not objectionable. Where conventionally-powered cars have to go to some lengths to achieve a relatively noise-free ride, the Tesla (and we have to say other electrics) do it almost by default. What sets the Tesla apart from other pure electrics is the amount of power available and almost contrarily, the amount of range. (Usually, electric vehicle high power/ performance is at the expense of range. Not so much here). siliconchip.com.au Tesla’s new twin-motor S85D model (available shortly in Australia), showing the “normal” front and added rear motors (in red). More importantly, it shows the battery “pack” – the underfloor area which houses the 7000 16850 lithium-ion cells wired in series/parallel to achieve a 400V, 85kWh powerhouse. The S85 model has a similar configuration but of course has only the one front-mounted motor. As we found in our test drives, that still packs an enormous punch! In the Model S85 we had for (unfortunately an all-toobrief) review, it was VERY obvious that this vehicle was so far ahead of any other pure electric that there really was no comparison. Impressive? Not just yes but Hell YES! Then again, at the price I guess it would have to be. The basic model sells for more than twice the price of the next most popular electric vehicle in Australia, the Nissan LEAF. Yes, we are completely discounting hybrids such as the Toyota Prius, Holden Volt etc, because these are not electric vehicles. They are petrol-powered vehicles with limited battery capability (in the case of the Prius) or with a battery charged by a petrol motor (in the case of the Volt). Where are they from? Tesla vehicles are fully imported from the USA. They’re built in a plant in Fremont, California, which is a story in itself. The Fremont plant was previously used to build GM and Toyota vehicles in a joint venture called NUMMI. Covering an area the size of 88 football fields, a section was purchased by Tesla (reportedly for the proverbial “song”) after NUMMI ceased production in 2010. The Tesla plant today bears little resemblance to the original, with significantly more automation and floors & walls painted gleaming white to reflect the total build quality demanded by Tesla and its CEO, Elon Musk. The company Various news items in 2012 and 2013 had Tesla Motors in significant financial trouble, with many financial gurus (and, it must be said, other grinning car manufacturers) forecasting its imminent demise. Indeed, it was reported at the time that Elon Musk was on the verge of selling Tesla Motors to Google (and later confirmed by him). However, vehicle sales picked up so this sale never progressed. Tesla kept on producing cars – and reported a A night-time view of the Tesla S85 controls featuring that magnificent A4-sized touch screen display. Virtually every vehicle function can be controlled from this screen or it can be used to display the view “out the back” or as seen here, the GPS navigation system. siliconchip.com.au June 2015  15 Back-seat passenger’s view of the S85 console. Impressive, isn’t it? positive cashflow for the first time in the last quarter of 2013. Tesla’s share price (Nasdaq TSLA), which opened at $US19.90 in August 2010 was more than ten times this (~$US226) at the end of April 2015. In the first quarter of 2015, they delivered more than 10,000 new vehicles but production capacity does not satisfy demand. The result is that for most models there is a long “wait list” (in Australia, you are looking at October/ November delivery for vehicles ordered now). Tesla’s sales model does not include dealers – you buy direct from Tesla (from their company-owned showrooms). This has got Tesla into some difficulty in the USA, where the powerful auto unions have been able to convince legislators in several states to disallow Tesla’s setting up showrooms in those states. The car You have to say this is one good-looking car. In fact, I noticed a lot of people admiring it during the day I was driving it around. The shape and styling has often been compared to several up-market competitors. It’s not a small car by any means; at 4976mm long, 1963mm wide and 1435mm high, its not dissimilar to a large, family sized luxury sedan (think BMW 7-series, for example). But at 2.1 tonnes, it’s probably about 500kg heavier than most of its competition – thanks largely to the 700kg, 400V battery pack. Inside, there’s plenty of room for a family of five (in very comfortable leather seats, with tons of legroom, even in the back). And because there is no pesky transmission tunnel, as you would find in all front-engine, rear-wheel-drive cars, the middle back seat is not cramped up. Luggage space is not skimped on, either, with 894 litres spread between the boot and bonnet, that’s quite a lot more 16  Silicon Chip than any car not specifically designed to carry loads (even then, it beats several mini vans!). Fold the rear seats forward (and flat) and capacity increases to 1800 litres. Just in case you missed that “boot and bonnet”, the tiny engine size means a lot more extra space than you might expect. And the lack of a bulky petrol tank helps a lot. Both front and rear luggage areas are fully carpeted. The instrument “panel” The first thing you’ll note when you sit in the driver’s seat is the huge LCD touch screen in the centre of the dash. It’s hard to explain just how striking – and clear – this screen is! At 430mm diagonal, (a bit deeper than the size of an A4 sheet of paper) it is mounted vertically into the dash. It can be set to have two horizontal half-screens or a single vertical full-screen. It’s not just an information display – it’s also the mechanism by which the vast majority of vehicle settings, operating information and preferences are displayed and/ or altered. It’s also the navigation screen – magnificently clear and detailed (much more than typical vehicle GPS screens) and it can be made full screen if you wish to either cover a greater area or obtain even more detail. And it also displays the images from the rear-facing camera, again, in far more detail than any vehicle camera we’ve ever seen. Once again, you can have half screen or full screen. Entertainment system We haven’t mentioned the Tesla’s extensive audio/entertainment capabilities – which are superb. You get the choice of several modes of radio (including internet radio and a couple I didn’t even recognise!) plus wide-ranging audio sources – again, either your CDs, DVDs, MP3s, cloudbased storage, internet music sources and much more. The siliconchip.com.au Here’s another view, this time 3/4, of the Tesla Model S showing the beautfully clean lines and styling, which attracts a LOT of attention! It’s been compared very favourably with some much more expensive marques. This could make the Tesla an attractive target for thieves. But unless they have the unique key, good luck with that! Even then, with Tesla’s smartphone app, you can see where your Tesla is at any time to within just a couple of metres. The car features an incredible amount of electronics and “creature comforts”. premium audio system is reported to have been developed “from the ground up” by Tesla but other reports suggest Alpine might figure in their somewhere. “Starting” the Tesla As you approach the Tesla (assuming, of course, that you have the key) the main thing you notice is that the previously flush door handles move out, ready to open the doors. There is nothing, as such, to “start”. Entering the car and sitting in the driver’s seat lets the system know you are ready to “rock and roll”. Just about everything is automatic. Placing your foot on the brake and moving the “gearstick” (which is merely a stalk on the right-hand side of the steering column) to F or R sets the car ready to drive. Take your foot off the brake and it will gently start rolling – as long as you have previously set it to “creep”. A word of warning: don’t plant your foot on the accelerator or you’ll probably leave your breakfast back where you started! Incidentally, proving that software developers have a sense of humour, Tesla engineers have labelled the twoposition acceleration mode settings “sport” and “insane”! “Starting” also initiates all the other processes that go on in the car. If you’ve entered a personal profile, it adjusts everything (seat position, air con, driving preferences, etc) to that. If not, the previously used setup is resumed. Now you can also set up profiles, navigation and so on for this trip. Obviously, this should be done while stationary, - setting up while mobile is definitely not recommended. Most setup is done on that beautiful, big touch screen right in the middle of the dashboard. Even “stuff” that has external controls is mostly accessible via that screen as well. Exiting the car This takes a little bit of getting used to, because you don’t turn a key off or even push a button – there is nothing to shut down. The car simply “goes to sleep” when you put it in “P” (for Park), lock the door and walk away. It’s a bit disconcerting to look in through the window and find the dashboard still activated, the touch screen still displaying pictures or vehicle data . . . and so on. But walk away from the car (obviously taking the “key” with you) and very quickly it all shuts down by itself. The motor In the S70 and S85, a single 310kW, 600Nm three-phase AC induction motor drives a single speed 9.73:1 gearbox which drives the rear wheels. The gearbox only has forward and reverse (and neutral/park) options selected by a stalk on the right-side of the steering column. The motor occupies quite a bit less space than an internal combustion engine – sure, there are ancillaries such as the AC inverter, air conditioning unit and so on but the result is the “engine bay” is rather roomy, so much so that it is given over to luggage space. The S85D model, when available here, will have two electric motors (totalling 515kW and 931Nm) and drive all four wheels. The battery pack It may surprise you to find that the lithium ion battery pack consists of many thousands of small cells – in fact, “18650”-sized 3.7V cells (or 18mm diameter x 65mm long, the same as found in many small rechargeable consumer products, toys, etc) are connected in series/parallel to achieve a high capacity (85kWh), high voltage (400V) battery. This is housed under the floor of the vehicle and is in fact a stressed member of the chassis, helping provide rigidity to the rear of the car. This also brings the centre of gravity to the lowest point possible, considerably helping with the car’s roadholding. Tesla’s batteries, supplied by Panasonic from Japan, have an energy density of 121Wh/kg, which are the most energydense packs in the industry. Compare this to the Nissan LEAF’s energy density of 79Wh/kg and its not hard to see why the Tesla range is so significantly higher. Where are the Australian government electric vehicle incentives? In most countries overseas, governments encourage electric car purchase through attractive (sometimes VERY attractive) incentives. These range from discounts or rebates of taxes, “green” incentives, use of transit or special lanes, reserved parking (often with free charging facilities) and so on. For example, the US federal government offers a $7500 federal tax credit for personal PEV purchasers. And some states top that up with another rebate ($2500 in California, for example). The UK has several incentives, ranging from a £5000 government grant, to no road tax, showroom tax or luxury vehicle tax and even an exemption from London’s congestion charge. For companies, they offer a 100% first-year write-down allowance. Here in Australia, there is little government incentive to buy an electric car. The government’s luxury car tax is less for a fuel-efficient vehicle (woopie doo – that applies to all fuel-efficient vehicles), while in the ACT electric vehicles attract no stamp duty. But that’s about it. In NSW, the incentives and/or reductions amount to a very round number. siliconchip.com.au June 2015  17 Here are two views of the Tesla most owners will never see: at left, looking inside the “engine bay” showing just how little room the engine actually takes. The rest are things like air conditioners, gearboxes, and so on. When completed, the whole of the additional space is given over to luggage space. The view at right is from the other side of the engine, over the battery compartment, from what would be cabin space. As mentioned earlier, there is a choice of 70kWh or 85kWh batteries. Until recently, Tesla offered a cheaper 60kWh battery pack. While slightly smaller than the current model’s packs, this 360V, 459kg battery gives a good idea of the way so many cells are packed into the space. In the 360V battery, 69 steel-cased cells are wired in parallel to form a “brick”; 99 bricks are connected in series to form “sheets” and 11 sheets form the whole battery pack – a total of 6831 cells. The battery is liquid-cooled and cell temperatures are constantly monitored by internal sensors. Lithium ion cells cannot be charged when they’re below 0°C, so if the temperature approaches zero the cells are heated at the same time as they are being charged. At the opposite end of the temperature scale, above a set threshold, cold air from the vehicle’s air conditioner is directed through the pack to allow charging in very hot climates. Because lithium ion cells contain neither heavy metals nor toxic materials, at the end of their life the battery packs could theoretically be disposed of in landfill. However, The rear-view camera vision quality is superb – as good as any we’ve seen. Here the screen is shared with GPS navigation – either can be made full screen. 18  Silicon Chip Just a tiny part of the Tesla’s comprehensive entertainment system – all touch-controlled, of course. It remembers your favourites so you don’t have to go hunting for them. Tesla goes one better: it has a recycling program which reuses or recycles over 60% of the battery already and aims to increase that to 90% in the future. New battery “gigafactory” Tesla is currently building a $5 billion dollar battery research and lithium-ion manufacturing facility on a 980 acre site outside Reno, Nevada. This alone is worth a story (and many have been written!) about the way Elon Musk and his team managed to build this mega-factory with $1.4 billion in tax breaks, free land and other incentives from the state of Nevada. Looking to the future, the company has options on another 9000 adjacent acres, which includes 7000 acres for a 140MW wind-farm. It will be a net-zero-energy factory, powered by renewable energy – solar, wind and even geothermal. Production will be ramped up from 2017, with 50GWh in annual production by 2020. It’s telling me that I have 311km of range left in the battery – but you wouldn’t discharge to flat in order to give your battery the maximum lifespan. Just about everything can be controlled from the touch screen, even such niceties as mirror tilt (in reverse) and mirror fold (when you stop and get out of the vehicle). siliconchip.com.au Inside Tesla’s manufacturing facility at Fremont, Cal, USA. The plant, now gleaming white inside, once manufactured GM and Toyota vehicles . . . and went broke! Tesla was reported to have bought the plant for next to nothing! Here’s Tesla’s huge new $5 billion battery production and research centre now under construction near Reno, Nevada, USA. The whole of the roof will be clad in solar panels and the building energy self-sufficient. Strangely enough, some reports suggest that Panasonic will still make the li-ion cells in this factory. But according to other reports in recent months, Tesla will also be manufacturing a range of large home and industrial batteries to either store solar power generated during the day or even store low-cost off-peak power for use during much more expensive peak times. (See the report “Tesla’s PowerWall” later in this issue.) It remains to be seen how successful this side of the enterprise will be – but if Elon Musk has anything to do with it . . . Sydney or Sydney/Brisbane. Tesla currently has Superchargers at its St Leonards showroom and also at the Star City casino (both in Sydney). We understand that Superchargers at the Tesla showroom in Chadstone (Melbourne) are imminent, if not already available. Tesla has recently announced a Supercharger for Goulburn, to add reassurance to the Sydney/Canberra journey. Tesla vehicles may also be recharged (albeit usually at a slower charge rate) at the many public charging stations now emerging around major cities. There are currently more than 200 public and private charging stations in Australia. A 230VAC single phase EVSE (Electric Vehicle Supply Equipment) “smart cable” is also included in the price of a Tesla – this must of course be installed in the owner’s premises at their cost. In December 2014, Tesla (USA) announced that they were embarking on a battery pack swap program with invited Tesla owners. While still a pilot program (and not available in Australia) Tesla is confident that if and when implemented, the battery pack could be swapped for a Charging, range anxiety etc With a quoted range of up to 500km per charge, most Tesla owners don’t suffer anything like the “range anxiety” owners of other electric cars experience. This can only improve in the future, with Tesla Australia planning to locate their “Supercharger” charging stations at suitable distances along the routes between eastern capitals – from Sydney to Melbourne by the end of 2015 and Sydney to Brisbane by the end of 2016. The Supercharger provides up to 135kW, giving 85kWh models almost 300km range in about 30 minutes. So basically it’s stop for a coffee, stretch your legs and charge the Tesla at the same time. 500km is more than enough range to travel, for example, from Sydney or Melbourne to the snowfields (where the car could be charged from ordinary power). It would also allow a single (or at worst two) stop trip between Melbourne/ When the right side of the speedo shows green, the Tesla is putting power back into the battery (via regenerative braking). Above this is an orange zone, showing the power (in kW) being used at the time. The left side is a conventional speedo; a digital equivalent is displayed in the centre. siliconchip.com.au Is lithium-ion still the way to go? Tesla is putting an enormous amount of faith in the lithium-ion rechargeable battery it currently uses to power its vehicles. But many critics are already saying that just as lead-acid batteries have had their day, the lithium-ion cell is also on the way out, promoting instead the aluminium-air batteries currently being developed by several organisations around the world. An aluminium-air battery generates electricity from the chemical reaction of oxygen (from the air) and aluminium, using water as an electrolyte. Their theoretical capacity is some 40 times greater than a similar-sized lithium-ion cell. Until now, however, this approach has been stymied by the reaction consuming the aluminium anode, which must be physically replaced rather than recharged. Last January, Japanese company Fuji Pigment announced that it had managed to suppress corrosion and reaction by-products, creating an aluminium-air battery that can be recharged by simply adding water. Ahh, isn’t that the holy grail: when “fill er up” means grabbing the garden hose? June 2015  19 Luggage space can only be described as cavernous – and there’s up to 1800l with the rear seats folded forward. fully charged pack in less than one minute (less time that it takes to fill a fuel tank!) and would indeed cost less than a tank full of fuel. This program is being evaluated to test technology and assess demand – ie, whether they are prepared to pay a small amount for a lightning-fast “charge” by swapping batteries, or would they prefer to fast charge at one or more “Supercharger” rechargers, at a rate of 640km range per hour of charge (or a full battery in less than an hour). The third option, obviously, is to charge at home or at a standard rate charger. The advantage of the latter is that many of these are free to use! While on the subject of range, Tesla assured me that the range displayed on the dashboard has proved to be extremely accurate, much more than that of (ahem!) the Nissan LEAF. Whether this is true or not is open to conjecture because any number of on-line forums state the opposite – they claim the “300 mile” range quoted by Tesla is much more likely to be in the low 200s, and sometimes worse. Once again, it all depends on the way you drive, the temperature outside the car, the terrain, the state of charge (and the state of battery) . . . all those things which affect all other electric cars. Cost to charge How much does it cost to charge a Tesla – and therefore, how much does it cost to run? That is a rather difficult question to answer because there are so many variables – the amount of charge left in the battery, for example, the cost of the mains power being used and even your electricity usage (high power users usually pay a premium). We’ve already mentioned that Tesla’s SuperChargers, many street-side and carpark chargers don’t actually charge you for power, so if you can use one of those at least most of the time you’re streets ahead! Note, though, that many do have a cost – but they’re not charging sheep stations (no pun intended). If you have to pay for power (eg at home), we’ve been assured that EVSE equipment can legally be connected to “off peak” circuits. In most capitals this costs less than 10c per kilowatt-hour. Or, if you have a smart meter, charging during the lowest rate period (usually 10pm-7am) will also 20  Silicon Chip Almost hidden in the front bumper is the Tesla’s forwardfacing radar unit which is part of the anti-collision system. Get too close to the vehicle in front and the Tesla will slow you down, or even bring you to a complete stop if necessary. get you similar rates. So if, for example, you’re charging at the rate of 10A (2.3kW) it’s going to cost you about 20c/hour to charge. If your (pay-for) charging station can deliver the (often very!) much higher charge rates the Tesla can handle, multiply up! For example, when I returned the review Tesla it was plugged into the St Leonards Supercharger and displayed a peak charging current of some 400A (92kW!) for half an hour or so, dropping quickly as the battery charged. At offpeak rates a full charge might cost a few dollars. Remember, though, that gives up to another 500km range. Battery safety Overseas (notably the US), there have been a few highlypublicised Tesla fires. However, given the number of Teslas now on the road, that number is very small – and analysis by Tesla and accident investigation authorities has not shown any cause for major concern. In fact, one report said that if it was anything but a Tesla, the outcome for the occupants would arguably have been much worse. When a petrol-powered vehicle has a serious accident, there can be a lot of fuel released and it can (and often does) catch fire, sometimes explosively. A battery vehicle involved in a serious accident is much less likely to suffer in this way because so much attention The gear selector is actually a stalk on the right side of the steering column. That took a bit of getting used to – every time I went to turn left I put it into neutral . . . siliconchip.com.au The green and blue beams in front of the car come from the on-board radar systems, while the yellow shading shows how the Tesla senses vehicles all around through its camera systems. The company has already demonstrated experimental autonomous (so-called “driverless”) cars using this and even more advanced technology. Yes, it was a demostration for the media but last year Elon Musk showed how quickly a Tesla could have its batteries changed – in fact, two Teslas had batteries swapped in the time it took to fill an equivalent petrol vehicle with fuel. Tesla are working on a pilot program to see if battery swapping would be popular enough to be viable. has been paid to shielding the battery pack against external damage, through the use of protective enclosures and jacketed cables. Even access to the high-voltage components requires special tools. In the event of significant impact or rollover (including air bag deployment), the high-voltage supply is automatically disconnected inside the pack. Universal (international) marking codes are used to enable first responders to disconnect power safely. Two others at the sides look for the white lane markers – they’re the ones which warn you if you’re drifting – while another, forward facing, is for anti-collision avoidance in conjunction with a bumper fitted radar. It first warns you, then takes action, if you are too close to the car ahead at the speed you are doing (it will even bring the car to a complete stop if necessary). The thresholds are all settable. One query I had was if any of the cameras recorded, a la a “dash cam”. Unfortunately, the answer is no, although I wouldn’t imagine it could be that hard to implement at factory level. Still, amongst all the incredible technology already in the Tesla, it’s a small quibble. Built-in safety Tesla sports an independent 5-star safety rating, not just in all their models but in every subcategory (the highest score ever recorded). There are so many safety features inbuilt (or available as options) that it is difficult to list them all. But one which caused us some brief angst, believe it or not, was the car’s out-of-lane warning – only because we didn’t know what the vibration was all about (it’s almost like a really bad tyre balance problem)! Tesla told us that was a particularly common “complaint” amongst new Tesla owners, like “what’s wrong with my car!!!”. They’re happy to say “nothing” but then it becomes a diplomatic problem to suggest “it’s your driving!”. There are four cameras built into the Tesla, one, rearfacing, is for the brilliantly clear rear-view video screen. Where’s my car? When I first saw the LEAF, Nissan told me it had an inbuilt 3G phone system which called the company every night with operational data. I asked if this could be used to interrogate the car to check its location (eg, if it’s stolen). Nissan told me that Australian privacy laws meant this could not be done (they’d tried, very hard). Obviously Tesla had no such problem. They too have a built-in 3G data system but theirs can also tell you (eg, via a smartphone app) exactly where the car is. Tesla’s service manager showed me where the five cars on hand were – within a couple of metres (including the one I was standing alongside). So if (somehow!!) your Tesla is stolen or hijacked, you can see exactly where it is. It’s the same technology that allows Tesla to wirelessly update the software and firmware which runs the car, or allows the owner to wirelessly set charging parameters, climate control and so on. Autopilot The “charging port” is located just in front of the left rear tailight assembly. Quite extensive charging information is displayed on both the dashboard and LCD screen. siliconchip.com.au Reports recently have suggested Tesla is well on the way to producing a driverless car. This could be a natural spinoff from the Tesla’s “Autopilot” option, where the vehicle automatically follows the road, steering around curves and varying its speed to match traffic flow. It also allows automatic lane changing – tap the indicator and the Tesla changes lanes when it is safe to do so! It will also notify you when it finds a parking spot – then automatically parks in it, controlling steering, acceleration and braking to back smoothly in. June 2015  21 TESLA MODEL S – SPECIFICATIONS Body Length: Wheelbase: Width: Track Front: Clearance: Head room: Leg room: Turning circle: Curb weight : Drive Battery: Motor: Drive inverter: Charging Inside each Tesla showroom you’ll find their “Design Studio” which lets you choose colours and trims, wheel types and so on. The car will be made to your specifications in America and delivered to Australia. Another nicety: sync your calendar/diary to the car (via your smartphone) and it will check current traffic conditions to make sure you leave in enough time to make your appointment. Before that, though, it turns on the climate control to your chosen (preset) levels. It can even automatically open the garage door and pull out of the garage by itself, to meet you at the curb! Yes, many of these things are options but they do give some indication of the sophistication (for want of a better word) built in to this remarkable machine. Machine? I reckon it’s almost human! 4980mm 2960mm 2190mm (With mirrors folded 196mm) 1660mm, Rear 1700mm 140mm (With air suspension 120 - 160mm) Front 990mm, Rear 900mm Front 1080mm, Rear 900mm 11.3m 2112kg 70kWh or 85kWh, lithium-ion battery, microprocessor controlled Three phase, four pole AC induction motor with copper rotor Variable frequency drive and regenerative braking system 10kW-capable on-board charger with the following input compatibility: 85-265V, 45-65Hz, 1-40A (optional 20kW-capable dual chargers increases input compatibility to 80A) Peak charger efficiency: 92% 10kW capable Universal Mobile Connector with 120V, 240V and J1772 adapters 3 seconds. And then there’s the all-wheel-drive two-motor S70D announced only a few days ago (it’s not yet available in the states so will be some time coming to Australia). Musk has stated that he aims to have a “Tesla for the masses” before too long. With a cheaper battery (which is not too far away) he aims to have a $US35,000 Tesla available by about 2017. And we’ve already mentioned Tesla’s incursion into Where to from here? other battery applications – and their continual research We’ve only been able to cover some of the rather amazing into extracting every last milliamp from the cells. They’re inclusions in the Tesla S85. There’s plenty more informa- reported to be well advanced in nano technology, increastion on Tesla’s website(s) and numerous third party forums ing the internal surface area of cells – and therefore making and websites if you wish to know more. But if you are at them perform even better. all interested in having your own Tesla, we suggest getting Elon Musk stated that the new Reno facility, which will onto their Australian website and organising a test drive. cost about $5,000,000,000 (yes, B for Billion!), should be You won’t be disappointed! online and producing batteries by the end of 2016. We’ve already mentioned He’s also said he wants the all-wheel-drive, twin mothat plant to be able to make How much, where from? tor S85D model already rehalf a million battery packs The Tesla S85 that we had for review sells for $AU129,000 each year – and that’s equal leased in the USA and not too far off here (but join the queue on the road. to the whole world’s current The new S85D will, when available sell for $169,000 on the road. production! if you want one!). From the There is a slightly lower cost S70 available which also lacks outside, apart from a couple of Impossible? Maybe . . . but badges it’s the same as the S85 some of the “niceties” (but is an outstanding vehicle nevertheless) “Do the Impossible” is one of SC model . . . until you “lift the and it sells for $99,000 on the road. An S70D (all wheel drive, two Tesla’s slogans. lid”. Its performance, subject motors) has also recently been announced in the USA. You can’t walk in, pay your money and drive out with a Tesla. of numerous tests overseas, is simply outstanding. Add- There’s quite a waiting list (several months), to some degree Our thanks to Heath Walker and ing the second motor sacri- caused by the inability of Tesla USA to meet international demand. Huw Williams of Tesla Australia To get on the waiting list, (or even to organise your own test for their assistance in making fices a bit of range (<10%) for greater speed and even more drive) you need to get in touch with Tesla Motors Australia, 10 the S-85 available for review. neck-snapping acceleration, Herbert Street, St Leonards NSW 2065. Tel (02) 8424 9500, website Photo credits: Tesla, Kevin with 0-100km/h in just over www.teslamotors.com/en_AU Poulter and Ross Tester 22  Silicon Chip siliconchip.com.au Real “Hands On”: Owning an Electric Car R range. The official figures are eaders may recall that we just a tad optimistic! have previously reviewed Nissan claim “up to 170km two 100% electric cars: range” on a full charge. There the Mitsubishi iMiEV (February are the usual disclaimers about 2011), followed by the Nissan LEAF how and where you drive, (August 2012). temperature, etc – just as you We also tried to get hold of might expect in a petrol or a Holden Volt when they were diesel-powered car. released but are still waiting (two There’s even a cute “range years later) for the General’s PR gauge” on the dashboard which people to get back to us! tells you how much battery It’s probably just as well that we charge (in kilometres) that didn’t get to review the Volt because you have left (sort of like a fuel unlike the iMiEV and the LEAF, it’s gauge in reverse). not a true electric car – yes, it runs Have a look at some of the off batteries but has a small petrol online forums and you’ll find motor to charge those batteries. “Hah hah hah. . . you’ll need a l-o-n-g extension lead!” Therefore, it requires fuel, not too dissimilar to other “hybrid” some pretty disrespectful names for this. Some of the more genteel electrics such as the Prius, some models of BMW, Lexus and refer to it as a “guessometer”. Good name, that! As my commute to work is <10km, 95% of the time range doesn’t Toyota Camry (among others). We were particularly impressed by the LEAF. I recall saying matter to me but the very best I’ve been able to achieve on a 100% charge, even when my range shows 160-170km – driving very that if I had a spare fifty grand, I’d buy one. I didn’t – so I didn’t! Circumstances change, not the least being a $12,000 price drop conservatively, in “ECO” mode, air-con off, etc etc – is about 135km. Steep and/or long hills knock the range around dramatically – and so last June (and prompted by a failing 16-year-old SUV) I bit the if you know the northern beaches of Sydney, you’ll know that it is bullet . . . and bought a LEAF. I did this with my eyes wide open – I’d read everything I could ALL hills. I live not far above sea level – to get anywhere means find and knew that it was strictly a commuter car with limited an uphill to start off with. Heading north-west from my place is a range. My partner has a Hyundai ix35 – if we wanted to go away long (7.5km) uphill, ranging from moderate to quite steep. That any distance we would take that. So yes, you pretty-much need 7.5km costs me up to 40km range on the guessometer! Sure, you get some back with downhill regeneration – but I to be a two-car family OR be prepared to drive your LEAF to the would be extremely surprised to find anyone in Sydney who gets airport and (if you need one) hire a car at your destination. But there were a few things I was to discover about the LEAF anything like 170km range on a charge. And remember, you have to be able to charge at the opposite end to come home again. So only after regularly driving one for nine months or so. First of all, I have to say that I am very, very happy with the LEAF. unless you’re staying long enough (overnight?) AND can plug in It’s by far the smoothest car I have ever owned (or until the Tesla to charge, the distance you can travel away is effectively halved! As an example, in February and March I made a few trips from test review even driven) and it is by far the quietest. I’m also extremely happy with its performance. Normally, I’m a Narrabeen to Umina, a distance of 85km. That trip encounters pretty sedate driver but if I really want to get away first at the lights, some not inconsiderable hills (both directions start with a long I can virtually always do so – even against some “performance” uphill) and I must admit to some range anxiety. With a 100% charge to start, I had between 15 and 25km range cars. The LEAF has incredible down-low torque and acceleration. left – and that’s limiting my speed to 100km/h on the M1 motorway. I’m also rather happy with my “fuel” consumption. Normally, I limit the charge (automatically) to 80% of capacity, as I had previously noted the battery drain difference between 100km/h suggested by Nissan to maximise battery life, and require a charge and 110km/h (a lot more than 10%!) so was not willing to risk it. There’s an on-dash active range map which suggests I could (usually) only about twice a week. While the supplied “charger” is fitted with a 15A mains plug (and therefore requires a 15A dedi- reach Newcastle on one charge. Oh yeah? I’d like to see that! Lastly, I’m often asked about battery longevity – that is, how cated outlet) I’ve measured the charge at 9.75A (<at>230VAC), with no real difference between a full battery or a half-charged battery. long the on-board 360V Li-ion battery will last before it must be My first electricity bill with the LEAF was almost exactly $100 replaced. Nissan guarantee 80% capacity after 10 years and some more per quarter than the corresponding quarter the year before. reports I’ve seen suggest they expect 15 years+. The problem is, of course, that we’re only a third of the way When petrol was between $1.00 and $1.30 per litre last year, I would have put $100 in every 2-3 weeks! So it’s not too much through that 15 years (since introduction), so no-one really knows. of a stretch to say that my “fuel” bill has dropped by ~75%! Of But apart from a few horror stories (manufacturing faults?), battery course, petrol prices dropped significantly in late 2014/early 2015 longevity is largely proving to be at least as good as projected. All of this, though, makes Tesla CEO Elon Musk’s latest statebut as I write this, they’re creeping back up again. . . I’m laughing! ments about long life (>15 years) and long range batteries (300 But what about the negatives? and even 500+ miles) sound rather exciting, especially if (as has Apart from the legion of “hah hah – you’ll need a l-o-n-g exten- been hinted) the technology that Tesla has been developing will be sion lead” jokes, the only “biggie”, as far as I am concerned, is made available to other manufacturers. Like Nissan? SC siliconchip.com.au June 2015  23 24  Silicon Chip siliconchip.com.au TESLA’S POWERWALL: A Game Changer? Purely by co-incidence, as we were reviewing and writing about the Tesla Model S, internet whispers started appearing about a secret new product being worked on by Tesla. Then came the official word: CEO Elon Musk would be hosting a major press launch on April 30 to reveal the big secret. By Ross Tester B y the time Elon Musk took to the stage, the whispers had become a roar – Tesla was about to release battery backup systems for home and industry. It was a natural progression from their work on the lithium-ion battery packs they’d developed for their electric vehicles but the detail was all that was left to reveal. As well as the “live” press launch, it was also beamed to the world as a webinar, so wherever you were, you could see the same message. And the message was pretty “cool”, at least as far as Tesla were concerned. For far too long, we’ve been saddled with lead-acid batteries as the main storage for, particularly, solar (PV) power systems. Lithium-ion batteries were simply too expensive. Of course, most installations (at least here in Australia) don’t have any storage; they’ve been grid-based systems which fed any excess power back into the electric power distribution grid. Those who got in early have been blessed with very high value feed-in Tesla CEO Elon Musk launching the PowerWall and PowerPack (for utilities), April 30 2015. siliconchip.com.au June 2015  25 One of Tesla’s 10kWh PowerWalls. Inside is 350-450V of lithium-ion cells and a DC/DC converter. It’s about 1300mm high, 860mm across, 180mm deep and weighs 100kg. rewards – as much as 66c per kWh. Those heady days have long gone but even today, you can put a solar power system in and reduce your electricity charges. But Tesla’s system is rather different to that. It is intended for either standalone (ie, not grid-connected) systems or hybrid systems, where there is battery backup as well as grid tie-in. Musk reasoned that everything about electricity production, usage and charges were out of step – the highest usage was in the morning, after most people had gone to work, and in the evening/night, after most people had come home. Either way, solar generation is minimal in the early morning and zero in the night, when you needed it most. You pay top dollar for power at these times too. What if the generation and storage of electricity could be “time shifted” - generate the power during the day when the sun was shining and use it 26  Silicon Chip during the peak periods mentioned above. All you would need would be a storage system capable of doing so! OK, that’s a bit of an over-simplification but you get the idea! immediately on announcement. (However the latest news [May 10] is that production through to the middle of 2016 is sold out – over 38,000 reservations had been received in that time)! Lead-acid battery disadvantages What’s in it? One of the major reasons for not using lead-acid batteries for storing electricity is the cost. Deep-cycle storage batteries are not cheap. Moreover, they need a lot of maintenance; they emit dangerous hydrogen gas when being charged; they sometimes leak (and their electrolyte, acid, is nasty stuff); they’re pretty temperamental about amount and depth of discharge; they don’t like being overcharged . . . and to top it all off, their life span can be pretty short (3-5 years is about average, 10 years exceptional; indeed, most deep cycle batteries only have a 2 year guarantee). Finally, when they have reached the end of their life, disposal is not as easy. They can’t be used in landfill, they can’t be destroyed and even many recycling centres that used to take plenty of lead-acid car batteries are becoming a bit reluctant to take them. Small wonder that most people with solar panels on their roofs stayed wellenough away from lead-acid batteries. Lithium-ion battery advantages While there are some parameters that need monitoring, for the most part lithium-ion batteries don’t suffer the disadvantages of lead-acids. They don’t need much maintenance at all, they’re much happier about charging and discharging (mainly because each cell is monitored and if necessary, equalised with other cells), they have a long lifespan (10 years would be minimum, possibly a lot more) and they don’t contain volatile materials so can even be disposed of in landfill. Or, as we reported in the earlier Tesla S85 story, they are looking at recycling as much as 90% of each cell in the future. Tesla’s PowerWall Two (related) products were announced on April 30, the PowerWall and the Tesla PowerPack. The latter is intended for large-scale applications. The first will start shipping shortly (within a couple of months) – in fact, Tesla Energy started taking orders The basic PowerWall comes in 10kWh “weekly cycle” and 7kWh, “daily cycle” models. Each contains enough lithium-ion cells to achieve a 350-450V supply. The PowerWall is designed to attach to a wall, inside or outside. Overall size of a single PowerWall unit is 1300mm high, 860mm wide and 180mm deep and weight is 100kg. Note that there is no DC-to-AC inverter built in but it does have a DC-DC converter, which means it should be compatible with solar panels (which generate DC). Up to nine PowerWalls can be interconnected to satisfy virtually all domestic demand. And the cost? The daily cyle (7kWh) PowerWall will sell in the US for $3000; the 10kWh weekly cycle for $3500. Let’s look at the more expensive one: in Australia, at current exchange rates and with GST that will probably sell for around $5000. For that, you get a ten year guarantee and minimal maintenance. Try buying, say, a 350V deep cycle lead-acid battery pack with anything like a 10kWh rating. Because you can only safely cycle down to, say, 40% you’ll need around 16kWh to be safe. At the moment, you’re looking at between $20,000 and $25,000. Invariably, that only gets you a 2-3 year guarantee and it also gets you all the trials and tribulations that go with large lead-acid battery installations, not the least of which is a total replacement after perhaps five years. Of course, prices are dropping . . . and Tesla’s PowerWall will have a lot to do with that! Other power sources One of the main reasons that Tesla’s PowerWall is likely to be a gamechanger is that for the first time, it makes economic time-shifting power demands. Solar panels are not the only means of charging batteries –wind and smallscale hydro are often mentioned. But the one which is often forgotten siliconchip.com.au PEAK SOLAR MORNING DEMAND EVENING DEMAND The average home uses more electricity in the morning and evening than during the day when solar energy is highest. Tesla’s Powerwall is designed to smooth out these curves. is the power grid itself. During peak periods, power charges are high. At “shoulder” times they’re lower and during off-peak times they can be quite low. Why not use cheap off-peak power to charge the batteries and either use it instead of expensive peak power. Or if you can get a reasonable feed-in tariff, sell it back to the power companies during peak times? We can already hear the screams: “you can’t get enough feed in tariff any more to make it worthwhile.” siliconchip.com.au Thinking big: Tesla also have plans for power generators and distributors to use very much larger battery banks to smooth out their own peak and trough cycles. Oh yeah? Go for a walk with Dr Google – you might be surprised to find that there are now companies in Australia (not the power companies!) who will buy stored power from you at much higher prices than the power companies offer. They on-sell it to match peak demand and therefore peak $$$ – and reward you with the proceeds (less their commission). If you think we’re talking cents per kWh, think again. It can be $/kWh! It is for all these reasons that we believe Tesla, and their $5000 lithium- ion battery, will be a game changer. Whether you’re using it to go completely off grid (now very much cheaper than it was), or putting in a hybrid system; whether you are looking at solar power or simply time-shifting cheap off-peak power into peak times, it’s a whole new ball game. And the best part? The game has only just begun! For more information, visit www.teslaenergy.com – or Google “Tesla Powerwall” and “Tesla Powerpack” sc June 2015  27 Artificial vision is becoming a reality The BIONIC EYE Vision is our most important sense, accounting for about 80% of information received by our brains. The loss of vision can therefore have a dramatic effect on a person, especially if they lose it through accident or disease. Now there is promising research on how to restore a basic sense of vision. A Finally, a method of human vision for the blind involving s with the well-established cochlear implant (“bionic ear”, of which Australia is a world leader) no hardware but just skill is also presented. which can restore a sense of hearing, there is now active research on how to restore a basic sense of vision, How the eye works In nature, ten different types of eye layout can be found. using an implantable visual prosthesis or “bionic eye”. So as not to give false expectations, artificial vision does The eye layout found in humans and vertebrate animals, cephalopods (squid and octopuses) and some spiders most not provide a visual experience like natural vision. Bionic vision is a popular theme in science fiction, two resembles a traditional camera. In this type of eye, called a camera-type eye, light enters notable examples being Colonel Steve Austin in “The Six Million Dollar Man” and Lieutenant Commander Geordi through the cornea which acts as a window and also refracts light like a meniscus lens, contributing two thirds of the La Forge in “Star Trek: The Next Generation” (see box). Like many other themes from science fiction, bionic optical power of the eye. It then passes through the iris which alters its diameter vision is also becoming a reality – even if the science is to adjust the amount of light entering the eye, then through in its infancy. Apart from implants to restore a sense of vision there the adjustable lens which adjusts its focal length to focus are also non-implanted prosthetic devices that work on the objects from different distances and then projects an image principle of sensory substitution whereby the sense of sight onto the light sensitive retina at the back of the eye. The eye lens also has a graded is converted into an alternative optical index (like modern optical sense such as touch or sound Part 1 - By Dr David Maddison fibres) for maximum efficiency and these will also be discussed. 28  Silicon Chip siliconchip.com.au and also contributes one third of the optical power of the eye. The retina Being the light-sensitive part of the eye, the retina is also the part which is often diseased or damaged, leading to a severe vision deficit or blindness. The retina is comprised of a number of layers containing neurons which communicate with each other via synapses. A neuron is an electrically active cell that can receive inputs, process them and produce an output. An output signal from a neuron is transmitted to other cells across a synapse (see SILICON CHIP, “Interfacing to the Brain”, January 2015). Some neurons are specialised as photoreceptor cells which are sensitive to light. The two main types of these specialised neurons are rods and cones. Rods are sensitive in low light and provide monochrome vision while cone cells are sensitive to colour and work in bright light. There are about 100,000,000 rods and 5,000,000 cone cells. Visual signals from the rods and cones are processed by other neurons in the retina to reduce the amount of visual data that has to be sent back to the brain. One of the ten layers of the retina is the ganglion cell layer. The rods and cones are connected to this layer via another type of neuron. The ganglion cells are a type of neuron that has a very long axon that extends from the eye back into the brain to form the optic nerve, optic chiasm and optic tract (see diagram and text below). It is the ganglion cells that carry information from the retina into the brain. There are about 1,500,000 ganglion cells. The axon is the part of the cell body that connects to other neurons and from which information leaves (See the above article from SILICON CHIP, January 2015, for discussion of Ganglion Cells Structure of a human eye. neurons and axons.) It is the rods and the cones, the photoreceptor cells which are most often damaged by disease while the underlying layers which carry visual information back to the brain such as the ganglion cell layer are usually left intact. These remaining layers can be used to introduce visual information to the brain via a prosthetic retinal implant in one type of bionic eye. Note from above there are around 105,000,000 rod and cone cells generating information and only 1,500,000 ganglion cells to convey that information back to the brain. This lack of a one to one correspondence is suggestive of the amount of data processing that has occurred in the eye itself. To complicate matters further, the surface of the retina is not uniform in its properties or photoreceptor density. Bipolar Cells (red) Horizontal Cell Amacrine Cells (blue) Photoreceptors Simplified cross section of a human retina. Counter-intuitively, light enters on the left of the diagram which is the inner part of the eye. This is the ganglion cell layer which is the connecting circuitry that takes information back to the brain. The light then travels toward the photoreceptors (rods and cones) which are at the outer part of the eye where light is converted to signals which are transmitted to the ganglion cells through several layers. This is the opposite arrangement to an imaging chip in a camera whereby the light sensitive elements are at the light receiving side and the connecting circuitry is beneath that. In the various layers, points of light from the rods and cones are processed to identify features such as movement, simple shapes, edges and bright points surrounded by dark points before the information is sent back to the brain for further processing. Image credit: “Retina layers1”. Licensed under CC BY-SA 3.0 via Wikipedia – http:// en.wikipedia.org/wiki/File:Retina_layers1.gif#/media/File:Retina_layers1.gif siliconchip.com.au June 2015  29 Image from the retina, showing higher resolution image from fovea, the small part of the retina responsible for the sharpest vision. The brain fills in for the rest of the retina which produces a less sharp image but is not noticed under normal circumstances. Frame grab from https://youtu.be/ 4I5Q3UXkGd0 The fovea is a small part of the retina, about 1.5mm in diameter, that is responsible for sharp vision, with a very high concentration of cone cells. The fovea is connected to about half of the nerve fibres in the optic nerve while the rest of the retina connects to the other half. The fovea represents only about 1% of the retinal surface but uses 50% of the visual cortex, showing its great importance in sight. Its visual field is small, equivalent to about two thumbnails at arm’s length so to get a sharp image of an object the eye has to scan back and forth to build up an image. The fovea also only has cone cells so is not sensitive at night. The blind spot You’ll probably remember those biology lessons at school where a card is moved in and out from one eye and at some point an “X” on the card disappears. That is caused by the blind spot, an area where the optic nerve passes through the retina and no photoreceptors exist. (See www.education. com/science-fair/article/eye-retinal-blind-spot/). Normally the brain makes up for the lack of receptors in that area so its effect is not noticed. The shape and size of the eye are also important considerations for bionic prostheses. The eye is not spherical but it is roughly the shape of two hemispherical sections joined together. Also, despite people coming in all shapes and sizes, the size of the eye between different individuals is remarkably uniform and is around 24mm front to back varying by only up to 2mm. This means perhaps only one size of visual prosthetic device that goes in the eye (or replaces it) will ever need to be manufactured. It has been estimated that the data bandwidth of the human eye is 8.75Mbits/s. The neurons could fire much faster giving a much higher speed but there is a trade-off of speed and energy and data processing efficiency. A question often asked and which is important for comparing natural vision to a bionic eye is what is the resolution of the human eye. It is not simple to answer that question because unlike a still camera, the eye does not record a static image. The eye records a video stream of sorts but the neural hardware of the eye and brain extract and see only that information that is relevant, somewhat like highly compressed 30  Silicon Chip video data where only changes in a picture are transmitted. The question is further complicated by the fact that the eye and body move and the brain assembles these images from different viewpoints into a type of composite image that has more information than the number of photosensitive cells in the eye would suggest (like taking a number of still images panning across a scene and assembling them into a larger image). Taking all of the above into account, one conservative estimate made by Roger Clark (www.clarkvision.com/ articles/human-eye/) for the resolution of the human eye is 576 megapixels to view a scene of 120° x 120° but the real field of view is even larger than this. Other estimates are that what we see is equivalent to the high resolution area of the fovea having a 7-megapixel resolution and the rest of the eye having a resolution of one megapixels. These issues are discussed in the video “What Is The Resolution Of The Eye?” https://youtu. be/4I5Q3UXkGd0 Structure of the visual system The visual system of an advanced organism such as a mammal usually consists of the following principal components: • the eye and its main component containing photo receptors, the retina; • the optic nerve for relaying information from the retina to the brain; • the optic chiasm which causes signals from the optic nerves to partially cross to allow the visual cortex to receive a complete visual field from both eyes and then combine them for stereoscopic vision; • the lateral geniculate body which has multiple functions and receives information from the retina via the optic nerve and optic chiasm and also processes that data before passing it on via the optic radiations to the visual cortex where the sense of vision is generated. Visual system of a human. Note how the visual fields represented by the green and orange colours start in the retina, partially cross at the optic chiasm and are finally mapped onto the visual cortex. siliconchip.com.au Even though the eye has the same basic optical elements as a camera as described above, it is far more than a camera and a lot of processing of visual data is done inside the retina itself with numerous different types of neurons involved as well as processing of visual data done elsewhere in the brain. Function of the bionic eye A bionic eye works by stimulating some part of the visual system in order to generate a sense of vision in cases where the eye or other components of the visual system are absent, diseased or defective. As the nervous system and brain use electric currents to convey information, electrical stimulation is the obvious choice to stimulate the visual system. Historical background The use of an electrical current to stimulate vision was first undertaken in 1755 by Frenchman Charles LeRoy who passed electricity through the eye of a blind man and this resulted in the him perceiving the sensation of light. Following that was the discovery of electrical activity in animal brains in 1875 but this involved exposing their brains which was a procedure not amenable to human experiments. The first EEG or electroencephalograph to record these brainwaves was taken of a dog in 1914 by Hans Berger who invented that machine. At the end of WWI in 1918 the first observations were made in Germany that electrical stimulation of the surface of the visual cortex in patients undergoing neurosurgical procedures under local anaesthesia resulted in the patient seeing dots of light or “phosphenes”. In 1924 Hans Berger recorded the first electrical activity from a human brain with scalp electrodes, a remarkable achievement at the time given the small voltages involved and the recording instruments of the time. Otfrid Foerster in 1929 investigated electrical stimulation of the occipital lobe (where the visual cortex is located) and reported that people could see a dot of light. The idea that many sites could be simultaneously stimulated to provide vision was postulated by W. Krieg in 1953. Of course, the complex electronics required to drive multiple electrode arrays in a portable package would not be available from some decades not to mention suitable implant materials. The measurement of electrical activity in the brain and its connection to visual processes was thus established leading to the possibility of artificial vision for the blind as well as a large array of other possibilities for interfacing the human brain to machines; see Interfacing to the Brain, SILICON CHIP, January 2015. Eye diseases and conditions to be treated Two common causes or visual impairment or blindness are among conditions sought to be treated with bionic vision: • Age-related macular degeneration is a condition resulting in the loss of central vision leading to the loss of abilities such as reading, facial recognition, reading clocks and street signs. Peripheral vision is maintained although the area of central vision loss gets larger with time. The fovea, responsible for high resolution vision, is part of the macula. • Retinitis pigmentosa is a degenerative condition of the siliconchip.com.au The bionic eye in science fiction The Six Million Dollar Man was a 1973 TV series which featured a bionic man, Colonel Steve Austin, with a bionic eye. What was portrayed as a fantasy 42 years ago, appears to be within the grasp of current or foreseeable technology. Also, Star Trek: The Next Generation featured Lieutenant Commander Geordi La Forge with a bionic eye. Catalog description of The Six Million Dollar Man’s bionic eye. Screen grabs from https:// vimeo.com/ 77027616 CAD diagram, very good for 1973 vintage, showing The Six Million Dollar Man’s bionic eye and interface circuitry to the visual cortex. The bionic eye of The Six Million Dollar Man. Lieutenant Commander Geordi La Forge from Star Trek: The Next Generation with his VISOR device (Visual Instrument and Sensory Organ Replacement) that can see most of the electromagnetic spectrum. It is interfaced to his brain via the optic nerves. The technology for this type of device seems a little further into the future than that of The Six Million Dollar Man’s device. June 2015  31 Representation of a parked car at different resolutions. In order of increasing resolution these images are 16 (4x4), 64 (8x8), 144 (12x12), 256 (16x16), 1024 (32x32), 4096 (64x64) and 16384 (128x128) pixels. Note that these images indicate the amount of information that might be conveyed at a particular resolution, not what a person would necessarily see. These images are also grey scale. Retinal and cortical prostheses currently display phosphenes (pixels) that are either off or on with no shades or colours. Also, in a current retinal or cortical implant, individual pixels will have space between them. The sensory substitution device, The vOICe does have 16 shades of “loudness”. (Courtesy Dr Peter Meijer, The vOICe.) eye due to the loss of photoreceptor cells and an increasing loss of peripheral vision resulting in tunnel vision and eventual blindness. In both the above cases, the photoreceptor cells have died but the neural pathway to the brain remains intact so in principle, this pathway can be activated with a retinal implant that stimulates the remaining pathway. Vision loss due to missing eyes or optic nerve damage can be treated by stimulation of areas such as the lateral geniculate body or the visual cortex within the brain. Ways of interfacing a bionic eye to the brain Consideration of the anatomy of the human visual system as described above suggests four ways a bionic eye can interface to the brain. An account needs to be made of the fact that the retina itself processes information and so does the lateral geniculate body and the visual cortex. The further along the visual pathway one goes before an interface is made it would seem that the more complicated it would be to make an effective prosthesis as the device might have to generate more “processed” visual data and less “raw” data. On the other hand, neuroplasticity, the ability of the brain to rewire itself might assist in developing a workable interface to any implanted prosthetic device. 1) As stated above, when disease affects the retina, it mainly destroys the photoreceptor cells leaving the ganglion cell layer, which transmits data to the brain, intact. Interfacing a device with this layer would therefore seem to be an effective way to interface a prosthetic device. Exceptions are if the retinal disease is so severe that even ganglion cells are destroyed or there is damage to the optic nerve. There are several locations within the retina where an implant can be located. Epiretinal implants are located on the inner surface of retina, subretinal implants are located behind the retina and suprachoroidal implants are located above the choroid and behind the retina. 2) Beyond the ganglion layer of the retina, there is a possibility of interfacing with the optic nerve although this involves challenges due to accessibility issues and also interfacing to a thin nerve with around about 1,000,000 nerve fibres. One such example is the Microsystem-based Visual Prosthesis (MIVP) which consists of a spiral cuff electrode wrapped around the optic nerve. Unlike retinal or cortical implants which produce monochrome phosphenes, coloured phosphenes have been reported in this stimulation method. Test subjects have also been able to locate and discriminate between objects. 3) Interfacing to structures such as the lateral geniculate body deep within the brain is possibly risky and complicated although this is a site being researched for interfacing a bionic eye. At the lateral geniculate body the visual data has not yet been so extensively processed that it has become too complicated to interpret and map. At this point a visual scene is mapped onto the brain tissue in a relatively simple way and bears a correspondence to the scene being observed. It has been estimated that the maximum resolution of an electrode array implanted at the location would be 40x40 per side. 4) The final interfacing possibility is the primary visual cortex of the brain (V1) which is close to the surface of the brain and relatively accessible. This area is specialised for processing information about stationary and moving objects and pattern recognition. The visual image of the retina is mapped onto V1 and a large portion of that retinal map corresponds to the fovea. Stimulation of this region of the brain enables a person to generate points of light (phosphenes) which can be used to generate a form of vision as has already been shown in experiments. A problem with using V1 as an interface is that the mapping of the retina is not linear so that, say, a square electrode area would not correspond to the same shape in the visual field. The first experiments in artificial vision The three possible locations of retinal implants. (Courtesy Bionic Vision Australia.) 32  Silicon Chip In the early 1960s Giles Brindley and W.S. Lewin in the UK started researching artificial vision and this resulted siliconchip.com.au in 1968 of the implant of 80 electrodes into the visual cortex of a blind person. The experiment was a success and the subject was able to identify letters and patterns in the phosphenes that were generated by electrical stimulation of the 80 electrodes and the research was published in a classic scientific paper in 1969. This lead to a major international conference at the University of Chicago which was to establish future directions for this work. Giles Brindley’s work inspired numerous similar research projects in the 1970s with the main objective of assisting the blind to read with the low resolution image provided by 80 or so electrodes. Many experiments were done stimulating the visual cortices of volunteers who were having neurosurgery for other reasons as well as volunteers having electrode implants. It soon became less important to assist the blind to read due to the development of talking books recorded on cassette tape and the emphasis became that of assisting the blind to navigate in their environment. This required a portable electronic package to do the visual processing required to create a usable image on the implanted electrodes but at the time creating a small portable processing unit was not possible with the electronics available; this technology would not be available until the 1990s. Jeremiah Teehan is credited by the Guinness Book of Jeremiah Teehan, the man who had the world’s first artificial vision system. Unfortunately, the implant deteriorated and had to be removed. The cortical implant is shown in image (a) and an x-ray of the implant in (b) the glasses/ camera combination is shown in (c) and the processing unit in (d). (From “Organic Bionics”, Wiley-VCH, 2012). siliconchip.com.au Records as the first person to have an artificial eye. The device was developed by the late William Dobelle and others. The record is dated 17th January 2000 and he had 68 platinum electrodes implanted on the surface of the visual cortex of his brain, although only 20 worked effectively and gave a narrow field of view, and he wore glasses containing a camera and an ultrasonic rangefinder as well as a 4.5kg visual processor unit on a shoulder strap. He had vision the equivalent of a severely short-sighted person with 20/400 vision and saw the outline of objects and letters. Unfortunately the implant deteriorated and had to be removed. The support electronics could be substantially miniaturised today. Another of William Dobelle’s patients, Jens Naumann, wrote an account of his experience with artificial vision called “Search for Paradise: A Patient’s Account of the Artificial Vision Experiment”. Also, see the video “Jens Naumann: Artificial Vision” https://youtu.be/JWMYW-SkURI His implant also deteriorated and he is again blind. Also see pictures of his implant at www.jensnaumann. green-first.com/gallery.shtml Early experiments with bionic vision as described above involved electrode arrays on the visual cortex but one alternative approach was to stimulate the retina itself. The first clinical trial of a 16 electrode retinal implant was made in 2002 by Second Sight Medical Products: www.2sight.com What was once only a dream of restoring vision in the blind has now progressed to a reality today with people actually using visual prostheses that give them some visual perception of the world. Desired resolution It should be noted that the objective of bionic eye research is not to provide the equivalent of natural vision as this is way beyond any technology currently available, but as with the cochlear implant, it is designed to give a workable, usable replacement for a lost or missing sense which may have much less fidelity than the natural equivalent but can still be of tremendous help to the person using the technology. An important question to answer is: what resolution of image is usable for a blind person to navigate about the world, say to walk to shops or catch public transport and read signs and food labels? This question applies equally to either a bionic eye or a sensory substitution device. It has been demonstrated in studies that a resolution of 32x32 pixels or 1024 pixels is more than enough to get meaningful and usable images. At lower resolutions a 4x4 array will provide motion detection capability, an approximately 100 electrode array will provide a navigational capability and an approximately 1,000 electrode array will provide facial and letter recognition. A video showing different resolutions of retinal implant can be seen at https://youtu.be/4gaBAIzAn-M [Project Xense Retinal Implant Simulation]. Note the separation between SC individual pixels. NEXT MONTH: In the final part of this mini series, we will look at some of the amazing advances being made here in Australia in the quest for the perfect Bionic Eye. June 2015  33 SILICON CHIP .com.au/shop ONLINESHOP Looking for a specialised component to build that latest and greatest SILICON CHIP project? Maybe it’s the PCB you’re after. Or a pre-programmed micro. Or some other hard-to-get “bit”. The chances are they are available direct from the SILICON CHIP ONLINESHOP. As a service to readers, SILICON CHIP has established the ONLINESHOP. 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PIC12F675-I/P PIC16F1507-I/P PIC16F88-E/P PIC16F88-I/P PIC16LF88-I/P PIC16LF88-I/SO PIC16F877A-I/P PIC18F2550-I/SP PIC18F45K80 PIC18F4550-I/P PIC18F14K50 UHF Remote Switch (Jan09), Ultrasonic Cleaner (Aug10), Ultrasonic Anti-fouling (Sep10), Cricket/Frog (Jun12) Do Not Disturb (May13) IR-to-UHF Converter (Jul13), UHF-to-IR Converter (Jul13) PC Birdies *2 chips – $15 pair* (Aug13) Wideband Oxygen Sensor (Jun-Jul12) Hi Energy Ignition (Nov/Dec12), Speedo Corrector (Sept13), Auto Headlight Controller (Oct13) 10A 230V Motor Speed Controller (Feb14) Projector Speed (Apr11), Vox (Jun11), Ultrasonic Water Tank Level (Sep11), Quizzical (Oct11) Ultra LD Preamp (Nov11), 10-Channel Remote Control Receiver (Jun13), Revised 10-Channel Remote Control Receiver (Jul13), Nicad/NiMH Burp Charger (Mar14) Remote Mains Timer (Nov14) Garbage Reminder (Jan13), Bellbird (Dec13) LED Ladybird (Apr13) 6-Digit GPS Clock (May-Jun09), Lab Digital Pot (Jul10) Semtest (Feb-May12) Batt Capacity Meter (Jun09), Intelligent Fan Controller (Jul10) USB Power Monitor (Dec12) GPS Car Computer (Jan10), GPS Boat Computer (Oct10) USB MIDIMate (Oct11) PIC18F27J53-I/SP USB Data Logger (Dec10-Feb11) PIC18LF14K22 Digital Spirit Level (Aug11), G-Force Meter (Nov11) PIC32MX795F512H-80I/PT Maximite (Mar11), miniMaximite (Nov11), Colour Maximite (Sept/Oct12), Touchscreen Audio Recorder (Jun/Jul 14) PIC32MX170F256B-50I/SP Micromite Mk2 (Jan15) – also includes FREE 47F tantalum capacitor PIC32MX170F256B-I/SP Low Frequency Distortion Analyser (Apr15) Bad Vibes (June 15) PIC32MX170F256D-501P/T 44-pin Micromite Mk2 (Now with Mk2 Firmware at no extra cost) PIC32MX250F128B-I/SP GPS Tracker (Nov13) Micromite ASCII Video Terminal (Jul14) PIC32MX470F512H-I/PT Stereo Audio Delay/DSP (Nov13), Stereo Echo/Reverb (Feb 14), Digital Effects Unit (Oct14) dsPIC33FJ128GP802-I/SP Digital Audio Signal Generator (Mar-May10), Digital Lighting Controller (Oct-Dec10), SportSync (May11), Digital Audio Delay (Dec11) Level (Sep11) Quizzical (Oct11), Ultra-LD Preamp (Nov11), LED Musicolor (Nov12) dsPIC33FJ64MC802-E/P Induction Motor Speed Controller (revised) (Aug13) dsPIC33FJ128GP306-I/PT CLASSiC DAC (Feb-May 13) ATTiny861 VVA Thermometer/Thermostat (Mar10), Rudder Position Indicator (Jul11) ATTiny2313 Remote-Controlled Timer (Aug10) ATMega48-20AU Stereo DAC (Sep-Nov09), RGB LED Strip Driver [-20AU chip] (May14) When ordering, be sure to nominate BOTH the micro required AND the project for which it must be programmed. 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Please email for a quote PRINTED CIRCUIT BOARDS PRINTED CIRCUIT BOARD TO SUIT PROJECT: PUBLISHED: COMPACT 12V 20W STEREO AMPLIFIER MAY 2010 PORTABLE STEREO HEADPHONE AMP APRIL 2011 CHEAP 100V SPEAKER/LINE CHECKER APRIL 2011 PROJECTOR SPEED CONTROLLER APRIL 2011 SPORTSYNC AUDIO DELAY MAY 2011 100W DC-DC CONVERTER MAY 2011 PHONE LINE POLARITY CHECKER MAY 2011 20A 12/24V DC MOTOR SPEED CONTROLLER MK2 JUNE 2011 USB STEREO RECORD/PLAYBACK JUNE 2011 VERSATIMER/SWITCH JUNE 2011 USB BREAKOUT BOX JUNE 2011 ULTRA-LD MK3 200W AMP MODULE JULY 2011 PORTABLE LIGHTNING DETECTOR JULY 2011 RUDDER INDICATOR FOR POWER BOATS (4 PCBs) JULY 2011 VOX JULY 2011 ELECTRONIC STETHOSCOPE AUG 2011 DIGITAL SPIRIT LEVEL/INCLINOMETER AUG 2011 ULTRASONIC WATER TANK METER SEP 2011 ULTRA-LD MK2 AMPLIFIER UPGRADE SEP 2011 ULTRA-LD MK3 AMPLIFIER POWER SUPPLY SEP 2011 HIFI STEREO HEADPHONE AMPLIFIER SEP 2011 GPS FREQUENCY REFERENCE (IMPROVED) SEP 2011 HEARING LOOP RECEIVER/NECK COUPLER SEP 2011 DIGITAL LIGHTING CONTROLLER LED SLAVE OCT 2011 USB MIDIMATE OCT 2011 QUIZZICAL QUIZ GAME OCT 2011 ULTRA-LD MK3 PREAMP & REMOTE VOL CONTROL NOV 2011 ULTRA-LD MK3 INPUT SWITCHING MODULE NOV 2011 ULTRA-LD MK3 SWITCH MODULE NOV 2011 ZENER DIODE TESTER NOV 2011 MINIMAXIMITE NOV 2011 ADJUSTABLE REGULATED POWER SUPPLY DEC 2011 DIGITAL AUDIO DELAY DEC 2011 DIGITAL AUDIO DELAY Front & Rear Panels DEC 2011 AM RADIO JAN 2012 STEREO AUDIO COMPRESSOR JAN 2012 STEREO AUDIO COMPRESSOR FRONT & REAR PANELS JAN 2012 3-INPUT AUDIO SELECTOR (SET OF 2 BOARDS) JAN 2012 CRYSTAL DAC FEB 2012 SWITCHING REGULATOR FEB 2012 SEMTEST LOWER BOARD MAR 2012 SEMTEST UPPER BOARD MAR 2012 SEMTEST FRONT PANEL MAR 2012 INTERPLANETARY VOICE MAR 2012 12/24V 3-STAGE MPPT SOLAR CHARGER REV.A MAR 2012 SOFT START SUPPRESSOR APR 2012 RESISTANCE DECADE BOX APR 2012 RESISTANCE DECADE BOX PANEL/LID APR 2012 1.5kW INDUCTION MOTOR SPEED CONT. (New V2 PCB) APR (DEC) 2012 HIGH TEMPERATURE THERMOMETER MAIN PCB MAY 2012 HIGH TEMPERATURE THERMOMETER Front & Rear Panels MAY 2012 MIX-IT! 4 CHANNEL MIXER JUNE 2012 PIC/AVR PROGRAMMING ADAPTOR BOARD JUNE 2012 CRAZY CRICKET/FREAKY FROG JUNE 2012 CAPACITANCE DECADE BOX JULY 2012 CAPACITANCE DECADE BOX PANEL/LID JULY 2012 WIDEBAND OXYGEN CONTROLLER MK2 JULY 2012 WIDEBAND OXYGEN CONTROLLER MK2 DISPLAY BOARD JULY 2012 SOFT STARTER FOR POWER TOOLS JULY 2012 DRIVEWAY SENTRY MK2 AUG 2012 MAINS TIMER AUG 2012 CURRENT ADAPTOR FOR SCOPES AND DMMS AUG 2012 USB VIRTUAL INSTRUMENT INTERFACE SEPT 2012 USB VIRTUAL INSTRUMENT INT. FRONT PANEL SEPT 2012 BARKING DOG BLASTER SEPT 2012 COLOUR MAXIMITE SEPT 2012 SOUND EFFECTS GENERATOR SEPT 2012 NICK-OFF PROXIMITY ALARM OCT 2012 DCC REVERSE LOOP CONTROLLER OCT 2012 LED MUSICOLOUR NOV 2012 LED MUSICOLOUR Front & Rear Panels NOV 2012 CLASSIC-D CLASS D AMPLIFIER MODULE NOV 2012 CLASSIC-D 2 CHANNEL SPEAKER PROTECTOR NOV 2012 HIGH ENERGY ELECTRONIC IGNITION SYSTEM DEC 2012 USB POWER MONITOR DEC 2012 1.5kW INDUCTION MOTOR SPEED CONTROLLER (NEW V2 PCB) DEC 2012 THE CHAMPION PREAMP and 7W AUDIO AMP (one PCB) JAN 2013 GARBAGE/RECYCLING BIN REMINDER JAN 2013 2.5GHz DIGITAL FREQUENCY METER – MAIN BOARD JAN 2013 2.5GHz DIGITAL FREQUENCY METER – DISPLAY BOARD JAN 2013 2.5GHz DIGITAL FREQUENCY METER – FRONT PANEL JAN 2013 SEISMOGRAPH MK2 FEB 2013 MOBILE PHONE RING EXTENDER FEB 2013 GPS 1PPS TIMEBASE FEB 2013 LED TORCH DRIVER MAR 2013 NOTE: The listings below are for the PCB only – not a full kit. If you want a kit, contact the kit suppliers advertising in this issue. For more unusual projects where kits are not available, some have specialised components available – see the list opposite. PCB CODE: Price: 01104101 $7.50 01104111 $10.00 04104111 $10.00 13104111 $10.00 01105111 $30.00 11105111 $15.00 12105111 $10.00 11106111 $20.00 07106111 $20.00 19106111 $25.00 04106111 $10.00 01107111 $25.00 04107111 $20.00 20107111-4 $80 per set 01207111 $20.00 01108111 $10.00 04108111 $10.00 04109111 $20.00 01209111 $5.00 01109111 $25.00 01309111 $20.00 04103073 $30.00 01209101 $10.00 16110111 $30.00 23110111 $25.00 08110111 $25.00 01111111 $30.00 01111112 $20.00 01111113 $10.00 04111111 $20.00 07111111 $10.00 18112111 $5.00 01212111 $25.00 01212112/3 $20 per set 06101121 $10.00 01201121 $30.00 0120112P1/2 $20.00 01101121/2 $30 per set 01102121 $20.00 18102121 $5.00 04103121 $40.00 04103122 $40.00 04103123 $75.00 08102121 $10.00 14102112 $20.00 10104121 $10.00 04104121 $20.00 04104122 $20.00 10105122 $35.00 21105121 $30.00 21105122/3 $20 per set 01106121 $20.00 24105121 $30.00 08109121 $10.00 04106121 $20.00 04106122 $20.00 05106121 $20.00 05106122 $10.00 10107121 $10.00 03107121 $20.00 10108121 $10.00 04108121 $20.00 24109121 $30.00 24109122 $30.00 25108121 $20.00 07109121 $20.00 09109121 $10.00 03110121 $5.00 09110121 $10.00 16110121 $25.00 16110121 $20 per set 01108121 $30.00 01108122 $10.00 05110121 $10.00 04109121 $10.00 10105122 $35.00 01109121/2 $10.00 19111121 $10.00 04111121 $35.00 04111122 $15.00 04111123 $45.00 21102131 $20.00 12110121 $10.00 04103131 $10.00 16102131 $5.00 PRINTED CIRCUIT BOARD TO SUIT PROJECT: PUBLISHED: PCB CODE: Price: CLASSiC DAC MAIN PCB APR 2013 01102131 $40.00 CLASSiC DAC FRONT & REAR PANEL PCBs APR 2013 01102132/3 $30.00 GPS USB TIMEBASE APR 2013 04104131 $15.00 LED LADYBIRD APR 2013 08103131 $5.00 CLASSiC-D 12V to ±35V DC/DC CONVERTER MAY 2013 11104131 $15.00 DO NOT DISTURB MAY 2013 12104131 $10.00 LF/HF UP-CONVERTER JUN 2013 07106131 $10.00 10-CHANNEL REMOTE CONTROL RECEIVER JUN 2013 15106131 $15.00 IR-TO-455MHZ UHF TRANSCEIVER JUN 2013 15106132 $7.50 “LUMP IN COAX” PORTABLE MIXER JUN 2013 01106131 $15.00 L’IL PULSER MKII TRAIN CONTROLLER JULY 2013 09107131 $15.00 L’IL PULSER MKII FRONT & REAR PANELS JULY 2013 09107132/3 $20.00/set REVISED 10 CHANNEL REMOTE CONTROL RECEIVER JULY 2013 15106133 $15.00 INFRARED TO UHF CONVERTER JULY 2013 15107131 $5.00 UHF TO INFRARED CONVERTER JULY 2013 15107132 $10.00 IPOD CHARGER AUG 2013 14108131 $5.00 PC BIRDIES AUG 2013 08104131 $10.00 RF DETECTOR PROBE FOR DMMs AUG 2013 04107131 $10.00 BATTERY LIFESAVER SEPT 2013 11108131 $5.00 SPEEDO CORRECTOR SEPT 2013 05109131 $10.00 SiDRADIO (INTEGRATED SDR) Main PCB OCT 2013 06109131 $35.00 SiDRADIO (INTEGRATED SDR) Front & Rear Panels OCT 2013 06109132/3 $25.00/pr TINY TIM AMPLIFIER (same PCB as Headphone Amp [Sept11]) OCT 2013 01309111 $20.00 AUTO CAR HEADLIGHT CONTROLLER OCT 2013 03111131 $10.00 GPS TRACKER NOV 2013 05112131 $15.00 STEREO AUDIO DELAY/DSP NOV 2013 01110131 $15.00 BELLBIRD DEC 2013 08112131 $10.00 PORTAPAL-D MAIN BOARDS DEC 2013 01111131-3 $35.00/set (for CLASSiC-D Amp board and CLASSiC-D DC/DC Converter board refer above [Nov 2012/May 2013]) LED Party Strobe (also suits Hot Wire Cutter [Dec 2010]) JAN 2014 16101141 $7.50 Bass Extender Mk2 JAN 2014 01112131 $15.00 Li’l Pulser Mk2 Revised JAN 2014 09107134 $15.00 10A 230VAC MOTOR SPEED CONTROLLER FEB 2014 10102141 $12.50 NICAD/NIMH BURP CHARGER MAR 2014 14103141 $15.00 RUBIDIUM FREQ. STANDARD BREAKOUT BOARD APR 2014 04105141 $10.00 USB/RS232C ADAPTOR APR 2014 07103141 $5.00 MAINS FAN SPEED CONTROLLER MAY 2014 10104141 $10.00 RGB LED STRIP DRIVER MAY 2014 16105141 $10.00 HYBRID BENCH SUPPLY MAY 2014 18104141 $20.00 2-WAY PASSIVE LOUDSPEAKER CROSSOVER JUN 2014 01205141 $20.00 TOUCHSCREEN AUDIO RECORDER JUL 2014 01105141 $12.50 THRESHOLD VOLTAGE SWITCH JUL 2014 99106141 $10.00 MICROMITE ASCII VIDEO TERMINAL JUL 2014 24107141 $7.50 FREQUENCY COUNTER ADD-ON JUL 2014 04105141a/b $15.00 VALVE SOUND SIMULATOR PCB AUG 2014 01106141 $15.00 VALVE SOUND SIMULATOR FRONT PANEL (BLUE) AUG 2014 01106142 $10.00 TEMPMASTER MK3 AUG 2014 21108141 $15.00 44-PIN MICROMITE AUG 2014 24108141 $5.00 OPTO-THEREMIN MAIN BOARD SEP 2014 23108141 $15.00 OPTO-THEREMIN PROXIMITY SENSOR BOARD SEP 2014 23108142 $5.00 ACTIVE DIFFERENTIAL PROBE BOARDS SEP 2014 04107141/2 $10/set MINI-D AMPLIFIER SEP 2014 01110141 $5.00 COURTESY LIGHT DELAY OCT 2014 05109141 $7.50 DIRECT INJECTION (D-I) BOX OCT 2014 23109141 $5.00 DIGITAL EFFECTS UNIT OCT 2014 01110131 $15.00 DUAL PHANTOM POWER SUPPLY NOV 2014 18112141 $10.00 REMOTE MAINS TIMER NOV 2014 19112141 $10.00 REMOTE MAINS TIMER PANEL/LID (BLUE) NOV 2014 19112142 $15.00 ONE-CHIP AMPLIFIER NOV 2014 01109141 $5.00 TDR DONGLE DEC 2014 04112141 $5.00 MULTISPARK CDI FOR PERFORMANCE VEHICLES DEC 2014 05112141 $10.00 CURRAWONG STEREO VALVE AMPLIFIER MAIN BOARD DEC 2014 01111141 $50.00 CURRAWONG REMOTE CONTROL BOARD DEC 2014 01111144 $5.00 CURRAWONG FRONT & REAR PANELS DEC 2014 01111142/3 $30/set CURRAWONG CLEAR ACRYLIC COVER JAN 2015 - $25.00 ISOLATED HIGH VOLTAGE PROBE JAN 2015 04108141 $10.00 SPARK ENERGY METER MAIN BOARD FEB/MAR 2015 05101151 $10.00 SPARK ENERGY ZENER BOARD FEB/MAR 2015 05101152 $10.00 SPARK ENERGY METER CALIBRATOR BOARD FEB/MAR 2015 05101153 $5.00 APPLIANCE INSULATION TESTER APR 2015 04103151 $10.00 APPLIANCE INSULATION TESTER FRONT PANEL APR 2015 04103152 $10.00 LOW-FREQUENCY DISTORTION ANALYSER APR 2015 04104151 $5.00 APPLIANCE EARTH LEAKAGE TESTER PCBs (2) MAY 2015 04203151/2 $15.00 APPLIANCE EARTH LEAKAGE TESTER LID/PANEL MAY 2015 04203153 $15.00 BALANCED INPUT ATTENUATOR MAIN PCB MAY 2015 04105151 $15.00 BALANCED INPUT ATTENUATOR FRONT & REAR PANELS MAY 2015 04105152/3 $20.00 4-OUTPUT UNIVERSAL ADJUSTABLE REGULATOR MAY 2015 18105151 $5.00 NEW THIS MONTH SIGNAL INJECTOR & TRACER PASSIVE RF PROBE SIGNAL INJECTOR & TRACER SHIELD BAD VIBES INFRASOUND SNOOPER CHAMPION + PRE-CHAMPION JUNE 2015 JUNE 2015 JUNE 2015 JUNE 2015 JUNE 2015 04106151 04106152 04106153 04104151 01109121/2 $7.50 $2.50 $5.00 $5.00 $7.50 By Nicholas Vinen The Bad Vibes Infrasound Snooper Back in March 2013 we published the Infrasound Detector for low frequency measurements. Now you can “listen” to low frequency vibrations with our Infrasound Snooper. It frequency shifts and amplitude modulates a frequency range of about 1Hz to 20Hz by about five or six octaves so that you can listen directly to wind turbines or elephants, crocodiles and other animals that communicate with infrasound. O UR INFRASOUND SNOOPER uses Digital Signal Processing (DSP) techniques in a PIC32MX170 microcontroller, an electret microphone, a DAC chip, a TL074 quad op amp and very little else, to drive a pair of headphones. High levels of infrasound can have a negative impact on your health but you might not even know when you are being exposed to low frequency vibrations unless they excite harmonics by rattling window panes and similar, because they’re otherwise inaudible. In January this year, a study by acous36  Silicon Chip tics expert Steven Cooper of Bridgewater Acoustics attracted a great deal of controversy over its findings which support the notion that infrasound from wind turbines can cause negative health impacts on people some distance away. At the SILICON CHIP offices, some of our staff recently experienced ill effects, including headaches and nausea, when a ground compacting machine was operating on a nearby building site. It evidently set up all sorts of standing waves in our building, as it moved around the construction site. Some “nodes” in our building were quite unpleasant places to be. So if you are living or working near potential sources of infrasound and are suffering from some of the potential symptoms, our Infrasound Snooper can certainly help. Our Infrasound Detector (SILICON CHIP, March 2013) allows you to measure the amplitude and frequency of infrasonic sound waves but the results can be somewhat difficult to interpret since you cannot hear the phenomenon. The Infrasound Snooper lets you assess the amplitude and frequency of siliconchip.com.au Scope1: amplified infrasound output from IC2c (green) and the modulated signal to the headphones (yellow) for a lowfrequency impulse of about 10Hz. The mode is AM+FM with low-frequency boost and you can see the output freq­ uency shifting for the positive/negative infrasound signal as well as the delay from the low-frequency boosting filter. Scope2: a similar impulse at a longer timebase than Scope1 (50ms/div rather than 20ms/div). The mode is AM+FM without low-frequency boost and thus the output waveform modulation corresponds very closely to the green input signal excursions. As before, positive excursions produce higher modulated frequencies than negative excursions. the waves but importantly, you can also hear the details – whether they are short, repetitive bursts, continuous waves or somewhere in between. Our Infrasound Snooper is housed in a small plastic box and uses a doublesided PCB (code 04104151) measuring 104 x 60.5mm. An electret microphone is mounted at one end of the case and a rotary switch on the lid offers a number of different listening modes. Circuit description Fig.1 shows the circuit details. Infrasonic sound waves are sensed with the electret microphone (MIC1) or an external microphone plugged into CON4. A 6.8kΩ pull-up resistor from the 5V regulated rail provides the electret’s operating current. The electret signal is AC-coupled via a 1µF capacitor to the non-inverting input of op amp IC2b, one section of a TL074 quad JFET-input op amp. In conjunction with the 1MΩ resistor, this capacitor forms a low pass filter with a -3dB corner frequency at 0.2Hz. Thus signals above 0.5Hz pass through with little or no attenuation. The 5V rail is used as a convenient DC bias point, to bring the signal within IC2’s supply rails, ie, roughly half-way between 0V and VCC which is typically 8.7V. IC2b operates as a simple buffer, feeding the following third-order active low-pass filter based around op amp stage IC2a which has a gain of two siliconchip.com.au Features & Specifications •  Converts infrasonic sound waves into audible waves via frequency shift modulation •  Minimal delay between detection of infrasound and audible response; essentially real-time •  Output volume proportional to infrasonic wave amplitude •  Output pitch deviation indicates infrasonic wave polarity •  Optional digital filter to compensate for typical low-frequency microphone roll-off •  Quick response time allows listener to determine nature of infrasound (pulsed, continuous, etc) as well as frequency and amplitude •  Operating input frequency range: approximately 1-20Hz •  Power supply: 9V battery, ~60mA current drain (9-15V DC plugpack can also be used) •  Five modes: AM+FM with or without microphone response compensation, AM only with or without microphone response compensation, FM only (fixed amplitude) June 2015  37 CON1 D1 1N400 4 22Ω 6-12V DC/AC POWER A 1 ON/OFF 2 3 S1b K 4 D2 1N 5819 A + Vcc K 6 100k 5 9V BATTERY Vcc +5V +5V VR2 10k 22k +3.3V IC2: TL074 6.8k 1M 470Ω 100nF 470nF 1 µF 5 4 IC2b 6 7 2.2M 470nF 22k 22k 2 22k INPUT 22pF 9 6.2k 3 IC2a 1 10 IC2c 47k 1 µF 8 6.8k 11 MODE 1 SELECT 2 3 2.2M 470nF + MIC1 CON4 4 S1a ELECTRET 6 5 SWITCH S1 SETTINGS 1: 2: 3: 4: 5: 6: OFF AM+FM+BOOST AM+FM AM+BOOST AM FM CON3 ICSP 10k 1 2 3 4 5 SC 20 1 5 INFRASOUND SNOOPER Fig.1: the complete circuit diagram. The infrasound is picked up by an electret microphone & then buffered, filtered & amplified by IC2b-IC2a before being fed to microcontroller IC1. IC1 digitises the signal & carries out the necessary signal processing before feeding it to DAC IC3. IC3 then feeds gain stage IC2d which in turn drives the output socket (CON5). (set by the pair of 22kΩ resistors at its pin 2). The filter is a Butterworth type which is pretty much flat from DC up to 20Hz, with gain rapidly falling off at higher frequencies. This is important since we need to apply a fair bit of gain to the infrasonic signals to scale them to an appropriate level for the microcontroller’s ADC (~1V RMS). Op amp IC2c provides the requisite gain which is variable using VR2. So the gain ranges from a minimum of 6x (47kΩ ÷ (10kΩ + 470Ω) + 1) to a maximum of around 100x (47kΩ ÷ (470Ω + W) + 1, where W is VR2’s wiper resistance). Thus VR2 acts as the unit’s sensitivity adjustment. 38  Silicon Chip The signal must then have its DC bias shifted to suit the PIC32MX microcontroller’s ADC, which runs from a 3.3V regulated rail. Thus it is AC-coupled with a 1µF capacitor and biased with a pair of 2.2MΩ resistors forming a voltage divider between the 3.3V rail and ground. This sets the DC level at pin 2 of IC1 at around 1.65V. The 6.8kΩ resistor protects IC1 from high voltages from IC2 during powerup, power-down and high signal excursions. IC1 digitises the signal and then applies some DSP-based filtering to correct for low-frequency roll-off due to the two coupling stages and the microphone’s response. To create an audible signal, the infrasound signal is rectified and then used to amplitude modulate a sinewave at about 200Hz. Some frequency modulation is normally also applied to this waveform, based on the pre-rectification signal. This allows the polarity of infrasonic excursions to be distinguished, based on the difference in resulting signal frequency. This modulated signal appears in digital (I2S) format at pins 5, 7 & 25 of IC1. The serial audio data is produced at pin 5 (RB1) which is mapped to one of the two internal SPI peripherals so that the data stream is uninterrupted. siliconchip.com.au REG1 78L05 Vcc +5V OUT IN REG2 MCP1700-3.3/TO GND GND IN 100 µF 100nF 16V 25V 78L05 GND 100 µF 220 µF +3.3V OUT IN OUT 16V 33k MC P1700 IN GND OUT +5V +3.3V LEDS 10Ω 470Ω MMC MMC 13 3 2 VDD AVDD RA1/AN1/VREF– SOSCO/RA4 RA0 /AN 0 /VREF+ PGED1/AN2/RB 0 10 9 6 AN 10 /RB1 4 SOSCI/RB4 AN11/RB13 RA3/CLKO AN12/RB12 RA2/CLKI PGEC2/RB11 RB2/AN4 IC1 PIC32MX170PIC3 2 MX170F256B PGED2/RB10 TD0/RB9 TCK/RB8 TDI/RB7 1 14 15 AN5/RB3 12 LOW BATTERY/ OPERATE PGEC1/AN3/RB1 VCAP PGEC3/RB6 λ LED2 CLIP K D1, D2 A 4 K 26 25 24 100nF 23 MMC 22 21 18 1 17 16 2 7 3 MCLR PGED3/RB5 K A A λ LED1 K 28 AN9/RB15 11 A 100nF 100nF 1k BitCLK W Sel DATA 5 Vdd IC3 TDA1 5 43 GND 4 AoutR VrefO AoutL 8 7 6 12 13 5 IC2d 100 µF 16V 680Ω 4.7nF 20 14 VR3 1k VSS 19 VSS 8 This data is clocked by a signal from pin 25 (RB14/SCK1). The left/right “word” clock is produced at pin 7 (RB3), also by the SPI peripheral, using its audio framing feature. These three signals pass to IC3, a TDA1543 16-bit oversampling DAC. We’ve used this chip for a number of reasons: it’s available in an 8-pin DIL package which is easy to solder; it runs from a single 5V rail; it’s quite cheap; it’s easy to interface to and its audio performance is respectable. Its outputs at pins 6 & 8 are current sink stages and since we only need a mono signal, they are simply connected together, filtered (to remove siliconchip.com.au OUTPUT 2 1 5 CON5 10 µF AVSS 27 4 3 6.3V TANT. OR SMD CERAMIC the digital aliasing artefacts) and converted to a voltage by remaining op amp IC2d. The 680Ω resistor sets the output voltage swing. IC2d’s pin 12 non-inverting input is connected to the 2.2V reference voltage which sets the DC level of the resulting signal. The Vref (pin 7) of IC3 has a dual purpose; the current drawn from this pin is internally amplified and added to the current sink by the left & right output pins. However, in this case, the circuit works best with no extra current sink, hence there is no load on the Vref pin. The DC in the output of IC2d is blocked by a 100µF electrolytic capaci- tor and biased to ground by the track of VR3, the volume potentiometer. The headphones or earphones are connected to its wiper via CON5 with no extra buffering. This is a relatively crude system but it works well enough. The main purpose is to allow the user to reduce the output to a comfortable level when used in conjunction with sensitive earphones. Power supply The Infrasound Snooper is designed to run off a 9V battery but a 9-15V DC plugpack could also be used. The supply current therefore flows through one of two reverse-polarity protection June 2015  39 1 µF CON4 S MIC1 VR2 10k Clip 1k LED1 LED2 A Batt VR3 1k INPUT + 10 µF PIC32MX170F256B IC1 1 100nF ICSP 2.2M 2.2M + 10Ω 33k 6.8k 22Ω 100 µF 470Ω 5819 D1 REG2 + 100nF CON3 100nF REG1 470Ω 1M 4004 Power/Mode A T 10k D2 220 µF + 47k 100 µF + 6.8k R S1 + 100nF Snooper IC3 100nF 22pF 470nF 9V 0V 100k C 2015 TDA1543 4.7nF 680Ω 22k 22k 22k 6.2k 22k + Infrasonic CON1 1 µF IC2 TL074 470nF ELECTRET MIC INSERT 470nF 04104151 9V BATTERY R 100 µF CON5 S T OUTPUT (BLUE OUTLINES REPRESENT COMPONENTS NOT USED IN THIS PROJECT) Fig.2: follow this parts layout diagram to build the PCB. Take care to ensure that all polarised parts are correctly orientated and use a socket for microcontroller IC1. Sockets are optional for IC2 & IC3. diodes, D1 for the plugpack or D2 for the battery. D2 is a Schottky diode, to minimise voltage drop and therefore extend battery life. Rotary switch S1 acts as both the power and mode switch. One pole connects the power supply directly to IC2 as well as to the input of REG1. This regulator provides the 5V rail for DAC IC3, the electret supply and for signal biasing in the input filter. It also feeds REG2, a 3.3V low-dropout regulator which powers microcontroller IC1. The other pole of S1 is connected to pins 6, 9, 10 & 11 of IC1 which are configured as inputs with internal pull-up currents enabled. Thus IC1 can sense which position S1 is in by determining which of these inputs is pulled low. If none are then the switch must be in the second position, as the circuit is not powered in the first position. IC1 monitors the battery voltage via a 4:1 divider (100kΩ/33kΩ), digitising the resulting voltage at its AN1 analog input (pin 3). If the battery voltage is low (<7V), it illuminates the low-battery LED (LED2) via its pin 12 output (RA4). The 470Ω currentlimiting resistor sets the LED current to around 2-3mA. Similarly, IC1 can light LED1 if there is an input signal overload, using its pin 4 output. The red LED is a little more efficient so operates at a lower current, with a 1kΩ current-limiting resistor resulting in around 1-1.5mA flowing. 40  Silicon Chip CON3 is a programming header for IC1 (if required) with a 10kΩ pullup resistor on its MCLR pin (pin 1) preventing unexpected reset events. IC1’s analog supply at pin 28 is lowpass filtered with a 10Ω resistor and 100nF bypass capacitor, while a 10µF capacitor at pin 20 is required for its internal core regulator. Construction All the parts except for the electret microphone are mounted on a doublesided PCB coded 04104151 (104 x 60.5mm). This can be clipped into a standard UB3 jiffy box. Fig.2 shows the parts layout on the PCB. Start by fitting the fixed resistors. Table 1 shows the resistor colour codes, although it’s better to check the values using a DMM. Note that since the same PCB was used for the Low Frequency Distortion Analyser, there are a number of component positions which are not populated (including some resistor locations). Diodes D1 & D2 can go in next, noting that D1 is a 1N4004 while D2 is a 1N5819. Be sure to orientate them correctly, with their striped cathode ends towards the bottom edge of the PCB. Follow with the IC socket(s). It’s a good idea to use a socket for microcontroller IC1 but they are not really necessary for IC2 & IC3. Instead, IC2 & IC3 can be soldered directly to the PCB for greater long-term reliability. Either way, make sure that the pin 1 notch/ dot of each IC goes towards the top of the board. This is especially critical if soldering the ICs in without sockets since you can’t easily remove them once they’re in! The two jack sockets are next on the list, followed by the ceramic and MKT capacitors. REG1 & REG2 can then go in but be careful not to get them mixed up as they look similar. Their leads will need to be cranked out using needle nose pliers to suit the pad spacing on the PCB. Now solder the DC socket in place, followed by the electrolytic capacitors. Be sure to orientate the electros correctly, with the longer (positive) leads towards the top edge of the PCB (see Fig.2). If using a tantalum type rather than an SMD ceramic for the 10µF capacitor, it too is polarised and can go in now. Now fit the two 9mm potentiometers. They’re different values so don’t get them mixed up (the 1kΩ pot may be marked “102” and the 10kΩ pot “103”). The polarised 3-pin header (for the microphone) can then be fitted with its keyway tab orientated as shown. The battery snap is next. Pass its leads through the two strain relief holes before soldering its leads to their respective pads on the top of the PCB as shown in Fig.2. You can then pull the leads back through the holes to reduce the slack. Note that they will probably be a tight fit, to provide the siliconchip.com.au   Table 2: Capacitor Codes Value 1µF 470nF 100nF 4.7nF 22pF IEC Code EIA Code   1u0  105   470n   474   100n   104   4n7  472   22p   22 of the cable, then carefully solder and crimp the leads at one end to the header crimp pins. That done, the crimp pins can be slid into the header (the tang goes into the narrow channel) until they lock into position. The next step is to determine which lead on the electret microphone is the positive and which is the negative. This may be marked but if not, use your DMM (set to ohms) to determine which lead is connected to the case – this is the negative (ground) lead. Next, slip 5mm-lengths of 3mmdiameter heatshrink over the insulation at the end of the cable leads, then solder these two leads to the microphone. Make sure that the positive lead from the header goes to the electret positive (the positive side is marked on the PCB, adjacent to CON4). Once the two leads have been soldered, slip the heatshrink sleeves over the solder connections and shrink them down to provide strain relief (see photo). This view shows the completed PCB assembly. Note how the battery snap leads are looped through strain relief holes before being soldered to the top of the PCB. necessary strain relief. The two 3.5mm switched jack sockets (CON4 & CON5) can now be mounted. Check that they sit flush against the PCB before soldering their pins. CON3, the ICSP header, can then go in but can be omitted if you’re using a pre-programmed microcontroller. Rotary switch S1 is mounted after first cutting its shaft so that it’s 30mm long, as measured from the top surface of the main body. This can be done using a hacksaw and the end of the shaft then cleaned up with a file to remove any burrs. It must be installed with its polarity-indicating plastic post orientated as shown on Fig.2 (ie, at the three o’clock position). Again, make µF Value 1µF 0.47µF 0.1µF .0047µF  NA sure it’s pushed down flat against the board before soldering its pins. Finally, solder the two LEDs in place. The longer leads are the anodes and go into the pads indicated with “A” on Fig.2. Tack solder these in place at full lead length; you can adjust the height and solder them properly once the box has been prepared. Microphone cable The next job is to make up a cable to connect the microphone. That’s done using a 70mm length of light-duty Fig.8 cable which is terminated at one end in a 2-way polarised header. Begin by removing about 3mm of insulation from the leads at each end Testing If using sockets, plug in the ICs, with their pin 1 dot or notch aligned as shown in Fig.2. If IC1 hasn’t already been programmed (you can buy a pro- Table 1: Resistor Colour Codes   o o o o o o o o o o o o o o o siliconchip.com.au No.   2   1   1   1   1   4   1   2   1   1   1   2   1   1 Value 2.2MΩ 1MΩ 100kΩ 47kΩ 33kΩ 22kΩ 10kΩ 6.8kΩ 6.2kΩ 1kΩ 680Ω 470Ω 22Ω 10Ω 4-Band Code (1%) red red green brown brown black green brown brown black yellow brown yellow violet orange brown orange orange orange brown red red orange brown brown black orange brown blue grey red brown blue red red brown brown black red brown blue grey brown brown yellow violet brown brown red red black brown brown black black brown 5-Band Code (1%) red red black yellow brown brown black black yellow brown brown black black orange brown yellow violet black red brown orange orange black red brown red red black red brown brown black black red brown blue grey black brown brown blue red black brown brown brown black black brown brown blue grey black black brown yellow violet black black brown red red black gold brown brown black black gold brown June 2015  41 (UB3 BOX LID) A CL 25.75 5 5 B B CL HOLE SIZES: HOLE A 6.5mm DIAM, HOLES B 3.0mm DIAM HOLES C 6.0mm DIAM, HOLES D 8.0mm DIAM 19 22 D 22 D C C 24 13.5 13.5 24 (FRONT SIDE OF UB3 BOX) ALL DIMENSIONS IN MILLIMETRES SILICON CHIP AM+Boost AM+FM AM+FM+Boost AM FM Off BAD VIBES Infrasound Snooper Overload Ext. Mic Gain On/Low Battery Vol. Output Fig.4: this front panel artwork can be copied and used direct or a PDF version can be downloaded from the SILICON CHIP website & printed onto photo paper or onto Datapol/Dataflex label paper. grammed micro from the SILICON CHIP Online Shop), do it now via CON3. External power can be supplied from the programmer (eg, a PICkit 3). Once all the ICs are in place, you can test the unit as follows: (1) Rotate S1 to the off position (fully anti-clockwise), then connect the battery. 42  Silicon Chip (2) Rotate S1 one step clockwise and check that the yellow LED flashes briefly, then periodically. (3) Turn VR2 & VR3 all the way down and connect a pair of headphones or earphones to the unit. (4) Turn VR2 & VR3 up slowly and blow on the microphone insert. After turning the pots up sufficiently, you Fig.3 (left): use this full-size template to drill the holes in the lid and front side of the UB3 case. should hear the modulated signal from the low frequency components of this sound. With the gain up high, if you blow hard enough, the overload (red) LED may light. (5) Switch S1 to the other positions and check that the sound produced by the unit changes. (6) Switch the unit off and remove the battery. If it doesn’t work as expected, carefully inspect the solder joints under magnification. Also check that the components are all in their correct positions and that the polarised parts (diodes, ICs, electrolytic capacitors etc) are orientated correctly. Case preparation If fitting the PCB into a UB3 jiffy box, you will need to drill four holes in the side of the case for the microphone input and headphone output sockets, plus the gain and volume adjustment knobs. The bottom section of Fig.3 shows the relevant drilling template – this can be copied (or downloaded from the SILICON CHIP website and printed out) and temporarily stuck to the side of the case (eg, using doublesided tape). Note that the top edge of the template must be aligned with the top edge of the box and centred horizontally. The holes must be accurately placed. siliconchip.com.au If you want to be able to run the unit from a plugpack, you will also need to drill a 5.5mm hole in the other side, to allow access to the connector. The same template can be used; simply drill the hole for the power jack centred on the same location as that used for the volume control pot on the opposite side. If in doubt, check the location of the power socket on the board before drilling. Fitting the microphone Above: the PCB is a snapfit inside the case, while the battery sits on a piece of non-conductive foam (see text). Start by drilling pilot holes (eg, 3mm) in each location and then enlarge them using larger drill bits, a stepped drill bit or a tapered reamer. Clean up any burrs, then remove the nuts from the two jack connectors, screw the nuts and washers all the way onto the potentiometers and check that the connectors and pots fit through the holes. A hole also has to drilled in the lefthand end of the case for the electret microphone. The hole should be positioned about 16mm down from the top of the case and centred horizontally. Start by drilling a small pilot hole, then carefully ream the hole out until the microphone is a tight fit. Once the mic fits, adjust it so that its face is flush with the outside of the case. It can then be secured inside the case using a small amount of neutral-cure silicone adhesive and the assembly placed aside to cure while the case lid is drilled. Front panel drilling Three holes are required in the case lid, for the two LEDs and switch S1. The drilling template is at the top of Fig.3 and it’s just a matter of drilling the holes to size and checking that the LEDs and switch shaft fit. Parts List 1 double-sided PCB, coded 04104151, 104 x 60.5mm 1 UB3 jiffy box (optional) 1 10kΩ 9mm single-gang potentiometer (VR2) 1 1kΩ 9mm single-gang potentiometer (VR3) 1 28-pin narrow DIL IC socket 1 14-pin DIL IC socket (optional) 1 8-pin DIL IC socket (optional) 1 piece non-conductive foam, approximately 65 x 40 x 8mm 1 PCB-mount DC socket (CON1) 2 3.5mm switched jack sockets (CON4,CON5) 1 2-pole 6-position rotary switch (S1) 1 medium-sized knob, to suit S1 2 small knobs, to suit VR2 & VR3 1 9V battery snap (BAT1) 1 9V alkaline battery (BAT1) 1 pair headphones or earphones siliconchip.com.au 1 5-pin header, 2.54mm pitch (CON3) (optional – see text) 1 PCB-mount electret microphone insert (Jaycar AM4011) 1 3-pin polarised header, 2.54mm pitch (CON6) 1 3-way polarised header plug 1 70mm-length light duty figure-8 cable 1 10mm length 3mm-diameter heatshrink Semiconductors 1 PIC32MX170F256B-I/SP 32-bit microcontroller programmed with 0420415A.HEX (IC1) 1 TL074 quad JFET-input op amp (IC2) 1 TDA1543 oversampling DAC (IC3) 1 78L05 5V regulator (REG1) 1 MCP1700-3.3/TO 250mA 3.3V LDO regulator (REG2) The next step is to make and attach the panel label (Fig.4). This can be copied or downloaded and printed onto photo paper and affixed to the panel using silicone adhesive. Alternatively it can be printed onto Datapol/Data­flex label paper and stuck onto the lid. The three holes are then cut out using a sharp hobby knife. Final assembly Assuming that the silicone around the microphone has cured, the PCB can now be installed in the case. It’s just a matter of angling the front of the board down so that the sockets and pot shafts go into their respective holes, then pushing down on the back of the board until it snaps into the integral side-rails. If it won’t go in, you may need to enlarge the holes slightly. Now trial fit the lid. If the LED heights are wrong, you will need to remove the PCB and adjust them accordingly. Once they fit properly, re-solder their leads and re-install the board in the case. The potentiometer nuts can then be wound forwards until they’re against the inside face of the case. Next, rotate S1 to off (fully anticlockwise), then connect the battery and place it on top of the PCB with a piece of non-conductive foam sandwiched in between. This will prevent shorts and also stop the battery from rattling around inside the case. Finally, screw the lid in place, then 1 red 3mm LED (LED1) 1 yellow/orange 3mm LED (LED2) 1 1N4004 1A diode (D1) 1 1N5819 1A Schottky diode (D2) Capacitors 1 220µF 25V electrolytic 3 100µF 16V electrolytic 1 10µF 6V tantalum or SMD ceramic (1210/1206/0805) 2 1µF 50V multi-layer ceramic 3 470nF 63V/100V MKT 5 100nF 50V multi-layer ceramic 1 4.7nF 63V/100V MKT 1 22pF disc ceramic Resistors (0.25W, 1%) 2 2.2MΩ 2 6.8kΩ 1 1MΩ 1 6.2kΩ 1 100kΩ 1 1kΩ 1 47kΩ 1 680Ω 1 33kΩ 2 470Ω 4 22kΩ 1 22Ω 1 10kΩ 1 10Ω June 2015  43 Scope3: amplitude modulation-only mode. The output freq­uency is fixed at around 185Hz and only its amplitude varies, increasing for either polarity of infra­sound pressure wave excursion. Each waveform shown here is at maximum sensitivity and this is how the unit should be used unless it is overloading due to intense infrasound. attach the knobs for S1, VR2 & VR3 (the jack socket nuts aren’t required). Using it Typically, you would use the device with the gain somewhere near maximum and the volume adjusted to a level which is not excessive for the headphones or earphones being used. Due to the way the volume control works, this is likely to be somewhere near maximum too, although lower settings may be necessary for “in-ear” ear-phones. Sealed headphones or in-ear phones have the advantage that you can more easily determine the level of infrasound emitted from sources which also produce audible frequencies. Scope4: frequency modulation mode. The signal amplitude is constant and high (generally the output volume should be turned down in this mode) and only the frequency changes in response to infrasonic waves picked up by the microphone. As before, the frequency increases for one polarity of wave and decreases for the other. That’s because they will do a better job of blocking those audible frequencies out and allow you to more clearly hear the output of the device. An example of this would be a door slamming shut. This can generate quite a significant infrasonic pulse but it may be difficult to hear the unit’s response against the audible noise of the door slamming. Other sources which can be used to test the unit include large air-conditioning units, passing trucks and large idling engines. When using one of the frequency modulation (FM) modes, it is possible to determine the polarity of an infrasonic pulse. One polarity will produce a sound which increases in frequency while the other will produce a sound that decreases in frequency. Regular pulses from the same source will normally have a consistent polarity. Typically, a compression wave will precede an expansion wave. Finally, note that a wind shield may be necessary for the microphone if the unit is used outdoors. As with the March 2013 Infrasound Detector, the windshield from a dynamic microphone could be used. Alternatively, a separate external electret microphone (plugged into CON4) could be used instead of the inbuilt electret. Just make sure is has the required high sensitivity, a good low-frequency response and is able to operate from the ~0.5mA bias current SC supplied by the unit. Are Your S ILICON C HIP Issues Getting Dog-Eared? $16.9 REAL VALUE AT Are your SILICON CHIP copies getting damaged or dogeared just lying around in a cupboard or on a shelf? 5* PLUS P &P Keep them safe, secure and always available with these handy binders Order now from www.siliconchip.com.au/Shop/4 or call (02) 9939 3295 and quote your credit card number. *See website for overseas prices. 44  Silicon Chip siliconchip.com.au End of Financial Year CLEARANCE OVER 200 DEALS - GET IN QUICK BEFORE WE RUN OUT! 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Made from high speed steel. 1mm steps. 4-12MM TD-2436 WAS $14.95 NOW $9.95 SAVE $5 12-20MM TD-2438 WAS $24.95 NOW $17.95 SAVE $7 NOW 9 $ 95 SAVE $5 Mini Bench Vice TH-1764 WAS $14.95 This strong, lightweight aluminium vice will clamp to surfaces up to 25mm thick and hold material up to 50mm thick. Great for repairs on the go. ALSO AVAILABLE: 270° CLAMP VICE TH-1769 WAS $24.95 NOW $19.95 SAVE $5 To order phone 1800 022 888 or visit www.jaycar.com.au $ NOW 3995 SAVE $10 Sheet Metal Bender TH-1763 WAS $49.95 This unit sits in the jaws of your bench vice (100mm+ recommended) and it retains itself in the vice with strong recessed magnets. Folds sheet up to 125 wide and bend steel strips up to 4mm thick and 25mm wide. See terms & conditions on page 8. IF YOU’RE A PROFESSIONAL AND REGULARLY PURCHASE ELECTRONICS GOODS FOR BUSINESS PURPOSES, YOU MAY BE ELIGIBLE FOR SPECIAL TRADE PRICES AT JAYCAR COMPANY STORES* ON SELECTED ITEMS. Conditions apply. See website for T&Cs * VISIT YOUR LOCAL JAYCAR STORE TODAY & FIND OUT HOW. Page 3 IP67 RATED TRUE RMS DIGITAL MULTIMETERS GREAT DEALS FOR REWARDS CARD HOLDERS Our range of high quality true RMS digital multimeter (DMM) provides the durability, accuracy and performance needed for the professional user. All DMMs are packed with multi functions to suit a wide range of electrical work, including AC Voltage, DC Voltage, AC Current, DC Current, Resistance, Capacitance, Frequency, Temperature (except QM-1549), Continuity and Diode Test. • Auto-ranging, data hold, relative measurement QM-1549 QM-1571 QM-1543 QM-1576 Special Features Value-for-money CAT IV DMM for most electrical works Wireless USB interface and logging software for computer based analysis Drop proof to 2m. Includes bargraph and K-type thermocouple. View live data, diagnose, email & share your results to the Cloud - all from your Smartphone! Display (Count) 4,000 4,000 40,000 40,000 Security Cat IV 600V Volts DC/AC 1,000V Amp DC/AC 10A Resistance 40M Frequency 10MHz REWARDS CARD $ Capacitance 100μF 100μF 40mF 40mF RRP $79.95 $109 $159 $229 MULTI-FUNCTIONAL DMM 8495 79 SPECIAL $ 129 QM-1576 SAVE $15 SAVE $30 SAVE $30 SAVE $40 QM-1020 Still the best way to test a capacitor. This well-made analogue meter has audible continuity and a transistor test, in addition to the normal set of functions. • AC/DC voltages up to 1000V • DC current up to 250mA • Resistance measurement IDEAL FOR TRADIES. ONLY 16MM THICK! $ 2495 Inductance / Capacitance Digital Multimeter SAVE $20 DOUBLE POINTS Pocket-Sized Digital Multimeter QM-1328 A handy pocket-sized multimeter with plenty of features. Large LCD display with autoranging, data hold and relative functions. • Cat III 600V, 4000 count • AC/DC voltages up to 600V • 115(H) x 60(W) x 16(D)mm DOUBLE POINTS 189 189 QM-1543 *Valid for purchase of QM-1020, QM-1328, QM-1548, or QM-1551. Insulation Meter $ SPECIAL $ QM-1571 Analogue Multimeter $ SPECIAL $ REWARDS CARD QM-1549 DOUBLE POINTS SAVE $15 QM-1493 WAS $209 Suitable for high voltage insulation testing up to 4 gigaohms at up to 1000V in electrical and electronic testing applications. • Cat III 1000V, 4000 count • Test Voltage & Current: 125V, 250V, 500V, 1000V <at>1mA nominal • Bargraph, test hold & lock 64 95 REWARDS CARD DOUBLE POINTS FOR REWARDS CARD HOLDERS ON THESE MULTIMETERS* Environment Meter QM-1594 WAS $99.95 Combines the functions of a sound level meter, light meter, humidity meter and temperature meter to help get the job done faster. • Cat III 300V, 4000 count • AC/DC voltages up to 250V • AC/DC current up to 10A • Resistance, non-contact voltage measurement SPECIAL REWARDS CARD QM-1548 Ideal for audio enthusiasts designing their own crossovers. • Cat III 600V, 2000 count • AC/DC voltages up to 1000V/750V • AC/DC current up to 10A $ • Hfe & temperature tests 4995 $ 2995 DOUBLE POINTS Best Value True RMS Digital Multimeter QM-1551 A powerful autoranging multimeter that includes non-contact voltage testing and measures temperature, resistance, capacitance and more. • Cat III 600V, 4000 count • AC/DC voltages up to 600V $ • AC/DC current up to 10A 5995 REWARDS CARD OFFER: UP TO 35% OFF THESE NON-CONTACT THERMOMETERS* *Valid for purchase of QM-7218, QM-1602, or QM-1601. EARN A POINT FOR EVERY DOLLAR SPENT AT ANY JAYCAR COMPANY STORE* & BE REWARDED WITH A $25 REWARDS CASH CARD ONCE YOU REACH 500 POINTS! * Conditions apply. See website for T&Cs. REGISTER ONLINE TODAY BY VISITING: www.jaycar.com.au/rewards Page 4 REWARDS CARD SPECIAL Mini IP67 Infrared $1995 SAVE $10 Thermometer QM-7218 $29.95 Ultra compact, non-contact thermometer with LCD readout in Celsius or Fahrenheit. 1:1 distance to spot ratio. • -33 to +110ºC (±2.5%) • 82(L) x 17(Dia)mm Thermocouple Thermometer Pocket-Sized Thermocouple Thermometer QM-1602 $39.95 Highly accurate and wide range with k-type thermocouple suitable for the lab, workshop or in the field. 2000 count. • Thermocouples included • -50 to +750ºC (±1%) • 118(L) x 70(W) x 29(D)mm Follow us at twitter.com/jaycarAU REWARDS CARD SPECIAL $ 2495 SAVE $15 QM-1601 $79.95 Fast response and laboratory accuracy, works with K-type thermocouples and offers 0.1 or 1° user-selectable resolution in Celsius or Fahrenheit. Monitor two separate temperatures or use the differential function to compare them. 2000 count. • Thermocouples included • -50 to +1300°C (±0.5%) • 172(H) x 84(W) x 42(D)mm REWARDS CARD SPECIAL $ 5995 SAVE $20 Catalogue Sale 24 May - 23 June, 2015 SMART DATA TOOLS FOR ON-SITE TESTING & DIAGNOSIS NOW 119 $ SAVE $30 USB Temperature / Humidity Datalogger QP-6014 WAS $149 Logs temperature and humidity readings and store them in internal memory for later download to a PC. • 32,000+ memory samples • Temp -40 to +70°C (±1°C) • Humidity 0 to 100% (±3°C) • Windows 2000/XP/Vista compatible NOW 169 $ $ SAVE $30 NOW 219 $ SAVE $30 Handheld Function Generator QT-2304 WAS $199 A bench top generator in a portable size. Produces sine, square, and triangle waveform signals with output frequency adjustment from 1Hz to 1MHz with maximum amplitude of 8Vpp. • Sweep modes: Linear/logarithmic, single/ bidirectional SAVE $50 Handheld Pocket Scope QC-1914 WAS $249 A complete portable oscilloscope in a tiny size. Aside from standard scope features, it has nifty tools for measurement of RMS speaker power, display hold function, and memory storage for 2 signals. Includes CRO probe and USB charge cable. • Real Time Sample Rate: 40MSa/s • Input 1mV to 20V per division in 14 steps 2-In-1 Handheld Scope & Multimeter QM-1577 WAS $399 Combines all functions of a 4,000 count True RMS CAT III digital multimeter and a 10MHz oscilloscope. One-keypress switches between DMM and DSO. Includes USB interface and PC logging software. • 128 x 128 graphic LCD display • Autoranging, AC/DC voltage (1000V), current (20A) • 50MSa/s sample rate PROFESSIONAL ENVIRONMENT METERS IDEAL FOR CHECKING BUILDINGS AFTER ALL THE RAIN $ 49 SAVE $5 Handheld pH Meter Pocket Moisture Meter $ 95 SAVE $15 2495 SAVE, SAVE, SAVE! NOW NOW $ NOW $ 99 SAVE $30 Professional Light Meter QM-1584 WAS $129 Extremely accurate with a rapid response and can store min and max values for easy comparisons. Measurement can be switched between Lux and FC (foot candles). • Max 400k lux • Separate photo detector ALSO AVAILABLE: REPLACEMENT SOLUTION 50ML QM-1622 WAS $139 This highly accurate unit allows you to easily measure the distance between two points beyond the common tape measure. It also allows you to automatically calculate area, volume or height. • Measurement 0.05 to 35m (±1.5mm) • Stores up to 20 measurements SAVE $20 Capture videos and images in areas where your head or hands simply can’t fit into. Ideal for seeing inside car engine bays, checking inside pipes, under grates, in ceilings, and more. • 640x480 resolution • Camera: 10mm (Dia) Network Cable Tracer XC-5083 WAS $99.95 Easily trace cables even when cables are in a bundle or hidden in punchdown blocks or wall plates. Also checks telephone line polarity and status ie. ring/busy/idle. • Single/multi tone signal 1.5M FLEXIBLE CABLE QC-3373 WAS $44.95 NOW $34.95 SAVE $10 7.0M FLEXIBLE CABLE QC-3374 WAS $64.95 NOW $49.95 SAVE $15 3-In-1 Stud Detector Professional Sound Level Meter WAS $399 NOW 109 $ 3495 USB Mini Inspection Cameras QM-1671 WAS $8.95 NOW $3.95 SAVE $5 Professional Laser Distance Meter FROM SAVE UP TO $15 NOW 7995 $ QM-1670 WAS $64.95 An accurate device for checking pH levels in water. Includes 9V battery, pH 7.0 buffer solution and QP-2310 WAS $29.95 calibration tool. Replacement pH solution available An intelligent meter with 8mm electrode suitable for separately. measuring water content in building materials and • Range 1-14 pH (±0.2 pH) wooden fibre articles. • Resolution: 0.1 pH • 6 to 44% (Wood) / 0.2 to 2.0% (Material) • 96(H) x 40(W) x 20(D)mm • 4 x LR44 batteries included NOW 349 WITH LASER LEVEL QM-1592 Scales for A and C weighting are included so it’s ideal for vehicle noise testing, traffic noise or any evidence-based noise testing. • 30 to 130dB (±1.4dB) NOW • IEC 61672-1 Class 2 $ compliant 329 SAVE $30 SAVE $70 QP-2288 WAS $59.95 Indicates proximity when you are near a stud via its large LCD and shows a target graphic when you’re spot on. Built-in voltage detection. • Detects wood, metal and live wire • Thumb dial adjustable feet for levelling the laser $ 4495 SAVE $15 REWARDS CARD OFFER: UP TO 35% OFF THESE AUTO TESTERS* *Valid for purchase of QP-2258, QP-2212, QM-1494, or QM-1448. RUGGED METAL BODY! REWARDS CARD REWARDS CARD SPECIAL SPECIAL 9 $ 95 REWARDS CARD SPECIAL 7 SAVE $6 $ 95 SAVE $5 3-In-1 Auto Tester QP-2258 $12.95 Quickly check the condition of your 12V battery, charger or alternator. Compact & lightweight. 12VDC. Cordless Voltage Tester QP-2212 $15.95 Quick and easy way to locate electrical faults without a bulky meter or ground wire. Works on 3-28V circuits. It lights up and buzz when positive voltage is detected. Probe is supplied with a V-Groove tip to make piercing wire insulation safe. To order phone 1800 022 888 or visit www.jaycar.com.au $ 44 95 SAVE $15 Multi-Function Circuit Tester QM-1494 $59.95 Designed for 12/24V vehicles, it tests polarity, voltage, short/open status, lights and more. Quickly test circuits without using jumper wires. All the features of a brand name unit at a fraction of the price. See terms & conditions on page 8. REWARDS CARD SPECIAL $ 5995 SAVE $20 Digital Tachometer QM-1448 $79.95 Measures up to 99,999RPM and can also count revolutions. Large LCD screen, laser pointer and min/max recall. 5 digits display. Four AA batteries included. Page 5 UP TO 70% OFF CLEARANCE STOCK TEST & TOOLS See website for technical specifications PCB Holder Repair Kit for iPhone® WITH 90MM MAGNIFYING GLASS Network Cable Tester - UTP/STP/ Coax/Mod 19 PIECE TH-1983 ORRP $12.95 TD-2113 ORRP $29.95 NOW 9 SAVE $3 $ PCB not included Forehead & Ear Thermometer NOW QM-7271 ORRP $29.95 $ SAVE $10 NOW 2295 SAVE UP TO 70% SF-5122 RQ-5289 RQ-5298 RQ-5285 PS-0532 PP-1154 PP-1148 PP-1128 PA-3692 PA-3690 HC-4066 HC-4062 PP-0209 PS-0280 HH-8607 HP-1156 ZV-1637 ZZ-8800 PI-6483 HOT! HOT! HOT! Blade Fuse Mini Wire Tap 15A Crystal 10MHz HC49U Crystal 38kHz DT38 Miniature Crystal 6MHz HC49U DC Socket 0.7mm PCB Mnt with Slide Switch IDC Locking Right-Angle Header 16 Pin IDC Locking Vertical Header 50 Pin IDC Right-Angle Header 34 Pin Plug 1.75mm to Suit Plugpack - Green Dot Plug 1.7mm to Suit Plugpack - Blue Dot Power Terminal Gold Plated 2GA Power Terminal Gold Plated 4GA RCA Plug Crimpless - Green RCA Socket Double - PCB Mount TO-220 Dual Heatsink Clamp Pk 100 TO-220 Rubber ORRPher Pk100 Voltage Regulator LM2678T-12 Wafer Card with PIC16F84A + 24LC16B ZIF Socket 28 Pin HOT! HOT! HOT! HOT! HOT! ORRP NOW SAVE $6.95 $4.50 $4.50 $4.50 $5.95 $1.75 $3.75 $2.25 $2.95 $2.95 $8.95 $8.95 $3.50 $1.95 $19.95 $17.95 $16.95 $11.95 $14.50 $1.95 $1.50 $1.50 $1.50 $2.95 $0.75 $1.95 $0.95 $1.65 $1.65 $4.95 $4.95 $1.50 $0.95 $11.95 $7.95 $8.95 $5.95 $6.50 $5.00 $3.00 $3.00 $3.00 $3.00 $1.00 $1.80 $1.30 $1.30 $1.30 $4.00 $4.00 $2.00 $1.00 $8.00 $10.00 $8.00 $6.00 $8.00 SAVE $8 WITH 200X ZOOM $ SAVE $12 NOW 2195 USB Digital Microscope 2MP QM-7201 ORRP $89.95 1995 $ SAVE $20 WITH SMARTPHONE APP NOW CAT. NO. PRODUCT NOW 1995 Body Thermometer QM-7272 ORRP $34.95 $ TD-2107 ORRP $29.95 $ SAVE $12 Ear Thermometer 30 PIECES XC-5076 ORRP $39.95 1795 $ 95 Electronic Tool Kit NOW 6995 QC-3197 ORRP $79.95 $ SAVE $20 NOW 5495 SAVE $25 HARDCORE COMPONENTS See website for technical specifications PLCC Socket Surface Mount 84 Pin PI-6630 ORRP $5.95 Power Terminal Gold Plated 0GA HC-4068 ORRP $8.95 NOW 95 c SAVE $5 NOW 3 $ 95 SAVE $5 D-Sub Socket 25-Pin Waterproof PS-1220 ORRP $19.95 NOW 1295 $ SAVE $7 NOW ZIF Socket 40 Pin 6 $ 50 PI-6484 ORRP $15.50 SAVE $9 AUTO & OUTDOORS See website for technical specifications NOW 9 $ 95 $ SAVE $10 NOW 2495 $ SAVE $10 Car Charger/Audio Kit iPhone not included. Car Holder & FM Transmitter FOR IPHONE®/IPOD® MB-3653 ORRP $19.95 FOR IPHONE®5 AR-3125 ORRP $34.95 Car OBD2 Computer Memory Saver Map Measure Digital WITH LED LIGHT XC-0374 ORRP $9.95 PP-2140 ORRP $9.95 NOW 4 NOW 6495 SAVE $15 NOW 5 Reversing Camera 12-24VDC Siren Waterproof Rechargeable Camping Shower NOW 2495 $ 95 $ 95 $ SAVE $5 SAVE $4 SAVE $10 Page 6 SAVE $30 Car Mini Dash Cam 1080p QV-3846 ORRP $79.95 LA-8903 ORRP $34.95 Follow us at facebook.com/jaycarelectronics NOW 169 $ WITH 5 INCH LCD MONITOR QM-3741 ORRP $199 YS-2802 ORRP $39.95 $ NOW 2795 SAVE $12 Catalogue Sale 24 May - 23 June, 2015 UP TO 80% OFF CLEARANCE STOCK AUDIO & VIDEO See website for technical specifications SAVE UP TO 80% CAT. NO. PRODUCT WQ-7299 AA-0373 AA-2097 AR-1895 LT-3205 WQ-7298 SL-3441 AS-2084 AA-2069 AA-2079 AM-4087 AX-3598 PT-0475 YN-8059 3.5mm/Toslink Fibre Optic Swappable Lead Amplifier Module Mono 0.5W Handsfree Aux Mic Lead For Smartphones Amplifier Stereo Wireless 2.4GHz 15WRMS Antenna Mount Adjustable Bracket Audio Lead Toslink-3.5mm Fibre Optic - 1m Disco LED RGB Light - Flashing Earphones for Kids with Volume Limiter Earphones Stereo/Bluetooth®/Rechargeable Earphones with TV Hearing Aid Microphone Desktop 3.5mm Plug Speaker Protection Grille 15" with Clips Wallplate Multimedia VGA/HDMI/RCA/3.5mm Wallplate VGA Socket with 4 Ports HOT! HOT! HOT! HOT! HOT! ORRP NOW SAVE $14.95 $11.95 $9.95 $99.00 $24.95 $9.95 $79.95 $9.95 $74.95 $129.00 $12.95 $12.00 $29.95 $9.95 $6.95 $5.95 $5.95 $49.00 $16.95 $4.95 $59.95 $3.95 $54.95 $79.00 $7.95 $2.00 $19.95 $4.95 $8.00 $6.00 $4 $50.00 $8.00 $5.00 $20.00 $6.00 $20.00 $50.00 $5.00 $10.00 $10.00 $5.00 NOW 7995 $ SAVE $20 NOW $ 99 SAVE $20 Cassette Player HDMI Switcher 4 Input GE-4139 ORRP $99.95 AC-1709 ORRP $119 WITH USB/SD ENCODER $ NOW 4495 SAVE $15 Video Converter DVI to VGA WQ-7445 ORRP $59.95 WITH AUDIO RETURN $ NOW 6995 SAVE $30 Speaker Stand EXTRA HEAVY DUTY CW-2860 ORRP $99.95 IT & COMMUNICATIONS See website for technical specifications SAVE UP TO 60% CAT. NO. PRODUCT WC-7729 MB-3695 HS-9016 WC-7717 AR-1889 AR-3320 XC-5202 XC-4949 XC-5412 WC-7510 XC-5220 XC-4691 XC-4143 WC-7736 YN-8364 Adaptor Plug - Micro-B USB to Lightning Battery Back-up Case to suit iPhone 5® Bicycle Bracket Mount for iPhone 3/4® Docking Station for Apple® to HDMI Device Docking Station/Speaker for iPhone®/iPod® FME to Telstra 4G USB Modem Cable Keyboard Foldable with Bluetooth® KVM & Data Transfer USB Cable Laser Pointer Plug-in for iPod®/iPhone® RS232 Extension Computer Lead 3m Speaker Wireless - Near Field Audio USB 3.0 Cloud Dock USB 3.0 Dual Port PCI-E Interface Card USB Retractable Lead A-Plug to MicroB Skt Wi-Fi Extender Dual Band HOT! HOT! HOT! HOT! HOT! HOT! ORRP NOW SAVE $14.95 $39.95 $19.95 $49.95 $49.95 $16.95 $39.95 $49.95 $19.95 $19.95 $39.95 $99.00 $34.95 $11.95 $89.95 $6.95 $29.95 $7.95 $24.95 $24.95 $6.95 $24.95 $34.95 $11.95 $11.95 $24.95 $59.00 $29.95 $6.95 $64.95 $8.00 $10.00 $12.00 $25.00 $25.00 $10.00 $15.00 $15.00 $8.00 $8.00 $15.00 $40.00 $5.00 $5.00 $25.00 $ NOW 27 95 $ SAVE $12 Stereo Car Handsfree Kit WITH BLUETOOTH® TECHNOLOGY AR-3130 ORRP $39.95 $ Panel Mount Bluetooth Receiver WITH MIC AR-3129 ORRP $49.95 95 $ SAVE $20 Wireless Presenter WITH MOUSE AND LASER XC-5413 ORRP $59.95 3495 SAVE $15 NOW 39 NOW NOW 399 SAVE $50 UPS Online Rack Mountable 1000VA/700W MP-5212 ORRP $449 SECURITY & SURVEILLANCE See website for technical specifications SAVE UP TO 70% CAT. NO. PRODUCT ORRP NOW SAVE QC-8627 MP-3351 QC-8644 LA-5024 SL-3232 LA-5156 LA-5355 LA-5214 LA-5262 LA-5005 LA-5174 LA-5304 LA-5303 LA-5163 $99.95 $39.95 $149.00 $44.95 $49.95 $299.00 $39.95 $19.95 $44.95 $19.95 $59.95 $24.95 $24.95 $9.95 $69.95 $24.95 $119.00 $29.95 $27.95 $209.00 $29.95 $8.95 $39.95 $4.95 $27.95 $9.95 $9.95 $6.95 $30.00 $15.00 $30.00 $15.00 $22.00 $90.00 $10.00 $11.00 $5.00 $15.00 $32.00 $15.00 $15.00 $3.00 Bullet Camera Weatherproof with IR 600TVL CCTV Power Distributor Box Dome Camera CCD 3-Axis with IR 800TVL Doorbell Wireless with MP3 Music Emergency Spotlight Rechargeable with PIR Intelligent GSM Wireless Alarm System Keypad Security 12VDC Keypad Shed Alarm Siren with 10 Sounds and Mic 12V Solar Powered Magnetic Entry Alarm Solar Wireless PIR Announcer Strobe Light Mini - Orange Strobe Light Mini - Red Water Leakage Alarm 120dB Siren HOT! HOT! HOT! HOT! HOT! To order phone 1800 022 888 or visit www.jaycar.com.au NOW $ 99 SAVE $50 Bullet Camera CCD WITH IR 650TVL QC-8634 ORRP $149 NOW 7995 $ SAVE $20 Wi-Fi IP Camera Ai-Ball VGA QC-3368 ORRP $99.95 See terms & conditions on page 8. NOW $ 99 SAVE $50 Dome Camera CCD WITH IR 650TVL QC-8636 ORRP $149 $ NOW 549 SAVE $150 DVR 16-Channel Network WITH 1TB HDD QV-3039 ORRP $699 Page 7 UP TO 60% OFF CLEARANCE STOCK Listed below are a number of discontinued (but still good) items that we can no longer afford to hold stock. Please ring your local store to check stock. At these prices we won’t be able to transfer from store to store. STOCK IS LIMITED. ACT NOW TO AVOID DISAPPOINTMENT. SORRY NO RAINCHECKS. POWER & LIGHTING See website for technical specifications CAT. NO. PRODUCT HH-8549 HH-8547 SB-2540 MB-3605 MB-3646 HM-3086 ST-3206 SL-2220 SL-2222 ST-3291 SL-3140 SL-3458 ZD-0373 AA-0595 ST-3085 SL-2210 SL-2216 SL-2231 SL-2207 SL-3472 ZD-0606 ZD-0605 SL-3465 ZD-0463 SL-3139 ST-3341 ST-3357 ST-3486 ST-2807 SL-3473 ST-3264 PP-4039 MS-6158 MP-3452 ST-3460 Aluminium Extrusion 2-Pce for LED Strip 1m Aluminium Extrusion for LED Strip 1m Battery Lithium 3.6V for Motherboard Battery Backup with Lightning® Connector Battery Bank with iPod® Charger 5000mAh Battery Clamps Stainless Steel 400A LED Book/Laptop Reading Light LED Candle Globe E14 2800K 3.2W 230Lm LED Candle Globe E14 4000K 3.2W 230Lm LED Cap Torch 160Lm LED Desk Lamp with USB Charger LED Downlight "Hockey Puck" Style 45Lm LED Downlight Kits 3000K 15W 900Lm LED Driver Constant Current - Dimmable LED Emergency Light with Magnetic Base LED Globe Dimmable/Bayonet 2800K 5W 400Lm LED Globe Dimmable/Bayonet 4000K 10W 900Lm LED Globe Dimmable/Screw 2800K 8W 500Lm LED Globe Dimmable/Screw 6000K 10W 900Lm LED Spotlight Gymbal Flush Mount 3W 165Lm LED Spotlight MR16 2800K 4.5W 220Lm LED Spotlight MR16 6000K 4.5W 250Lm LED Strip Lamp For Vehicles C. White 140Lm LED Strip Warm White 500(L)x8(W)mm 12V 150Lm LED Table Lamp 3500-5500K 270Lm LED Torch Multi-Functional Dynamo LED Torch with Radio & Dynamo Charger LED Torch Yellow 300 Lumens LED USB Flexible Light 6000K 300Lux LED Wall/Desk Mount Gooseneck Lamp 75Lm LED Worklight Low Cost 12V Mains Double Adaptor with Night Light Mains Sockets IR Controlled Wireless Mains Travel USB Adaptor Torch Magnetic with Gooseneck 150Lm HOT! HOT! HOT! HOT! HOT! HOT! HOT! HOT! ORRP NOW SAVE $29.95 $22.95 $15.95 $34.95 $59.95 $9.95 $19.95 $19.95 $19.95 $12.95 $39.95 $17.95 $99.00 $12.95 $14.95 $14.95 $29.95 $22.95 $29.95 $34.95 $19.95 $19.95 $24.95 $14.95 $89.95 $19.95 $29.95 $19.95 $14.95 $19.95 $29.95 $9.95 $26.95 $12.95 $44.95 $14.95 $10.95 $5.95 $19.95 $39.95 $4.95 $11.95 $11.95 $11.95 $7.95 $29.95 $12.95 $39.00 $9.95 $9.95 $9.95 $17.95 $12.95 $17.95 $24.95 $9.95 $9.95 $19.95 $8.95 $74.95 $11.95 $21.95 $11.95 $9.95 $14.95 $21.95 $4.95 $9.95 $6.95 $21.95 $15.00 $12.00 $10.00 $15.00 $20.00 $5.00 $8.00 $8.00 $8.00 $5.00 $10.00 $5.00 $60.00 $3.00 $5.00 $5.00 $12.00 $10.00 $12.00 $10.00 $10.00 $10.00 $5.00 $6.00 $15.00 $8.00 $8.00 $8.00 $5.00 $5.00 $8.00 $5.00 $17.00 $6.00 $23.00 NOW 6 $ SAVE $8 SAVE $30 Snap-On Battery Terminals RED / BLACK 500A HM-3087 ORRP $14.95 $ Solar Panel Monocrystalline 12V 90W ZM-9086 ORRP $249 NOW 2495 $ SAVE $15 NOW 2995 SAVE $20 LED Spot / Running Lamps 12V 120Lm SL-3445 ORRP $39.95 LED Worklight 240V IP65 600Lm ST-3263 ORRP $49.95 NOW $ NOW 219 $ 95 89 NOW 139 $ SAVE $30 SAVE $30 LED Worklight Rechargeable 30W 1500Lm SL-2889 ORRP $119 HID Spot / Search Light 3200Lm WITH PAN / TILT ST-3377 ORRP $169 DON’T MISS OUT ON OUR YEARLY CLEARANCE! VISIT OUR WEBSITE WWW.JAYCAR.COM.AU TERMS AND CONDITIONS: REWARDS CARD HOLDERS FREE GIFT, % SAVING DEALS, DOUBLE POINTS & REWARDS OFFERS requires active Jaycar Rewards Card membership at time of purchase. Refer to website for Rewards Card T&Cs. DOUBLE POINTS ACCRUED during the promotion period will be allocated to the Rewards Card after the end of promotion. LISTED ON PAGES 6 TO 8 are a number of discontinued (but still good) items that we can no longer afford to hold stock. Please ring your local store to check stock. At these prices we won’t be able to transfer from store to store. STOCK IS LIMITED. ACT NOW TO AVOID DISAPPOINTMENT. SORRY NO RAINCHECKS. SAVINGS OFF ORIGINAL RRP (ORRP). Australian Capital Territory South Australia Port Macquarie Ph (02) 6581 4476 Mermaid Beach Ph (07) 5526 6722 Belconnen Ph (02) 6253 5700 Rydalmere Ph (02) 8832 3120 Nth Rockhampton Ph (07) 4926 4155 Adelaide Ph (08) 8231 7355 Fyshwick Ph (02) 6239 1801 Shellharbour NEW Ph (02) 4256 5106 Townsville Ph (07) 4772 5022 Clovelly Park Ph (08) 8276 6901 Smithfield Ph (02) 9604 7411 Strathpine Ph (07) 3889 6910 Elizabeth Ph (08) 8255 6999 Sydney City Ph (02) 9267 1614 Underwood Ph (07) 3841 4888 Gepps Cross Ph (08) 8262 3200 Woolloongabba Ph (07) 3393 0777 Modbury Ph (08) 8265 7611 Reynella Ph (08) 8387 3847 New South Wales Albury Ph (02) 6021 6788 Taren Point Ph (02) 9531 7033 Alexandria Ph (02) 9699 4699 Tuggerah Ph (02) 4353 5016 Bankstown Ph (02) 9709 2822 Tweed Heads Ph (07) 5524 6566 Blacktown Ph (02) 9678 9669 Wagga Wagga Ph (02) 6931 9333 Bondi Junction Ph (02) 9369 3899 Warners Bay Ph (02) 4954 8100 Brookvale Ph (02) 9905 4130 Warwick Farm NEW Ph (02) 9821 3100 Campbelltown Ph (02) 4625 0775 Wollongong Ph (02) 4226 7089 Castle Hill Ph (02) 9634 4470 Coffs Harbour Ph (02) 6651 5238 Croydon Ph (02) 9799 0402 Aspley Ph (07) 3863 0099 Dubbo Ph (02) 6881 8778 Browns Plains Ph (07) 3800 0877 Erina Ph (02) 4365 3433 Caboolture Ph (07) 5432 3152 Fairy Meadow Ph (02) 4225 0969 Cairns Ph (07) 4041 6747 Gore Hill Ph (02) 9439 4799 Caloundra Hornsby Ph (02) 9476 6221 Victoria Western Australia Cheltenham Ph (03) 9585 5011 Coburg Ph (03) 9384 1811 Bunbury Ph (08) 9721 2868 Ferntree Gully Ph (03) 9758 5500 Joondalup Ph (08) 9301 0916 Frankston Ph (03) 9781 4100 Maddington Ph (08) 9493 4300 Geelong Ph (03) 5221 5800 Mandurah Ph (08) 9586 3827 Hallam Ph (03) 9796 4577 Midland Ph (08) 9250 8200 Kew East Ph (03) 9859 6188 Northbridge Ph (08) 9328 8252 Ph (03) 9663 2030 Osborne Park Ph (08) 9444 9250 Mornington Ph (03) 5976 1311 Rockingham Ph (08) 9592 8000 Ringwood Ph (03) 9870 9053 Ph (07) 5491 1000 Roxburgh Park Ph (03) 8339 2042 Capalaba Ph (07) 3245 2014 Shepparton Ph (03) 5822 4037 Hobart Ph (03) 6272 9955 Launceston Ph (03) 6334 2777 Queensland Melbourne City Maitland Ph (02) 4934 4911 Ipswich WE HAVE MOVED Ph (07) 3282 5800 Mona Vale NEW Ph (02) 9979 1711 Springvale Ph (03) 9547 1022 Labrador Ph (07) 5537 4295 Newcastle Ph (02) 4968 4722 Sunshine Ph (03) 9310 8066 Mackay Ph (07) 4953 0611 Penrith Ph (02) 4721 8337 Thomastown Ph (03) 9465 3333 Maroochydore Ph (07) 5479 3511 Werribee Ph (03) 9741 8951 Tasmania Northern Territory Darwin Ph (08) 8948 4043 Arrival dates of new products in this flyer were confirmed at the time of print but delays sometimes occur. Please ring your local store to check stock details. Savings off Original RRP. Prices and special offers are valid from 24 May - 23 June, 2015. YOUR LOCAL JAYCAR STORE Free Call Orders: 1800 022 888 HEAD OFFICE 320 Victoria Road, Rydalmere NSW 2116 Ph: (02) 8832 3100 Fax: (02) 8832 3169 ONLINE ORDERS Website: www.jaycar.com.au Email: techstore<at>jaycar.com.au Occasionally there are discontinued items advertised on a special / lower price in this promotional flyer that has limited to nil stock in certain stores, including Jaycar Authorised Stockist. These stores may not have stock of these items and can not order or transfer stock. SERVICEMAN'S LOG Diversifying – it’s not that easy Diversifying into smartphone and tablet repairs seemed like a good idea some time ago but experience has proven otherwise. And no more was this brought home to me than a scrape I got myself into with a couple of smartphones I recently wasted a lot of time on. In this business, the name of the game is diversification. This often means changing direction and focus from an existing core business model to something new (yet hopefully complementary) in order to increase custom and income potential. Indeed, I’ve talked about this before because on many levels, the computer repair industry is a dying one. The golden days enjoyed by the local computer guy have long gone due to a now much more tech-savvy public and due to turn-key software and related systems that require no specialist know­ ledge to set up, configure or maintain. Ten years ago, just about every household boasted a desktop com- puter that was typically shared by the whole family. Sometimes there would be a couple of machines; one for the kids and one for mum and dad. These days, however, many households no longer bother with a desktop computer because the kids likely have their own smartphones and/or tablets for doing school work (and communicating with each other via social media), while mum and dad also have smart-phones and perhaps a work-supplied laptop or tablet on which to do their Internet banking, “Skypeing” and emailing. Now I know I’m being terribly stereotypical but such generalisations hammer home my point. While in some instances a laptop, phone or tablet can Dave Thompson* Items Covered This Month •  No-name smartphone repair •  Industrial machine servicing •  Modifying & repairing an offgrid battery charger *Dave Thompson runs PC Anytime in Christchurch, NZ. Website: www.pcanytime.co.nz Email: dave<at>pcanytime.co.nz never replace a desktop for some tasks (eg, high-end architectural or graphics designers), the fact remains that the number of families owning a communal desktop computer has significantly declined over the past few years. These days, when the “family” desktop starts playing up or reaches its end-of-life, it’s typically not repaired or replaced because there is no longer a need for it. And this scenario is increasingly being repeated. Understandably, people can’t rationalise spending even a few hundred dollars on something they are not going to use anywhere near as much as they used to, especially when they have other gadgets that can do a similar job. Another nail Unfortunately, the demise of the desktop is just another nail in the coff­in for the computer serviceman because a large portion of our bread and butter work goes with it. And while there can be valid arguments for repairing a laptop, in most cases they are so cheap to buy and the parts so ridiculously expensive (or not even obtainable) that repairing them has become either uneconomical or simply not feasible. The same philosophy applies even more so to smartphones and tablets, which leaves retail sales or, at a stretch, consulting work as the only potential income streams for micro-businesses like mine. In the case of sales, however, we simply cannot compete with the siliconchip.com.au June 2015  53 Serviceman’s Log – continued large retailers and as for consulting work, anyone can find out pretty much anything they need to know on Google these days – all at no cost. So shelling out even minimum wage money to get a “specialist” in isn’t warranted. When I discuss this with other people, the first thing many suggest is getting into smartphone and tablet sales and repairs. That’s not a silly idea until you look at the nuts and bolts and in fact, I seriously considered doing that a few years ago when I first saw the writing on the wall for computer repairs. I even went so far as to set up tentative import chains from Asia to supply phones, tablets and even some computer hardware. On paper and in theory, this initially looked very promising and I was extremely excited about the prospects. I could buy low and sell high enough to remain competitive and still make money but it didn’t take long for the cracks to start showing. For a start, much of the hardware wasn’t up to the quality that we’ve come to expect. Most no-name phones look the part in the glossy promotional material and some even work quite well for a while. However, they really are built to a price and as such do not stand up to everyday use as well as their more-expensive brand-name 54  Silicon Chip cousins. Out of a dozen of the best quality phones I could find to import and sell, every single one came back within six months with problems that would cost more to repair than it would to simply replace the phone. But that wasn’t the end of my problems, as I found out when I tried to return them under warranty to the various suppliers. That’s when the system really fell apart as not one vendor was interested in helping to sort it out. In the end, I wore the costs myself in an effort to maintain credibility with my customers. Apart from the damage to my business, what really depressed me was that my hopes had been dashed. Importing and selling products in this way was not the answer I was looking for. The fact remains that many of today’s “tech” devices are purposely engineered to be consumable – that is, to simply be replaced if or when they fail. In my experience, most people who bring in a phone or tablet with a broken screen or some other fault don’t want to spend more than a few dollars to get it repaired. Indeed, most are taken aback when they discover the cost to replace an iPhone, iPad or Samsung Galaxy screen, preferring instead to use this as an excuse to go and buy a new (and usually fancier) phone. And I don’t blame them one bit. Recent experience A recent experience of my own illustrates why it just isn’t worth trying to eke out a living by importing no-name hardware from Asia or by offering to fix high-end phones and tablets, no matter how lucrative it may appear to be on paper. My wife and I both needed new phones, with our old models years out of date and “er-in-door’s” one finally giving up the ghost. As a result, she looked through some of the websites of vendors we’ve dealt with before online and found a brand-name phone that was reasonably priced and which boasted the features we both wanted. It certainly looked good to me and because it was branded and priced a bit higher than some of the no-name ones we’d seen in the past, we decided to take a punt and order two of them When they arrived, it certainly looked like the gamble had paid off because the phones were beautiful, fast and had everything we could ever want in a phone. Setting them up was a breeze and transferring our data from the old phones almost too easy, so it wasn’t long before we both had our respective phones on-line and in use. But there was one small niggle: Nina’s phone sometimes wouldn’t hang up after making a call. The screen initially wouldn’t respond to any touch commands but after about 30 seconds it would suddenly work and we could then hit the “hang up” button. By itself, it wasn’t a major problem but it was annoying. What’s more, it soon became apparent that the fault not only occurred when making a call because at other times, the screen would be nonresponsive for about 30 seconds before suddenly becoming usable again. At that point, I offered to swap phones because my handset didn’t exhibit any of those problems. Nina uses dual SIM cards in her phone and indeed one of the main reasons we purchased this model was because of the dual SIM feature, which allows both work and private use in the same handset. I don’t use two SIMs so perhaps it was her use of dual SIMs that was causing the screen “freezing” problems in her phone? After swapping the phones, she no longer had problems but now I was experiencing the screen “freezes”, so it was definitely the phone that was causing the problem and nothing to do with running two SIM cards. Because I mainly use my phone for business, we swapped them back while I looked into possible causes and solutions, something that requires a lot perseverance due to the enormous amount of information posted online in various forums. One disadvantage was that with newer phones, there is often not much information online but I looked anyway, in case someone else had experienced the same issue. The first place I looked was on the phone manufacturer’s website and I downloaded their “link” software, hoping I could use this to install upgrades or troubleshoot potential issues. Strangely though, I couldn’t find our specific model listed on the site and that rang a few warning bells far off in the back of my mind. The downloaded software “talked” to the phone quite happily but informed me that there were no updates siliconchip.com.au available or required. And that appeared to be about the limit of the functionality of that particular program. A little more research on the model number, chip version and firmware information took me to forums where people were claiming that the phone was fake and that the manufacturer (and it looked increasingly like it wasn’t who we thought it was) had spoofed the hardware ID to make it look like something it wasn’t. By that stage, there were more alarm bells going off in my head, only louder this time. About this time, just before Easter, Nina decided to uninstall an app on the phone because it was persistently downloading unwanted games and other rubbish – the bane of the modern smartphone owner. Strangely, mine didn’t do this and we had previously tried using other apps we’d purchased to “freeze” this games app. However, it just seemed to circumvent any attempts at stopping it, which is why she eventually decided to uninstall it. Once it had been uninstalled, the phone immediately rebooted but then got stuck in a loop, with the Android shell crashing then restarting, crashing then restarting and so on. Did I hear bells again? Yes, and they were lot louder now . . . Luckily, Easter was coming up and I thought I’d use some of my spare time (that I had intended to use to make a valve amplifier project I’d been planning) to tidy this phone up and get it going again. And so, over Good Friday, I spent many hours on it, initially trying to get it going before eventually resorting to restoring it to its factory settings. It did this OK but unfortunately, when I restarted it, the shell was still crashing, so something else had to be wrong. Fortunately, I had an identical phone and my reasoning was that I’d find a utility to back up its ROM (ie, the entire operating system and applications) and upload the file into Nina’s phone. Problem solved – well, that was the theory anyway. Rabbit hole This phone uses a chip-set called “MTK” and some clever person has written a set of tools specifically for phones running this family of processors and has made it freely available for download. Once I had this software, it should then be a simple matter of siliconchip.com.au copying my ROM and then flashing it back to Nina’s handset. But of course there was a problem – and this is what I’ve found when working on phones and tablets; one problem leads to another, then to another and so on until I could barely remember how far down the rabbit hole I had gone. The problem here was that since we’d had these phones for a couple of weeks before all this started happening, I had swapped the standard Android KitKat bits and pieces that came with the phone with a custom one I’d used before on my old phone. Simply put, this app stores the standard user interface into another folder and replaces it with a new one, so that every time the phone boots it loads the new interface and leaves the old one in storage. I’d also done this with the web browser, SMS/Messaging app, the standard file manager, the screen lock (that bit when you wake the phone up and swipe to unlock) and the phone dialler, replacing them with custom apps with more features. Initially, I thought that when I “ripped” my ROM to my hard disk, it would pick those custom bits up and take them along too but I was wrong. All went well when I flashed Nina’s phone via the USB interface but when it booted, it didn’t have a user shell, dialler, SMS, browser or file manager, or any other component that I had customised on my phone. I could pull the “shade” down and access the phone’s settings but that was it. If I’d had a file manager, I could have found and installed the apps I needed but I didn’t. And if I’d had a browser, I could have used Google Play to download the apps and install them. But I didn’t have any of those things and nor could I get them onto the phone. No problem, I thought, I’ll simply restore my phone to standard, then go through the same process, this time flashing all the right bits and pieces to get things going. The spanner in this theory was that when I restored my phone, it ended up doing the same thing as Nina’s! Aaarrgghhh! By this time, it was Saturday afternoon and I had spent many more hours on this than I should have. What’s more, I was further away from a result than ever before. By now, Nina was commenting on the amount of time it was taking and I agreed; I needed to resolve this problem. Unfortunately, Google offered no relief – nobody had any suggestions for the pickle I had got myself into. I slept on the problem and then spent half of Sunday trying different things, including installing Android’s June 2015  55 Serviceman’s Log – continued SDK (application development suite) and using an ADB console (think DOS prompt on Windows machines) to try to “side-install” apps I’d previously downloaded or found on my own phone. I finally got it all connected but every time I tried to install an “apk” file (a standard Android app file), I got an error stating that the “apk” was corrupt and no matter what I did, I couldn’t install any apps this way. By Monday, I was thoroughly sick of it and with two dead phones in front of me, I sat back and took stock. I had a ROM missing some components, so I tried finding software to disassemble and repack the ROM with the right bits. I eventually found such software and repacked the ROM but it wouldn’t flash (more error messages and hair pulled out). And then I realised something; each time I had restored a phone using the MTKDroid tools app, it offered to install a couple of utilities (unfortunately not the kind that would have helped me out), side-loading them via an automatic ADB console. This system worked, so I hit upon the idea of changing the three “apk” files it was installing. Basically, I would get it to install my file manager and web browser “apk” files by renaming them and putting them in the same folder as the MTK “apk” files. I did this and pressed the upload button and . . . yes! The file manager installed and worked! The web browser failed but when I renamed its files and 56  Silicon Chip tried them one at a time, I managed to install a locker, file manager, root browser and web browser and thus could finally download and install the rest of what I needed By this time, it was 7 o’clock in the evening of Easter Monday. I finally had the job done but when people ask me what I did over Easter, I sheepishly hold my tongue and just say that I had a relaxing weekend! The phones are working fine now but this episode clearly demonstrates why fixing phones and tablets isn’t a viable career move. Aside from the frustrations and the lost time that could have been spent with loved ones, there’s no way I could ever charge enough for a job like that. I’ll have to find another way. Industrial machine servicing Now for something completely different – servicing and refurbishing industrial metal-forming machines. G. S, of Montrose, Tasmania has some interesting stories to tell . . . In an earlier contribution, I mentioned that I have a small company that designs controls for machines and does factory automation. However, we do get saddled with the odd service job, especially when electricians draw a blank. One such case concerns a client I have had for several years. He owns a substantial building products company that makes roofing iron, gutters, fascias and purlins etc. He has fairly old machines that I have managed to keep going by re-building the control gear and he is also lucky enough to employ a fitter who used to work for a metal-forming machinery manufacturer. Between us, we can pretty much get anything working but we get some unusual legacy problems from the previous owners at times. Because my client has a lot of confidence in us, he is always purchasing old machines that other manufacturers were looking to dump. Normally, when a machine reached its use-by date, the owner would purchase a new machine then have the old one cut up and scrapped, to prevent someone getting it running and creating competition. However, because Tasmania is viewed as a foreign land, we are not seen as competition by the mainlanders who are usually only too happy to sell their “junk” to us. In one instance, I was summoned to look at a “new” panbrake folder. This was a monster that could bend nearly eight metres of 3mm sheet. It also had a hydraulic-powered slitter on its back. An electrician had hooked it up and it all seemed to run OK. However, when a fold was called for and the apron began to swing, the clamp would open slightly and release the work piece. It turned out that this was why the previous owner had got rid of it. He had had it upgraded to carry the slitter and it had not worked properly since then. Apparently, he’d had a number of siliconchip.com.au Before Modification After Modification Modifying & Repairing An Off-Grid Battery Charger Deciding to fix something rather than simply scrap it is often a gamble, both in terms of time and money. And of course, there’s never any guarantee of success. Fortunately, it was a gamble that paid off when J. D. of Dubbo, NSW decided to repair a faulty off-grid battery charger . . . This story has two aspects: (1) the actual technical challenge of the repair and (2) the vexed question as to whether the item concerned was actually worth saving. Basically, I have an off-grid system supplying power to my house, or more exactly, two identical systems, with the house wiring split. One system can keep us going at a pinch if necessary. The entire system was installed nearly 20 years ago and has two separate battery chargers (Woods Dialomatic 2440) connected to a generator, so that batteries can be used when it is cloudy for more than a few days. Both chargers had been faultless until a couple of years ago when they both failed about six months apart. After some troubleshooting, I determined that the problem in each unit was on the mains control circuit board. I then took them to a local technician who replaced the boards (at some cost), after which they again functioned normally. Although they are nearly 20 years old, they do not see all that much use. In the first year, for example, they operated only about five hours. Recently, one of them ceased working again and as it was only a siliconchip.com.au year since the repair, I took it back to the technician. A week or so later I got a call to say that they could not repair it, as the parts were no longer available. I called the manufacturer (yes, the units were Australian-made and the company is still manufacturing equipment) and they told me that there were only two parts not available for that model – the transformer and rectifier. And yes, they had just had an enquiry about a rectifier from Dubbo. Because I was an established customer of theirs, they offered to sell me a current-model replacement charger for just over $1000. Although my chargers are only about 20 years old, the design is actually about 40 years old according to the manufacturer I picked up my charger from the local technician the following day and he offered a replacement charger, a little smaller and presumably made in China, for $600 or there­abouts. However, for the time being, I decided to see if anything could be done to resurrect the faulty unit. After all, what could be so special about the rectifier? Once home, I pulled the covers off and examined the unit. The transformer actually has two secondary windings and the rectifier is in fact two separate half-wave rectifiers, each comprising two diodes soldered to 150mm lengths of 19mm-diameter copper pipe. The copper pipes act as heatsinks and the whole lot is assembled onto a fibreglass board. At least one of the diodes had shorted internally and the resulting heat had melted the solder, disconnecting the diode from its copper pipe and disconnecting the negative battery lead in the process. So it was no wonder that the charger had failed completely. The problem was, how could it be fixed? After going through the Jaycar catalog, I decided to try using two BR354 35A bridge rectifiers with their outputs paralleled. And to keep them cool, these would be mounted on the largest alloy heatsink that would fit in the available space. These parts duly arrived and it was then just a matter of assembling everything in the case. This wasn’t quite as easy as it sounds though, since very heavy wiring is required throughout. Once the job was finished, the charger was tested and reconnected and it then functioned normally for an entire tank of fuel in the generator. This repair probably took about four hours of work but that included scratching around in the shed for suitable wire, tags, bolts, etc. I also spent a total of $43 for parts which is considerably less than the replacement cost for the charger. So why didn’t the technician repair it the way I did? I can see a few reasons, including liability, lack of time and warranty issues. However, it does make you wonder just how much equipment gets scrapped when it could be repaired for much less than the cost of replacing it. June 2015  57 Serviceman’s Log – continued people look at it with no result, so in the end he decided to dump it. However, my client heard about it somehow and offered him a few dollars for it. In fact, it actually cost him more to ship it. Anyway, I watched what it was doing and it looked like the problem was in the PLC (programmable logic controller) program, as it was sending a short pulse to the “open” hydraulic valve on the clamp every time a fold was called for. This made it awkward as I didn’t have the tools to program this particular species of PLC. Nor did I feel inclined to spend a heap of money on the programming tools. This called for some lateral thinking. As the problem only occurred when the apron was asked to swing, the obvious answer was to block the clamp-open valve during the swing. As a result, I added a relay across the apron valve, with its normally closed contact in series with the clamp-open valve. That solved the problem and the customer was happy with his purchase. With that job out of the way, I was then asked to take a look at a machine that rolled corrugated roofing. This had been acquired a few years previ- ously and it had been a mess, with the control box containing a rat’s nest of oil-soaked wires. Many of these wires did nothing, having been replaced but never pulled out. At the time, I rebuilt the control box and rewired it. The hydraulics were also replaced so there was not much left to go wrong except the Pegasus electronic controller. It turned out that this controller was now the problem, as the display was faulty. A cursory glance through the display window revealed that the vacuum fluorescent display was covered in cracks. After a few “subtle” questions, the machine’s operator admitted that the display had been intermittent the past few days and it had blinked out in the middle of a large job. He was under a bit of stress at the time and he took it out on the controller with his fist. It must have been pretty good effort to crack the display though, considering it was behind a thick polycarbonate window. Fortunately, Pegasus is a good, welldesigned (and still manufactured) Australian product, so we were able to get hold of a new display overnight. It is very easy to get into the controller, Servicing Stories Wanted Do you have any good servicing stories that you would like to share in The Serviceman column in SILICON CHIP? If so, why not send those stories in to us? In doesn’t matter what the story is about as long as it’s in some way related to the electronics or electrical industries, to computers or even to car electronics. We pay for all contributions published but please note that your material must be original. Send your contribution by email to: editor<at>siliconchip.com.au Please be sure to include your full name and address details. 58  Silicon Chip by removing just four nuts. All the connectors are plug-in and the main PCB can be removed in a couple of minutes. This reveals the back of the display, which is held in place with a couple of screws. It all fits together with a SIL socket on the main PCB lining up with long SIL pins on the display. A similar arrangement is used to connect the controller’s keypad. The connector on the board was the source of the intermittent display operation. It had loose contacts and vibration from the machine was causing them to go open circuit, usually at inconvenient times. It was a simple matter to replace it. I then turned my attention to the broken display which was well and truly shattered. It came out easily and I tried to simply drop the new one in place. I found it all lined up OK but it didn’t feel right, as it seemed to go down against a hard surface when it should have had some clearance. I removed it and took a closer look with a head magnifier (my eyes are not what they used to be) and found the remains of another display still in place. It turned out that someone had earlier glued this display directly to the polycarbonate window. When this display was damaged, they chipped out as much as they could and simply put a new one on top of the wreckage, screwing it down tightly and thus giving it no protection against impact. Using an electrician’s hammer and chisel (ie, pliers and screwdriver), I carefully chipped out all the remains. This then allowed the new unit to fit properly and there were no further issues. Purlin roll formers Some time after that, my client purchased three Purlin roll formers that allowed him to cover 150, 200 and 250mm sizes and save the ongoing issue of changing dies in the only machine he had. These things run to six figures each but he managed to buy the lot for five figures delivered and “could I get them running?”. Getting them so cheap was cause for worry but I said I’d see what could be done. When I turned up, I was surprised to find two very nice-looking machines that had already been installed, while the third one was under a tarp in the yard waiting for a new building to house it. They were Chinese-made, all built to a common footprint about 12 siliconchip.com.au metres long and all using an 18kW hydraulic power pack and a 15kW motor to drive the rollers. This seemed a bit of a waste, as the hydraulic pump could have easily done both jobs. There was also no brake on the machines which I found rather strange. The control box used a panel PC running a SCADA package. It had nice graphics and a PLC to do the thinking, along with a hefty VSD (variable speed drive) driving the roller motor. All this was housed in a desk console which had spent time in the rain, as no one felt the need to worry about something heading to the scrap yard. There was no-one to go to for information so I was on my own. It also turned out that the previous owner had given up as he couldn’t get a good result from them, even after getting the controls rebuilt locally. This was not looking good. In fact, this was no longer a service job but a total rebuild. In the end, I designed a control PCB using a Comfile Technologies Cubloc device. This has two high-speed counters and with appropriate I/O is ideal for control jobs like this. It sent serial data to a 250mm Comfile display mounted behind a 6mm polycarbonate window (these are actually touch panels but it’s safer to keep fingers [fists!] off them), while the input came from a 16button Storm keypad. This was all mounted on the door of a new control enclosure. In addition, this enclosure contained all the necessary bits to run the machine, including a star/delta starter for the hydraulic pump and a new Bonfiglioli VSD for the roller motor. The VSD was chosen as it has builtin algorithms to operate cranes. These give it the ability to accurately park using electronic and mechanical braking while under heavy load (which I was sure we were going to need). I also added Sick safety lock-outs and emergency stop relays which for some reason the manufacturer failed to fit to the guards. The theory of operation of a roll former is pretty simple. It punches holes and cuts to length using a counter attached to a device that gives a pulse for every millimetre travelled. Fairly obviously, it has to be accurate. We rebuilt the first machine, replaced all 62 bearings and fired it up. Apart from the hydraulic hose connections being crossed over, everything siliconchip.com.au did as it should – or so we thought. We ran a test length of four metres and found it was out by 80-plus millimetres. I then adjusted the speed control so that it ran fast but slowed to a crawl when it got to within 100mm of a stopping point. I also programmed it for impressed current braking which slows the motor quickly by driving high-current DC into the motor for a couple of seconds. This reduced the discrepancy to 17mm, however subsequent runs gave differing values over and under the target value. We watched the motor and found it still did a lot of revs after the stopping point before coming to a halt, even with DC injection. It also rolled back several revs due to slack in the chain drives and probably the 2-tonne roll of steel strip pulling it back. It was plain that a real motor brake was needed. An after-market brake was purchased and the fitter made up appropriate adapters. This time the measurements were inaccurate but consistent, so the brake was doing its job. We now turned our attention to the rotary encoder, which uses a wheel pressed against the strip. This should allow the encoder to deliver one pulse for every millimetre of strip, provided the wheel is the correct diameter. It wasn’t so the fitter got to work and produced a wheel that was about as close as was possible with the tools available. This closed the discrepancy to within a few millimetres. We solved that last discrepancy by using a new encoder manufactured by Sick. This thing is pure genius as it’s possible to program the output pulses per rev – up to 10,000. We finished up with 1999 pulses per rev and with a few software tweaks it gave us better than 1mm accuracy in a 10-metre run which was good enough. As can be imagined, it all took quite a long time to get everything right but the machine now accurately measures and punches. What’s more, my client still spent less than half the cost of a new machine while getting a “better than new” machine. We now have to refurbish the remaining two machines but that’s not the end of it. My client has just announced that he’s acquired a top hat Purlin roller of the same design. “It’s been sitting outside for a while”, he told me, “but I reckon you should be able to get it SC going, don’t you think?” Introduction to PCBs Part 2: How to read and understand a PCB manufacturer’s technical capability statement Imagine sending a PCB design to a manufacturer but they ask for some changes to suit their manufacturing capability. How would you feel when these changes take days to implement and disturb your project planning? Extremely frustrating! Here are some tips to avoid this: 1. If your manufacturer has separate capability statements for prototype and production manufacturing, please ask for a copy and refer to the correct one. It is possible to manufacture small-volume PCBs with tighter tolerances so if you require PCBs in small numbers, you may choose their tightest capability statement. 2. The three basic limitations are: (a) Etching limitation: (ie, minimum track width/spacing). For 1oz standard finish, 5-6 mil (i.e. 0.127-0.152mm) is the minimum track width and spacing. With special attention, 3.5-4 mil (i.e. 0.089-0.102mm) can be achieved on small to medium volume production. Thicker copper can increase the clearance requirements up to 12 or 13mils. (b) Hole size limitation: Most manufacturers accept finished hole sizes from 0.3mm to 6.35mm as standard. Some manufacturers charge extra for 0.25mm finished holes (standard for QualiEco Circuits). A few manufactures can also accept 0.25mm, 0.2mm or even 0.15mm by paying extra. Holes less than 0.15mm are only possible by laser drilling, which is quite expensive. (c) Bonding & drilling limitation: (for multilayer PCBs only). Keep in mind the gap between edge of the hole and nearest copper area (track/pad/pour) in inner layers. For multi-layer PCBs, drilling is performed after bonding so this criterion is extremely critical for PCB manufacturers, as is plating tolerance. 3. Minimum copper and solder mask pad size around holes: (a) Copper pad size – most manufacturers define copper pads around holes as “annular ring”. There is a minimum annular ring size you need to maintain everywhere in the design. (b) Solder mask pad size – a solder mask prevents solder bridges between adjacent pads and traces during soldering process. Most manufacturers define them as “mask openings” which are slightly larger than the pads. Brought to you by the technical team at pcb<at>qualiecocircuits.com.au siliconchip.com.au June 2015  59 Audio Signal Injector & Tracer . . . with optional tiny add-on RF probe This Audio Signal Injector/Tracer is ideal for troubleshooting AM radio and audio circuits. It comprises a 1kHz oscillator (the Injector) and an in-built preamp and amplifier with a headphone jack (the Tracer) so you can trace signals right through an amplifier or radio circuit to locate faults. By JOHN CLARKE This photo shows the complete Audio Signal Injector/Tracer together with its optional RF Demodulator Probe at right. A T SOME STAGE, everyone involved in electronics will need to find a fault in an audio circuit. It might be a circuit you have just built, a repair job for a friend or a job to be done in your workplace. And while you can often check voltages if you have a circuit diagram, sooner or later Main Features •  Hand held & battery powered •  1kHz injector output •  Adjustable injector level •  Tracer input attenuator •  Tracer volume control •  Audio output to headphones or small speaker •  Low battery indication •  Optional RF probe for AM modulation detection 60  Silicon Chip you will probably need to trace the progress of an actual signal though the various stages. For example, you might feed a signal into the input and then find that it disappears as it feeds through a capacitor. The obvious conclusion would be that the capacitor is faulty (open) or it has not been properly soldered into circuit. To do this sort of fault-finding, you need a suitable signal (one you can hear) and a small amplifier so you can listen to the signal at various stages in the amplifier or AM radio being tested. So our Audio Signal Injector/Tracer has a 1kHz oscillator as the Injector and a small amplifier as the Tracer. AM radio adds an extra complication because you need to listen to a modulated radio signal as it goes from stage to stage in the circuit. For that you need an optional RF demodulator probe and we show how to build one in the article on page 68 of this issue – it’s tiny! Mind you, if you are repairing an amplifier, you may not need the Injector’s audio signal, provided you have a CD player or even a smart phone which has music tracks. One the other hand, a music signal is not always ideal if you are using an oscilloscope and want to see if the signal becomes distorted at a particular stage in the circuit. In that case, you might find the Injector more convenient as you trace a signal of known shape through the circuit. As mentioned, our Injector is a 1kHz oscillator and you can see the shape in the accompanying scope grab designated Scope 1. It looks a bit like a sinewave but is actually a somewhat “rounded” square wave. It has a maximum amplitude of about siliconchip.com.au The Audio Signal Injector/Tracer is ideal for tracking down faults in audio amplifiers and preamplifier stages. And by adding the optional RF Demodulator Probe, it can be used to trace signals through the RF stages of AM radios as well. You can listen in to the traced signal via either headphones or an external speaker but the latter should be used if checking high-voltage circuits. Specifications 2V RMS but it can be adjusted down to just few millivolts. This means that it will cover virtually all signal tracing situations, from sensitive audio preamplifiers and the audio sections of AM/FM radios, right up to high-powered guitar and public address amplifiers. Then we come to the Signal Tracer. It needs a small amplifier to listen to small signals in sensitive circuits but it also needs an input attenuator so that it is not overloaded by the much larger signals, perhaps 50V or more, that you might find in a high-powered amplifier. You also need a volume control so that your ears are not blasted as you step through a circuit. Finally, both the Injector and Signal Tracer need to be protected from any high voltages that may be present in a solid-state or valve circuit. If you feed the Injector into a circuit operating at 300V DC, for example, you siliconchip.com.au Power: 9V at 2.3mA Tracer input impedance: ~6.45MΩ to 10MΩ, depending on attenuator setting Tracer signal gain: adjustable from 2x to 20x Tracer attenuator: 1:1, 1:10, 1:100 & 1:1000 Tracer signal frequency response: 70Hz to 3kHz Injector signal: 1kHz rounded square-wave Injector signal level: adjustable from 0-2V RMS (5.6V peak-peak) with a 9V supply Headphone output: 6.6V peak-peak maximum into 16Ω with a 9V supply Test circuit DC voltage: ±300V DC maximum recommended don’t want it to be blown to shreds and by the same token, if you touch the Tracer probe onto a similar highvoltage point, you don’t want it to be “cooked”. Our circuit takes care of those possibilities. Our Injector/Tracer is housed in a compact plastic case with an internal battery compartment. It has a pair of jack sockets for the output of the Injector and a BNC socket for the input to the Tracer. Next to that socket is a 4-position slide switch for the Attenuator which has settings of 1:1, 1:10, 1:100 and 1:1000. Input impedance The input impedance of the Tracer is rather high, varying between about 10MΩ and 6.45MΩ, depending on the setting of the input attenuator. This means that the impedance of the June 2015  61 Scope 1: the 1kHz waveform generated by the oscillator looks a bit like a sinewave but is actually a “rounded” square wave. It has a maximum amplitude of about 2V RMS but can be adjusted down to just a few millivolts. Tracer will not load down or affect the operation of the circuit being tested. The high-impedance input also means that the Tracer probe can be used to directly test ceramic (crystal) phono cartridges or piezoelectric pick-ups on musical instruments such as a violins. To connect signal to the Tracer you can use a 1:1 oscilloscope probe or any shielded cable with a BNC plug at one end and a suitable connector at the other, such as an RCA plug or a pair of alligator clips. More about this later in the article. The on/off switch, a power LED and the two knobs for the Injector level   Warning! When using the Audio Signal Injector/Tracer with high-voltage circuitry (eg, in a valve radio), take care not to touch any part of the circuit with your hand. Always treat the circuit as though it has mains voltage present. As stated in the article, use a small extension speaker rather than headphones when using the unit with high-voltage circuitry. Small non-powered extension speakers are available for use with iPods and similar MP3/MP4 players. The use of a small speaker will remove the possibility of deafening clicks or even a high-voltage shock should there be a fault within the Audio Signal Injector/Tracer or if the earth lead becomes disconnected. 62  Silicon Chip Scope 2: this scope grab shows the Schmitt trigger operation of IC1a. The yellow trace shows the charging and discharg­ ing of the 6.8nF capacitor from 3V to 6V etc, while the green trace shows the resultant square-wave output at pin 1. and Tracer volume controls are at one end of the case while the 3.5mm headphone jack is on the side, adjacent to the 4-position Attenuator switch. Circuit description Let’s now take a look at the circuit of the Audio Signal Injector/Tracer – see Fig.1. As shown, it’s based on an LMC­ 6482AIN CMOS dual rail-to-rail op amp and a handful of other components. One op amp is used for the Signal Injector while the other is used for the Tracer. The output frequency of 1kHz is set by the 100kΩ resistor and 6.8nF capacitor connected to pin 2, the non-inverting input. The three resistors connected to the pin 3 inverting input set the threshold voltage (at pin 3) at 1/3Vcc or 2/3Vcc, depending on whether the output of IC1a is high or low. So with Vcc = 9V, the input (threshold) voltage at pin 3 will be either +3V or +6V. When power is applied to the circuit, the 6.8nF capacitor at pin 2 will be discharged (ie, 0V), so pin 2 will be lower than pin 3. Therefore the output at pin 1 will be high (+9V) and this charges the 6.8nF capacitor via the 100kΩ resistor between pins 1 & 2. When the capacitor voltage rises just above 6V, pin 2 becomes higher than pin 3 and so the op amp’s pin 1 output switches low, to 0V (remember, this is a “rail-to-rail” op amp). So now pin 3 is at 3V and the capacitor discharges via its 100kΩ resistor until pin 2 is just below pin 3, whereupon the pin 1 output goes high again to recharge the capacitor. This continuing cycle generates a 1kHz square wave which is filtered using a 6.8kΩ resistor and 22nF capacitor to give a “rounded” waveform, as shown in Scope 1. The Schmitt trigger operation of IC1a is demonstrated in Scope 2, which shows the charging and discharging of the 6.8nF capacitor from 3V to 6V etc in the yellow trace. The lower green trace shows the resultant square-wave output at pin 1. Note that the amplitude of the square-wave is shown as 9.8V – we used a fresh 9V battery. Potentiometer VR1 connects across the 22nF capacitor to provide the Injector level control. This is AC-coupled to the output terminal via a 100nF 630V capacitor. We specified a high voltage rating for this capacitor so that the Injector output can be connected to a high voltage on the circuit under test without damage. For the same reason, diodes D2 & D3 clamp any high voltage from an external circuit (eg, a valve radio being tested) at the wiper of VR1 to 0.7V above or below the 9V and 0V supply rails. The 10MΩ resistor across the 100nF capacitor is there to discharge the capacitor when it is disconnected from the circuit under test. The 1kΩ resistor in series with the Injector output limits peak current to the clamping diodes. Tracer circuit The input signal from the BNC siliconchip.com.au POWER D1 1N5819 +9V A 100k 100k K IC1: LMC6482AIN 3 1 IC1a 2 100k 100k D2 A 6.8k INJECT LEVEL VR1 10k LIN 22nF 100nF K K INJECT OUT 1k 100nF 16V A 2.2k GND 10M D3 BANANA SKT A BC 327, BC33 7 +9V B K BNC TRACER INPUT D4 100k 9.1M 910k 91k 1:1 ATTENUATOR S2 1nF 100k A 10M 1:10 E 8 5 7 IC1b 6 4 E 1:100 1:1000 C 10M 2.7k A 100k 10 µF 16V 100 µF 16V CON1 Q1 BC327 3.5mm JACK SOCKET 100k VR2 50k LOG D1: 1N5819 1 µF 16V A VOLUME LED1 2.7k K A SC C 220pF D5 10k 20 1 5 Q2 BC337 620Ω B K E C B 1kV 9V BATTERY ZD1 5.6V 100 µF BANANA SKT 630V K 6.8nF A K S1 λ LED1 AUDIO SIGNAL INJECTOR & TRACER K ZD1 A K D2–D5: 1N4004 A K Fig.1: the circuit is based on dual op amp IC1. IC1a operates as a Schmitt trigger oscillator and this generates the injector signal, with VR1 setting the output level. The traced signal is fed in via a switched attenuator and then fed to op amp IC1b. Its output signal is then buffered by Q1 & Q2 and fed to CON 1, while VR2 sets the op amp gain. socket is fed to 4-way slider switch, S2 and the attenuator resistors. The resistors provide for division ratios of 1:1, 1:10, 1:100 and 1:1000. Following S2, the signal is coupled via a 1nF 1kV ceramic capacitor to the pin 5 non-inverting input of IC1b. This is tied via two series-connected 10MΩ resistors to a voltage divider (two 100kΩ resistors) which provides a reference at 4.5V ie, half the 9V supply. Diodes D4 & D5 clamp any high voltage input signals to 0.6V above or below the 9V supply rails. IC1b is connected as a non-inverting amplifier and its pin 7 output drives a complementary emitter follower stage using transistors Q1 & Q2. These provide a buffered output to the headphone socket via a 100µF coupling capacitor. Note that the emitter follower output stage is operated with no quiescent siliconchip.com.au current but is within the negative feedback loop of the op amp to minimise crossover distortion. The 50kΩ volume control (VR2) is also in the op amp’s feedback loop, connected in series with a 2.7kΩ resistor. In conjunction with the 1µF capacitor and series 2.7kΩ resistor from pin 6 to 0V, this allows the AC gain to be varied from between two and 20. The DC gain is unity, by virtue of the 1µF capacitor. Note that while the amplifier is mainly intended to drive headphones, it can also be used to drive a small speaker and we recommend this if you are doing signal tracing in a highvoltage circuit which might cause deafening clicks when you touch the probe on high voltage points. ates from a 9V battery, fed in via toggle switch S1. Diode D1 gives protection if the battery is inadvertently connected the wrong way around. A high-intensity red LED is used for power indication. It is bright when the supply is at 9V but drops to a dim glow when the battery is flat, by virtue of ZD1, a 5.6V zener diode in series with the LED. When the battery is fresh, ie, putting out 9V or maybe as much as 10V, we will have 1.8V across the red LED, 5.6V across ZD1 and 1.6V or more across the 1kΩ resistor so that 1.6mA or more flows through LED1. As the voltage falls, the voltage across the 1kΩ resistor also falls. At a battery voltage of 7.4V or less, there is very little voltage across the 1kΩ resistor and so LED1 will be dim. Power supply RF demodulator probe As already noted, the circuit oper- As previously noted, if you want June 2015  63 VR1 100 µF Q2 + This photo shows how switch S2 is mounted. It’s soldered to a pin header so that its top metal face is 12.5mm above the PCB. BC337 620Ω 2.7k 4004 4004 D5 1kV 220pF 2.7k 1 µF D4 LMC6482 100k 6.8k 100k 2.2k D3 22nF Q1 PHONES Inject fitted. These are installed at the five external wiring points, at TP GND (near LED1) and at the bottom right of S2. IC1 can then be soldered in place. Do not use a socket for this IC, as this would exacerbate noise pick-up. CON1 100k 10M 10M 100k 1k 4004 S 100nF 630V – (-) TO BATTERY CLIP to troubleshoot an AM radio with the Tracer, you need to have an additional demodulator probe for the amplitude-modulated (AM) RF signals that should be present in the circuit being tested. As stated, a suitable RF demodulator probe is described on page 68 of this issue. Construction The Audio Signal Injector/Tracer is built on a double-sided PCB coded 04106151 (85 x 63mm). This is housed in a plastic remote control case measuring 135 x 70 x 24mm. A panel label measuring 114 x 50mm is attached to the front of the case. To make the assembly easy, the PCB 100k TO SHIELD PCB 10k S2 91k + 910k 9.1M 10M + GND Tracer GROUND SOCKET 1nF R TRACER INPUT BNC SOCKET 10 µF T CUT LUGS SHORT (SEE TEXT) AUDIO SIGNAL INJECTOR & TRACER D2 INJECTOR OUTPUT SOCKET 4004 6.8nF + 100 µF 100k 100k 5 V6 ZD1 100k TP GND D1 50k LOG 10k LIN 100nF BC327 LED1 S1 VR2 15160140 K IC1 A 5819 Fig.2: follow this parts layout diagram to build the PCB assembly. Be sure to install the 100nF 630V and 1nF 1kV capacitors in the positions indicated and note that S2 is mounted on a pin header (see photo). /1 /10 COM Installing switch S2 /100 /1000 Switch S2 does not mount directly onto the PCB but is instead raised off the PCB using a 6-way DIL pin header. Before installing this DIL header, remove a pin from each side so that there are three pins, then a gap, then two pins (ie, on each side of the header to correspond with the switch pins). That done, position the header on the PCB with the longer pins facing upwards, then push each pin down so that it extends only 5mm above the top of the PCB. The pins on the underside EARTH PC STAKE FOR S2's METAL COVER is designed to mount onto the integral mounting bushes within the case. The top of the PCB is also shaped to fit around the case mounting pillars at that end – see Fig.2 and photo. Fig.2 shows the parts layout on the PCB. Begin by the installing the resistors. Table 1 shows the resistor colour codes but it’s also a good idea to check each one with a digital multimeter before soldering it to the PCB. The diodes can go in next. Note that there are two different types – D1 is a 1N5819, while D2-D5 are 1N4004s. Be sure to mount them with the correct polarity, then install zener diode ZD1, again taking care with its polarity. The seven PC stakes can now be   Table 2: Capacitor Codes Value µF Value IEC Code EIA Code 100nF 0.1µF   100n   104 22nF 0.022µF   22n  223 6.8nF 0.0068µF   6n8  682 1nF 0.001µF    1n  102 220pF   NA  220p  221 Table 1: Resistor Colour Codes   o o o o o o o o o o o o No.   3   1   1   8   1   1   1   2   1   1   1 64  Silicon Chip Value 10MΩ 9.1MΩ 910kΩ 100kΩ 91kΩ 10kΩ 6.8kΩ 2.7kΩ 2.2kΩ 1kΩ 620Ω 4-Band Code (1%) brown black blue brown white brown green brown white brown yellow brown brown black yellow brown white brown orange brown brown black orange brown blue grey red brown red violet red brown red red red brown brown black red brown blue red brown brown 5-Band Code (1%) brown black black green brown white brown black yellow brown white brown black orange brown brown black black orange brown white brown black red brown brown black black red brown blue grey black brown brown red violet black brown brown red red black brown brown brown black black brown brown blue red black black brown siliconchip.com.au can then be soldered to their respective pads, making sure that the header itself is flush against the PCB. Once it’s in position, switch S2 can be mounted by soldering its pins to the top of the header pins, so that its top metal face sits 12.5mm above the PCB (see photo). The best way to do this is to lightly tack-solder two diagonally-opposite pins first, then make any necessary adjustment before soldering the remaining pins. Don’t forget to resolder the first two pins, to ensure reliable connections. Once it’s in position, the adjacent earth PC stake is soldered to the earth tag on S2’s metal cover. Completing the PCB Now for the capacitors. Install the 100nF 630V polyester and 1nF 1kV ceramic capacitors in the positions shown, then install the remaining MKT polyester types. The electrolytics can then go in, taking care to fit each one with the polarity as indicated on Fig.2. Note that the tops of the electrolytics must be no more than 12.5mm above the PCB, otherwise you will not be able to fit the case lid later on. Follow with potentiometers VR1 & VR2, toggle switch S1 and the 3.5mm socket. VR1 is a 10kΩ linear potentiometer while VR2 is a 50kΩ log potentiometer, so don’t get them mixed up. LED1 can then be installed – it mounts horizontally with its leads bent down through 90° exactly 7mm from its lens, so that they go through the PCB pads. Push it down so that its horizontal lead sections sit exactly 6mm above the PCB (use a 6mm-wide cardboard spacer) and check that it is correctly orientated before soldering it to the PCB. That completes the PCB assembly. It can now be checked and placed to one side while the case is drilled. Preparing the case Figs.3 & 4 show drilling templates for the front panel and for the top of the case. They can either be photocopied from the magazine or downloaded as PDF files from the SILICON CHIP website and printed out. It’s just a matter of cutting the templates out, temporarily attaching them to the case panels and then drilling the various holes. The top of the case requires holes for potentiometers VR1 & VR2, switch S1 and LED1, while the front panel is drilled to accept the two siliconchip.com.au banana sockets, the BNC socket and slide switch S2. The rectangular cut-out for S2 is best made by drilling a row of holes inside the cut-out area, joining these and then filing the job to shape. The two banana socket holes can simply be drilled and reamed to size but the BNC socket hole needs to be shaped as shown on the template. It can be made by first drilling a small hole in the centre, then finalising its shape using small files, with the flat side positioned as shown. A hole must also be cut in one side of the case to accept the 3.5mm jack socket. To do this, temporarily position the PCB in the case, mark out the socket position, then remove the board and make a semi-circular notch in the base using a small round file. Once that’s been done, temporarily assemble the case and complete the hole by filing a matching semi-circular cut-out in the lid. Finally, you have to remove an internal pillar inside the case lid so that it doesn’t foul the nut for the earth banana socket. This can be done using side cutters. Note also that, as provided, the banana socket terminals are too long for the case and have to be shortened by 5mm. A fine-tooth hacksaw blade is the best tool for this job – do not bend the terminals, as they will break. File off any sharp edges after cutting them to length. Having drilled all the holes, the front panel label can be attached. This can be downloaded from the SILICON CHIP website, printed out (preferably onto photo paper) and affixed to the lid using either glue or neutral-cure silicone. Alternatively, for a more rugged label, print it out as a mirror image onto clear overhead projector film (be sure to use film that suits your printer), so that the printed side will be on the back of the film when the label is affixed. The film will have to be attached using a light-coloured silicone applied evenly over the surface, as the lid is black. Another option is to print the panel onto either an A4-size “Dataflex” sticky label (for ink-jet printers) or a “Datapol” sticky label (for laser printers) and directly attach this to the case lid. These labels are available from http://www.blanklabels.com.au and sample sheets are available on request to test in your printer. INJECTOR OUT + TRACER VOLUME INJECT LEVEL POWER WARNING! Do not use headphones or earbuds when testing high voltage HEADPHONES circuits. Use extension speaker instead. 1 10 100 1000 + + GROUND TRACER IN TRACER ATTENUATOR SILICON CHIP Audio Signal Injector & Tracer Fig.3: this front-panel artwork can be copied or down­loaded from the SILICON CHIP website and used as a drilling template. End Panel Drilling Guide 5mm 3mm 7mm 7mm Fig.4: the end panel drilling template. Drill pilot holes first to ensure they are accurately positioned, then carefully enlarge them to size. Once the label is in position, cut out the holes using a sharp hobby knife. Making a shield PCB Since the tracer has such a high input impedance, it has the potential to pick up hum from transformers but it will also pick up the injector signal as well, due to direct radiation of the injector signal into the input attenuator and other components in the op amp’s input circuitry. We can reduce this by a significant amount by installing a small shield board, made from copper laminate, underneath the PCB, with its copper side earthed to the PCB’s GND stake. The dimensions of this shield board are shown in Fig.5. It fits between the June 2015  65 Parts List 1 remote control case, 135 x 70 x 24mm (Jaycar HB-5610) 1 double-sided PCB, code 04106151, 85 x 63mm 1 single-sided shield PCB, code 04106153, 62 x 63mm 1 panel label, 114 x 50mm 1 9mm square PCB-mount 10kΩ linear potentiometer (VR1) 1 9mm square PCB-mount 50kΩ log potentiometer (VR2) 1 SPDT PCB-mount toggle switch (Altronics S1421) (S1) 1 DP4T PCB-mount slider switch (TE Connectivity STS2400PC04) (element14 Cat. 1291137) (S2) 1 PCB-mount 3.5mm stereo jack socket (CON1) 2 knobs to suit VR1 & VR2 1 panel-mount BNC socket 1 blue insulated banana socket (Jaycar PS-0423) 1 green insulated banana socket (Jaycar PS-0422) 1 9V alkaline battery 1 9V battery snap connector 4 No.4 x 6mm self-tapping screws 7 PC stakes 1 DIL 6-way pin header 7 7 7 7 ALL DIMENSIONS IN MM 62 BLANK PCB COPPER ON UNDERSIDE 20 Semiconductors 1 LMC6482AIN dual CMOS op amp (IC1) 1 3mm high-intensity red LED (LED1) 1 BC327 PNP transistor (Q1) 1 BC337 NPN transistor (Q2) 1 5.6V 1W zener diode (ZD1) 1 1N5819 Schottky diode (D1) 4 1N4004 diodes (D2-D5) Capacitors 2 100µF 16V PC electrolytic 1 10µF 16V PC electrolytic 1 1µF 16V PC electrolytic 1 100nF 630V polyester 1 100nF 63V or 100V MKT polyester 1 22nF 63V or 100V MKT polyester 1 6.8nF 63V or 100V MKT polyester 1 1nF 1kV ceramic 1 220pF disc ceramic Resistors (0.25W, 1%) 3 10MΩ 1 6.8kΩ this, solder a short piece of wire to the copper side and then connect its other end to the earth pin (GND) for the BNC connection, on the PCB. The shield PCB is then secured inside the case using silicone adhesive. Final assembly 63 28 7 4 Fig.5: this diagram shows the dimen­ sions of the blank shield PCB. four integral pillars used to mount the PCB and it has a cut-out to clear the back of the Injector jack sockets. Alternatively, if you don’t wish make your own shield board, you can buy a ready-made board from the SILICON CHIP Online Shop (code 04106153). The shield board is installed in the case with its copper side facing downwards, away from the underside of the PCB (otherwise it would short the component pigtails!). Before doing 66  Silicon Chip 1 150mm length of hookup wire 1 50mm length of single core shielded wire Now for the final assembly. First, attach the sockets to the front panel, then solder short lengths of hook-up wire to the Inject and GND terminals on the underside of the PCB. That done, pass these leads up through their respective holes in the PCB, ready to solder to the banana socket terminals. Next, attached a short shielded cable (for the BNC socket) to the GND and Tracer PC stakes on the top of the PCB. The 9V battery snap can then be fitted. Its leads are fed through from the battery compartment before being looped through stress relieving holes in the PCB and soldered to the “+” and “–” terminals. The next step is to fit the end panel to the potentiometers, switch and LED and install this into the base of the case. The PCB is then secured using four No.4 x 6mm self-tapping screws that go into integral mounting pillars. 1 9.1MΩ 1 910kΩ 8 100kΩ 1 91kΩ 1 10kΩ 2 2.7kΩ 1 2.2kΩ 1 1kΩ 1 620Ω Test Leads Tracer In Option 1:  1 x 1:1 oscilloscope probe Option 2:  1 x BNC plug-to-RCA plug lead fitted with a PC stake and 5mm & 10mm heatshrink tubing (see text) Option 3: 1 x BNC line plug, 1 x RCA line plug, 1 x 500mm-length of single core shielded audio cable, 1 x M4 nut, 1 x PC stake and 2mm, 5mm & 10mm heatshrink tubing (see text) Injector Out Option 1:  1 x multimeter lead set with accessory alligator clips Option 2:  1 x red banana plug, 1 x black banana plug, 1 x red alligator clip, 1 x black alligator clip, 1 x 500mm length of red medium-duty hookup wire, 1 x 500mm length of black medium-duty hookup wire (made into two banana plug to alligator clip leads). Once it’s in place, complete the wiring to the banana sockets and the BNC socket, then secure the lid to the base using the supplied screws. You will need to make sure that the wires do not interfere with the banana sockets – if they are sandwiched beneath the banana sockets, they will prevent the lid from fully closing. Similarly, any wires running over the battery compartment or over the slider switch will prevent the case from closing. If necessary, move the wires out of the way using a small screwdriver as the case is being closed. Finally, fit the battery and the assembly is complete. Test leads As mentioned earlier, a 1:1 oscilloscope probe makes a suitable test lead for the Audio Signal Injector/Tracer’s BNC input. Alternatively, a cheaper test probe can be made using a BNCto-RCA lead. This can be a commercial lead but these tend to be made from stiff large-diameter cable. A do-it-yourself cable using a line RCA plug, a line BNC plug and standard shielded audio cable will be much more flexible. The connections to siliconchip.com.au The shield board is installed in the case with its copper side facing down and is secured in place using silicone adhesive. Its copper side is connected to the GND stake on the main PCB. the BNC plug can be made using the method described in the article on the RF Demodulator Probe. The tip of the RCA plug can be used as the probe but note that the outer metal earth shell must be insulated using 10mm-diameter heatshrink tubing to prevent it making contact with the circuit under test. In addition, a PC stake can be soldered to the centre pin of the RCA plug to extend it. That’s done by first drilling a 1mm hole in the end of the plug’s tip, then inserting the PC stake and soldering it. It’s a good idea to cover the RCA plug’s centre terminal with 5mm dia­meter heatshrink tubing, leaving only the PC stake “probe” exposed. This will help prevent inadvertent shorts when probing closely-packed circuits. The injector signal can be fed out using a multimeter probe. Alternatively, you can use a lead fitted with a banana plug at one end and an alligator clip lead at the other. A banana plug-toalligator clip lead can also be used for the ground lead. Testing To check that the unit is working correctly, connect the “Injector Out” signal to the “Tracer In” (BNC) socket, then plug in headphones (or earphones) and listen for the 1kHz signal. Assuming that it’s present, check that siliconchip.com.au This is the view inside the completed unit. Make sure that the wiring leads to the banana sockets aren’t squashed under them as the lid is closed (push the leads towards the outer edge of each hole using a small screwdriver). the level varies when the “Inject Level” potentiometer, the “Tracer Volume” potentiometer and the “Tracer Attenuator” switch are adjusted. As noted above, if the tracer input is disconnected from a circuit, the unit will pick up hum and the 1kHz injector signal due to the tracer circuit’s high input impedance (ie, the 1kHz signal will be heard even when there is no connection). The pick-up level will depend on the capacitance of the input cable, the attenuator setting (S2), the injector level setting (VR1) and the gain (Volume) setting (VR2). Obviously, it will be at a maximum when the attenuator is set to 1:1 and VR1 & VR2 are at maximum but this combination of settings would not be used in practice. Basically, it’s just a matter of choosing settings to suit the job at hand and to minimise extraneous noise pick-up. Under normal use and when connected to a circuit for testing, the crosstalk from the injector will be minimal and will be swamped by the signal from the circuit under test. Ground connections Finally, note that when using the Audio Signal Injector/Tracer, the Ground banana socket must be connected to the ground of the circuit under test. This can be done using a lead fitted with an alligator clip as described above or by using the earth lead on the 1:1 oscilloscope probe. Now turn to page 68 for the optional SC RF Demodulator Probe. June 2015  67 By JOHN CLARKE Simple unit uses just a handful of parts . . . AM RF Demodulator Probe For Signal Tracers If you want to troubleshoot an AM radio with the Signal Tracer/ Injector described in this issue, you need a demodulator probe to detect the amplitude-modulated RF signals that should be present in the circuit being tested. This one is compact and easy to build. Fig.1 shows the circuit details of the RF Demodulator Probe. It uses a fast BAT46 Schottky diode (D1) as the detector and its output is filtered with a 1nF capacitor to remove the RF signal, leaving the audio modulation which can then be fed to the Tracer. The audio frequency response of the probe is about -3dB down at 1.6kHz, as set by the 1nF capacitor and associated 100kΩ resistor. Since the RF probe is intended for use in valve AM radios, its 100pF capacitor is a 1kV rated ceramic type. PROBE TIP 100pF Note that the probe is a passive device and requires no external power. Construction The RF probe is built on a PCB coded 04106152 (45 x 11mm) – see Fig.2. Install the two 100kΩ resistors and the two capacitors first, followed by the diode. Check that the diode is correctly orientated (ie, banded end towards the right). The probe tip is made using a 3-way right-angle pin header. Solder this in place and then cut the outer two pins flush with the end of the D1 BAT46 A PCB, leaving just the centre pin. PC stakes are used to terminate the three external wiring connections. Fit these to the PCB, then attach the earth wire to the GND stake and the shielded cable to the SIG and GND terminals. The shielded wire and the earth wire are then secured to the PCB using two cable ties. Once all the parts are in place, the assembly is covered in a 55mm length of 16mm-diameter heatshrink tubing that’s shrunk down with a heat-gun. The far end of the earth lead can RF PROBE DETAILS K 1kV 100k 1nF 100k EARTH CONNECTION SC 20 1 5 RF DEMODULATOR Probe TO BNC PLUG SHIELDED CABLE BAT46 A K Fig.1: the circuit uses a BAT46 Schottky diode (D1) as the detector plus a 1nF capacitor to filter out the RF signal. The 100pF 1kV input capacitor blocks DC signals, while the 100kΩ resistor sets the frequency response to -3dB at 1.6kHz. 68  Silicon Chip siliconchip.com.au SHIELDED CABLE TO BNC PLUG CABLE TIES PROBE TIP 1kV BAT46 D1 SIG GND 100k 100pF 100k 25150140 RF Probe 1nF WIRE TO EARTH CLIP Fig.2: the parts layout on the small PCB. Make sure the 100pF capacitor is rated at 1kV and take care with the orientation of Schottky diode D1. The photo at right shows the completed PCB before the heatshink sleeve was fitted. THREADED FERRULE OF BNC PLUG SHIELDED CABLE ROUND EDGES OF M4 HEX NUT WITH FILE, THEN SCREW NUT OVER BENT-BACK SHIELD BRAID & CABLE WIRES OF SHIELD BRAID BENT BACK OVER CABLE SHEATH BNC PLUG SLEEVE Fig.3: this diagram shows how the shielded audio cable is connected to the BNC plug (see text). CENTRE PIN COVER CENTRE CONDUCTOR WITH HEATSHRINK TUBING be terminated in an alligator clip or a hook clip, while the shielded cable goes to the BNC plug. Note that this type of plug is designed for use with a larger-diameter shielded cable than the shielded audio cable used here. However, a satisfactory connection can be made if an M4 metal nut is used as part of the assembly hardware. Fig.3 shows the details. The first step is to file the six corners off the M4 nut, so that it will fit into the back of the BNC plug. Once that’s done, strip the outer insulation and the centre wire insulation as shown in Fig.3 and solder the centre wire to the BNC socket’s centre pin. Next, bend the shield wires back along the cable and twist the M4 nut on over these wires. A short length of 2mm-diameter heatshrink tubing is then used to cover (and stiffen) the centre wire before it meets the centre pin, after which the plug sleeve can be fitted and the threaded ferrule tightened to secure the assembly. Finally, the wire can secured inside the threaded ferrule using SC neutral-cure silicone sealant. Fig.3: the yellow trace in this scope grab shows a 1MHz carrier from an old Leader signal generator, amplitude modulated with a 400Hz audio signal. The modulation depth is about 30%. The green trace shows the 400Hz (actually 392Hz) audio modulation from the RF probe. Note that the recovered modulation is a somewhat distorted sinewave. siliconchip.com.au RF Probe Parts List 1 PCB, code 04106152, 45 x 11mm 1 BNC line plug 1 right-angle 3-way SIL header 1 500mm-length of single core shielded wire 1 black alligator clip 1 300mm-length of black hook-up wire 1 BAT46 Schottky diode (D1) 1 1nF MKT polyester or ceramic capacitor 1 100pF 1kV ceramic capacitor 2 100kΩ 0.25W resistors 2 100mm cable ties 1 M4 metal nut 3 PC stakes 1 55mm-length of 15mm-diameter heatshrink tubing 1 5mm-length of 2mm-diameter heatshrink tubing Fig.4: the yellow trace in this scope grab shows a 1MHz carrier from an old Marconi signal generator, amplitude modulated with a 400Hz audio signal. The modulation depth is about 30%. The green trace shows the 400Hz (actually 397Hz) sinewave audio modulation from the RF probe. June 2015  69 Subscribe to SILICON CHIP and you’ll not only save money . . . but we GUARANTEE you’ll get your copy! JUNE 2015 ISSN 10302662 06 ü 100% Li n q battery powe ü 100% pe-io q r rformance ü 100% exhi q laration 9 771030 2660 01 9 PP255003/01272 $ 95* NZ $ 12 90 INC GST INC GST At last! e experienW ce the mighty Helping th blind to seee Bionic Eyes Handy test gear! Signal Tracer & Injector BAD VIBES INFRASO U SNOOPE ND R When you subscribe to SILICON CHIP (printed edition) in Australia, we GUARANTEE that you will never miss an issue. Subscription copies are despatched in bulk at the beginning of the on-sale week (due on sale the last THURSDAY of the previous month). It is unusual for copies to go astray in the post but when we’re mailing many thousands of copies, it is inevitable that Murphy may strike once or twice (and occasionally three and four times!). So we make this promise to you: if you haven’t received your SILICON CHIP (anywhere in Australia) by the end of the first week of the month of issue (ie, issue datelined “June” by, say, 7th June), send us an email and we’ll post you a replacment copy in our next mailing (we mail out twice each week on Tuesday and Friday). Send your email to: missing_copy<at>siliconchip.com.au 4 4 4 4 4 Remember, it’s cheaper to subscribe anyway . . . do the maths and see the saving! Remember, we pick up the postage charge – so you $ave even more! Remember, you don’t have to remember! It’s there every month in your letter box! Remember, your newsagent might have sold out – and you’ll miss out! Remember, there’s also an on-line version you can subscribe to if you’re travelling. Convinced? We hope so. And we make it particularly easy to take out a subscription - for a trial 6-month, a standard 12-month or even a giant 24-month sub with extra savings. Here’s how: simply go to our website (siliconchip.com.au/subs) – enter your details and pay via Paypal or EFT/Direct Deposit. You can order by mail with a cheque/money order, or we can accept either Visa or Mastercard (sorry, no Amex nor Diners’). If mailing, send to SILICON CHIP, PO Box 139, Collaroy NSW 2097, with your full details (don’t forget your address and all credit card details including expiry!). We’re waiting to welcome you into the SILICON CHIP subscriber family! 70  Silicon Chip siliconchip.com.au CIRCUIT NOTEBOOK Interesting circuit ideas which we have checked but not built and tested. Contributions will be paid for at standard rates. All submissions should include full name, address & phone number. FRIEDLAND D780 +~~– 8V 230V 230V AC INPUT W04 4N25 1N4004 T1 A 3 6 1 K ILLUMINATED BELL PRESS 4 x 1N4004 OR WO4 BRIDGE + K DOOR CHIME Wireless door chime repeater There are lots of situations where the standard domestic front door bell can’t be heard by the home’s occupants. You might be in the garden, in the shed or you might have a hearing problem. This Wireless Door Chime Repeater uses a bridge rectifier connected across an existing low-voltage door chime and each time the doorbell switch is pressed, the AC voltage High-side Mosfet switch with optocoupler control There are a number of high-side Mosfet driver ICs but this circuit takes a discrete approach, with an optocoupler used to isolate a low voltage (12V) switching signal from the gate of a P-channel Mosfet. To briefly explain, most Mosfet switching circuits use an N-channel Mosfet as a “low side” switch, with the load connected between the positive DC rail and the Mosfet’s drain. However, that configuration does not suit many applications where the load needs to have one side connected to the low voltage . . . continued on page 72 siliconchip.com.au 6 λ 2 A K K – 1 K ~A A R1 10k ~ ARLEC WM7A WIRELESS PUSHBUTTON SENDER OPTO1 4N25 C1 10 µF + 1 5 2 – 4 63V A across the Door Chime solenoid drives the bridge rectifier and the LED inside an optocoupler to trigger one or more wireless door chimes. These units can be located as required or carried around by the resident if they have a hearing problem. Capacitor C1 acts to damp the voltage spike from the bell, buzzer or gong solenoid’s inductance. It also prevents phantom rings by filtering any stray pulses or RF pickup on the front door bell wiring. The prototype was built around an Arlec DC322 Series 3 Door Chime. The wireless bell press uses a WM7A PCB, with the press switch contacts applying around 3V to the gate of a small surface-mount Mosfet. The four mounting pins of the switch project through to the top of the PCB. Use a multimeter to determine the switch contacts, then solder a couple of wires to the appropriate switch pins and connect them to the output transistor of the optocoupler. Roger Forsey, Seaholme, Vic. ($35) Q2 SUP53P06-20 +HV IN S Q1 BC549C 10k +12V IN + – ON + 12V–12V DC–DC CONVERTER B 10 µF – D1 BAT46 25V 0V’ (HV–12V) 1k 1 2 OFF G E + A K OPTO1 H11L1 6 C D 270Ω LOAD 4 λ 5 0V BC549C B BAT46 A K E SUP53P06-20 D G C D S June 2015  71 Circuit Notebook – Continued D1 1N5817 33 µH 0.5A A 330 µH 0.5A K +5V 6mA 100 µF 10 µF 100nF 2 3 ON/OFF S1 Vin SW SENSE SEL SHDN K 7 6 REG1 LT1301 GND 1 ILIM 4 A 220k 5V – 2.37V 3 IC2a 4.5V BATTERY (3xAA) Low ohms meter has LCD Most digital multimeters tend to have difficulty measuring low values of resistance. With this in mind, this circuit was designed to measure resistance from 0.1Ω to 100Ω and to displays the result on an LCD. This involves feeding the unknown resistance with a constant current source and measuring the voltage drop across it. A PIC micro then calculates the resistance and drives the display. If you look at the specifications of the PIC16F88 microprocessor, you can see that it has an inbuilt 10-bit analog to digital converter (ADC) and inputs RA2 & RA3 set the voltage range for the ADC. On this circuit RA3 is supplied with +2.5V from an LMZ285-2.5 reference, RA2 is connected to 0V volts and the input is High-side Mosfet switch . . . continued from page 71 side of a DC supply while the Mosfet switches in the “high side”. A good example is a motor in a speed control circuit where its frame needs to be connected to the negative DC supply. This high side switch circuit has an SUP53P06-20 P-channel Mosfet (Jaycar Cat. ZT-2464) connected to a high-voltage supply and the load 72  Silicon Chip G D E 1 B Q1 BC559 IC1: OPA2336 C 120k 100nF 27k 12k 100nF 33Ω 1M S VR2 50Ω 8 8 470 µF Q2 IRFU9120 VR1 500Ω 2 PGND 120Ω VR1 LM285Z –2.5 5 54mA RESISTOR UNDER TEST 100 µF 39k 5 6 IC2b 7 4 1k connected to RA4. If you calculate two to the power of 10 (10-bit), the result is 1024. If you now divide 2.5V by 1024, the resolution of the ADC as 2.4 millivolts per step. If we arrange the rest of the circuit so that when 100Ω is fed with a constant current and the voltage at the input RA4 is 2.44V, then the ADC result will be (2.44 ÷ 2.5) x 1024 ≈ 1000. If you use the same current and change the resistance to 50Ω the ADC will read 500. In other words, the value stored in memory for the ADC result will always be 10x the resistance. When the resistance is below 10Ω, the microprocessor is programmed to increase the current through the resistor by a factor of 10 which improves the accuracy of the measurement. From the value stored in the ADC, the microprocessor calculates the actual resistance value and sends is connected between the Mosfet’s source and the 0V line of the high voltage supply. Note that there must be full isolation between the inputs and outputs of the DC-DC converter. Optocoupler OPTO1 provides isolation of the gate control signal of the Mosfet. Switch S1 feeds 12V via a 1kΩ resistor to the internal LED of OPTO1 and this pulls the output at pin 5 down to the 0V line of the floating 12V DC rail. the parallel data for display on the LCD. The constant current is provided by op amp IC2a and transistor Q1 and this sets the current to 6mA (for resistors between 10Ω and 100Ω). In this condition, pin 13 of IC1 (RB7) is at +5V which means that Mosfet Q2 is off, so the constant current is provided by 500Ω trimpot VR1 in series with the 150Ω resistor. As the current is 6mA and the voltage on the positive input of IC1with respect to +5V is -2.37V (obtained from the 2.5V zener diode and the 12kΩ and 100kΩ resistor divider) then the value of the total resistance should equal (2.37 ÷ 6 ) x 1000 = 395Ω. Hence trimpot VR1 should be set at about 245Ω. When measuring resistances below 10Ω, Mosfet Q2 turns on and the current is now determined by the 33Ω resistor in series with 50Ω This pulls down the gate of Q2 via diode D1 and the 270Ω resistor and so Q2 turns on. When OPTO1’s pin 4 goes high, the base of transistor Q1 is pulled high, turning it on and thus discharging the gate of Q2 for a faster turn-off. When fed with a high-speed gate pulse signal, the circuit will happily run to at least 100kHz. Gregory Freeman, Mt Barker, SA. ($50) siliconchip.com.au +5V 4.7k 13 18 1k 17 15 16 3 +2.5V 2 1 K A Vdd RB7 RA5/MCLR RA1 RB6 RB5 RA0 OSC2 OSC1 IC1 PIC1 6F8 8 PIC16F88 RA4 RB4 RB3 RB2 RA3 RB1 RA2 RB0 4 12 11 8 10 6 9 16 8 15 7 14 6 13 Vss VR2 LM285Z –2.5 5 4 Vdd EN 1 ABL RS D7 D6 16 x 2 LCD MODULE (162B-CC-BC-3LP) CONTRAST D5 VO D4 D3 D2 D1 D0 Vss R/W 7 12 11 10 9 3 5 VR3 10k KBL 2 10 µF LM 285 Z-2.5 BC559 K S IRFU9120 B 1N5817 A 1k 470Ω 14 270Ω A K NC trimpot VR2, (all in parallel with the 150Ω resistor and trimpot VR1). We know have 6mA flowing though VR1 and VR2 should be set at about 11Ω to provide the additional 54mA. Op amp IC2b monitors the voltage developed across the resistor under test. It is connected as a noninverting DC amplifier with a gain of about 4. The OPA2336 is a rail-to-rail CMOS op amp which is needed in this application. In the case of measuring a 100Ω resistor, the voltage developed across the test resistor will be 0.6V. This is amplified by IC2b and fed to the RA4 input of IC1. This is converted and E C D G D the result is displayed on the 2-line x 16 character LCD. The circuit is powered from an LT1301 switchmode step-up regulator which produces +5V from three AA alkaline cells and it will continue to work down to +3V from the cells. To give long battery life, a momentary contact pushbutton is used as the power switch. An additional 330µH inductor is connected in series with the regulator’s output to ensure a low hash supply for the sensitive ADC circuit. When measuring low-value resistors, the resistance of the connecting leads can give rise to an elevated Les K answer as they is this m err onth’s w are in series inner of a $15 0 gift vo ucher fro with the resistor m Hare & F orbes being measured. To overcome this, you need to have two sets of wires connecting to the resistor being measured. One set provides the current and the other set is connected to the input terminals (via the 27kΩ and 39kΩ resistors of IC2b) to measure the voltage. In the prototype, a 3mm shielded audio cable fitted with crocodile clips was used for connecting to the resistor under test. At the crocodile end, both the shield and the centre conductor were connected to the clip. At the other end of the first cable, the shield was connected to 0V and the centre conductor connected to the 39kΩ resistor. For the second cable, the shield was connected to the collector of Q1 and the centre conductor connected to the 27kΩ resistor. In this way, the shield carries the current and the centre conductors are connected to the voltmeter circuit. To calibrate the unit, first adjust the trimpots to the values stated above. Then connect an 82Ω 0.1% resistor and adjust trimpot VR1 so that the display reads 82.0Ω. Do the same with an 8.2Ω resistor only this time adjust trimpot VR2 so that the display reads 8.2Ω. If the resistor is over 100Ω, then the display will read “over range”. The software for the micro, Low ohms.bas, can be downloaded from www.siliconchip.com.au Les Kerr, Ashby, NSW. co n tr ib u ti on MAY THE BEST MAN WIN! As you can see, we pay $$$ for contributions to Circuit Notebook. Each month the BEST contribution (at the sole discretion of the editor) receives a $150 gift voucher from Hare&Forbes Machineryhouse. That’s yours to spend at Hare&Forbes Machineryhouse as you see fit - buy some tools you’ve always wanted, or put it towards that big purchase you’ve never been able to afford! 100% Australian owned Established 1930 “Setting the standard in quality & value” www.machineryhouse.com.au siliconchip.com.au 150 $ GIFT VOUCHER Contribute NOW and WIN! Email your contribution now to: editor<at>siliconchip.com.au or post to PO Box 139, Collaroy NSW June 2015  73 Champion Preamp By LEO SIMPSON You can use this simple unit as a general-purpose stereo preamp or as a dual-channel preamp, with a microphone for one channel and guitar in the other. One channel can have fixed gain while the other is variable with an on-board trimpot or external potentiometer. Better still, it gives good performance and will work over a wide range of supply voltages. A RE YOU ONE of the thousands of readers who built our very popular PreChamp preamplifier from the July 1994 issue? This is still very popular and available as a kit but it is only a single-channel unit and its 2-transistor design is quite basic. With the inexorable march of technology, it is now possible to do much more, in a module which is only a little larger and with the bonus of two channels rather than one. Better still, this 2-channel design draws less current than the PreChamp. I should state at the outset that this 2-channel preamp is not a brand-new design. It is based on the preamp section of the Champion amplifier module which was featured in the January 2013 issue. The major feature of that article was the tiny AN7511 monolithic amplifier chip which can deliver up to 7W peak power, depending on load Main Features •  2-channel preamplifier configurable •  •  •  •  for different inputs Low distortion Low current drain: 2mA Signal-to-noise ratio: ~80dB Operating voltage range: 6-12V with LP2950CZ-5.0 5V LDO regulator; 12-20V with 78L09 9V regulator 74  Silicon Chip and supply voltage. The preamp section might have been seen almost as an afterthought but it would be a pity for it to have passed mostly unnoticed. Which is partly why we have decided to devote an article just to the preamp; that and the fact that we have recently had a number of requests for preamps which would be neatly answered by this design. So what is good about it? First, it can use one of two dual rail-to-rail op amps and these have the outstanding feature of maximum output voltage swing. So, for example, if you have a 9V supply rail, the maximum undistorted output voltage can be within a whisker of 9V peak-to-peak; about 8.5V p-p, to be more precise. That is much better than the old PreChamp design and you don’t have to tweak the input bias to obtain it. Another advantage is that the spec­ ified rail-to-rail op amps can be designed into a preamp with a very high input impedance. This is highly desirable if you want a preamplifier to suit a ceramic phono cartridge or a piezoelectric pick-up in a musical instrument such as a violin. In both cases, an input impedance of 5MΩ is desirable for good bass response. Optional electret microphone One of the attractions of the Pre- Champ was that you could install an on-board electret microphone. The only modification required was to add a bias resistor. That feature can also be included in this 2-channel design and you could, in fact, have two electret microphones, although for useful channel separation you would need to install them both on shielded leads. Circuit details Let’s have a look at the circuit which is similar to but not exactly the same as the preamp in the January 2013 article. Fig.1 shows the details. Both channels are shown and the dual op amp is an LMC6482. Since we are employing a single DC supply rail, we need a halfsupply reference from which to bias the inputs of both op amps. This reference is derived from the supply rail via a voltage divider consisting of two 10kΩ resistors bypassed with a 100µF electrolytic capacitor. We can use such high-value resistors for the divider because the bias current drawn by each input of the op amps is a just a fraction of a picoamp. On the other hand, we want that bypassed half-supply to have quite a low impedance, hence the relatively large capacitor value of 100µF. Both op amp circuits are identical although it is possible to have different gains in each channel, depending siliconchip.com.au PREAMP POWER + 12–20V DC D1 1N5819 1 A 2 – K REG1 78L09 1 0 0 µF 25V 10k +9V OUT IN GND 10 µF musical instrument such as a guitar but you can easily increase or reduce the gain to suit by changing the value of R5 and you can change the input impedance as well. For example, if you want to configure it for a dynamic microphone, R2 & R3 are changed to 100kΩ each to give an input impedance of 50kΩ, while R5 is changed to 100kΩ to give a gain of 101 times (41dB). If you want to install an electret microphone insert on the PCB, you would install it in place of 100pF capacitor C101. At the same time, R101 is changed to 10kΩ and it provides the bias current for the electret. The other end of the 10kΩ resistor is connected to the positive supply rail, from REG1. Finally, R102 is omitted, R103 is 220kΩ and the gain is set to 23 (27dB) with R105 being 22kΩ. + 4 .5V 10k 100nF 100 µF CON1 PREAMP IN1 1 2 CON2 R1 100Ω R2 2.2M TO PIN 1 OF CON3 WHEN ELECTRET MIC FITTED 100nF 3 2 C1 100pF 8 100Ω 1 IC1a 4 R5 56k R3 2.2M CUT TRACK 100Ω ADDED ELECTROLYTIC CAPACITOR FERRITE BEAD R4 1k LINK TO +9V RAIL FROM REG1 WHEN ELECTRET MIC FITTED PREAMP IN2 10pF 100 µF + 4 .5V R101 2 CON3 R102 100nF 5 6 C101 100pF VR2* 10k CON4 CUT TRACK 10k R105 R103 OPTIONAL ELECTRET MIC INSTALLED INSTEAD OF C101 7 IC1b PREAMP OUT VR1* 10k LOG IC1: LMC6482 1 100 µF R104 1k ADDED RESISTOR * ONLY ONE OF VR1 (16mm POT) OR VR2 (TRIMPOT) TO BE INSTALLED 10pF + 4 .5V 78L09, LP2950CZ-5.0 SC  20 1 5 GND 1N5819 CHAMPION PREAMP A K IN OUT Ceramic cartridge Fig.1: the preamplifier circuit. It’s based around dual rail-to-rail op amp IC1. The signal from each input is AC-coupled and biased to half supply, then amplified and re-biased to 0V DC before being fed to CON4. on your application. For the moment though, let’s assume that both are identical and we will just describe channel 1, based on op amp IC1a. The input signal from CON2 passes through a low-pass filter consisting of a 100Ω resistor (R1) and a small ferrite bead in series, together with a 100pF capacitor connected to the 0V line (C1). This is to attenuate any RF signals that may be picked up by the input leads. There is also a 2.2MΩ resistor to pull the input signal to ground (R2). If you are going to feed the preamp with an iPod or similar player you will need to use a much lower value of, say, 1kΩ to provide it with sufficient load current. For the moment though, the values we have shown on the circuit for channel 1 are selected to suit the pick-up in an electric guitar. The signal is then AC-coupled via a 100nF capacitor to pin 3 of IC1a and a 2.2MΩ resistor biases the op amp’s input to the half-supply rail. This ensures that the output waveform will swing symmetrically within the supply rails of dual op amp IC1. The two 2.2MΩ siliconchip.com.au resistors on either side of the 100nF AC-coupling capacitor are in parallel as far as the signal source is concerned, setting the unit’s input impedance to around 1.1MΩ. IC1a buffers and amplifies the signal from CON2 while IC1b does the same for the signal from CON3. Gain is set at 57 times (35dB) by the 56kΩ (R5) and 1kΩ (R4) feedback resistors. The 10pF feedback capacitor reduces the gain for high-frequency signals, giving a little extra stability and noise filtering. Changing the gain Note that this high gain suits a Another interesting application is to use the Champion preamp with a stereo ceramic cartridge (don’t laugh; this was a standard fitment on millions of record players and many people are dragging them out to listen to their old record collections). Ceramic cartridges require a high input impedance and this is an easy option with this preamp. Both R2 & R3 are specified at 10MΩ, giving an input impedance of 5MΩ which ensures good bass response. The gain does not need to be high though and so we can set R5 to 2.7kΩ. This gives a gain of 3.7 (11.3dB). The same configuration can be used for a piezo pick-up on musical instrument such as a violin. So to summarise, depending on Table 1: RC Gain Selection Values Input Gain R1/101 C1/101 R2/102 R3/103 R4/104 R5/105 Guitar 57 100Ω 100pF 2.2MΩ 2.2MΩ 1kΩ 56kΩ Microphone 101 100Ω 100pF 100kΩ 100kΩ 1kΩ 100kΩ Electret 23     10kΩ* – – 220kΩ 1kΩ 22kΩ MP3 28 100Ω 100pF 1kΩ 220kΩ 1kΩ 27kΩ Piezo Pick-up 3.7 100Ω – 10MΩ 10MΩ 1kΩ 2.7kΩ * Connect one end of this resistor to the +9V rail from REG1. June 2015  75 100µF TOP VIEW OF PCB 100nF 10pF VR2* 10k + VR1* R104 1k 10k + 100 µF CON2 + 100 µF Out CON4 CUT TRACKS + 10pF 10 µF Power 100 µF 25V + + 10k CON1 100nF R5 + C1 IN 2 100pF R2 IN 1 R3 100Ω 100nF IC1 BEAD R1 R4 1k CON3 R102 R103 UNDERSIDE OF PCB + 01109121 R105 + 100pF BEAD LMC6482 C101* 100Ω R101 100Ω − REG1 78L09 D1 + 5819 * OPTIONAL ELECTRET LINK WHEN ELECTRET MIC FITTED INSTEAD OF C1 * FIT EITHER VR1 OR VR2, NOT BOTH INSTALLED INSTEAD OF C101 Fig.2: follow this layout diagram to assemble the PCB. It’s best to cut the tracks first and then check with a continuity meter before fitting the parts. Table 2: Resistor Colour Codes   o o o o o o o o o o o Value 10MΩ 2.2MΩ 220kΩ 100kΩ 56kΩ 27kΩ 10kΩ  2.7kΩ 1kΩ 100Ω 4-Band Code (1%) brown black blue brown red red green brown red red yellow brown brown black yellow brown green blue orange brown red violet orange brown brown black orange brown red violet red brown brown black red brown brown black brown brown what type of source you are using and the gain required, you can easily obtain the required input impedance and gain. Table 1 shows the values to use. Two outputs In the original Champion preamplifier, the outputs of the two op amp stages are mixed using a pair of resistors and then AC-coupled to potentiometer VR1 or VR2, depending on which is installed. In our application, we want two separate outputs and so if an output level control is to be used, it can only affect one channel. As shown on the circuit of Fig.1, the output of IC1b connects to VR1 (or VR2) via a 100Ω resistor and 100µF DC blocking capacitor. The wiper of VR1 then connects to one terminal on CON4. The output of IC1a is also fed via a 100Ω resistor with a second blocking capacitor and bias resistor added under the board. This output goes to the other terminal on CON4. Note that two track cuts on the PCB need to be made, in order to give this independent two channel operation. IC1 is powered via a 78L09 lowpower 3-terminal 9V regulator, assuming you are using a DC plugpack with 76  Silicon Chip 5-Band Code (1%) brown black black green brown red red black yellow brown red red black orange brown brown black black orange brown green blue black red brown red violet black red brown brown black black red brown red violet black brown brown brown black black brown brown brown black black black brown   Table 3: Capacitor Codes Value 100nF 100pF 10pF µF Value 0.1µF NA NA IEC Code EIA Code 100n 104 100p 101 10p 10 an output of 12V or more (up to 20V DC). This regulator is fed from CON1 via Schottky diode D1 which protects against reversed supply polarity. Note that if you intend using a 9V battery for this project, you may want to employ the LP2950CZ-5.0 5V regulator. No other modifications are required if you make this change but the preamplifier will inevitably have a reduced output voltage swing and therefore a reduced overload margin for strong input signals. Construction You will be using the Champion PCB for this project (code 01109121) and you will need to cut off the section for the AN7511 audio amplifier. Don’t discard it – it’s a handy little amplifier module in its own right and the AN7511 amplifier chip is quite cheap. Parts List 1 PCB, code 01109121, 57 x 41mm (see text) 1 PCB-mount electret microphone insert (Jaycar Cat. AM4011) (optional; see text) 1 10kΩ log PCB-mount 16mm potentiometer (VR1) OR 1 10kΩ mini horizontal trimpot (VR2) 2 ferrite beads, Jaycar LF1250 4 mini 2-way terminal blocks (CON1-CON4) (omit one if electret is installed) 1 8-pin DIL socket 4 M3 x 10mm tapped Nylon spacers 4 M3 x 6mm machine screws 1 short length hookup wire (60mm) Semiconductors 1 LMC6482 or LMC6032 dual op amp (IC1) (eg, Jaycar ZL3482) 1 78L09 or LP2950CZ-5.0 5V LDO regulator (REG1) (eg, Jaycar ZV1645) – see text 1 1N5819 Schottky diode (D1) Capacitors 1 100µF 25V electrolytic 3 100µF 16V electrolytic 1 10µF 16V electrolytic 3 100nF MMC or MKT 2 100pF ceramic (omit one if electret is installed) 2 10pF ceramic Resistors (0.25W, 1%) 3 10kΩ 2 100Ω See Table 1 for R1-R5 Note: Jaycar will be selling a kit of parts for this project – Cat. KC5531. The remaining preamplifier PCB measures just 57 x 41mm. It has provision for mounting pillars at its four corners and four 2-way connector blocks. One of those blocks is used as the terminals for the two preamplifier outputs. Since there are changes to the component layout, this means that you will have to follow the parts layout of Fig.2 and ignore most of the resistor values shown on the screen-printed layout on the PCB itself. You also need to cut the copper tracks of the PCB in two places as shown on Fig.2. Having cut the tracks, start the assembly by installing the resistors. siliconchip.com.au +3 11/05/15 12:00:11 Pre-champion Frequency Response 1.0 +2 11/05/15 12:15:43 Pre-champion THD+N vs Frequency Input signal = 50mV RMS, gain ≈ 27, bandwidth = 80kHz 0.5 Total Harmonic Distortion + Noise (%) +1 Amplitude Variation (dBr) 0 -1 -2 -3 -4 -5 -6 -7 0.2 0.1 0.05 LMC6482 0.02 LMC6032 0.01 .005 -8 .002 -9 -10 10 20 50 100 200 500 1k 2k 5k 10k 20k 50k 100k .001 20 50 100 200 Frequency (Hz) Fig.3: frequency response is within +0,-0.5dB between 30Hz and 20kHz with -3dB points around 8Hz and 55kHz. It’s less than 1dB down at 20Hz. 500 1k 2k 5k 10k 20k Frequency (Hz) Fig.4: the LMC6032 has about half the noise of the LMC­ 6482. The LMC6032 requires slightly more operating current than the LMC6482 but still under 1mA. These two larger-than-life-size views show the completed PCB assembly. Note the wire link on the back of the PCB when an electret mic is used. You will need to refer to Table 1 for the values for R1-R5 and R101-R105. Table 2 shows the colour codes but it is good idea to check each value with a multimeter before fitting it. A ferrite bead should be slipped over one leg of each 100Ω input resistor, if fitted (ie, R1 & R101). Follow with diode D1 and then fit the IC socket with its pin 1 notch orientated as shown. Next, fit the 78L09 or LP2950CZ-5.0 regulator, REG1. Follow with the ceramic and monolithic capacitors. The 2-way terminal blocks are next, each installed with its wire entry holes facing outwards. Note that CON3 is not installed if you have fitted an electret microphone insert for channel 2. The next step is to decide whether to fit potentiometer VR1 or trimpot VR2. It will only control the output signal level from one channel and you may decide to link it out. You can then fit all the electrolytic capacitors. In each siliconchip.com.au case, the longer lead goes into the hole marked with a “+” sign. Once those parts are in, fit the M3 x 10mm tapped spacers to the corner mounting positions using M3 x 6mm machine screws. If you are installing an electret, wire a 10kΩ resistor in the position for R101 and connect the end adjacent to CON3 to the output of the 3-terminal regulator. We show this with a dotted red line on Fig.2. In addition, R102 and C101 are omitted. If you are going to use only one channel of the preamplifier, it’s a good idea to short the unused channel’s input to 0V by using a wire link for resistor R1 (or R101) and by shorting the two terminals of CON2 (or CON3). When you have carefully checked your assembly and soldering against the circuit of Fig.1, Table 1 and the overlay diagram of Fig.2, you are ready to apply power. Check that the output of REG1 is 9V (or close to it) if a 78L09 has been fitted. If an LP2950CZ-5.0 has been fitted, REG1’s output should be close to 5V. Next, turn off the power, insert the op amp (carefully), power back on and then check the DC voltage at pins 1 & 7. In each case, they should be sitting at half supply; 4.5V for a 9V supply and 2.5V for a 5V supply. Performance Figs.3 & 4 show the frequency response and total harmonic distortion curves of the preamplifier. Note that of the two op amps we’ve specified, the LMC6032 gives the best performance but it isn’t as easy to get as the more common LMC6482. To achieve a THD+N this low, the preamp will need to be installed in an earthed metal box. Otherwise, hum and RF pick-up will reduce the signalto-noise ratio and consequently the total harmonic distortion perform­ SC ance. June 2015  77 SPIKE: improved software for the Signal Hound By JIM ROWE When we reviewed the Signal Hound USB-SA44B mini spectrum analyser in the October 2014 issue of SILICON CHIP, we were very impressed with the performance of both the hardware and its accompanying software. Now Signal Hound has come up with a greatly enhanced software pack­ age to go with the USB-SA44B and their other instruments. I N OUR ORIGINAL review of the USB-SA44B spectrum analyser, we were particularly impressed with the analyser hardware itself. Inside its compact 77 x 27 x 167mm aluminium case there is an advanced narrow-band SDR receiving system tuning over the range from 1Hz to 4.4GHz and delivering a level of performance that compares very favourably with high- end self-contained spectrum analysers – but at a fraction of their price. We were also impressed with its software package which controls the USB-SA44B hardware box (and the optional USB-TG44A tracking generator) from your PC as well as accepting, processing and analysing the output data stream from it to produce the analyser’s output display and measurements. Fig.1: a full-screen grab of Spike in “real time” mode scanning at a centre frequency of 1090MHz, showing Persistence on the spectrum plot (lower centre), with a 2D spectrogram above it. 78  Silicon Chip The software did have a few rough edges but we judged them to be fairly minor and not significant, considering the excellent performance of the USBSA44B hardware. But early this year Signal Hound released a greatly enhanced version of their software package, renamed “Spike”. And in the last three months or so they’ve released a number of upgraded versions of Spike. We’re reviewing the latest version at the time of writing: Spike 3.06. This is now being provided on the CD accompanying the USB-SA44B and other analysers purchased new. Existing users can download it at no charge from Signal Hound’s website at www.signalhound.com/spike It comes as a zip file which includes its matching USB drivers. A PDF of the User Manual for the new software can also be downloaded from the same website. Spike 3.06 is compatible not just with the USB-SA44B but also with the rest of the Signal Hound products, including the USB-TG44A tracking generator. There are two versions, compatible with the 32-bit or 64-bit versions of either Windows 7, 8 or 8.1. Note that although the Spike softsiliconchip.com.au Fig.2: a spectrum plot showing the Sydney DRMT DAB+ signal block centred on 204.5MHz in channel 9A, captured using Spike 3.06 and saved as a JPEG file. Fig.3: another plot centred on 92.9MHz, showing the Sydney ABCFM signal spectrum (bottom) with a 2D spectrogram above it. Spike again saved it as a JPEG file. ware can be downloaded and installed at no charge, it will only work with Signal Hound devices like the USBSA44B. When you start up the software it automatically searches the PC’s USB ports to see if one or more of the devices is connected. When it finds one, it displays the device’s serial number and other information (like internal temperature and firmware revision) at bottom right on its main display window; otherwise it refuses to proceed. What’s new? The first thing you notice when you fire up Spike (in my case, with a USBSA44B) is that the user interface window has been completely revamped. The main display graticule is now centred on the screen, with control panel menus running down either side. It’s less crowded than before, having been proportioned to suit the 16x9 wide-screen aspect ratio used on most modern laptops and PC monitors. As before, the main functions, settings and facilities are selected using a menu bar and toolbar running along the top. The control panel menus on the left side then allow you to set the Measurement trace and marker parameters, any offsets that may be required and settings for Channel Power and Occupied Bandwidth measurements. The menus on the right side control panel allow easy setting of all sweep parameters: Frequency (Centre, Span, Start, Stop and Step, plus the ability to set the analyser for either Full Span or Zero Span [more about this later]); siliconchip.com.au Fig.4: this full-screen grab shows Spike 3.06 in real-time scanning mode, centred at 1090MHz (the frequency used by commercial aircraft for ADSB). The 2-D spectrogram is shown above the spectrum plot itself. Amplitude (Reference Level and Graticule Divisions, plus the ability to select either manual or automatic internal gain, attenuation and preamp enabling); Bandwidth (RBW and VBW); and finally Acquisition options such as Video units, Detector mode and Sweep Time. This is not Spike’s only display graticule or control menu panel, as will become clear shortly. So Spike’s initial window is much snazzier than that of the original Signal Hound software. But that’s only the start of its new features and capabilities, because the new software can now take full advantage of the capabilities of Signal Hound’s analyser hardware – including those of the USB-SA44B. For example, you can now select either of two different types of spectrogram to accompany the analyser’s main amplitude vs frequency display: a 2D spectrogram which gives the moving “waterfall” display or a 3D spectrogram which gives a series of sweep displays receding into the distance. These can both be helpful when you’re trying to look for significant events. Another nice new feature applying to the main graticule display is persistence. When you enable this feature, the current signal trace is accompanied by a “community” of earlier traces, in colours representing their time prior to the current trace. It’s a bit like having a fixed spectrogram displayed directly behind the June 2015  79 Fig.5: another screen grab showing Spike in real-time scanning mode, centred at 1090MHz, this time with a 3-D spectrogram shown above the spectrum plot. Fig.6: this screen grab shows Spike 3.06 in “zero span” mode – another of its exciting new features, designed to facilitate modulation analysis. It shows the actual spectrum plot at lower left, with the modulation plotted against time at upper left and the I/Q IF output stream at lower centre. A summary of the signal and modulation data is shown at upper centre. trace itself, in the main graticule. There’s another new feature that’s even more impressive: Spike now provides a real-time spectrum analysis mode, to allow capturing occasional short-term events which can easily be missed in normal sweep analysis if they occur during the “dead time” between sweeps. In real-time analysis mode, Spike takes advantage of the ability of Spectrum Hound’s analyser hardware to stream its full IF bandwidth back to the PC (via the USB cable) continuously, with no time gaps. So by limiting the sweep span to the maximum instantaneous bandwidth, Spike is now able to process and analyse every spectrum sample in real time. Incidentally, the spectrogram and 80  Silicon Chip persistence features can be applied in real-time mode just as easily as in sweep mode. If this isn’t enough, there’s now a zero-span analysis mode too. This might sound a bit strange but it’s really quite easy to understand. In zero span mode, Spike directs the analyser to stay locked to the centre frequency you’ve set, while it again streams the full IF bandwidth back to the PC. This allows Spike to demodulate any AM, FM or PM modulation which may be present on a signal at that centre frequency. As a result, when Spike is in zero-span mode, the screen changes dramatically, with the RF amplitude vs frequency spectrum graticule reduced in size and moved to the lower left, while the modulation is displayed plotted against time in a new graticule across the top. In addition, the I and Q components of the analyser’s IF data stream are displayed in a third graticule at lower right, alongside the amplitude vs frequency plot. Then if you enable Spike’s AM/FM modulation analysis feature, the upper modulation vs time graticule contracts to the left, and quite a bit of modulation analysis data is displayed in the top right quadrant. You’re shown a continuously updated summary of RMS, Peak+ and Peak- modulation percentages, plus the modulation frequency and RF centre frequency, together with the SINAD (dB) and THD (%) figures. Other features There are other noteworthy features as well, including: (1) The ability to call up an Audio Player function, to listen to any AM or FM modulation of the centre frequency signal via the PC’s speakers; (2)  The ability to call up a Measuring Receiver function, to display various key parameters of the centre frequency signal; (3)  The ability to record the data from an analyser session as a file on the PC, and also to replay a recorded file for further analysis; (4) In zero-span mode, there’s also the ability to save a short duration I/Q capture, either as a binary file or in a text-based format such as a CSV (comma separated variable) file; (5)  The ability to plot phase noise and (6)  If you add a USB-TG44A Tracking Generator to your set-up, the software can be easily set up to perform scalar network analysis. In short, Signal Hound’s new Spike 3.06 software really expands the measurement applications of their USB-based spectrum analysers (like the USB-SA44B) dramatically, as well as taking full advantage of the hithertohidden performance features of the analyser hardware. The new User Manual for Spike is also a significant improvement on the original manual, which was already pretty good. In Australia and New Zealand, Signal Hound products like the USB-SA44B and the USB-TG44A are distributed by Silvertone Electronics, now based in Wagga Wagga, NSW. You’ll find their website: www.silverSC tone.com.au siliconchip.com.au Final part of our quality Weather Station based on System designed by Armindo Caneira* Built and written by Trevor Robinson *www.meteocercal.info The Wireless Display Unit In the last part, we built the RX unit and configured Cumulus to collect, record and display your weather data. Now we are going to complete the Weather Station by building the handy little Wireless Display unit (WDU). T he Wireless Display unit actually evolved from the RX unit (which, incidentally, can also be used as a WDU with some minor mods). It receives wireless data on a 433MHz link from the RX unit (see part 3), which in turn has received data from the outside weather sensors via the TX unit (see part 2). It also sends data from its own DHT22 temperature and humidity sensor. The main differences between the two is the barometer sensor and the run/program pullup switching has been omitted. And of course, it has its own firmware file. Beside having a display screen, it only has one push-button switch (the Display Mode switch) and a LED. The LED blinks when data is received over the 433MHz link. The WDU is powered through its Mini-B USB connector, so you will need a 5V DC power pack with a mini-B USB connetor or a Mini-B USB cable to connect it to a suitable power supply like a USB phone charger. Once again, like the RX unit, you have the option of one of the following five different displays: TFT – ILI9341 2.4” or 2.2” (320x240) or the ST7735 1.8” (160x128) Alphanumeric LCD: 20x4, or 16x2 with I2C module Constructing the Wireless Display Unit The WDU PCB purchased from Meteocercal will al- A completed WD unit with a 2.4” TFT display siliconchip.com.au June 2015  81 (Above): reverse side of the WD PCB; the “top” side at right has the Arduino Nano and 433MHz modules fitted. ready have the surface mount components soldered on, as shown above (there is also an SMD on the opposite side). These can be a bit tricky without the correct tools. Once again, like all electronic kitset projects, it’s easiest to install and solder in the smallest components first: the resistors and capacitors. Next install the LED, observing the polarity, followed by the header and antenna connectors. Like last month, it’s best to install the Nano using a suitable socket. But if you are soldering the Nano directly to the PCB, it’s good practice (as with all heat sensitive components) to stagger the soldering of the pins to help avoid localisation of heat build up. Finally install the BX-RM06 ASK OOK RF receiver module vertically on the WDU board. Ensure that the component side of this board goes to the outside of the WDU board pin – its easy to install this component back-to-front if care isn’t taken. Not only will it not work, it will quite likely be damaged (and it’s a pain to desolder!). The WDU board is now complete but before moving on, double check your work, looking for solder bridges (especially between module and header pins) and cold solder joints. A jeweller’s loupe or magnifying lamp are great tools for getting a good close-up view. the Dupont female to female wires to make life easy. The backlight jumper needs to remain in place, but you may need to tweak the contrast potentiometer. LCD Connecting the display screen Both of these are dependent on what sort of case you get. The momentary action pushbutton switch should be connected by soldering wire to the contacts and then the other end to the contacts of the header connector plug. The LED can be soldered into its position on the PCB, though it would be better to use a suitable length of cable to connect it to the PCB from somewhere visible on the case. The push button changes the display mode as per the table below: Much of the following information is repeated from last month’s (Part 3 – The Receiver) issue because the Wireless Display Unit and Receiver Unit share a common heritage and indeed, most parts TFT pin assignment are interchangeable. TFT display Use nine of the Dupont female to female wires to connect PCB pin headers to TFT pin headers. Currently the SD card and touch overlay are unused. Alphanumeric LCD PCB TFT Display 2.4” TFT – ILI9341 320x240 SCLK SCLK MOSI SDA CS CS RST RESET SDI(MOSI) PCB LCD GND GND This is the same as what we did for 5V the RX unit. We’ll cover it briefly again, 5V just in case your dog ate your homework SDA SDA last article. Solder four header contact pins to SCL SCL one end of whatever length of cable you DHT22 Temp. Sensor require. The maxiPCB Schematic Pin DHT 22 pins mum length this cable can be is five metres. GND 1 (GND) 3 OR 4 Solder and heatshrink 2 (D6) 2 the other end to the DAT four legs of the DHT22 5V 3 (5V) 1 sensor. Ensure the pin assignment matches the table above. Push button (display mode switch) and LED (data received indicator) SCK Display Mode Switching LCD TFT CS Short press Nothing Toggles the Display off/on RESET Long press Nothing Toggles the big font size screen DC A0 D/C 5V VCC VCC GND GND GND The LCD connection LED process is simpler as it LED+ LED+ only uses four wires. LED- LED- No connection You can also use four of needed 82  Silicon Chip Connecting the DHT22 temperature sensor Pinouts Button Action Double press     Toggles the information screen The information screen shows the firmware version, TX unit voltage and case temp from the TMP36 sensor. Programming the WeatherDuino Pro2 Nano Since you are now an old hand at programming Arduinos, we shouldn’t have to go into too much detail here. If you siliconchip.com.au Another view of the completed WDU PCB, this time showing the method of mounting the 433MHz wireless link. Take care with this – with four pins at each end it’s not difficult to solder it in the wrong way . . . but rather more difficult to unsolder it and fix your mistake! need a refresher, part two had an in-depth guide to setting up the IDE and part three covered reading and altering of the WeatherDuino code to suit that application; maybe read those again. Acquire the required firmware Download the required firmware file from here: www. meteocercal.info/forum/Thread-WeatherDuino-Pro2-WDSoftware-Latest-Release Save the file to wherever, then extract the contents into your Arduino sketch folder which should be in the \users\ your_username\Documents\Arduino folder. Click “OK” on any merge or overwrite dialog boxes. Now go into that folder and double click the folder WeatherDuino_WD_vxxx_bxxx (the “x”s change by release version). Then in that folder there should be a file called WeatherDuino_WD_vxxx_bxxx.ino – double click that to open it in the Arduino IDE. Configuring the code Now we need to tweak a few lines to suit our WDU setup. Scroll down to around line 44. We need to start by changing the code to suit our display type, so pick your display type number from the comment section: 0= TFT 160x128 ST7735, 1= TFT 320x240 ILI9341, 4= 20x4 LCD, 5= 16x2 LCD Say your have the big LCD display, you would change the line to read this: #define DisplayType 4 // 0= TFT 160x128 ST7735, 1= TFT 320x240 ILI9341, 4= 20x4 LCD, 5= 16x2 LCD The big TFT display is set to the default so you would just leave that line as is. Next is the Backlight timeout: byte BackLight_Timeout = 0; // Timeout for TFT backlight in minutes (1 to 255). 0= Always ON siliconchip.com.au You have the option of having it on continuously (though a short button press turns it off) or setting the timer to turn it off automatically some time after the last button press. Your choice. If you want to just manually turn off the backlight then just leave the default setting. Next is the Temperature sensor type. Since we when with the good old DHT22 you can left this line alone also. The next line you also leave at the default setting of 1 #define Board_Type 1 // 0= Standard Boards, 1= Extended version Wireless Display Boards Pretty simple configuration on this unit isn’t it? Save it with a filename that reflects your setup so if you wish to tweak/change it in the future, you will know what it is. Compile and upload it to the Nano by pressing the right arrow in the Arduino IDE. After a short period of time the WeatherDuino Pro2 Wireless Display unit should reboot and a little while later the inside temperature should be displayed and after a little more time the outside data should display. If the IDE produces errors its usually one of two things: 1: File too big. Your are not running the Arduino IDE version 1.5.8 or greater. 2: The library files are not where the IDE is expecting them. Double check they are in the sketch folder or manually import them in the IDE (Sketch/Import Library). That’s all folks! We hope you enjoyed creating this project and find the data this weather station creates is more reliable and accurate than your previous station may have produced, or even the weatherman on the radio. We certainly did! When you get you weather station online, please leave a post on the Meteocercal forum so you can have your station added to the WeatherDuino user map here: www.meteocercal.info/forum/misc.php?page= WeatherDuino_Users_Map SC June 2015  83 Vintage Radio By Ian Batty The Philips model 198 transistor radio Philips’ first Australian-made transistor set Housed in an attractive leatherette case, the model 198 was Philips’ first Australianmade transistor set. It was a 7-transistor design and both it and the later model 199 offered excellent performance. B EGINNING IN Eindhoven in 1891 and founded by Gerard Philips and his father Frederik, Philips became one of the world’s largest technology companies but today it concentrates on lighting and healthcare. The company began manufacturing in Australia in 1931 but produced only two models before temporarily halting production and then resuming in 1934. Philips then quickly grew to become one of Australia’s largest electronics manufacturers, with radios sold under 84  Silicon Chip the Briton, Mullard and Fleetwood brand names. TV receiver production subsequently started in 1956 and continued until the 1980s. In addition, Philips manufactured valves, TV picture tubes and transistors, including the famous OC44/45 and OC70/ 71/72/74 series that many of us bought to build our first transistor sets. Design highlights Described in Vintage Radio for April 2015, Australia’s first transistor radio, the AWA 897P, was released in 1957. This was followed just a year later by Philips with their model 198. Like the 897P, this was another 7-transistor design and the case used by Philips was modelled on a previous valve version, the compact AC/battery model 196. AWA’s engineers used three audio stages in the 897P, based on four transistors and three transformers. By contrast, Philips opted for a design that was to become standard, with just three transistors and two transformers used for the audio amplifier. Like AWA, Philips paid attention to Australian conditions, by employing a thermistor-stabilised output stage. They also added adjustable output stage bias, as described below. The Philips 198 was more compact than the AWA 897P and it looks somewhat like a small cosmetics case. But don’t let its “domestic” appearance fool you – it really is a very good radio. The accompanying photos show the set’s controls which are, from left to right: Volume, Off, Treble/On and Bass/On along the top and, on the front panel, a tuning control with integral dial. Philips 198 chassis details Like Bush’s TR82C and AWA’s 897P, the Philips 198 uses a pressed-andpunched metal chassis. Its successor (the 199) is similar but with sufficient differences to warrant a separate circuit diagram (the major differences are noted in the text). The 198 has five of its transistors installed in chassis-mounted rubber grommets, with the leads wired to adjacent solder tags. By contrast, the two output transistors are held in heatsink clips which are screw-mounted on the underside of the chassis. Unlike the AWA set, the chassis sits horizontally inside the case, allowing some access to the underside where most of the components are mounted on tagstrips. The IF transformers and the LO coil, however, are mounted versiliconchip.com.au Fig.1: the circuit details of the Philips 198. TR1 is the converter stage, while TR2 & TR3 are the IF amplifier stages. D2 is the detector and this feeds buffer stage TR4 which in turn drives an audio amplifier based on TR5-TR7. tically, so that the chassis still needs to be removed for any detailed work, including alignment. The case itself is made from leatherette-covered “composite” material (cardboard), while the front dial at top-right turns easily with a direct drive. To the left of the dial is a large speaker grille. Power is controlled by pushbutton switches, so the volume pot only controls the volume. Because it doesn’t also function as an on/off switch, the volume pot doesn’t have to be turned down to or up from zero each time the set is turned off or on, thereby extending the pot’s life. Circuit details Fig.1 shows the circuit details of the Philips 198. Transistor TR1 is the converter stage and this operates as an autodyne oscillator with collector-emitter feedback. AGC is not applied to this stage, so TR1 operates with fixed bias. As shown, TR1’s bottom divider resistor (R2) and its bypass (C4) are connected between the “cold” (bottom) end of the ferrite rod’s two windings (tuned and base) and ground. This means that the bottom of the antenna windings are at base bias voltage, thereby providing a handy test point. By contrast, the later 199 model connects both antenna windings directly siliconchip.com.au to ground, with the bottom of the base bias circuit going to the top of the base winding. The base-emitter voltage is only 50mV, since converters must operate close to Class B conditions to give the non-linear “modulating” effect needed for frequency conversion. Because the tuning gang uses identical sections, padder capacitor C9 is included to modify the capacitance range of the oscillator section so that the local oscillator tunes from about 990-2060kHz. The only unusual feature is that the oscillator coil’s secondary is held at the converter’s collector voltage. While this eliminates any potential difference between primary and secondary, it’s not common practice. Converter TR1 feeds the first IF stage (TR2) via IF transformer L3/L4 which has tuned and tapped primary and secondary windings. TR2 is gaincontrolled by the AGC system and due to the high feedback capacitance of alloyed-junction transistors, this stage is neutralised by feedback via C13 from the second IF transformer’s untuned (and untapped) secondary. By contrast, in the 199 model, this feedback is derived from an overwind on the second IF transformer’s primary. In addition, the second IF transformer has a tuned and tapped secondary. The second IF stage is based on TR3 and runs with fixed bias. It’s also neutralised, via C19, and both the 198 and 199 models derive feedback from the third IF transformer’s secondary. The third IF transformer uses a tuned, tapped primary and a lowimpedance, untuned secondary to feed demodulator diode D2. AGC circuit Depending on the strength of the incoming RF (and IF) signal, diode D2 provides a negative DC output to the base of TR4, the first audio/AGC stage transistor which is connected as an emitter follower to buffer the detector. Stronger IF signals will therefore cause TR4’s emitter current to increase but it does not amplify the resultant audio, merely passing it to the following volume control potentiometer (R20). However, the DC signal from TR4’s emitter is then filtered by capacitor C14, so that the resultant DC voltage is more or less proportional to the IF signal strength. This DC voltage is applied to the emitter of TR2 and if this voltage increases, TR2’s gain will tend to be reduced. As a result, changes in signal strength are counteracted and the set’s output remains substantially constant for vary­ing signal strengths. June 2015  85 The model 198 is built on a metal chassis, with point-to-point wiring. Five of its transistors are installed in chassismounted rubber grommets while the two output transistors are held in heatsink clips which are screw-mounted on the underside. As well as AGC, the set also includes an “overload diode”, better described as an “AGC extender”. Simply controlling one stage (such as TR2) only provides a limited range of control. In this set, the stage gain is some 30dB and thus simple AGC can only counteract about this range of input signal. After that, the audio output begins to rise noticeably or the second IF stage goes into overload. To prevent this, auxiliary AGC diode D1 is connected between the primary of the first IF transformer (L3) and the collector supply to TR2 at the junction of R7 and C16. This latter junction sits at about -5.4V DC but is effectively at signal ground due to C15. By contrast, D1’s anode at L3’s primary sits at about -6.2V DC and is at IF signal level. It’s also connected (via L5) to converter TR1’s collector. With no signal, D1 has around 0.8V of reverse bias. As TR2’s collector current falls with increasing signal, its collector voltage (developed across R7) rises. This pulls D1’s cathode towards the supply voltage and (importantly) reduces its reverse bias. As TR2’s collector current falls further with increasing signal strength, D1 eventually begins to conduct and damps the IF signal at TR1’s collector, thereby preventing it from increasing. The result is that the model 198 has 86  Silicon Chip effective AGC and provides consistent audio output levels over a wide range of signal strengths. R32-C32, with the 100nF capacitor increased in value for the 199. Audio stages The push-pull Class B output stage is based on TR6 & TR7 and has thermistor-compensated bias (R29). This bias can be adjusted using R27. The model 198 also has a shared 5Ω emitter resistor (R31) but this was removed for the 199. At 5.5mA, the bias current is a little higher than in most other sets but I found that I was able to set it to almost zero with no noticeable increase in crossover distortion. The alignment guide, by the way, recommends running the set for three minutes prior to checking or adjusting the output stage bias. In the model 198, audio stage feedback is applied from TR6’s collector to TR5’s base via two paths. First, there is a permanent feedback path via R22-C27 (the 199 uses a single 220kΩ feedback resistor and takes the feedback from the speaker terminal). And second, Bass switch S1/S2 switches C29 and R30 across the feedback path to apply extra treble roll-off (the 199 uses slightly different values here). In operation, this brings the upper -3dB point down to just 2kHz (the model 199 also derives this “top-cut” feedback from TR6’s collector). S3/S4 (Treble) switches in C33 to The audio stages begin unconventionally with the emitter follower/ buffer stage based on TR4. It’s more usual to see a common-emitter stage here but given the AGC design (which feeds some current through NTC thermistor R16 in order to operate), it makes sense. In operation, TR4’s bias is temperature-stabilised by R16, presumably to prevent TR4’s AGC action from being disturbed by high or low ambient temperatures. Following TR4, the signal is fed to the remaining audio stages via volume control pot R20. Its circuit configuration is also unconventional: its “hot” end connects to TR4’s emitter and its “cold” end goes to TR5’s emitter, which produces about 0.7V DC across the pot. However, because TR5’s emitter is at AC (signal) ground, R20 works just fine as a volume control. The peculiarity is that there is standing DC across the pot, which is usually a recipe for noisy operation. Audio driver TR5 is a conventional transformer-coupled stage. No treble roll-off is applied here but was added in the 199 model. It is, however, applied in the output stage using Push-pull output stage siliconchip.com.au This is the under-chassis view of the model 198. The set was still in working order and no parts had to be replaced, although the set did require alignment adjustments in order to optimise its performance. provide extra bypassing for the demodulator (this is absent on the 199). Like the Bass switch, it also turns the set on via its second set of contacts. By the way, the circuit shown here is a redrawn version, since the original circuit isn’t all that clear (at least as found online). The original component numbering has been preserved. Restoration The set shown here was quite tatty when I took it out of storage. On the outside, its leatherette-covered composite case and tuning dial were dirty and the metalwork was tarnished and corroded. In addition, the Philips badge on top (just behind the switch well) and the “All Transistor” badge inside the escutcheon were both bent. It’s a common problem and of the four 198/199 sets I have, this one was the best preserved. I attacked the leatherette case first using a microfibre pad but soon noticed that some of the fawn colour was transferring to the pad. I’d also had a similar experience of colour lifting with the Bush TR82C, so I’ll use these microfibre pads with caution in future. In the end, the case was cleaned using spray cleaner, a toothbrush and good old-fashioned elbow grease. I then repeated the exercise on the tuning and volume control knobs. The lettering on the switches was almost absent but I decided to leave restoring them for another time. The metal strap covers, the switchbank end pieces and the Philips badge all cleaned up nicely with Brasso but the escutcheon trim was more problematic. Rather than polish it out of existence, I siliconchip.com.au Philips 199 Transistor Radio – Differences The 199 and 199AC look very similar to the model 198 but incorporate several component and configuration changes, as follows: (1) Bypass capacitors C11 & C14 changed from 40nF to 10nF; (2) Neutralising capacitor C13 changed from 65pF to 50pF and connected to an overwind on IFT2’s primary rather than to its secondary; (3) Neutralising capacitor C18 (15pF) becomes C19 (10pF); (4) Audio input coupling capacitor C25 (2µF) becomes C26 (10µF); (5) Treble-cut capacitor C25 (10nF) added between TR5’s collector and ground (model 199 only); (6) Treble-cut capacitor C32 changed from 100nF to 220nF; (7) Feedback capacitor C29 (Bass position) changed from 300pF to 200pF; (8) Feedback resistor R22 reduced from 470kΩ to 220kΩ and its parallel capacitor C27 deleted; (9) Feedback resistor R30 increased from 100kΩ to 220kΩ and resistor R31 replaced with a link. (10) As noted in the article, the 199 sets alter the connection from the ferrite rod to the base of converter stage TR1. (11) The 198 derives all of its audio feedback from TR6’s collector. In the model 199, it’s permanently derived from the speaker, while Bass position feedback is still derived from TR6’s collector and the Treble switch feedback has been omitted. left it with the minimum of treatment. Unfortunately, the strap stitching had all but disappeared but that’s also a job for another time. On the other hand, the electronic circuitry all looked good, with no battery corrosion or other visible issues. How good is it? So just how well does the Philips 198 transistor radio perform? The answer is “surprisingly well”. First, the selectivity is quite narrow, being just ± 2kHz at the -3 dB point and ±20kHz for 60dB down. It’s wider than the AWA 897P’s with its six tuned IF circuits, however. The RF performance was so good it had me rechecking my results. During alignment, I discovered that the oscillator coil slug was jammed tight. Another set had the same problem but after some fiddling about with various other adjustments, I managed to obtain 50mW output for a signal strength of just 40µV/m at 600kHz and 42µV/m at 1400kHz (although with only 16dB and 15dB S/N ratios respectively). In the absence of oscillator adjustment, the classic solution is to adjust the antenna circuit by sliding the tuning coil along the ferrite rod. Sliding June 2015  87 All controls except for the tuning control are mounted on the top of the case. These include the volume control at left plus pushbutton switches for power off, treble/power-on and bass/power-on. The lettering has mostly worn off the pushbutton switches. it towards the centre gives increased inductance, while moving it towards the end reduces the inductance. However, this adjustment on my set didn’t offer much improvement. I then decided on more drastic measures in the form of a hot-air gun applied to the oscillator coil, the intent being to soften the wax covering sufficiently to loosen the slug. It did no good; the slug still wouldn’t move. In the end, rather than damage the slug by over-zealous pressure, I left the set with the best alignment possible. In order to obtain the standard 20dB S/N ratio, the signal strength needed to be about 60µV/m at 600kHz and 65µV/m at 1400kHz. Compared to the AWA 897 and to the even betterperforming Bush TR82C, this little Philips set is an absolute gem. It’s nearly as good as the most sensitive set I’ve tested so far, the outstanding Pye Jetliner. It’s also interesting to compare it to its model 196 valve predecessor. On test, my 196 required a radiated signal of just 25µV/m at 1400kHz for a 50mW output and just 6µV at the aerial terminal for the same output. The Philips 198’s AGC control is excellent, with the output rising by just 16dB for an input signal increase of some 66dB. It does go into overload after some 40mV is fed directly into the converter’s base. This is equivalent to a field strength of about 500mV/metre, so “overload” for this set means “sitting right under the tower”. Audio performance Like most small sets, the audio performance is adequate without being outstanding. Its frequency response from volume control to loudspeaker with S3/S4 in the “Treble” position is around 100Hz to 3.9kHz, with a 3dB peak at 250Hz. Switching S1/S2 to “Bass” position cuts the top end response to around 2kHz. By contrast, the overall response when measured from the antenna terminal to the loudspeaker is only about 150Hz to 1kHz (S3/S4 in the “Treble” position). The audio stage goes into clipping at about 160mW output, at which point the total harmonic distortion (THD) is around 6%. This increases to about 10% THD at 180mW. At 50mW, it’s a bit under 1% and it maintains this figure for an output of just 10mW. This indicates that crossover distortion is well-controlled. If the battery voltage drops to 4.5V, it clips at around 45mW. However, even at this low supply voltage, the cross­ over distortion is only just noticeable at 35mW output. Would I buy another? So would I buy another model 198 or 199? Well, I did actually. It’s the look-alike 199C which is fitted with alloy-diffused OC170/169s in the RF/ IF end and OC74s in the output stage. If you can get either the 198, the 199 or the 199C, you’ll have a fine little set that may appear unremarkable compared to other designs. But once you start using it, you’ll be reminded of just how good it is. We’ll find out just how good the 199C is in a forthcoming article. Further reading (1) For the 198 and the 199 circuits, see Ian Malcolm’s Transistor Radio Page: http://transistor.bigpondhosting.com/ circuits/philips198.jpg (2) For information on the 199AC, including service data, see Kevin Chant’s website: http://www.kevinchant.com/ uploads/7/1/0/8/7108231/199ac.pdf SC Radio, Television & Hobbies: the COMPLETE archive on DVD YES! A MORE THAN URY NT QUARTER CE ICS ON OF ELECTR HISTORY! This remarkable collection of PDFs covers every issue of R & H, as it was known from the beginning (April 1939 – price sixpence!) right through to the final edition of R, TV & H in March 1965, before it disappeared forever with the change of name to EA. For the first time ever, complete and in one handy DVD, every article and every issue is covered. If you’re an old timer (or even young timer!) into vintage radio, it doesn’t get much more vintage than this. If you’re a student of history, this archive gives an extraordinary insight into the amazing breakthroughs made in radio and electronics technology following the war years. And speaking of the war years, R & H had some of the best propaganda imaginable! ONLY Even if you’re just an electronics dabbler, there’s something here to interest you. Please note: this archive is in PDF format on DVD for PC. Your computer will need a DVD-ROM or DVD-recorder (not a CD!) and Acrobat Reader 6 or above (free download) to enable you to view this archive. This DVD is NOT playable through a standard A/V-type DVD player. SILICON CHIP 88  Silicon Chip 62 $ 00 +$10.00 P&P Order now from www.siliconchip.com.au/Shop/3 or call (02) 9939 3295 and quote your credit card number. siliconchip.com.au PRODUCT SHOWCASE Watts Clever? This is! This “clever” 6-way powerboard from Jaycar is designed to automatically turn on and off ancillary devices when a main device is turned on or off – eg, a PVR, DVD player, cable receiver, amplifier, etc, when the TV set is turned on. If each extra device took 5-10W on standby, you could save $$$ in wasted electricity over time. A “control” socket takes the main device; four “auto” sockets handle the ancillaries and an “always” socket is powered whenever power is applied to the powerboard. The slave sockets come on about 2-3 seconds after the “control” appliance has been turned on. When the control appliance is turned off, the slave sockets turn off about 9 -10 seconds afterwards. It has a 10A total rating so should handle most domestic applications. We envisage these could also be very handy for the workshop or Contact: service bench. Catalog number is Jaycar Electronics MS-4081, currently (All stores and website sales) on sale for $24.95 Tel: 1800 022 888 Website: www.jaycar.com.au (was $39.95). SAF Tehnika’s 2-40GHz “Spectrum Compact” Looking for a compact measurement solution for the 2-40GHz licensed microwave frequency bands? Here is a range of five powerful, ultra light, handheld Spectrum Analysers, designed specifically for outdoor use by network and microwave radio engineers performing equipment installation or data gathering for siteplanning purposes and a variety of other challenging situations. They feature internal data logging, while the SMA connector allows the units to Contact: integrate with any Clarke & Severn Electronics antenna or waveguide 4/8A Kookaburra Rd, Hornsby NSW 2077 system. No laptop Tel: (02) 9482 1944 or other equipment Website: www.clarke.com.au is required on site. Want a FREE Emona Catalog? It’s one of the electronics industry’s most prized catalogs . . . and you can get your own copy, free of charge, simply by logging on to www.emona.com.au/shortform A PDF copy will automatically download. And while you’re there, check out the Emona website for all things in electronics test & measurement. siliconchip.com.au Is it a programmable relay? Is it a PLC? The SG2 Series from Teco Westinghouse offers the capability of a small PLC with the price of a programmable relay. They feature various I/O configurations of isolated digital inputs, transistor and relay outputs, analog inputs and expandable I/O modules. This intelligent relay will control almost all discrete systems. Some models have a 4x16 character LCD screen and keypad for operator feedback and control. Five buttons on the front allow the operator to easily view and change variables in the program. Functions include timers, high-speed counters, PWM, PID loops, real time clock with summer/winter change, password protection and heaps of other goodies, while some models come with a built-in RS485 Modbus RTU port, which can operate in master or slave mode allowing communication to other peripherals such as host computers, Contact: PLCs etc. Ocean Controls Pty Ltd P r i c e s s t a r t a t PO Box 2191, Seaford BC, VIC 3198 $149.95+GST for the Tel: (03) 9782 5882 SG2-12HR-D Website: www.oceancontrols.com.au NiCd/NiMH Charger kit is cheap & easy-to-build This ‘intelligent’ NiCd/NiMH Battery Charger from Shapely Designs is suitable for automatically charging a wide range of batteries for many applications. It was designed for high current and rapid charge applications such as cordless power tools and model racing cars. These battery packs are expensive and can be difficult to purchase. This charger uses the cell manufacturer’s recommended charge method to safely and quickly charge batteries. You add a suitable power supply – various options are available, from a completely pre-assembled PCB at $50.00 (you supply the case, etc) right through to a bare PCB (you construct from your own components). A pre-programmed PIC is also available for $15.00, or full code listing for you to program your own PIC (1612F615-I/ Contact: SN) is on the website, along Shapely Design with details of the options Website: www.shapely.asia available. June 2015  89 ASK SILICON CHIP Got a technical problem? Can’t understand a piece of jargon or some technical principle? Drop us a line and we’ll answer your question. Send your email to silicon<at>siliconchip.com.au High-voltage probe for multimeters I was just wondering if SILICON CHIP has ever presented a 6000V or 10,000V probe adaptor for multimeters (I saw the High-Voltage Probe for Oscilloscopes in the January 2015 issue). Commercial high-voltage probes are available for multimeters but they cost many times more than the cost of a multimeter. It could be a useful project, if it hasn’t been done already. (B. P., via email). •  Have a look at the EHT Stick, a 1000:1 high voltage probe for multimeters, in the April 2010 issue. It is rated for use up to 35kV. You can see a free 2-page preview of the article at www. siliconchip.com.au/Issue/2010/April/ A+1000%3A1+EHT+Probe An Altronics kit for this design (Cat. K2559) is available. Battery charge controller for drill packs I recently purchased a reasonably good battery drill from Bunnings with their Ozito brand. As usual, the charger is not up to scratch. I think it only lights a couple of LEDs, one to show power is on and the other when the battery is connected. I remember seeing a couple of projects in SILICON CHIP regarding drill chargers. The battery packs (it came with two) have 12 1.2V 1200mAh Nicad batteries, giving a total of 14.4V. Can you point me in the right direction as to which project I need? (M. F., via email). •  Have a look at our Cordless Power Tool Charger Controller in the December 2006 issue. You can see a free 2-page intro to the article at www. siliconchip.com.au/Issue/2006/December/Cordless+Power+Tool+Char ger+Controller Loudspeaker protector for SC480 amplifier I am putting together a pair of SC480 amplifier modules (SILICON CHIP, January & February 2003) and I want to add a Loudspeaker Protector, mainly to avoid switch-on thumps. I was advised by the staff at my local electronics supplier to purchase the Loudspeaker Protector for the CLASSiC-D amplifier (SILICON CHIP, November & December 2012), on the basis that it can cope with a range of amplifier supply voltages. Is it suitable or do you have another design that I should use? Also, I want to connect a headphone socket to the two amplifier modules. Can I just use a pair of 390Ω 1W resistors to do this? (J. M., via email). •  You have been given a classic “bum steer”. The CLASSiC-D protector is only suitable for the CLASSiC-D amplifier, as it has a pair of optocouplers to monitor the “protect LED” in each channel of the amplifier module. It will not work with any other amplifier module. You need one of our general-purpose loudspeaker protectors and we would nominate the design featured in the October 2011 issue. It is still available as kit from Altronics (Cat. K5167) or you can purchase the PCB from our Online Shop. Mind you, a Loudspeaker Protector is not strictly necessary with the SC480 amplifier modules since they already incorporate short-circuit and over-current protection in the form of a PTC (positive temperature coefficient) thermistor in series with their outputs. This goes high in resistance when an overload condition occurs and reverts to a low resistance if the fault condition is removed. However, the PTC thermistors will DMM Confused By DC With Superimposed 100Hz Ripple I have a fully assembled Curra­ wong valve amplifier that’s failing its preliminary checks – specifically excessive levels of AC on all the DC supplies. I’ve spent many days troubleshooting this and tried everything I can think of, including double-checking every component and joint. As per the instructions, the valves have not been inserted yet. I’ve applied power and the blue LEDs light immediately. After 20 seconds or so the power LED changes from red to green. All good. I’ve attached a power supply schematic with DMM measurements shown. 90  Silicon Chip The only things I can add that might help are that if I take the same measurements with my old moving coil meter, the DC voltages are pretty much the same but all the AC voltages are about half those indicated by the DMM. I’d guess that the AC I’m measuring isn’t 50Hz. The power LED cycles and I have lower DC and AC voltages even when the fuses have been removed! I did do a lot of testing with CON7 disconnected because I didn’t want to have to worry about the lethal voltages all the time. I still had the same AC and DC voltages at CON9 and on the 12V DC supply. There were still small AC and DC voltages on the HT supplies. If there’s anything you can suggest I’d really appreciate it; a lot of investment in terms of time and money here. Please don’t publish this if I’ve done something really stupid! (D. H., via email). •  We think everything in your amplifier is probably OK and that your multimeter is confused. If you are going to check for AC on a DC line, you need to measure it via a high voltage blocking capacitor. Try using 100nF 400V. Editor’s note: this diagnosis subsequently proved to be correct. siliconchip.com.au Problem With The CLASSiC DAC Recently I built your CLASSiC DAC project from a series of articles in 2013 and I found that it had excellent sound and performance and is very versatile and useful with a wide variety of digital music sources. I have been a keen builder of all of your major hifi projects. However, after successfully operating the project for about a month, it refuses to start up normally. During normal operation, I noticed that there were occasions where the unit would lock up (would not play music but I could select inputs) but I was always able to successfully reset the unit by reconnecting the 9VAC plugpack supply. I now find that the DAC has locked up completely, is no longer responsive to the remote control inputs and no longer plays music. The only sign of life is the flashing of LED number 6 on the front panel. I have checked the power supply voltages and they are all on spec. When the DAC is first connected to the plugpack, all the input LEDs flash very briefly then the yellow sampling LEDs light in sequence from right to left before extinguishing. Finally, after a delay of several seconds, the SPDIF input LED (input 6) flashes regularly. It cannot be turned on by the remote or front switch. I have tried changing the four switch settings but the symptoms are the same. Also, if the SD card is inserted, it is not offer any muting of switch-on and switch-off thumps. If it occurs, any switch-on thump is likely to be due to a preamplifier you might connect in front of the SC480 module, so if you won’t be using a preamplifier, there should not be any switch-on thump and any switch-off thumps should be very slight. If you do decide to use the Loudspeaker Protector with the SC480 modules, you could consider omitting their PTC thermistors and just wire shorting links in their place. That way, you will get slightly lower distortion and slightly better damping factor for your loudspeakers although the improvement will be largely academic. And yes, your method for connecting the headphone socket will be fine. siliconchip.com.au not detected, as indicated by LED8 and LED6 goes into a periodic flashing mode. Presumably the CPU is executing a self-check routine and it has found something amiss with the hardware, I/O states, clock or software. I am not sure where to fault-find with these symptoms. What checks should I conduct with hardware and is it possible to check the CPU file using the ICSP connection and verify the checksum? I purchased the HEX file along with the hardware from your Online Shop but I cannot find any way to download it to reflash the CPU. Having sampled how well this project sounds I am really keen to get it going again. (J. C., Armadale, Vic). •  There appear to be two different things going on here. Switching an associated power amplifier on or off can “upset” the CLASSiC DAC and the DAC requires a reboot to operate properly. We think what’s happening is that there is a large mains/EMI spike when the amplifier’s supply current is interrupted and this is coupling into the CLASSiC DAC and possibly resetting the DAC chip. The microcontroller is still trying to communicate with it but since the DAC has been reset and its settings have been lost, it doesn’t work properly. When this happens, sometimes you still get audio but it sounds distorted, as if the bit-stream format set- Converting watts to lumens On the question of different types of lights and relative outputs, what is the formula to convert Watts to Lumens? For example, what is the Lumen output for a 12V 100W spotlight. (W. S., via Facebook). •  It all depends on the efficiency of the particular light. So what type of spotlight are we talking about? Standard incandescent, Xenon, halogen, white LED or HID (high intensity discharge)? That list ranges from the least efficient to the most efficient; more or less. Just to confuse the issue, spotlights also tend to be rated in candle power and it is really not possible to compare these parameters ting in the DAC is no longer correct. Adding shielding to the plastic case could help, especially around the CS8416 IC. Modifying the software to periodically check if the DAC’s settings have been “lost” or corrupted and re-initialising it if so could also help. It’s strange because the Reset line is actively held during normal operation but perhaps the EMI spike is big enough to couple directly into the IC. Unfortunately, we haven’t yet had the time to fully investigate this. You are right that the S/PDIF input LED flashing is a sign that one of the self-test routines has failed. At power-up the unit checks that it can communicate with the PLL1708, then the CS8416, then the CS4398. LED6 flashing probably indicates a failure to communicate with the CS4398. We suggest that you carefully inspect its soldering. It’s possible that one of the leads is not properly soldered and it was making sufficient contact to operate earlier but due to thermal expansion or a bump or something else, it no longer is. You might as well check the other SMDs at the same time but we’d concentrate on the CS4398. Re-flowing its leads may fix the problem. If not, it’s possible the IC has failed, although that seems pretty unlikely. Check the micro also since a soldering problem on its pins may also have this effect. Editor’s note: reflowing the IC pins subsequently fixed the problem. since candle­power is a measure of the most intense part of the beam and that, in turn, depends on the focus of the lamp and any lens or reflector. Ultimately, you have to look at the lumen rating of the particular lamp you are considering. In general, as far as automotive spotlights are concerned, HID lamps and the latest high brightness white LED lights are far more efficient than the older halogen types. Question about LED clusters I am interested in using ultra-bright LED clusters of the type used in the Oatley Electronics Solar Skylight kit but I can’t find any basic information June 2015  91 Regulators For Low-Frequency Distortion Analyser I noticed that the circuit for the Low Frequency Distortion Analyser in the April 2015 issue has a +5V rail which isn’t used. The accompanying text explains why two regulators are used but is there any reason why they can’t be replaced with an LP2950CZ-3.3 regulator? This particular device has a wider input range (2.3-30V) and its use would also save on a couple of capacitors. Talking about regulators, are there any hard and fast rules when it comes to choosing the values of the filter/smoothing capacitors on either side of a regulator? Some circuits I’ve seen would suggest the larger the better but data sheets show relatively small values. (T. B., via email). •  You could use a regulator which will tolerate a higher input voltage and get rid of the 78L05 but note that this means that all the dissipation will be in the one regulator. Given (eg,power calculation). Is there an idiot’s guide? (T. U., via email). •  We presume you mean the LED clusters used in the Oatley Electronics K328 Solar Skylight kit (SILICON CHIP, January 2013). These use 20W LED clusters (20W, 34V, 0.7A) each comprising two parallel strings, with each string containing 10 series-connected 1W LEDs on a metal substrate. At 20W, each string draws 350mA and has 34V across it. So the typical 1W LED in the 10-LED string has about a 3.4V drop across it when driven at 350mA. This is just over 1W (1.19W) each. Overall power delivered to the LED cluster is about 23.8W, assuming a 34V voltage drop and and 700mA current flow. The cluster will need to have a heatsink to dissipate the power delivered to the LEDs as there will be considerable heat developed when powered at 20W. While LEDs are more efficient in producing light compared to incandescent lamps, they are still inefficient, overall. So expect that you would need to dissipate at least 18W of heat when driving the LED cluster at 20W. Ideally, the LED cluster should be driven at a lower current than 700mA since LED power should be de-rated as the temperature rises. As far as specifications are con92  Silicon Chip the relatively low current drawn by this circuit, that probably isn’t an issue, even for a small TO-92 device. Part of the reason we did it this way is that most small 3.3V regulators are not designed to handle an input voltage above 6V; obviously some do, including the LP2950CZ-3.3 that you mention. The other reason is that the 5V rail is used for other purposes when the PCB is built for the alternative function presented in this issue (ie, the Infrasonic Snooper). You really need to check the data sheet for a particular regulator to determine capacitor values and types. Some regulators (primarily low-dropout types) are fussy about capacitor value and ESR. Sometimes they provide a graph showing the combinations of capacitance and ESR which will provide stability over some operating current range. In most cases, higher capacitance is not a problem but it isn’t unheard of for too large a capacitance to cause loop stability problems and possibly also start-up problems due to the high initial charging current. For the input capacitor, usually ESR is more important than capacity because instability due to poor input bypassing usually occurs at high frequencies. Something like a 1µF ceramic is fine for most regulators, especially if there is bulk capacitance upstream. Higher values for the output filter capacitor usually improve transient response but there are diminishing returns; 100µF is usually much better than 10µF but 1000µF may not be much better than 100µF. Paralleling a high-value capacitor with a low-ESR 1µF ceramic can be a good idea to better handle fast transients. cerned, you could check various manufacturer’s data on 1W LEDs to see what they recommend with regard to running at full power and the de-rating with temperature. For some information on driving 1W LEDs see www.youtube.com/ watch?v=piET0Biqo0I #2 on to enable Top-up and switch #3 on to enable Trickle Charging (see also the last section of the article). Follow the instructions to set the corresponding charge rates using trimpot VR3. Missing functions in burp charger I would like to use a different LCD module from that specified for the Spark Energy Meter (SILICON CHIP, February & March 2015). Instead, I want use one sold by Dick Smith Electronics (Q2220) and Oatley Electronics for many years. I will be building at least two of the Spark Energy Meters and I have several of the DSE LCD modules. Both modules are differential with 200mV sensitivity, have an input loading of 10MΩ and provide access to the decimal points. I can find very little information on the Jaycar module. I cannot work out how Dr Hugo Holden has made the Jaycar module have a common signal and power supply earth and still work, so I am struggling to make the conversion (the DSE version shows how this can be done). (G. L., via email). •  One approach to drive the Dick Smith Q2220 LCD module (and the Oatley Electronics module) would be I have recently built the Burp Charger (SILICON CHIP, March 2014) from a Jaycar kit and everything works except for the trickle charge and topup functions. After checking the board for faults I presumed the problem was in the programmed micro (IC1). I then purchased another programmed chip from Jaycar, with the same result. Reading from the write-up suggests that these functions can be added later, if required. Does this mean that they are not programmed on the IC1 purchased from Jaycar or in the original kit? If this is so, how do I get them programmed? (J. S., via email). •  Trickle and Top-up modes for the Burp Charger are set using DIP switches S2, as shown in the panel in the lower left corner of the circuit diagram on page 69 of the original article. Switch Different LCD for Spark Energy Meter siliconchip.com.au to use the negative supply generator as shown in the “12V metering system using the same battery for meter power” diagram. Then power it from the 5.6V rail of the Spark Energy Meter and apply the voltage from IC3c’s output to Vin of the Q2220 LCD module. RA would be 10kΩ and RB 470kΩ. This resistive divider reduces IC3c’s output voltage by a nominal 48 times. The calibration trimpot within the module will need to be adjusted to correct for the fact that the RA and RB resistive divider only divides by 47.8 rather than 50 and for other resistance tolerances in the Spark Energy Meter, such as the 150Ω 5W resistor. That calibration is as described in the Spark Energy Meter article. An alternative arrangement that does not require the negative supply may be possible. That would be with J3 open and J1 and J2 closed. You would need to be able to isolate the -In terminal on the Q2220 from the GND (ground) terminal. Then it would be just a matter of connecting the Common and -Vref, Vin and -In on the Q2220 to the equivalent COM, REL, INHI and INLO as shown for when using the Jaycar module. Note that for the Q2220, RB would be a wire link and RA out of circuit. For the decimal point, the circuit diagram for the Q2220 shows that a decimal point needs to be connected to the inverted backplane that’s provided by the collector signal of transistor Q1. The recommended method would be to use another 5V reed relay (the same type as RLY1) with its coil connected in parallel with RLY1. The contacts would then connect across the P1 decimal point jumper connection on the Q2220. Spark Energy Meter calibration query I am building the Spark Energy Meter from the February & March 2015 issues. With the Calibrator, I had to change the 220kΩ resistor to 270kΩ so I could adjust the output to 250Hz. It could not go any lower than 260Hz without changing the resistor for whatever reason, possibly something at my end. I assume when you connect the Calibrator to the Spark Energy Meter for calibrating the LCD to display “100” (mJ), it requires the spark plug be connected? Yes/No? siliconchip.com.au Alternative Modules For GPS Frequency Reference I want to build the GPS Frequency Reference (SILICON CHIP, February & March 2007) and I want to know if the Garmin GPS unit is still available. If not, are there suitable alternatives please? Also, what type of 35mm film canister is used for the mini oven. Is it a plastic version of the metal/aluminium type? And is there a reason why no power on/off switch was included with this unit? (P. O., via email). •  As far as we know, Garmin no longer makes the GPS-15L receiver module but we believe Garmin has a replacement module for the GPS15L called the GPS-15xL. This is a direct replacement but with more sensitivity. Also, both Sparkfun (www.sparkfun.com) and Futurlec (www.futurlec.com) have receiver modules that should be compatible with the GPS Frequency Reference and they are not too high in price. Futurlec has a MINIGPS module which will operate from either 3.3V or 5V, has an SMA socket which is compatible with an external active For some reason the LCD displays around 170 during the calibration procedure (spark plug inserted); possibly I have made a mistake somewhere. I will check the resistors etc. (P, M., via email). •  The spark plug is is not connected to an ignition coil during the calibration procedure. Simply apply the calibrator signal across the 150Ω resistor. If the reading is too high and cannot be adjusted with the LCD trimpot, there is possibly an incorrect resistor value on the PCB. Note that the spark plug can be connected to the zener diode PCB but it should not be connected to a running ignition coil when calibrating. Tidal clock project wanted What about this as a SILICON CHIP project – a tide clock that shows high and low tides? There are tide clocks but they are not accurate and need calibrating often. The tide times change frequently. antenna and has a 1pps output. Sparkfun has two possibilities: the Venus GPS Logger, with the Venus638FLPx receiver inbuilt, again with the ability to provide a 1pps output and to work with an external active antenna. It will apparently work from a 3.5-12V supply. Secondly, they have the Sparkfun GPS Module with the Trimble Copernicus II SMD receiver mounted on a small DIL PCB module (1.1 x 1.25”). This one seems to have all the necessary outputs and has an SMA socket for an external antenna. However, it will only operate from a 2.7-3.3V power supply, so it would need a small added regulator to work inside the GPS Frequency reference. The mini crystal oven in the 2007 GPS-based Frequency Reference used a cylindrical plastic film canister. We did not provide for a power on/off switch on this unit because it was designed to run from an external DC supply and it was envisaged that the unit would be left on for long periods at a time. My idea is that the tide times be obtained from a government server and used to indicate the hours to high and low tides as on a tide clock. Normally the high tide is at the 12 o’clock position and low tide at the 6 o’clock position. Maybe a stepper motor could be used or maybe the minute hand of a quartz crystal clock movement with the stepper motor directly driven by a microcontroller. Maybe there could be a advanced version that also has a 7-segment display at the 12 o’clock high tide and 6 o’clock low tide position to also show the tide times. I should add that I know about smartphone apps to check the tide but I think a wall clock would be more convenient. (R. W., via email). •  We think it would be a lot of work to program the clock for all available sites in Australia, let alone other countries. And that is without showing the prediction for tide heights. We recently incorporated world time zones into the Nixie Clock With GPS Time (SILICON CHIP, February & March 2015) and that really involved June 2015  93 Light Dimmer With No Interference Wanted I live in an area with poor AM radio reception and I find that all normal light dimmers cause major interference when they are in use. Do you have a solution? (M. K., via email). •  As it happens, there are two approaches which may help with your AM reception and its susceptibility to interference. The first is to build or purchase a noise-cancelling loop antenna. These can be very effective in improving AM reception and we have published several designs in the past, as can be found by doing a search for loop antenna on our website. You can see some previews at: www.siliconchip.com.au/Issue/2009/January/AM+Broadcast+Band+Port able+Loop+Antenna www.siliconchip.com.au/Issue/2007/October/AM+Loop+Antenna+ %2526+Amplifier www.siliconchip.com.au/Issue/2005/March/Shielded+Loop+Antenna+ For+AM+Radios However, you may also want to build one or more light dimmers which produce no radio interference. For this you need a non-switching design which does not employ a Triac. For that we would nominate our Deluxe Fan Speed Controller from the May 2014 issue. This is based on a highvoltage Mosfet. In effect, it can be regarded as a variable resistor in series with the incandescent lamp you want to dim. This means it is much less efficient than a Triac switching dimmer and it has a maximum lamp load of 60W. You can see a 2-page preview at: www.siliconchip.com.au/Issue/2014/May/ Deluxe+230VAC+Fan+Speed+Controller a great deal of programming. We also think that since there are the smartphone apps you mention and easy access to similar information from many websites, most readers interested in the tides would simply go to their computer or smart phone. For example, in your area you can get relevant tide information from http://tides.willyweather.com.au/vic/ mornington-peninsula/earimil-beachsouth.html Defective transformer in Multi-Spark CDI I ordered the PCB and hard to get components from your site for the Multi-spark CDI (SILICON CHIP, December 2014 and January 2015). After I completed the circuit, transformer and everything else according to your explanation, I put the CDI on a bench power supply. Everything was OK and the voltage level adjusted to 300V. Connected to the car reluctor triggering, I adjusted the sensitivity as described. I started the car and it started right away, with prompt response of the gas pedal and everything. But 10 minutes after the initial fire, the CDI just powered off and it doesn’t fire. 94  Silicon Chip I measured everything that can be measured with an instrument, discrete components, transformer etc and everything is OK but the oscillator is not working and there is not 300V on the test point. Can I check the SMD ICs without the use of an oscilloscope because I don’t have it? Something has obviously burned up because the CDI worked for 10 minutes and then it just stopped. And every measurable component is OK, except the ICs which I can’t check without the oscilloscope? Any suggestions? (A. F., Skopje, Macedonia). •  The most likely the problem is a breakdown in the transformer secondary winding due to arcing or where there is a large voltage differential between turns on the secondary. DI box modifications I built the DI box (SILICON CHIP, May 2006) which I have just taken apart to replace a damaged socket. The circuit of the October 2014 project is almost but not quite identical to the May 2006 project. I note that the unit I built has a 4.7kΩ resistor between the jack tip and the transformer yellow wire but the new version only has resistors on the stereo input and they are 2.2kΩ, not 4.7kΩ. Does the presence or absence of the 4.7kΩ resistor alter the performance? Should I remove the resistor from my box? I can easily add a 3.5mm stereo socket with two 2.2kΩ resistors to my 2006 box. (G. C., via email). •  The May 2006 DI box had a combined mono and stereo input and required stereo mixing resistors that were included whether using a mono jack or not. For a mono signal, the input signal is reduced to one half its original level at the coupling transformer input. The October 2014 DI Box has separate mono and stereo inputs and this means that the mono input need not have attenuation resistors but only resistors for the stereo input that acted to mix stereo. Using separate mono and stereo inputs as in the October 2014 DI box can give better a signal-to-noise ratio for the mono input but since the signal-to-noise ratio is below the noise floor of our instruments, the improvement is not measurable. It would be easy enough to include the stereo socket on the May 2006 DI Box and use the same circuitry as the October 2014 DI Box. The use of 2.2kΩ instead of 4.7kΩ resistors for stereo mixing will not noticeably change the signal-to-noise ratio – it will give a theoretical improvement of almost 1dB, assuming a 10kΩ input impedance for the coupling transformer. Induction Motor Speed Controller malfunction I am having problems with the Induction Motor Speed Controller unit when it comes to controlling speed via the external mode for a 240VAC single phase motor. It works with the internal pot but not the external mode. It also all worked on my 3-phase 1.5kW motor when it was first built and it has had all the recommended modifications carried out. After trying to get it to work on the 240VAC single-phase motor I put it back onto the 3-phase motor and experienced the big bang! On inspection the current shunt resistor was missing. I believed this happened to your original controller (SILICON CHIP, April & May 2012) as mentioned in the December 2012 article. The only thing I had forgotten to siliconchip.com.au MARKET CENTRE Cash in your surplus gear. Advertise it here in SILICON CSiliconChipAddDark.ai HIP FOR SALE 1 24/02/2015 3:37:39 PM WORLDWIDE ELECTRONIC COMPONENTS LEDs, BRAND NAME and generic LEDs. Heatsinks, fans, LED drivers, power supplies, LED ribbon, kits, components, hardware, EL wire. www. ledsales.com.au tronixlabs.com - Australia’s best value for hobbyist and enthusiast electronics from adafruit, DFRobot, Freetronics, Raspberry Pi, Seeedstudio and more, with same-day shipping. MOVING SALE: bargains galore on our new website. We have to reduce our stock. Audio & video equipment, cables, components, mag’s, books, etc. www.questronix.com.au PCB MANUFACTURE: single to multi­ layer. Bare board tested. One-offs to any quantity. 48 hour service. Artwork design. Excellent prices. Check out our specials: www.ldelectronics.com.au After 30 years am closing down, so massive price reductions to clear stock. 1/4 Watt Resistors $0.55C per 100; 0.6W 1% Metal Film Resistors $1.10 perM 100; Batteries & PCB Products – Perth Metro or Pick Up Only. All other items 50% off CatalogueY Price. Minimum Purchase $11.00 + Freight. CM www.iinet.net.au/~worcom MY CY recent projects and some not so recent projects: www.siliconchip.com.au or phone (02) 9939 3295. Leaders in Essential Electronic Components Reduce Your Costs On Millions Of Parts 4000+ brands Free e Delivery Available Availa CMY K KIT ASSEMBLY & REPAIR DAVE THOMPSON (the Serviceman from SILICON CHIP) is available to help you with kit assembly, project troubleshooting, general electronics and custom design work. No job too small. Based in Christchurch, NZ but service available Australia/NZ wide. Phone NZ (+64 3) 366 6588 or email dave<at> davethompson.co.nz PCBs MADE, ONE OR MANY. Any format, hobbyists welcome. Sesame Electronics Phone 0434 781 191. sesame<at>sesame.com.au www.sesame.com.au KEITH RIPPON KIT ASSEMBLY & REPAIR: * Australia & New Zealand; * Small production runs. Phone Keith 0409 662 794. keith.rippon<at>gmail.com PCBs & Micros: SILICON CHIP can supply PCBs and programmed microcontrollers and other specialist parts for VINTAGE RADIO REPAIRS: electrical mechanical fitter with 36 years ex­ perience and extensive knowledge of Safe . Secure . No Form Filling F www.x-on.com.au valve and transistor radios. Professional and reliable repairs. All workmanship guaranteed. $10 inspection fee plus charges for parts and labour as required. Labour fees $35 p/h. Pensioner discounts available on application. Contact Alan on 0425 122 415 or email bigal radioshack<at>gmail.com WANTED WANTED: EARLY HIFIs, AMPLIFIERS, Speakers, Turntables, Valves, Books, Quad, Leak, Pye, Lowther, Ortofon, SME, Western Electric, Altec, Marantz, McIntosh, Tannoy, Goodmans, Wharfe­ dale, radio and wireless. Collector/ Hobbyist will pay cash. (07) 5471 1062. johnmurt<at>highprofile.com.au ADVERTISING IN MARKET CENTRE Classified Ad Rates: $32.00 for up to 20 words plus 95 cents for each additional word. Display ads in Market Centre (minimum 2cm deep, maximum 10cm deep): $82.50 per column centimetre per insertion. All prices include GST. Closing date: 5 weeks prior to month of sale. To book, email the text to silicon<at>siliconchip.com.au and include your name, address & credit card details, or phone Glyn (02) 9939 3295 or 0431 792 293. set were the DIP switches; they were all in the off position. I see that you have some parts that upgrade the controller if it suffers failures. Would my single-phase problems be in the PIC microcontroller’s program? (D. H., via email). •  We doubt the software was at fault. If there were still software problems, siliconchip.com.au other constructors would be having similar issues. We are assuming you were changing the EXT DIP switch setting when changing between the internal and external speed pots. We can only imagine that a hardware fault in one channel such as faulty soldering on the IGBT bridge or one of the SMD capacitors has caused strange behaviour and eventual failure. We can supply the up-rated IGBT bridge IC (30A/60A) and replacement shunt resistor for $40 + postage. Note though that you may also need to replace IC2 and possibly some of the optocouplers as these may have also continued page 96 June 2015  95 Next Issue The July 2015 issue of SILICON CHIP is on sale in Newsagents by Thursday 25th June. Expect postal delivery of subscription copies in Australia between June 22nd and July 3rd. been damaged. The former is available from Jaycar or Altronics. If you’re going to replace those parts you should inspect all the solder joints carefully, especially the SMD capacitors, to minimise the chance of another failure after doing the repair work. Headphone amplifier for hearing-impaired My hearing aids do a reasonable job of improving intelligibility when listening to TV or music via an A/V amplifier and speakers. However, for private listening via headphones, I was wondering if you would consider a project for a small stereo amplifier/ equaliser between the headphone sock- KEEP YOUR COPIES OF AS GOOD AS THE DAY THEY WERE BORN! ONLY 95 $ 1P4LUS p&p A superb-looking SILICON CHIP binder will keep your magazines in pristine condition. * Holds up to 14 issues * Heavy duty vinyl * Easy wire inserts ORDER NOW AT www.siliconchip.com.au/shop et and ’phones which would have an individually adjustable or programmed boost response to mirror one’s hearing loss curves, as programmed into the hearing aids? What do you think? (T. S., Tauranga, NZ). •  What do other readers think of this idea? LED strobe not bright enough I was wondering if you could assist me. I have built the LED Strobe project (SILICON CHIP, September 2008), as supplied in kit form by Altronics. However, the LED does not appear to be as bright as other 1W LED lights I use. In fact, it is considerably dimmer. I have powered the kit from a small 12V sealed lead-acid rechargeable battery (12V 7.0Ah) to make it portable and re-chargeable. I need to use the unit in day conditions (not direct sunlight but still a fair amount of light where I need to work) and at present I am limited to pre-dawn and post sunset operation. Is there any way to modify it so that I can increase the LED brightness? (C. K., via email). •  The 1W LED is being driven with the correct current, so you may need to use the 3W white version of the Luxeon or Cree LED to get more light. Q1 would need to be replaced with an IRF540 Mosfet with the gate, drain and source in the base, collector and emitter connections for Q1 respectively. The 220Ω resistors from RB4 and RB5 should be changed to 22Ω. Then the 3W LED can be driven with higher current. This requires that the 39Ω 5W resistor be replaced with two paralleled 22Ω 10W resistors. Additionally, the 1N4004 diode (D1) needs to be a SC 1N5404 (3A) diode. Advertising Index Altronics.........................loose insert Emona Instruments........................ 3 Hammond Manufacturing............... 8 Hare & Forbes.......................... OBC High Profile Communications....... 95 Icom Australia................................ 5 Jaycar .............................. IFC,45-52 KCS Trade Pty Ltd..................... 7,24 Keith Rippon ................................ 95 LD Electronics.............................. 95 LEDsales...................................... 95 Master Instruments...................... 11 Microchip Technology................... 13 Mikroelektronika......................... IBC National Instruments...................... 9 Ocean Controls.............................. 6 Questronix.................................... 95 Radio, TV & Hobbies DVD............ 88 Sesame Electronics..................... 95 Silicon Chip Binders................ 44,96 Silicon Chip Online Shop........ 34-35 Silicon Chip Subscriptions........... 70 Silvertone Electronics.................. 27 Tronixlabs..................................... 95 Worldwide Elect. Components..... 95 X-ON Electronic Services............ 95 WARNING! SILICON CHIP magazine regularly describes projects which employ a mains power supply or produce high voltage. All such projects should be considered dangerous or even lethal if not used safely. Readers are warned that high voltage wiring should be carried out according to the instructions in the articles. When working on these projects use extreme care to ensure that you do not accidentally come into contact with mains AC voltages or high voltage DC. If you are not confident about working with projects employing mains voltages or other high voltages, you are advised not to attempt work on them. Silicon Chip Publications Pty Ltd disclaims any liability for damages should anyone be killed or injured while working on a project or circuit described in any issue of SILICON CHIP magazine. Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. SILICON CHIP also disclaims any liability for projects which are used in such a way as to infringe relevant government regulations and by-laws. Advertisers are warned that they are responsible for the content of all advertisements and that they must conform to the Competition & Consumer Act 2010 or as subsequently amended and to any governmental regulations which are applicable. 96  Silicon Chip siliconchip.com.au