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DYNAMIC _ E SERVICING - VINTAGE RADIO - COMPUTERS - AMATEUR RADIO - PROJECTS TO BUILD Sony's nel/V ca,ncorder eli,ninates the shakes PROJECTS FOR MODEL RAILROADS YOU COULD WIN "'-~~~ \ \\ \ THREE CAC \ \ \ \ \ \ \ \ \ . . ♦ ' . -• _. . . . !- ., -- - - - - --~- - .... - -- (' - ~ ~- .... AV-COMM ~ A SATELLITE DISH AND TWO RECEIVER SYSTEMS SOFTWARE PACKAGES BTC .4.tJffOilK} 15 TEMPERATURE CONTROLLED SOLDERING STATIONS VIDEO/AUDIO SURROUND SOUND PROCESSOR 120W STERO POWER AMPLIFIER STEREO PRE-AMP WITH MAGNETIC PHONO OR MICAMPLIFIEA-ONE '"1amo ONE PAIR OF JAMO LOUDSPEAKERS ZELt:!f. ONE PAIR OF PEERLESS PSK/60/2 LOUDSPEAKER KITS ONE PAIR OF DYNAUDIO IMAGE 5 LOUDSPEAKERS PROUDLY SPONSORED BY Have you driven a ford ... lately? · ll·,lt ~ttrttsfuamo (e PHILIPS A-ONE Ill Vol.6, No.2; February 1993. FEATURES 1 The Silicon Chip 5th Birthday Sweepstakes Enter & you could win a car - lots of other prizes as well HERE'S A PROJECT that's just for fun. It's a robotic car that behaves just like a cockroach. Put it on the ground, switch it on & it heads for a dark corner. Turn to page 16. 6 Microwave Disinfection Of Medical Waste by J. Cusack & M Taitz A new technique that doesn't harm the environment 14 Sony's New 8mm Video Camera by Leo Simpson An active prism system eliminates the shakes PROJECTS TO BUILD 16 Build The Electronic Cockroach by John Clarke A robot car that seeks the dark 26 Three Simple Projects For Model Railroads by Terry Mowles Train controller, traffic light simulator & points controller MAKE YOUR MODEL railroad layout more realistic & interesting by building the projects described on page 26. They include a low-cost train controller, a traffic lights simulator & a points controller. 38 A Low Fuel Indicator For Your Car by John Clarke Lights a lamp when it's time to fill up 46 The MAL-4 Microcontroller Board, Pt.3 by Barry Rozema Step-by-step assembly instructions plus test programs 56 Audio Level/VU Meter With LED Readout by Bernie Gilchrist A peak hold facility lets you accurately set recording levels 80 A 2kW 24VDC To 240VAC Sinewave Inverter, Pt.5 by John Clarke Chassis wiring & final check-out SPECIAL COLUMNS "'"'7,-- THE SERVICEMAN tried all the usual short-cuts on a Thorn TV set this month but still had to fix the set the hard way. His story starts on page 64. 42 Computer Bits by Darren Yates File backups plus a useful utility for LHA & PKZIP 64 Serviceman's Log by the TV Serviceman A story to support Murphy's Law 96 Vintage Radio by John Hill The awakening of the Dragon DEPARTMENTS 4 Publisher's Letter 9 Mailbag 24 Circuit Notebook 54 Back Issues 73 Order Form 74 100 101 102 104 Product Showcase Ask Silicon Chip Notes & Errata Market Centre Advertising Index RUNNING OUT OF PETROL is inconvenient at best & dangerous at worst. This project reminds you to fill up by lighting a lamp when the fuel drops below a preset level. See page 38. FEBRUARY 1993 3 Publisher & Editor-in-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) PUBLISHER'S LEITER Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Darren Yates, B.Sc. Reader Services Ann Jenkinson Sharon Macdonald Sales & Marketing Mgr. Sharon Lightner Phone (02) 979 5644 Mobile phone (018) 28 5532 Regular Contributors Brendan Akhurst Garry Cratt, VK2YBX Marque Cro.zman John Hill Jim Lawler, MTETIA Bryan Maher, M.E., B.Sc. Jim Yalden, VK2YGY Bob Young Photography Stuart Bryce Editorial Advisory Panel Philip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc., B.E. SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. A.C.N. 003 205 490. All material copyright©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Magazine Printers Pty Ltd, Alexandria, NSW; Macquarie Print, Dubbo, NSW. Distribution: Network Distribution Company. Subscription rates: $42 per year in Australia. For overseas rates, see the subscription page in this issue. Liability: Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CH IP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. Editorial & advertising offices: Unit 1a!77- 79 Bassett Street, Mona Vale, NSW 2103. Postal address : PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 979 5644. Fax (02) 979 6503. ISSN 1030-2662 4 SILICON CHIP Australia's unseen electronics industry From time to time, some of our readers express concern that the Australian electronics industry is dying or dead and that this is a symptom of the problems with our economy in general. Well it is true that our economy does have problems, in common with many countries around the world. And it is also true that we have a worryingly high level of imports. But all is not black; far from it. Surprising though it may seem, there is a large electronics industry in Australia although it is very fragmented. This may be news to many of our readers because there are few Australian brands represented in the consumer electronics market and therefore people naturally assume that the industry has largely disappeared. In fact, the amount of electronics manufacturing in this country is much larger than it ever was in the past, and considerably larger than before 1973 when we had a substantial consumer electronics industry. The biggest sector is in communications but it is represented right across the board and a considerable amount is exported. As an example of this, a press release has just crossed my desk telling of $131 million of exports in 1991 from IBM's Wangaratta plant - this in spite of rumours in the press about IBM's long-term plans. More surprising still, 25% of Australia's exports are manufactured goods and this has a substantial electronics component. Still not reassured? Go into a club or casino and see all the poker machines - most are made in Australia. Or go into an amusement parlour - again, most of the machines are made in Australia. Or what about your computer modem? Again, it is probably made in this country. Or what about all the security electronics in the places where you live, work, shop or play? Again, it is mostly made in Australia. I could go on but it is clear that electronics manufacturing is happening on a large scale in this country and has been for many years. The question which then arises is should the Government do more to encourage local industry? The classic answer is to say yes but each time government acts to help one particular sector of the economy it causes distortions in other sectors. However, it would be good if government did more to buy locally made products - too often overseas made goods are favoured. Overall though, there are considerable grounds for optimism about Australian industry and the electronics industry in particular. 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PluG FKEE tlliG 111011tll gst a /2 volt <at> 450111A Cllargsr (BC450J wortll Iii'. </5 SCSI (50 way cent.) * SCSI to DB25 cable $12.95 * SCSI to SCSI cable $12.95 * SCSI Terminator $15.95 only $159.95 PluG· FKEE tlliG 111011tll rsesivs:1 · 250g Goldsr, wortll 17.</5 I • Goldsr Gueksr tool, wortll Ill </5 I • PCB lloldsr, wortll f '1.50 Total Va/us $2'1.40 2 way Data Switch Boxes * DB-25 or Centronics type - only $39.00 SPIRAL HARNESS WRAPPING ,ir---.-■ Available in two sizes. 12325 Min. I.D. - 6m~m-&_ _ _,..~ , 140mm 12volt 55wa!t 13mm. · Fog Lamp Kit Great for * 2 - 140mm Fog Lamps r • wiring looms. Keeps wiring neat. Available only in black. * 2 - Lens Protectors * 2 - 55W Halogen Globes FINEST 185 Micron T2440 MK II Soldering Station Quality "lla11d Had-" Ethernet Cables by Mr. Geoff Wood Esq. 14mcd<at> 20mA 3mm - $3.50 10+ - $3.15 5mm - $3.50 10+ - $3.15 * Auto Power Off. * Max/Min/ Av. 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Will even operate with a Modem. Gavs f/0.</5, pluG rsesivs a FKEE ea11 of PortaGol gaG, wortll $6.</5 PLCC Extractor Tool 12v DC to 240v AC Inverter 427 * 140 watts. Now$22.95 IDC Connectors only $159.00 Female IDC:IDC10 - $1.95 IDC14 - $1.95 IDC16 - $1.95 IDC20 - $2.75 IDC26 - $2.75 IDC34 - $2.75 IDC40 - $2.95 IDC50 - $4.60 Male IDC:IDC10 - $2.95 IDC14 - $3.50 IDC16 - $3.95 IDC20 - $4.50 IDC26 - $4.95 IDC34 - $5.50 IDC50 - $6.95 * * * * * * * * * * TDA2822 - $5.95 TDA2030 - $9.95 * * * * * Valves * 6L6 - $14.50 * EL34/6CA7 - $14.50 * 12AX7 - $10.~0 Bargain Software for IBM - All one price - Only $9.95 ea. ( Available in 3.5· & 5.25. ) ENTERTAINMENT: * Goodbye Galaxy * Paganitzy * Shrapnel City * House of Horror * Jungle of Doom David Reid ENT. (cont.) * Hugo 11-Whodunit * Forbidden Planet * Chinese Checkers * Crystal Caves * World Empire ENT. (cont.) * Wolfenstien 3D * Mahjongg VGA EDUCATION: Sky Globe Blackjack * * EDUC. (cont.) Amy's 1st Primer Word Rescue PC - Fastype Animated Math Animated Alphabet * * * * * . Ph: (02) 267 1385 127 York St, SYDNEY 2000 Electronics P.O. Box O103,SYDNEY 2000 Fax: (02) 261 8905 A.C.N. 001-372-372 UTILITIES: * Viruscan * Toy Box 11 APPLICATION: * Lable Magic * As Easy As ~·'(f, .,,.~aI(~"o~ · •" APPL. (cont.) Print Partner FormGen 11 Draft Choice Resume Profes * * * * ( When ordering, please specify disk size ) Postal Charges $5 - $25 ......... $4.00 $26 - $50 ...... $6.00 $61 - $100 ..... $7.00 $101 - $499 .. $9.00 $600 • ............ FREEi Microwave disinfection of medical waste Hospitals & clinics generate large quantities of potentially dangerous medical waste which must be safely disposed of. Now there is a new method whereby the material is first shredded & then disinfected by exposure to microwave radiation. By JOHN CUSACK & MARK TAITZ* The subject of waste disposal has become of major concern in industrial countries in recent years. Latent dangers, such as possible groundwater pollution, mean that waste should no longer be simply dumped in landfills. And public concern about air pollution has put a question mark against the traditional incineration method of disposal. Very few people are aware of the large quantities of medical waste pro6 SILICON CHIP It is obvious that uncontrolled disposal and open landfill dumping carry a risk of disease transmission. But more than anything else, it has been the spread of AIDS that has focused public concern on infection control and environmental practices within the health care industry. Sterilisation or incineration? The options for treating infectious waste in the past have been sterilisaduced by hospitals, pathology laboration (by autoclaving) or incineration. tories, clinics and doctors' practices. . Waste which has been sterilised can In the United States alone, more than be burnt or shipped to landfills. In the 600,000 tonnes of medical waste are latter case though, it should be thorgenerated every year by the health oughly shredded into tiny fragments care industry. This includes blood and which are unrecognisable as medical blood products, cultures and stocks waste. This is because many municiof infectious agents, "sharps" (neepal landfills now reject even treated dles, razors, etc), as well as pathologi- medical waste when it still recogniscal wastes. By the end of the decade, able. the amount of such waste is expected In Australia, most medical waste to grow significantly. (called "contaminated waste") is dis- ◄ Left: the microwave disinfection process is housed in a steel housing not unlike a standard shipping container. The waste is shredded, sprayed with steam & then irradiated with microwave energy to disinfect it. The end product is unrecognisable as medical waste. k l.r !.. '"' posed of by high temperature incineration or sealed in yellow plastic bags which are trucked to municipal landfills and then immediately buried in designated areas by bulldozer. The first method brings concern about air pollution while the second has concerns about groundwater contamination. Autoclaves are high pressure steam vessels, designed originally for sterilising medical instruments. The process involves heating the waste, usually with saturated steam, to 131 °C and keeping it at this temperature for up to 45 minutes. It must be continuously checked to see that the material being sterilised has actually attained the required temperature, the pressure in the autoclave being about two bar (ie, about two atmospheres). However, the standard small autoclaves on the market are not suitable to treat the large volumes of waste produced by the health care industry. Some large hospitals have their own medical waste incinerators. Initially designed for the disposal of large pathological wastes, they are n0t able to process in an environmentally sound way today's broader medical waste stream, which can include about 15% plastics and 20% non combustible material. Furthermore, due to public concerns about air pollution, the incineration facilities would have to be equipped with special air cleaning systems. It is estimated that in the USA alone, as many as 90% of the 5000 medical waste incinerators currently in operation will have to be shut down as US clean air standards become more stringent. Municipal waste incineration Another option is disposal in municipal waste incineration plants but this creates other problems, although these facilities are usually technically •••• Six microwave generators, operating at 2450MHz, thoroughly disinfect the waste material as it passes beneath them on a conveyor. well equipped for disposing of medical waste. The main problem lies in the transportation and handling of the waste. Between being packaged in the hospital and fed into the furnace, there must be no chance of it going astray, coming into contact with workers, or causing any kind of contamination. Also, municipal solid waste incinerators typically do not operate at temperatures sufficiently high enough to ensure thorough destruction of all micro organisms. The microwave solution ABB Sanitec, Inc recognised that the medical community, arid particularly large regional hospitals, required an on-site treatment facility which is safe, environmentally sound and cost effective. Their response to this need was to develop a system which disinfects the waste by heating it with conventional microwaves. The waste is first shredded into tiny, confetti-like particles and then moistened with high temperature steam. Afterwards, the granulated material is passed beneath a row of microwave generators which thoroughly disinfect it. After processing, the mat~rial is unrecognisable as medical waste and is quite acceptable for dumping in municipal landfills. In 198 7, the first medical disinfection system of this kind was placed in commercial operation at a university hospital in Germany. ABB Sanitec has since continued to develop the technology and units have been delivered to health care institutions and FEBRUARY 1993 7 temperature throughout. Strip charts record the variables necessary to substantiate disinfection, while continuous monitoring ensures that the requirements for thorough treatment are exceeded by a comfortable margin. A lockable port, just below the shredder, provides easy access for introducing standard testing samples. Waste volume reduction The end product is greatly reduced in volume and is unrecognisable as medical waste. It can also be burnt in a high temperature incinerator to produce steam for heating or electricity generation. commercial medical waste disposal companies in Europe and North America. Microwave plant The waste treatment equipment is housed in a steel all-weather shelter measuring 7.2 metres long, 3.3 metres wide and 2.8 metres high. The total weight of the unit is about 11 tonnes. A single electrical mains connection rated at 75kW for the larger unit and just one water hook up are necessary. Enough space must be provided in front of the inlet hopper to allow transportation and handling. At the output end, there must also be a hopper for removing the disinfected material, which is reduced to about 20 percent of its original volume. Since there are no liquid discharges (the small amount of water used is absorbed into the waste residue), a sewer connection is not necessary. The process does not use chemicals or bleaching agents. Fully enclosed and self-contained, the unit can be installed outdoors. Many systems are currently being operated in the loading dock areas of hospitals. 8 SILICON CHIP An automatic hoist lifts the waste container and tips the contents into the hopper at the top of the unit. Before the hopper opens, the air inside it is treated with high temperature steam, then extracted through a high efficiency particulate air (HEPA) filter to emininate any potentially harmful air-borne pathogens. To reduce its volume, the waste is then shredded into tiny particles. The granulated material is automatically conveyed into the treatment chamber, where it is evenly sprayed with high temperature steam. The mixture passes beneath six microwave generators, each with an output of 1.2kW. These heat the mixture to between 95°C and 100°c and maintain it at this temperature for a minimum treatment time of 30 minutes. The microwave generators are standard industrial units with an output frequency of 2450MHz. The microwave generators ensure fast and even heating to the required temperature and uniform disinfection of each granule. Sensors and microprocessors control the entire process, ensluing the proper treatment time and the correct The end product is a granulated solid waste which, since it harbours no risk of infection, is acceptable for dumping in municipal landfills. Even vials, hypodermic needles, syringes and plastic tubing are thoroughly shredded into tiny fragments which are unrecognisable as medical waste. Important for the end disposal is the fact that the waste is reduced by this process to only about one fifth of its original volume. Besides reducing transportation costs, this also has considerable benefits for eventual dumping in landfills or incineration. It is also a reason for using the unit at some hospitals to process waste that is not defined as infectious by present regulations. The heat value of the end product is also very high. At about 20 MJ/kg, it is even higher than that of good firewood. Treated waste is successfully burned in several waste-to-energy plants in the USA and Europe. Low operating costs The total operating costs, covering power, water, labour, maintenance, spare parts and consumables, are low. In America, they have been calculated to be about 9 cents/kg, a low figure compared with the cost of sterilisation or incineration methods. At present, there are more than 30 units in operation in Europe and North America. The two models currently available in Europe are designed for capacities of 150kg/h and 250kg/h. In North America, where the units are also manufactured, only the 250kg/h unit is currently being marketed. The smaller unit will become available during 1993. Acknowledgment Our thanks to Asea Brown Boveri Pty Ltd for permission to reproduce this article which originally appeared in the October 1992 issue of "ABB Review". The authors are employed by Sanitec, Inc, USA. SC MAILBAG Projects for marine modellers I am writing to you on behalf of the many fine scale marine modellers, who up till now have been neglected in your publication. Your articles on remote control to date have been very interesting but they don't really cover my hobby. I do not know to what extent your forthcoming articles will cover speed controls for fine scale marine use. We don't require very high current capacity but do require smooth operation in both forward and reverse, with 612V range. Due to the average size of our vessels, the actual size of the unit is not so important. We also need circuits or articles on making switching and sound units for marine use; eg, foghorns, steam whistles, destroyer sirens, etc. A. P. Cagnacci, Maritime Model Boat Club, Mona Vale, NSW. Comment: Bob Young does intend to do a version of his speed controller circuit with reverse, although it will be some months before it will appear in the magazine. Thanks also for the suggestions for articles on sound units for foghorns, steam whistles, etc. Help wanted with H&M model railway controller Please, please would you print a request for information regarding the Hammant and Morgan 5000 Model Railway Controller. Mine has an elusive electronic problem which requires a circuit diagram to solve. I have contacted Hornby Hobbies in the UK (because they took over H&M) but to no avail. I was able to contact a very helpful West Australian enthusiast who supplied me with a Zero One circuit but, regrettably, it is nothing like the H&M 5000. If any reader out there can help, I would be most grateful. Thanks for a great magazine. However, there are still many railway modellers out there hoping to get to grips with a steam sound simulator that has everything, including steam sound (chuff-chuff), steam whistle, a diesel horn, and a good amplifier that's built in. I have built all your previous circuits. The most successful was the SteamSound Simulator from April 1992. It works well as a train-mounted system but six out of ten for the "offtrack" conversion. The Track Tester works well electronically but it must have a good quality heavy wagon (steel) with individually sprung wheels, otherwise contact can be lost with the track and this will give false readings. And nobody, and I mean nobody, can build the perfect track, taking into account all the distortions due to heat and cold. W. Criddle, Cooroy, Qld. Comment: if any reader can help with a circuit diagram for H&M 5000 model railway controller circuit, we will forward it on. Project suggestions for the magazine Sometimes it must be very difficult to choose the projects that you and your regular contributors design for the magazine. You can't satisfy everyone all of the time but I must say that your range over the life of the magazine has been pretty good. Your readers should also make suggestions as to what they would like but based on some sort of reasoned argument that may appeal to a majority of your readers. I would like to make the following suggestions: (1). A moisture meter to indicate the sap content of wood. These days, many people are retiring early and taking up the hobby of woodcrafting and the moisture content/sap content is very important as to how the wood is to be treated by the woodworker. Commercial meters are available but, of course, are pretty pricey. As an indication, in Tasmania there are at least three wood guilds (the one in my area has some 70 to 80 members on its books). (2). An automatic shut-off valve in the hot water line to the shower. If my SILICON CHIP, PO Box 139, Collaroy Beach 2097. memory serves me correctly, a reader requested such a device a little while ago. He probably has the same trouble that so many families have - the young in the family believing that hot water costs nothing and that they can stay under the shower for hours at a time. I know of no commercial device that can be set for say a three minute shutoff time (to be variable). A. Willox, Launceston, Tas. Running 3-phase motors from single phase power On page 99 of your October 1992 issue, regarding running 3-phase motors on single phase, you said you didn't think that it was possible. A friend of mine bought a mediumsize milling machine fitted with 3phase motqrs and he lives in an area where · only single phase power is available. A local electrician made a low-cost modification to allow them to work on single phase. I don't know how efficient this is, and I would regard it as purely an emergency measure, but the fact is it does work. I asked him about starting and he said that these seemed to start OK. However, he had previously used a similarly modified 5hp 3-phase motor on another machine that occasionally didn't start, in which case he would switch it off, turn the motor slightly, and it would go next time. By coincidence, this afternoon I saw an advertisement for books, including one titled "How To Run A 3-Phase Motor From A Single Phase Supply". It was from Plough Book Sales, PO Box 14, Belmont, Vic, 3216. R. Heinke, Quorn, SA. Comment: it seems as though a number of schemes have been used in the past to allow a 3-phase motor to run from a single phase supply. However, most of these are fairly "irregular" in their concept and would not produce the same efficiency in the motor. There is also a difficulty with reliable starting. We still regard the principle as not being a good one but cannot deny that it can be done. FEBRUARY 1993 9 Build the Best - Forget the Rest! Top quality kits plus three exciting new releases! LED VU METER Q EXCLUSIVE TO US! LOW FUEL INDICATOR Q If you've ever run out of fuel in your car, you'll see the value of Designing your own Audio system this low-cost kit. It lights a 12V warning lamp when the fuel or just updating old style equipment drops below a pre-determined level. Harder to ignore than your that uses an analogue VU meter, standard gauge, the light could save you a great deal of this unit offers the advantages of inconvenience and embarrassment. fast response and peak hold display. Comes with PCB, case, 12V panel Comes with PCB, red, mount lamp and all necessary yellow and green LEDs components, including auto plus all necessary connectors for ease of installation. components and hardware. Cat K-4210 • Shortform kit 111 • 12 LEDs (red, yellow & green) • Can operate from a II supply voltage of between 11-40volts Feb '93 . Cat K-5370 111 ~~~ = ; ,, ,, D Feb '93 ,-,~ .,; 1'\11 $1495 ;__, .·,-;:~"?-~ VK POWERMASTER MK 2 The new and improved Powermaster Mk2 kit gives you all the power you'd ever want for transceiver and bench-top power installations. Its flexible design allows you to choose the appropriate transformer for your desired power output level, opening up many possibilities for customising your own particular installation. For example: CURRENT RATING: SURGE CONTINUOUS PEAK TRANSFORMER (1 MINUTE) (PULSE) BA 10A 20A 25A 25A 15A 20A 25A 5A M-2000 M-2010 UPGRADED M-2010 For those who remember the original Powermaster, the addition of a 20A panel meter to the kit plus provision for an optional 12V cooling fan will make even higher power configurations possible with perfect safety. On the cosmetic side, the supplied case is now an attractive black powder-coated steel unit - an advance over the previous bare aluminium box. Other improvements include: A front-panel overload protection reset switch and a primary slow blow fuse with finger proof fuse holder. The ~it includes all components (excepting those that depend on your choice of transformer), all hardware and a pre-punched silk-screened chassis. Cat K-3400 <at> JAN'93 QQQ ;,;;,<K~ "" i :Jf.,1 [z] PLEASE CHECK YOUR NEAREST STORE FOR AVAILABILITY. AS SOME KITS MAY STILL BE IN PRODUCTION. FM RADIO . ~ ~ -i p 2 9 95 r;(!'J:..,~ RF VIDEO MODULATOR These are nearty·$20 anywhere else! Convert your video or computer output to standard TV input with this Video Modulator. All the hard work's done... it comes pre-tuned and aligned and can be switched to VHF channel 1 or 0. Has RCA socket and built-in voltage regulator. (Complete with Data Sheet). Cal K-6043 Unbelievable Low Price! 50MHz FREQUENCY COUNTER QQ Low in cost, yet giving high accuracy, this low-cost 50MHz frequency counter gives you just about every measurement you need in this category - for far less money than comparable commercially available counters. Comes complete with all components, PCB, hardware, LED display, case, plug pack & a pre-punched silk screened front panel. Cal K-7337 \OM~, I l tOU IN(Y (0U N1!1 10 SILICON CHIP 1fl,,, New to ktt buUd;ng? Then t~ th;s os , an ideal first project! This simple FM ~- . • ~.-/" radio receives all of your favourite FM .,.. / _,,, stations, uses only two low-cost , ,.,,-, $ Integrated Circuits (ICs) and runs off a 9V battery. It's a great 'hands-on' way to learn about Radio Frequency (RF) circuits and Audio Frequency (AF) amplifiers. This short-form kit comes with FM radio IC & Audio IC, PCB, speaker, components and other hardware. • Cal K-5014 • Battery not included Nov'92 With sound, Cat L-5226 6995 5 Huny in for these! Due to a scoop ~ - -.. purchase, we have limited stocks of these -------=:::-;; !!:::::;::::i;tr,,,;,,::::---12cm (4.8") black & white NTSC video '••·==:::=:,i==============:•• monltors-suitableforuseinsecurity ~ C e,~ , 0 ---==:,,,,,E{~iil systems or for any project you might ;;, oC~~'.J ·· dream up! ...-:::,::noV 2 2 Cat L-~ ~ VU" . 12cm (4.8") NTSC, 1.5V p.p B&W Horizontal15.7KHz Vertical- 60Hz 1 2 3 a 5 6 7 B 9 * 0 t1 0 digitor DIGITOR HANDS-FREE 55MHz TRANSCEIVER DIGITAL ACCESS KEYPAD With up to 500m range and no license required, this Is an ideal local-area or first-time-user transceiver. Powered by a 9-volt battery, It comes complete with belt clip and an earpiece/tieclasp microphone for handsfree use. Has selectable pushto-talk or voice activation and a sensitive dual conversion receiver. Cat D-1095 A digital keypad with raised keys that can be fitted to alarm systems, security door applications, etc. It comes with a mounting block and is finished in brushed stainless steel.... so It looks great. Ifs fitted with a tamper switch for added security. Cat L-5284 $6995ea sAVE $20 . . ·, . :, . . · ., •,: •, Horizontal resolution: 525 lines Audio output (Electret mic.): 170mW 16OHM (L-5226 only) Dimensions: 195mm L x 145mm W x 140mm H Power Source: 13.5-15V DC, 600mA Spec1f1cahons: CRT size: Video Input: Scanning Frequency: ♦--: :::-.:·:·.: $4995 ANALOGUE MULTIMETER A hi,9h quality multimeter with a 3 ½ mirrored scale and 25 ranges plus DB. Safety features include overload protection as well as diode & fuse protection. In addition, it has an automatic TR (transistor) quality and type checker (ie - PNP or NPN), 1.5 & 9V battery checker, continuity · test and temperature measurement (-20°C to 150°C). Comes complete with a temperature probe and tilt stand. AC VOLTAGE • 25 ranges plus DB FINDER • Sensitivity: 20,000 Ohm/V Now there's no need to put' • DC Volts: 0.1, 2.5, 10, 50, 250, yourself at risk! This device 1000V detects the electromagnetic • AC Volts: 10, 50, 250, 10OOV field surrounding cables, • DC Current 50uA. 2.5mA. sensing any AC voltage above 25mA. 250mA. 10A 120 volts and warns you with • AC Current: 10A both an LED and an audible • Resistance: x1, x10, "buzz". At this low price, there's x1 K,x1 OK no excuse for not having one! • Temperature: -20°C to 150°C CatQ-1531 $ CatQ-1028 1695 $6 9 95 FEBRUARY 1993 11 A Wealth of Knowledge (at bargain prices)! 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Ideal for maki ng up keyring transmitters or other one-button remote controls, they come complete with battery clips and a pocket clip on the back. $2 25 ~ .-.- $1 $13 95 Cat N-1804 Cat N-1805 Cat N-1807 PLASTIC 'MINI TRANSMITTER' CASE hardware below: Q .31 .31 .31 .31 .31 .31 .31 .31 .38 .38 .46 .46 .46 .46 .53 .60 2.5mm x 1.5M #4 3.7mm x 1.5M #5 2.2mm x 1.5M Just in case .. First pick the appropriate PCB, then all you need is the 'Momentary On' push-button switch .45 .45 .45 .45 .45 .45 .45 .45 .55 .55 .65 .65 .65 .65 .75 .85 E!!!!!!dj Pro Wick Pro Wick Unfluxed Nude Wick Pro Wick Pro Wick 12 Volt Battery 10 or more .24 .24 .24 .24 .24 .24 .24 .24 .24 .24 .24 .24 .24 Keep It Clean! .24 .24 .28 .28 .28 Grime is the natural enemy of all electronic .28 ~ ~ equipment -keep your computer spotless .28 -~ wit I I these fine Elyspray products. .28 ~ ✓ .28 ·- - Computer Keyboard & Case Cleaner Cat N-3001 .31 ,.....,.,. _,; Computer Screen Cleaner Cat N-3002 .31 .35 lll!ll!!!!!!I .38 .38 Suck Up That Solder! .46 .49 DESOLDERING BRAID .56 De-solder a job in just seconds - this stuff slurps it right up! .66 .73 Pro Wick 1.5mm x 1.5M #2 Cat N-1802 $3.75 1.02 Pro Wick 2.2mm x 1.5M #3 Cat N-1803 $3.75 1.30 MAKE UP YOUR OWN MINI TRANSMITTER! Cat S-3335 4800 4802 4804 4806 4808 4810 4812 4814 4816 4818 4820 4822 4824 4826 4828 4830 Price s49s cat P-7572 ALARM BARREL SWITCHES Ideal for use on alarms or any project where security is important, these quality keyed switches will keep out unauthorised users. ~ Standard keyed Cat L-5290 $9.95 Mini Standard keyed ~ Cat L-5295 $9.95 Tubular-keyed Cat L-5291 $12.95 Mini Tubular-keyed Cat L-5296 $10.95 . •P""""\'!a FROM $C)95 (Additional Battery Clip Cat H-2496 $1.95) DS XPRESS PHONE & MAILORDER SERVICE Outside Sydney (FREE Call) 008 22 6610 Sydney And Enquiries - (02) 888 2105 FAX: (02) 805 1986 or write to DS XPAESS, PO BOX 321 N/AYDE NSW 2113 All Major Credit Cards Accepted. 0/Nite Courier Available. STORE LOCATIONS: NSW • Albury 21 8399 • Bankstown Square 707 4888 • New Store Location - Blacktown Shop 301, 22-24 Patrick St 671 7722 • Brook vale 905 0441 • Bondi 387 1444 • Campbelltown 27 2199 • Chatswood Chase 411 1955 • Chu llora 642 8922 • Gore Hill 439 5311 • Gosford 25 0235 • Hornsby 477 8833 • Hurstville 580 8622 • Kotara 56 2092 • Uverpool 800 9888 • Maitland 33 7868 • Miranda 525 2722 • Newcastle 611896 • North Ryde 878 3855 • North Sydney (Greenwood Plaza) 964 9467 • Orange 618 400 • Parramatta 889 2188 • Penrith 32 3400 • Railway Square 211 3777 • Sydney City 267 9111 • Tamworth 88 1711 • Wollongong 28 3600 ACT• Belconnen (06) 2531785 • Fyshwick 280 4944 VIC• Ballarat 31 5433 • Bendigo 43 0388 • Box Hill 8900699 • Coburg 363 4455 • Dandenong 794 9377 • East Brighton 592 2366 • Essendon 379 7444 • Footscray 689 2055 • Frankston 783 9144 • Geelong 232 711 • Melbourne City 399 Elizabeth St 326 6088 & 246 Bourke St 639 0396 • Richmond 4281614 • Ringwood 879 5336 • Springvale 547 0522 QLD • Booval 282 6200• Brisbane City 229 9377• Buranda 391 6233• Cairns 311 515 • Capalaba 245 2870 • Chermside 359 6255 • Maroochydore 791 800 • Rockhampton 27 9644 • Southport 32 9033 • Toowoomba 36 4300 • Townsville 72 5722 • Underwood 341 0844 • SA • Adelaide City 2321200 • Beverley 3471900 • Elizabeth 255 6099 • Enfield 280 6088 • St. Marys 277 8977 WA• Cannington 451 8886 • Fremantle 335 9733 • Perth City 481 3261 • Midland 250 1460 • Northbridge 328 6944 TAS • Hobart 31 0800 • Launceston 344 555 NT• Stuart Park 81 1977 STORES ACROSS AUSTRALIA AND NEW ZEALAND 8 1448 FEBRUARY 1993 13 Sony's new camcorder stops the shakes There are many camcorders on the Australian market & they all have the same problem: when you use them in telephoto (zoom) mode, the image tends to shake. Now Sony has released this new model which modulates an active prism to cancel the shakes. By LEO SIMPSON If you haven't had a look at camcorders recently then it is likely to be a revelation to see just how small they have become while continuing to provide more and more operating features. Essentially, the new Sony CCDTR805 offers just about every currently available feature you could think of plus two that are not available in other cameras - wobble cancellation using an active prism and a zoom microphone system. Before we go on to describe these two key features, let's just briefly discuss the camcorder itself. As you would expect, the CCDTR805E is based on Sony's 8mm video cassette format which is virtually the same size as a standard audio cassette and thus it allows a very compact camera. The cassette is loaded and unloaded by a motor drive system and it can record or play for 90 minutes in single play mode and 3 hours in long play mode. Naturally, if you were recording under battery power you would need to change the battery several times during the course of a single cassette. Dimensions of the camera are 109 x 106 x 189mm (W x H x D) and it weighs just over 1.1kg with the cassette loaded and a battery pack clipped on. With these small dimensions and light weight it really is quite comfortable to use. The image device is a CCD (charge coupled device) which is 8.5mm square with 470,000 pixels (picture elements). The recording system is PAL to CCIR standards or His which is a system separating the luminance from the chrominance for better video bandwidth. To take advantage of the better pictures of the HiB system though, you also need a video monitor which can accept S-video connectors (4-pin mini DIN). The sound recording system is stereo via the inbuilt stereo/zoom microphones or via external microphones (connected via a stereo mini jack plug). As is standard with most camcorders, the electronic viewfinder is black and white and it has a number of tell-tales on its screen to tell you about operating modes such as shutter speed, lens setting, battery condition and so on. Shutter speeds are selectable over a wide range: 1150th, 1/120, 1/ 250, 1/ 1000, 1/2000, 1/4000 and 1/10,00oth of a second. Naturally, the higher speeds can only be used if you have very bright lighting but they certainly reduce blurring of fast moving objects. This camera can be used in really dim conditions and is rated down to 3 lux (candle light) and up to 100,000 lux (bright sunlight). Naturally, for the most noise-free pictures, you should use the brightest light available. Filled with liquid having a high refractive index (the same refractive index as that of glass) Lens '--v----"' Active prism Apex angle of the active prism is changed (optical axis is bent). Fig.1: these diagrams show how a liquid-filled active prism is bent to change the optical path & thus compensate for hand movement or other vibrations. The prism will deflect the light path by ±3° in both the horizontal & vertical directions to cancel pitch & yaw. 14 SILICON CHIP Sony's new CCD-TR805E camcorder has a 2-speed lOx power zoom, a stereo zoom microphone & a multi-directional remote control. The outstanding feature though is the "steady shot" image stabilisation system which provides wobblefree pictures, even in telephoto mode. The CCD-TR805E has facilities for white balance plus automatic OT manual focus, manual exposure control, video titling, time and date (including international and summer time), fade-in and fade-out (normal and mosaic) and edit search. The last feature allows you to view the last few seconds of your last recorded scene. The automatic focusing system is very effective and works well through windows, even though Sony state that you will probably have to resort to manual focusing in this condition. Remote control Now why would you want remote control on a camcorder? It might sound like a gimmick but there are two good reasons to have it. First, the camcorder is crowded with controls and so it is handy to have a remote control when playing back through a monitor rather than having to sit next to the unit. Second, the remote control allows you to set up the camera on a tripod and then include yourself in the recording. The remote must be the smallest which is physically possible. It uses a lithium battery and is not much larger than the UHF single button remote controls used for car burglar alarms. The zoom microphone also might be regarded as being of doubtful utility until you think seriously about it. The TR805E has three microphone meshes on the front but there are actually four electret microphone in- serts inside the camera body. When the lens is at its wide-angle setting, the microphone inserts work in stereo, picking up sound from a wide area to the right and left of the camera. However, as you use the 10x zoom and the lens moves from wide-angle to telephoto mode, the stereo pickup pattern then becomes inappropriate. You need to pick up sound from a narrow angle in front of the camera while sounds to the left and right then become a nuisance, masking the sounds you want. Hence, the Sony TR-805E gradually changes the sound pickup from a wide-angle (cardioid?) stereo pattern to a unidirectional mono pickup. In practice, it is a very useful feature and one which you won't think about at all once you have used it. Image stabilisation And now we come to the "steady shot" image stabilisation system which sets this camcorder apart from others. Some readers will be aware that are several image stabilisation schemes for camcorders already in the marketplace. The first of these is a motor-driven gimbal system whereby the lens and CCD imager together are mechanically stabilised against hand movement. The other methods involve manipulating the signal from the CCD image so that the effective picture area of the CCD is moved to compensate for hand shaking. In effect, the full picture area of the CCD is not used which means that the resolution is slightly reduced. And then there is Sony's active prism method which is clever indeed. The active prism consists of two glass panes connected with bellows and filled with a liquid having the same refractive index as glass. The prism is placed in front of the normal lens and can be bent horizontally or vertically to keep the image centred on the CCD at all times. According to Sony's literature, the front glass pane has a coil system to compensate for pitch {vertical movement) while the rear glass pane has a similar coil system to compensate for yaw (horizontal movement). The optical axis can thus be moved by a total of ±3° horizontally and vertically to compensate for hand shake. Two systems of movement detection are currently employed in camcorders with movement compensation. The first detects the motion and direction of the image deflection by using memory and image processing information from the CCD and this is most appropriate to the CCD image manipulation scheme mentioned above. However, it does not work well with Sony's active prism because it introduces a 1-frame lag (ie, 1/5oth of a second). Hence, the method used for movement detection on the TR-805E camcorder involves a triangular pole with a piezoelectric transducer on each face. One piezo device is energised at 25kHz which causes the others to produce the sarrie signal when the camcorder is at rest. When movement occurs, there will be a difference between the two transducer signals and this is amplified and processed by the unit's internal microprocessor to produce the correction signals applied to the active prism coils. A large or slow movement of the camcorder is assumed to be a normal panning or tilting operation and is therefore ignored by the microprocessor. The description above is considerably simplified compared to the actual operation of the active prism but it summarises the principle involved. The system certainly works well and this can be simply demonstrated by turning it off after which you will find just how much you do shake about, especially when the camcorder continued on page 78 FEBRUARY 1993 15 ,..,~ Buildlllis Electronic Cockroach Here's a project that's just for fun. It's a robotic car that behaves just like an electronic cockroach. Put it on the ground, switch it on & it heads for a dark comer. By JOHN CLARKE In the early days of semiconductor electronics, electronically controlled toys were very popular. For the first time, it was possible to build in complex control systems that were either too difficult or impossible using mechanical techniques. Those early models were quite expensive due to the high cost of the 16 SILICON CHIP parts but, of course, this situation no longer applies. Parts are now quite cheap and low-cost motors and wheels are easily obtainable from hobby shops and parts retailers. This electronically controlled car, dubbed the "E,lectronic Cockroach" (because it seeks the dark), is an inexpensive toy that will give you a chance to combine your elec- tronics skills with a few simple mechanical skills. It uses two ICs which cost around $1 each and two motors which are only $3.95 each. What does it do? Basically, the Electronic Cockroach runs along the floor and steers away from the light. It runs straight ahead if there is equal light intensity on each side of the vehicle but if one side is darker than the other, the vehicle steers fowards the dark. A real cockroach has six legs but our electronic version has to rnake do with three wheels - two at the front and one at the back. The two wheels at the front are independently driven by separate motors while the wheel at the rear simply trails behind. This rear wheel is mounted on a swivel from the motor. In our circuit, each motor is driven by a pulse width modulated (PWM) voltage signal rather than by a continuous DC voltage as in the original idea. This technique ensures that the peak vpltage is always applied to the motor, regardless of the speed control setting. Rather than varying the DC level, the speed of the motor is set by varying the pulse width. TRIANGLE WAVEFORM PIN 6, IC2a +6V APPLIED MOTOR VOLTAGE ov LOW BACK EMF TRIANGLE WAVEFORM PIN 6, IC2a 1-+-- -~ - - - , - - + -- Speed regulation --'r +6V1-.----, APPLIED MOTOR VOLTAGE ov Fig.1: the motor speed in the Electronic Cockroach is controlled by comparing the motor's back-EMF with a triangle waveform to derive a voltage pulse train. If the motor slows, the back-EMF falls & the pulse length increases to bring the motor back up to the correct speed. axle and can rotate through a full 360 degrees. At the front of the vehicle are three light detectors (LDRs), one in the centre facing straight down and two at the corners facing to either side. These LDRs measure the light intensity and provide control signals to switch the motors on and off accordingly. Incidentally, the idea for this car comes from Shaun Williams from Alawa, NT. He originally sent in a circuit for a vehicle which used LDRs and a motor gearbox drive for the two front wheels. We thought that the idea was good enough to develop further, while reducing the cost as much as possible. In particular, we wanted to eliminate the motor gearbox drive. Although being the best way to drive the vehicle, it would have added about $40 to the project and this would have reduced its appeal. Eventually, we decided to drive the front wheels from the motors via rubber bands, a technique that's cheap but effective. Because the drive ratio from the motor to the wheel is not as high as that available from a gearbox, the motor drive circuitry was also redesigned to obtain the greatest possible torque Another worthwhile feature of the circuit is speed regulation. This helps the motor to maintain its speed even if the gradient changes or the motor is loaded due to the nature of the "terrain" (eg, thick carpet). Fig.1 shows the basic principle of the feedback control. What happens is that the circuit monitors the backEMF generated by the motor. BackEMF is the DC voltage generated by the motor to oppose the current through it. The faster the motor spins, the greater the back-EMF. This back EMF is compared with a triangle wave generated by an oscillator and the resulting pulse waveform then drives the motor. When the motor is running at high speed, (ie, when it is unloaded), it produces a high back-EMF and so the voltage pulses applied to the motor are quite narrow. However, if the motor is loaded, it slows down and the back-EMF drops. The circuit then automatically increases the width of the pulses (and thus the average voltage) to increase the motor speed. Circuit details Let's now take a look at the circuit details - see Fig.2. Although at first sight it appears to use a lot of op amps, these are all contained in two quad comparator ICs (ICl & IC2) These comparator ICs are LM339 devices which can operate down to 2V. T~eir outputs are open collector which means that you must to use a pull-up resistor to obtain a high output. The advantage of open collector outputs in our circuit is that they can be connected together as OR gates. The circuit is also somewhat simpler than it first appears because the two motor drive circuits are identical. IClc, IClb, ICla and Ql drive one motor (Ml), while ICld, ICZb, ICZc and Q2 drive the other (M2). ICZa is the triangle wave generator PARTS LIST 1 PC· board, code 08310921, 207 x 83mm 2 Johnson 170 motors (available from model shops) 8 2mm screws and nuts 2 42mm diameter plastic wheels (Aristo-craft or equivalent) 1 150mm-length of 1/8-inch brass tubing 1 150mm-length 1/8-inch brass threaded rod 4 brass nuts to suit 1 22mm aluminium knob 2 12mm brass untapped spacers 2 9mm brass untapped spacers 2 6mm brass untapped spacers 4 1/8-inch steel washers 1 4-way AA square battery holder 1 battery clip for holder 4 AA alkaline cells 4 6 x 60mm diameter rubber bands 1 SPDT toggle switch 3 ORP12 or equivalent LDRs (LDR1 -LDR3) 2 10kQ horizontal trimpot Semiconductors 2 LM339 quad comparators (IC1 ,IC2) 2 BD646 PNP Darlington transistors (01 ,02) 1 3.3V 1W zener diode (ZD1) 2 1N4002 1A diodes (D1 ,D2) 2 1N4148 switching diodes (D3,D4) 1 5mm red LED (LED1) Capacitors 1 470µF 16VW PC electrolytic 1 100µF 16VW PC electrolytic 2 10µF 16VW PC electrolytic 3 2.2µF 16VW PC electrolytjc 1 0.1 µF MKT polyester Resistors (0.25W, 1%) 1 68kQ 1 22kQ 6 10kQ 11.2kQ 11 1kQ 1 390Q 1 180Q 1 47Q Miscellaneous Solde·r, tinned copper wire. referred to earlier. This device is wired as a Schmitt trigger oscillator by virtue of the 68kQ feedback resistor conn·ected between pins 1 & 7. It oscillates by the following action. FEBRUARY 1993 17 +6V - - - - - - - - - - - , +3.3V - - - - - - - - - - 111 SPEED VR1 10k 10k +3.3V V+ 2 1k 13 LDR1 LEFT ORP12 03 1N4148 1k 2.2 + 111 BACK EIIF 1k 16VWi +UV 1k 68k 1.2k 10k LDR2 CENTRE ORP12 1 .,. J7.J 10k BCE .,. 22k v'v 2.2 + 16VW+ +6V +3.3V - - - - - - - - - - - V+ 112 SPEED VR2 10k +3.3V 14 1k 04 1N4148 LDR3 RIGHT ORP12 1k .,. 1k 2.2 + 10 + 16VW+ 16VW+ 112 BACK EIIF 1k .,. .,. .,. POWER l° ... S 1-;.:_:.,._ : _ _ _ _ _+---\'147'1J:lr-6V_ - T 6V: + __,.,.__ __,.,.___ +3.3V 1800 V+ ZD1 3.3V 1W 100 + J .,. ···1 ELECTRONIC COCKROACH Fig.2: IClb, I Cl a & Ql drive motor Ml on one side of the vehicle, while IC2b, IC2c & Q2 drive motor M2 on the other. Normally, Ml is controlled by IClb which compares the back-EMF with a triangle waveform generated by IC2a. When IClb's output switches high, pin 1 ofICla goes low & turns on Ql to pulse the motor. However, ifless light falls on LDRl than on LDR2, pin 13 ofIClc switches low & the motor turns off. LDR3, ICld, IC2b & IC2c control M2 in exactly the same manner. 18 SILICON CHIP When power is first applied, the 2.2µF capacitor on pin 6 has no charge and so the output at pin 1 is high. The 2.2µF capacitor now charges via the 22kQ resistor until the voltage at pin 6 exceeds the voltage on pin 7. When that happens, pin 1 switches low and the 2.2µF capacitor discharges via the 22kQ resistor until the voltage on pin 6 drops below the voltage on pin 7 again. Pin 1 of IC2a now switches high again and so the cycle is repeated indefinitely for as long as power is applied. Thus, the 2.2µF timing capacitor is alternately charged and discharged via the 22kQ resistor and the resulting output is a triangle waveform as shown in Fig.1. This waveform has an amplitude of about 200mV (1.541. 76V) and a frequency of about 66Hz. This triangular waveform is applied to the non-inverting inputs of comparators ICla, IClb, IC2b & IC2c. IClb compares the triangle waveform with the voltage on its pin 4 (inverting) input, as set by trimpot VRl and the back-EMF developed by the motor (Ml). This voltage sets the duty cycle of the voltage pulses that appear on IClb's pin 2 output, as shown in Fig, 1. The voltage pulses from IClb are next inverted by comparator stage IC la. This stage uses the triangle waveform at its non-inverting input (pin 7) as a voltage reference. The voltage pulses from IClb swing between DV and 3.3V, whereas the triangle waveform varies between 1.54V and 1.76V. Thus, when the output ofIClb swings low, pin 1 of ICla is pulled high and vice versa. Note that the output of ICla is pulled high to +6V (via a lOkQ resistor), despite the fact that the supply rail to the IC is less than this figure. This is possible because of the open collector output and ensures that PNP transistor Ql fully turns off when pin 1 is pulled high. When pin 1 of ICla swings low, Ql is turned on via a lkQ current-limiting resistor. This transistor is a Darlington type (BD646) with a minimum DC gain of 750. Thus, we only require a small amount of base current to ensure that the transistor is fully turned on (ie, saturated) when driving the motor. Dl protects Ql by quenching any large spikes that are generated by the motor when the transistor turns off. Fig.3: install the parts on the PC board as shown in this wiring diagram. The three LDRs should all be mounted at full lead length (see text) . D3 and its associated components make up the back-EMF monitoring circuit. Note that because we only want to sample the back-EMF developed across the motor, this sampling process must take place when Ql turns off. When Ql is off, the back-EMF developed by the motor is sampled by a voltage divider consisting of two lkQ resistors. D3 will be forward biased during this time and so a sample of the back-EMF also appears across the 10µF filter capacitor. This voltage is further filtered by a lkQ resistor and a 2.2µF capacitor and then applied to pin 4 of IC1b. Thus, if the back-EMF rises, the voltage on pin 4 ofIClb also rises, the output pulses from IC1b narrow, and the motor slows down. Conversely, if the back-EMF falls, the voltage on pin 4 falls and so the output pulses lengthen to bring the motor back up to speed. VR1 adjusts the initial voltage level on pin 4 and thus sets the overall speed of the motor. When Ql turns on, D3 is reverse biased and thus the voltage previously developed across the 1DµF filter capacitor does not change. The second motor, M2, is controlled in exactly the same manner by ICZb, ICZc and Darlington transistor Q2. The back-EMF of this motor is monitored via diode D4, while VR2 sets the overall speed of the motor. LDR control From the foregoing, it might seem that the two motors run continuously but that is not the case. Instead, one or both motors can be switched off, depending on the light falling on the three LDRs (LDR1 , LDR2 & LDR3). LDR2 monitors the ambient light level and, in company with its associated 1.ZkQ resistor, sets the voltage at the non-inverting inputs of comparators IC1c and IC1d (pins 11 & 9). If the light level goes down, the resistance of the LDR increases and the voltage on pins 11 & 9 also increases. In the case of motor Ml, comparator IC1c monitors the voltage across LDR1 and compares this with the voltage across LDR2. If less light falls on LDR1 than on LDRZ, the voltage on pin 10 ofIClc will be greater than that on pin 11. As a result, IC1c's output (pin 13) switches low and pin 1 of IC1a goes high. This turns Ql and motor Ml off and so the vehicle turns towards LDR1 (assuming that MZ is running). Conversely, if more light falls on LDR1 than on LDR2, IC1c's output effectively goes open circuit and so has no effect on IC1a. IC1b thus supplies a PWM waveform to IC1a as described before and so Ml runs at normal speed. LDR3 controls motor MZ in exactly the same manner. If less light falls on LDR3 than on LDR2, motor M2 switches off and so the vehicle steers in the opposite direction. Note that a 1.2kQ resistor is used in series with LDR2, while lkQ resistors are used in series with LDR1 and LDR3. This arrangement ensures that both motors switch off if there is equal light on all three LDRs. So, when the Electronic Cockroach crawls into a dark corner, it automatically switches its motors off to conserve the batteries. Power supply Fig.4: each motor shaft is fitted with a 10mm length of brass tubing as shown in this diagram. A solder mound is then added to the tubing so that the rubber band stays on the shaft. Power for the circuit is derived from a 6V battery pack consisting of four AA cells. Sl switches the power on or off, while LED 1 lights when the power is on. The 6V rail directly powers the Darlington transistors (Ql & QZ), while the ICs are powered via a decoupling circuit consisting of a 180Q resistor and a 470µF capacitor. This decoupling network filters out any supply rail ripple that's caused by the heavy current drawn by the motors. Finally, a regulated 3.3V rail is derived using zener diode ZD1 and a 1D0µF capacitor. This regulated rail FEBRUARY 1993 19 MOTOR SHAFT- Fig.5: this plan view shows how the motor shafts are coupled to the front wheels via the rubber bands. Position the axle so that Jhe rubber bands stretch by about 7mm when they are installed & adjust the spacers so that the wheels clear the PC board by 2mm. MOTOR -SHAFT RUBBER BAND- UNDERSIDE OF PC BO ARD 12mm UNTAPPED BRASS SPACERS SOLDERED 6mm UNTAPPED BRASS SPACERS / WHEEL RUBBER - BAND WASHERS TO PC BOAR~D_\ _ _ _~,-"'-t I - - - -----------1 \ ADJUST FOR RUBBER BAND TENSION 1/8" BRASS TUBING WHEEL I '\ CRIMP END WITH PLIERS 2mm j 130mm supplies the LDR networks and provides the bias for ICl b and IC2b. Construction A PC board coded 08310921 (207 x 83mm) accommodates all the parts see Fig.3. Before installing any of the parts , check the holes sizes for the motor mounts and th e rear wheel pivot. The motor mounts should be drilled to 3mm while a 5mm hole will be required to accept the 9mm-long spacer that pivots the rear wheel. This spacer should be soldered into place so that it protrudes about 3mm above the board surface (see Fig.6). Follow the overlay diagram care- fully when installing the parts on the PC board and don't forget the eight wire links (note: the prototype differs slightly from Fig.3). Make sure that the semiconductors and electrolytic capacitors are all oriented correctly. The two Darlington transistors are mounted with their metal tabs towards the motors. The three LDRs should all be mounted at full lead length. Adjust LDR1 and LDR3 so that they face sideways, as shown in the accompanying photograph. LDRZ should be adjusted so that it faces towards the floor. The two motors can now b e mounted in position using 2.5mm machine screws and nuts and their leads soldered to the PC board. Note that the red wire of motor 1 runs to Dl's cathode, while the red wire of motor 2 runs to D2's anode. This is necessary because the motors must run in opposite directions to each other. The circuit can now be checked for correct operation. Wind both trim pots fully clockwise, then switch on and check for +5V (approx.) on pin 3 of each IC. ZD1 should have a nominal 3.3V across it. Now place some insulation tape over LDR2 and rotate one of the trimpots until its corresponding motor begins to run. When it does, do the same for the other motor. Adjust the RESISTOR COLOUR CODES 0 0 0 0 0 0 0 0 0 20 No. 1 1 6 11 1 1 1 SILICON CHIP Value 68k.Q 22k.Q 10k.Q 1.2k.Q 1kn 390.Q 180.Q 47.Q 4-Band Code (1%) blue grey orange brown red red orange brown· brown black orange brown brown red red brown brown black red brown orange white brown brown brown grey brown brown yellow purple black brown 5-Band Code (1%) blue grey_ black red brown red red black red brown brown black black red brown brown red black brown brown brown black black brown brown orange white black black brown brown grey black black brown yellow purple black gold brown motors for slow running and check that each motor exhibits quite a lot of torque when you try to stop it by grabbing hold of its shaft. If it does, then the back-EMF feedback control is working correctly. Finally, check that each motor stops when you cover its corresponding LDR with your finger. The motor should immediately restart when you remove your finger, If all is OK, switch off and move on to the mechanical assembly. If it doesn't work, go over the board carefully and check for wiring errors. NUT E ,§ .., 9mm UNTAPPED BRASS SPACER SOLDERED IN HOLE IN PCB ..,____ WASHER "NUT \ 118' THREADED BRASS ROD 22mm DIA ALUMINIUM KNOB Mechanical assembly The first step in the mechanical assembly is to fit a 10mm length of 1/8-inch diameter brass tubing over each motor shaft. To do this, cut two 10mm lengths of tubing with a hacksaw and file the ends smooth. This done, crimp each piece lightly at both ends using side cutters, then push them onto the motor shafts (see Fig.4) . To keep the rubber bands running true, a convex mound of solder is applied to the centre of each shaft. This ensures that the rubber bands remain on the shafts and don't wind off when the motors start to run. If the belt begins to wander off centre, it will quickly restore itself. To form this convex mound, run the motor at slow speed by shorting out its LDR, apply the iron and allow the solder to slowly build up on the shaft. When a sufficient mound. has built up , remove the iron and allow the solder to cool with the motor still running. Warning: if the motor is allowed to run too fast during this procedure, you may end up with molten solder flying off the shaft. As a r,.<,.~ ' - - 9mm BRASS SPACER 60mm DRILL HOLE THROUGH KNOB THIS END I Fig.6: the rear wheel assembly is made up using a 22mm-diameter aluminium knob, a 150mm-length of threaded brass rod, two 9mm spacers & several nuts & washers. Make sure that the knob spins freely on its spacer & that the pivot assembly operates correctly before soldering the nuts to the threaded rod. Below: the arrangement of the front & rear wheel assemblies can be gauged from this "under-the-chassis" view. Note that a small piece of black cloth was glued to the rear wheel (ie, to the aluminium knob) so that its appearance matched that of the other wheels. ~ FEBRUARY 1993 21 precaution, we strongly recommend that you wear safety goggles to prevent possible eye injury. Once the solder has cooled, it can be further shaped using a small file. Again, this is best done with the motor running slowly. Wheel assembly The first step in the front wheel assembly is to find the correct location for the axle. To do this, temporarily fit one of the wheels to the axle, position it on the underside of the PC board, and install the rubber band as shown in Fig.5. Now position the axle so that the rubber band stretches slightly (5-8mm should be about right) and mark the position of the axle on the board with a pencil. The axle runs inside two 12mm spacers which are soldered to the underside of the PC board, with additional free-running 6mm spacers fitted to ensure that the inside edges of the wheels just clear the PC board. Fig. 5 shows the details. Initially, the two 12mm spacers should be lightly tack soldered into position. This done, test the assembly by fitting the axle, 6mm spacers and wheels. Adjust the lateral position of the 12mm spacers to provide the correct amount of wheel clearance from the board (about 2mm), then complete the solder joints. The wheels can now be permanently installed by cutting the axle to length and crimping the axle ends with pliers as shown in Fig.5. Note that two small washers are fitted between each wheel and the crimped axle end to ensure that the wheel turns freely. Don't just use one washer here. If you do, it may bind on the crimped end of the axle and make the wheel difficult to turn. The pivoting rear wheel assembly is shown in Fig.6. On the prototype, this wheel was made from an aluminium knob. The normal shaft hole was drilled right through the knob to accept a 1/8-inch threaded brass rod, . while a 9mm brass spacer serves as the wheel bush. This brass spacer is simply fitted into the existing 6mmdiameter shaft hole in the knob. The wheel assembly is fitted to one end of the brass rod and secured with a nut on either side. Make sure that the wheel turns freely but without too much play before permanently soldering the nuts in position. This done, bend the rod into a U-shape around the wheel as shown in Fig.6, taking care to ensure that the rod finishes up at right angles to the axle. The end of the rod is then bent upwards through 90° about 60mm from the axle, so that it fits through the vertical spacer soldered to the PC board. Secure the wheel assembly to the vertical spacer using nuts and washers as shown in Fig.6. The battery holder can be secured to the PC board using two rubber bands (the same size as those used to drive the motors). To improve their appearance, we dyed the rubber bands black using normal fabric dye (just follow the hot pan dying procedure outlined on the packet). In normal operation, LDR2 should face down towards the floor for best results. If you find that the car only runs when LDR2 is covered, increase the value of the 1.2kQ resistor to 1.5kQ Finally, you can easily modify the circuit so that the 22 SILICON CHIP 0 0 0 0 T"'"4 (\J CJ' 0 T"'"4 M CD 0 u Cl) Fig.7: here is the full-size pattern for the PC board (code 08310921). Check your board carefully to ensure there are no etching defects before installing any of the parts. vehicle turns away from the dark rather than towards it. This is achieved simply by connecting motor Ml to motor M2 's pads on the PC board and vice versa. The lead polarities must also be swapped over, so that the motors continue to run in the correct direction. SC When we in 1989 decided to design Australia's finest range of loudspeakers, we soon realised the potential we had on our hands. By designing and building the speakers in Australia, and by using the ultimate drivers available, we could challenge the best loudspeakers from around the world. With this in mind we now set out to achieve our go~. The choice of drivers was obvious: DYNAUDIO. They are known the world over as being the finest drivers available. The high cost however, makes their use prohibitive for those speaker manufacturers who only produce mass market speakers. Our intention though, was not to make another mass market range of loudspeakers, but rather Australia's finest. The next step was to appoint a design team. The ideal team should have not only the best technical qualifications and facilities, but also a great love and appreciatic;m for music. With the design team chosen, work began in February 1990. Now followed an exhaustive but rewarding 14 months of intensive research and development. Numerous prototypes were built and refined until each model fulfilled its objectives: Being the finest in its class. The listening panel comprised not only the design team, but also Hi-Fi critics and leading audio dealers from around the country. Each prototype was compared against the more expensive imported equivalents until the design team was fully satisfied. In June 1991 Australia's finest range of loudspeakers was released : DYNAUDIO IMAGE. WE HAVE DONE All WE CAN ..... NOW IT'S UP TO YOU ! Acknowledgements: Acoustical Design: Glen Leembrugen & David Connor, Sydney Australia Dynaudio Drivers: Mark Thorup & Peter Larsen, Skanderborg Denmark Solen Capacitors: Dennis Quellet, Quebec Canada Bi-wiring Terminals: Ben Fan, Taipei Taiwan Monster Cable: Noel Lee, San Fransisco USA Cabinet Builder: Scott Krix, Hackham South Australia Listening Panel: Glen Leembruggen, David Connor, Pat Hayes, Les Cardilini , Philippe Luder, Dahl Murphy, Carlo Di Martino , Craig McNeil, Michael Henriksen, David Jacobs, Tom Manning For more information and name of nearest dealer please contact: &an Audio Pty. Ltd., P.O. Box 242, Hawthorn Vic 3122 Ph. (03) 429 2199 Fax (03) 429 9309 CIRCUIT NOTEBOOK Interesting circuit ideas which we have checked but not built and tested. Contributions from readers are welcome and will be paid for at standard rates; H:RNtES ~ 0 . 2 2 CIRCUITRY HANDS FREE SPEAKER +12V COURTESY LIGHTS 10k 1M DOOR ~ SWITCHESr 4.7k 10k -:- Horn blower for mobile telephones They say that necessity is the mother of invention and that certainly applies to this circuit. My brother is a plumber and has a new mobile phone and an associated hands-free set for his van. Naturally, he doesn't want to expose his expensive new phone to the hazards of wa- Square wave frequency doubler Using just one 4011 quad NAND gate IC, this circuit accepts a squarewave signal and doubles its frequency. ICla and IC1b are connected as inverters, with IClb driven by the output ofICla. Both gates also drive separate single-pole RC filters, each filter consisting of a .001µF capacitor and a 6.8kQ resistor. When a square-wave signal is applied to the input, the outputs of ICla and IClb are out of phase. When the inputs ofIC1a or IC1b go 24 SILICON CHIP -:- ter, sand and dust on building sites. This simple circuit plugs into the hand-free circuit and blows the horn whenever the phone rings, thus allowing him to leave the phone in the safety of the van. The "trigger" signal for the circuit is picked up from the "hot" side of the hands-free loudspeaker via a 0.22µF capacitor. Thus, when the phone rings, the resulting voltage pulses charge a 2.ZµF capacitor via D3 and a couple of series resistors. DZ clips any large negative-going spikes, while D4 clamps any large positive-going spikes to the +12V supply rail. Comparator stage ICla (LM339) compares the voltage developed across the 2.ZµF capacitor with a reference voltage on its non-inverting input (pin 5). This reference voltage is set by VR1 which basically functions as a sensitivity control. When the voltage on pin 4 exceeds the reference voltage (ie, when the phone rings), -pin 2 of ICla switches low and turns on Ql and relay RLY1 to sound the horn. To prevent the circuit from operating when the van is being driven (ie, . . . . - - - - - - - - - - - - - - - +3-15V high, the resulting output low ·causes a negative-going spike to appear at pins 8 & 9 of IClc. This gate converts these spikes into output pulses at pin 10 and these pulses occur on each edge of the input signal to ICla (ie; one pulse on the rising edge and one on the falling edge). So we end up getting two pulses for each input pulse. The· width of the output pulses is a function of the RC time constants at the outputs of IC1a and IC1b. The period of the input frequency must be greater than twice these RC time constants. Darren Yates, SILICON CHIP. when the ignition is on), comparator IC1b pulls pin 4 of IC1a low and thus turns off Q1 and the relay. When the ignition is off, pin 1 of IC1b is open circuit and the circuit operates normally. Another problem is that hands-free speech can also trigger the circuit. This problem was solved by using one of the door switches to shunt the input signal to earth via D1 when the door is open. This means that handsfree conversations must be made with the door open when the vehicle is parked but this is the normal situation for my brother anyway. Alternatively, you can use a switch to shunt the trigger signal if you wish to converse with the doors shut. The duration of the horn blasts can be adjusted using sensitivity control VR1. Glen Host, Doubleview, WA. ($35) Simple way to make PC boards This idea might seem silly but it actually works. If you are fortunate enough to have a PC and CAD software that will print a circuit board layout on your laser printer, then you have all that is needed for instant circuit boards. Once you have prepared your design on the computer, print it on the laser printer as you normally would. There are a few things to note though. First, you have to print it" actual size" (1:1) and second, it has to print "wrong reading" (component side). Take a blank piece of copper clad board, thoroughly cleaned, and lay the printed copy on it face down. Using moderate pressure and an ordinary domestic clothes iron set to "cotton" (see, we told you it was silly), iron the paper on to the copper. Be careful not to move the paper as you go. After a few seconds the toner will stick to the copper. It seems to be best to keep the heat on until the fibreglass board itself is hot as well. Leave the board with the paper attached to cool for a minute and then place it in warm water and allow it to soak for a few more minutes. You can then carefully remove the paper, leaving the toner firmly adhered to the copper surface. Any pieces of paper left behind can be carefully rubbed off with your finger. The toner makes an excellent resist and the board is Robotics interface for PCs This interface circuit was designed to operate a crane made out of Swiss Meccano directly from the PC under the control of a GWBASIC program. There are eight motors powering the crane so eight of the interface circuits shown here must be used. Each of these data lines is connected to an optoisolator (OPT1). When the output line goes high, the internal LED lights and turns on the internal phototransistor. This turns on transistor Q1 which energises the relay coil and turns on the appropriate motor. Resistor R3 limits the current through the base of Q1, which is protected against negative voltage spikes by diode Dl. The accompanying program shows how each relay can be switched on individually. P. Dumuid, Adgate, SA. ($25) ----------------o+SV PC PRINTER PORT DB25 D2-D9 C1 + 220 16VW- R1 1k OPT1 4N28 A. R4 150D LED1 RED 5V RELAY NEC MR62-5a PC GND 2 ':' R2 2.2k ~'"{ ONE OF EIGHT 10 KEY OFF: CLS 20 NOS$=" FIRST":GOSUB 50: H=I: NOS$=" SECOND": GOSUB 50: G=I: NOS$=" THIRD": GOSUB 50: F=I 30 NOS$=" FOURTH": GOSUB 50: E=I: NOS$=" FIFTH": GOSUB 50: D=I: NOS$=" SIXTH": GOSUB 50: C=I 40 NOS$=" SEVENTH": GOSUB 50: B=I: NOS$=" EIGHTH": GOSUB 50: A=I: GOSUB 90: CLEAR: GOTO 10 50 LOCATE 1,1: PRINT"WHAT OUTPUT DO YOU WANT TO GO TO THE ";NOS$;:INPUT "OUTPUT(1/0)";I 60 LOCATE 1,1: PRINT" 70 RETURN 80 END 90 OU=O 100 PRINT "A=";A;:IF A= 1 THEN OU=OU+ 128: PRINT" 128" ELSE PRINT"" 110 PRINT "B=";B;:IF B = 1 THEN 0U=OU+64: PRINT" 64' ELSE PRINT" O' 120 PRINT "C=";C;:IF C = 1 THEN 0U=OU+32: PRINT" 32" ELSE PRINT" O' 130 PRINT "D=";D;:IF D = 1 THEN OU=OU+ 16: PRINT" 16' ELSE PRINT" O' 140 PRINT "E=";E;:IF E = 1 THEN 0U=OU+8: PRINT" 8' ELSE PRINT" O' 150 PRINT "F=";F;:IF F = 1 THEN 0U=OU+4: PRINT" 4" ELSE PRINT" O' 160 PRINT "G=";G;:IF G = 1 THEN 0U=OU+2: PRINT" 2' ELSE PRINT" O' 170 PRINT "H=";H;:IF H = 1 THEN OU=OU+ 1: PRINT" 1" ELSE PRINT" O' 180 OUT &H0378,0U: PRINT" ";OU 190 INPUT DUMMY$ 200 RETURN now ready to etch in the normal way. Naturally, this method is not perfect. If you design a board with tracks 0.1mm thick spaced 0.2mm apart, then you can't expect good results. But if you can avoid using fine tracks or running tracks too close·together, then it is far more accurate than using the felt pen method. You can also experiment with different paper stock. I found that "Matt Art" achieves the best results. Glen Andersson, Ashfield, NSW. ($15) FEBRUARY 1993 25 SIMPLE PROJECTS FOR MODEL RAILROADS Most model railroad layouts are fairly basic but by spending just a few dollars and a little time with a soldering iron, you can make your layout far more realistic and interesting. These three circuits are easy to build and can be added to virtually any model railroad layout. 1. Train Controller Our first circuit is for a Low-Cost Model Train Controller with simulated inertia - see Fig.1. Many model railroad sets come with a simple rheostat controller but these give poor lowspeed running characteristics. They also give rise to jack rabbit starts and a model that slows or even stalls on curves and gradients. Unlike a rheostat controller, the circuit of Fig.1 behaves as a constant voltage source at any given throttle setting and this gives much improved control at low running speeds. In particular, starting is much smoother and the model no longer stalls or slows when the going gets a little tough. Of course, a pulse power controller gives even better control but is much more expensive than the controller described here. As a bonus, our low-cost controller 26 SILICON CHIP These three low cost projects will enhance the appeal of any model railroad layout. They include a low-cost train controller, a traffic lights simulator & a points controller. By TERRY MOWLES provides simulated inertia and braking. This is just a fancy way of saying that the train adjusts its speed gradually when you vary the throttle and slows gradually when the brakes are applied, just like a real train. A couple of preset pots allow you to adjust the amount of inertia to suit your layout. How it works Fig.1 shows the circuit details. It's basically a beefed-up version of the controller published in the November 1990 issue. The original circuit could supply up to 1.2A whereas this new version can supply up to 3A. This is useful if you want to multiple-head locos, particularly if they have smoke generators, lighting and sound generators. Power is derived from a 3A 12V AC source (eg, via a mains transformer) and this is rectified by diodes D1-D4 to provide about 17V DC. Alternatively, the bridge rectifier can ,be bypassed and the unit operated from a 12-18V DC source. This voltage is then tapped off by throttle control VRl and applied to the base ofQl via Sla, D5, VR2 and a series 5.6kQ resistor. Ql and Q2 form a Darlington output stage and this is forward biased as soon as the voltage on Ql 's base reaches 1.3V. Q2 then conducts and supplies voltage to the track via a 0.22n 5W resistor. Double pole switch B 12-18VAC 05 1N4007 SPEED VR1 5k 0 INERTIA VR2 1k EOc VIEWED FROM BELOW 0 PLASTIC SIDE m BRAKE S1a 0 B A~K ECB 47 + 25VW_ S1b + 4700 25VW- FORWARD S2a 4700 REVERSE BRAKE LEVEL VR3 1k FORWARD S2b TO TRACK REVERSE LOW COST 3A TRAIN CONTROLLER Fig,1: the circuit uses Ql & Q2 to buffer the output of throttle control VRl. Q3 provides overload protection by reducing the drive to Ql when the voltage across the 0.22Q resistor reaches 0.65V. S2 provides forward/reverse switching by swapping the supply polarity to the track. Q3, LED 1 and the 0.22Q resistor provide overload protection. Normally, the voltage across the 0.220 resistor is less than 0.65V and Q3 has no affect on the circuit operation. When a short circuit occurs, the output current shoots up until there is about 0.65V across the 0.220 resistor. Q3 then turns on and reduces the drive to Ql, thus limiting the output current to about 3A. LED 1 indicates that an overload has occurred. VR2 and its associated 4700µF capacitor provide simulated inertia for the throttle. This inertia effect occurs TO TRACK a~ S1 s2[ ~ ~ because it takes t1me for the capacitor to charge or discharge to its new level each time the throttle is varied. D5 prevents the 4700µF capacitor from discharging through VR1 when the throttle setting is reduced. VR3 and the 4700µF capacitor provide the braking inertia. When braking switch Slb is closed, Sla opens and the 4700µF capacitor discharges via the 4700 resistor and VR3. This gradually reduces the voltage on the base of Ql so that the train slows to a stop. When the brake is subsequently released, the train builds up speed to its previous setting (assuming that VR1 is not touched in the meantime). Note that it is not necessary to reFig.2: wire up the Thain Controller as shown in this diagram, The circuit shows the pin connections for transistors Ql, Q2 & Q3. Note that Q2 should be fitted to a large finned heatsink for cooling. duce the throttle to zero before applying the brakes. That's because Sla switches the throttle out of circuit when braking is applied. Building the controller Fig.2 shows the wiring details for the controller. Mount the parts on the TRAIN CONTROLLER PARTS LIST 1 PC board, 106 x 48mm 1 5kO linear potentiometer (VR1) 2 1kO PC-mounting trimpots (VR2,VR3) 2 DPDT miniature toggle switches (S1 ,S2) 1 finned heatsink (see text) 1 TO-3 mounting kit (mica washer plus insulating bushes) Semiconductors 1 BD139 NPN transistor (Q1) 1 2N3055 NPN transistor (Q2) 1 BC337 NPN transistor (Q3) 4 1N5404 silicon diodes (D1-D4) 2 1N4007 silicon diodes (D5,D6) 1 red ~ED (LED 1) Capacitors 1 4700µF 25VW PC electrolytic 1 47µF 25VW PC electrolytic Resistors (0.25W, 5%) 1 5.6kO 1 4700 10.2205W FEBRUARY 1993 27 It's also possible to bolt the transistor directly to the heatsink, provided that you make sure that the heatsink does not touch any other component. That's because the heatsink will now float at the full supply voltage if there is no isolation. 2. Traffic Light Simulator The Train Controller PC board can be hidden under the layout, while the controls can be mounted in a small plastic case to give a walkaround throttle or they can be mounted on the main console. If you intend operating the unit from a DC source, install D1-D4 anyway so that the supply can be connected with either polarity. The 5W resistor should be mounted about 5mm proud of the T03 -....;;;:::.;;;;:;~;:::;::;:;;::::;;:~ DEVICE board, so that the air can circulate beneath it to provide additional coolMICA ing. We mounted the LED directly on ~WASHER the board but it could also be mounted ~ elsewhere (eg, on a control panel) and C connected by flying leads. C> C> HEATSINK C Be sure to install the LED with the correct polarity, otherwise the overload protection circuitry won't work ~ INSULATING ~ BUSHES (its anode lead is the longer of the two). Use medium-duty hook-up wire tfltJ-R<at> for the connections to the power supS~~~EA~ ply, track and switch S2, since these <at> <at>w~m~s leads carry currents up to 3A. The remainder of the wiring (ie, to the ©> LED, Sl and VR1) can be run using <at>NUTS rainbow cable or light-duty hook-up Fig.3: here are the mounting details wire. for Q2. It should be isolated from the Finally, power transistor Q2 must heatsink using a mica washer & be mounted on a large finned heatinsulating bushes. sink, since it dissipates quite a lot of power. Fig.3 shows the mounting dePC board exactly as shown, taking . tails. Note that the transistor is electricare to ensure that all polarised parts · cally isolated from the heatsink using are correctly oriented. In particular, a mica washer and two insulating note that the metal face of the BD139 bushes. Smear all mating surfaces with (Ql) faces towards the 4700µF capaci- heatsink compound before bolting the assembly together. tor. e s~::~:~iF 28 SILICON CHIP Fig.4 shows the circuit for the Thaffic Light Simulator. This was first published in SILICON CHIP in November 1989. It drives green, red and yellow LEDs to accurately simulate traffic light cycles at an intersection. 555 timer IC1 is wired as an astable oscillator and this provides a clock signal for IC2, a 4017 decade counter. IC2 's 0-9 outputs go high in turn on each successive clock signal and drive several sets of OR gates made up by diodes D1-D20. These OR gates then drive transistors Q1-Q6 to control the traffic light LEDs (LEDs 1-12). Note that each transistor drives two LEDs of the same colour, one for each opposing light set. When pin 3, pin 2 or pin 4 of IC2 is high, Ql turns on and lights LEDs 1 & 2 (green) for one set of lights. Q4 will also be turned on during this time TRAFFIC LIGHTS PARTS LIST 1 PC board, 92 x 78mm 9 PC stakes Semiconductors 1 555 timer (IC1) 1 4017 decade counter (IC2) 1 7805 3-terminal regu lator (REG1) 6 BC548 NPN transistors (0106) 4 green LEDs (LED1 ,2, 11, 12) 4 yellow LEDs (LED3,4,9, 10) 4 red LEDs (LED5,6,7,8) 20 1N914 silicon diodes (D1 D20) 1 1N4007 silicon diode (D21 ) Capacitors 1 220µF 25VW PC electrolytic 1 100µF 16VW PC electrolytic 2 10µF 16VW PC electrolytic 1 0.1µF metallised polyester Resistors (0.25W, 5%) 6 100kO 6 4700 1 82kO 1 2200 1 4.7kO 1 1500 100k ~ ~ 16 ~ ~ D4 1N914 1 2 4 7 Vk s ~ IC2 4017 D5 10 4 5 1 6 5 14 82k 7 6 9 IC1 555 11 13 ~ ~ 10 + ~ D17 1N914 16VW+ +9V D21 1N4007 +12V 100 + 2200 16VW+ LED7-8 GREEN LED9·10 YELLOW 1500 ~ B ROC VIEWED FROM BELOW ~ Jt 100k 100k ~ ~ ~ ~ ~ I G0 TRAFFIC LIGHT SIMULATOR Fig.4: the Traffic Light Simulator uses 555 timer IC1 to clock decade counter IC2. This device then drives the traffic light LEDs via transistors Q1-Q6 & a number of OR gates formed by diodes D1-D20. Fig.5 (right) shows how the parts are installed on the PC board. Each output driv~s tw,p LEDs of the same colour, one for each opposing set of lights. HIGH12J (via an OR gate consisting ofD11-D16) and this turns on the two red LEDs for the other set of lights. The other diode OR gates ensure that the remaining LEDs for each set of lights turn on and turn off in the correct sequence as the 4017 counts up. For example, when pin 7 is high, Q2 and Q4 are on and this lights LEDs 3-4 (yellow) and LEDs 7-8 (red) . As with real traffic lights, there is a brief period of time when both sets of lights are red (ie, pin 10 or pin 11 high). Each complete cycle takes about 25 seconds and is then repeated. The timing period can be altered by .changing the timing components in the oscillator (ICl) . Power for the circuit can come from any +12V DC source and this is applied to REGl to derive a regulated +9V rail. Diode D21 protects the circuit against reverse supply polarity. Finally, a lOµF capacitor and 4. 7kn resistor are used FEBRUARY 1993 29 Protect your valuable issues Silicon Chip Binders These beautifully-made binders will protect your copies of SILICON CHIP. They feature heavy-board covers & are made from a distinctive 2-tone green vinyl. They hold up to 14 issues & will look great on your bookshelf. * High quality * Hold up to 14 issues * 80mm internal width * SILICON CHIP logo printed in gold-coloured lettering on spine & cover Price: $A 11 .95 plus $3 p&p each (NZ $6 p&p). Send your order to: Silicon Chip Publications PO Box 139 Collaroy Beach 2097 Or fax (02) 979 6503; or ring (02) 979 5644 & quote your credit card number. Use this handy form l ----------Enclosed is my cheque/money order for $._ _ _ or please debit my □ Bankccird □ Visa □ Mastercard Card No : Card Expiry Date _ _/_ _ Signature _ _ _ _ _ _ _ __ Name _ _ _ _ _ _ _ _ __ Address_ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ P/code_ __ ., _ _ _ _ _ _ _ _ _ _ _ ,1 30 SILICON CHIP This is the finished Traffic Light Simulator board. Take care with component orientation & note that diode D21 is a 1N4007 type. The remaining diodes are all 1N914 types & are installed with their cathodes towards transistors Q1-Q6. to provide a power-on reset signal for ICZ. This is necessary to ensure that the 4017 starts reliably each time power is applied to the circuit. capacitor's charge is dumped via DZ into one of the two solenoids that are used to control the points (one to open them and one to close them). During Construction Fig.5 shows the PC board parts layout for the traffic light simulator. You can install the parts in any order but take care with component orientation. The outputs that drive the LEDs are all marked on the PC board. Note that each output drives two LEDs of the same colour, one for each opposing set of lights. The LED anodes are all connected together and wired to the +9V output on the PC board. 3. Points Controller The final circuit is the Points Controller - see Fig.6. It can be powered from any 12-15V AC or DC source. Dl half-wave rectifies the incoming voltage in the case of an AC supply, or provides reverse polarity protection in the case of a DC supply. When power is applied, Ql conducts and quickly charges the 2200µF capacitor. At the same time, LED 1 lights to indicate that the circuit is ready. The points can now be opened or closed by pushing one of momentary-contact pushbutton switches (either S1 or S2). As soon as S1 or S2 is pushed, the There is room on the Points Controller PC board for a second 2200µF discharge capacitor, should this prove necessary to operate the solenoids. POINTS CONTROLLER PARTS LIST 1 PC board, 54 x 36mm 1 TIP41 C NPN transistor (01) 3 1N4007 silicon diodes 1 red LED (LED1) 1 2200µF PC electrolytic 1 2.2kQ 0.25W resistor 1 3900 0.25W resistor Why pay $1000's for encyclopedias? If you own a computer with a CD drive, then you can own the 22 vol NEW 1991 Grolier Electronic Encyclopedia for $160. Let the computer do the scanning! LQQK PARENTS SQNy; Computer Requirements either, 1) IBM PC. PS2 or compatible, 512K. MSDOS 3.0, VGA card & Monitor CD ROM Drive OR 2) Apple Macintosh with CD Rom Drive. LQQK PARENTS CD\ROM & SOFTWARE ~ s: ~ II MIXED-UP MOTHER GOOSE* SONY LASER LIBRARY FAMILY. II COMPTON'S ENCYCLOPEDIA ' • Ill LANGUAGES OF Iii THE WORLD Translates to and from Chinese, Danish, English, Finnish, French, German, Italian, Japanese, Norwegian, Spanish & Swedish. Translations can be exported directly to WP packages (Chinese and Japanese display only). Includes the full text of 18 dictionaries in 12 languages. - equivalent to 132 dictionaries! COMPUTER REQUIREMENTS (for package) XT/AT Compatible, 512k Ram. DOS 3.1 Hard disc drive - half size slot Recommended: VGA Monitor & VGA adapter Mouse * Requires VGA TITLE POPULAR CD ROMS DESCRIPTION - Battlechess Beethoven Symph No. 9 Bible Library Beauty & the Beast Chessmaster 3000 Encyclopedias: - Compton's Family - Compton·s Multimedia - Grolier 1991 Family Doctor Food analyst Games Pak No. 1 Games Pak No. 2 Great Cities No. 1 Great Cities No. 2 Guiness Book of Records Just Grandma and Me Kings Quest V Languages of the World Microsoft Bookshelf 1991 Edition Mixed up Mother Goose National Geographies Mammals Night Owl Shareware Ver. 6 Nurses Medical Partner Plant Doctor Publish-it Sherlock Holmes Sleeping Beauty Timetable of History, Science & Innovation VGA Spectrum Where in the World is Carmen San Diego Windows 3.1 - Microsoft Wing Commander- Secret Wing Commander- Ultima World Atlas An interactive game designed to stimulate your child's imagination with full colour graphics and digitized sound, voices and music. · · , Compton's Encyclopedia (from Brittanica) contains full text of 26 volumes, 9 million words, 32,000 articles, 1500 illustrations including sound and speech recording. Forget flipping through volumes, instead, follow key pathways on words and subjects - access information in the blink of an eye. $860 l!I NATIONAL GEOGRAPHIC Ill SOCIETY'S MAMMALS* Not only Is this Software • Educational - It's fun too! Not only can this fantastic software package educate you and your children, it also can provide hours of entertainment. Info on 200 animals, photos, range maps, motion clips, essays and 155 animal vocalizations . II WORLD ATLAS* -- The World Atlas brings the entire globe to your computer screen. This atlas, almanac and world fact book in one, gives you instant access to over 240 fully detailed, EGA/VGA colour maps and a huge database of international information. PACKAGE CONTENTS Sony internal drive CDU 535 which supports CD Rom mode 1 & 2 & Audio Value $540 (one year warranty) Sony bus interface card (half card value $180) Software - 6 CD's as detailed - Value $998 Microsoft CD - Rom Extensions SPECIAL OFFER - all for IBM (also Mac where shown) ORDER PRICE Chess with sound and animation D $90 Microsofts musical journey (also MAC) D $135 9 Bibles 3000 Sermons, 6 dictionaries D $90 Classic story - music and sound effects D $90 A classic game - now a classic CD D $90 - see above as above plus animated sequences see above - (also MAC) Invaluable Information, 1500 Q & A's - (also MAC) USDA's database, nutrients, calories- analyse foods Games - inc Chessmaster, Bruce Lee, Black Hole Games - inc Loopz, Puzzle Gallery, Robot Tank Tour London, New York, Sydney and 7 others Tour Berlin, Chicago, Rome, and 7 others Multimedia - the best seller plus pictures and sound A living book - childrens' interactive fun A classic game - now a classic CD See above Windows version - see above see above see above 600MB of IBM compatible code, 10,000 programs Nursing literature from Medline 1962-89 Text and Images on horticulture. weeds, etc DTP Program incl, WP, 69 fonts, 1000 clips Consulting Detective - interactive game Interactive Fairytale - adventure game Timelines with sound and animation (also MAC) Clip art, animations, games, digitized music Deluxe version of the bestseller The best seller in•compact format Popular game plus Secret Missions 1 & 2 Popular game plus Ultima V1 see above - (also MAC) D D D D D D D D D D D D D D D D D D D D D D D D D D D D D $410 $690 $160 $135 $90 $70 $70 $135 $135 $159 $90 $90 $159 $159 $90 $90 $90 $190 $90 $135 $90 $90 $90 $90 $135 $135 $90 $90 $90 I'll MICROSOFT • 1M BOOKSHELF 1991 ., · . _- This indispensable collection of reference materials includes the American Heritage Dictionary, Roget's II Electronic Thesaurus, the World Almanac and Book of Facts, Barlett's Familiar Quotations, and more. For added efficiency, all reference volumes interface directly with more popular word processing programs. CDU 535 DRIVE SPECS 5¼" Half-Height Internal 340ms avg. access time 150KB sustained data transfer rate 600KB burst data transfer rate 8KB buffer Output jacks for stereo and head phones r - MAILTH,scouPONroDAv- , I I (Allow 14 days for delivery) I I I I I I .:~.(~:>........... . . I D D I D I I I I I I I I I I II I I I II I PELHAM PTY LTD I enclose cheqoe, money order for$..................... 1 :r~:r:~;~::r::.. Address ............................................................ :........... ............................................... Postcode .................... . Phone ..................................... Fax no ........ ,................ . BANKCARD MASTERCARD VISA Card Number: Expiry date.................................................................... Cardholders Signature ............................... .................. . L 1at Floor, 100 y.,.... Road, Pennant HIiia 2120 Ph (021 HO 8988 Fax (02t 980 n91 See ue II Booth 141, HOME COMPUTER SHOW, Melbourne I I I I II I II I I .J D1 1N4007 12-15V AC OR DC Q1 TIP41C Fig.6 (left): the Points Controller uses the discharge qirrent from a 2200µF capacitor to control the points solenoids. This capacitor is charged via Ql when power is applied. The capacitor discharges & Ql turns off each time one of the pushbutton switches is press_ e d. Fig.7 (below) shows the parts layout on the PC board. ~ J ---------e--o BCE $1 E D2 1N4007 ~ TO POINTS SOLENOIDS ----------e--o + GND 12-15V AC OR DC +V TO 51 AND 52 GND 2200 25VW_ LED1 GNDo-------------t------oGND POINTS CONTROLLER this time, DZ also pulls Ql's base below its emitter and so Ql is turned off. This ensures that the points solenoid only receives a brief current pulse from the charged capacitor and prevents it from burning out if the button is held down for too long. The ZZ00µF capacitor charges via Dl and Ql again as soon as the pushbutton switch is released. D3 protects Ql against any large negative-going spikes that are generated when the solenoid turns on. By the way, you can use this circuit to control as many sets of points as you wish - just wire in additional m,omentary contact pushbutton switches to control their solenoids. Construction Assemble the parts on the PC board as shown in Fig. 7, making sure that Where to buy the kits Kits for these projects are available from T. A. Mowles, PO Box 491, Noarlunga Centre, South Australia, 5168; or from Force Electronics stores in Adelaide, South Australia. The prices are as follows: (1 ). Train Controller (does not include heatsink or TO-3 mounting kit) .. $27.95 (2). Traffic Light Simulator (includes 12 miniature LEDs) ..... .......... ....... $22.95 (3). Points Controller (does not include switches) ..... .. ....... ....... .. ..... ....... $9.95 Payment should be made by cheque or money order. Please add $3.50 for p&p or $5 for 2-5 kits. Note: copyright of the PC board patterns is retained by T. A. Mowles. all polarised parts are correctly oriented. Note that some points solenoids may require more current than can be delivered from a single ZZ00µF capacitor. For this reason, there's space on the board for a second capacitor if required. No heatsink is required for the TIP41C since it only dissipates a few milliwatts. If the LED brightness is insufficient, reduce the value of the series 2.ZkQ current limiting resistor. In some cases, it may be necessary to come down to 1.ZkQ. SC RESISTOR COLOUR CODES No. TRAIN CONTROLLER 0 0 0 0 1 1 1 Value 4-Band Code (5%) 5-Band Code (1%) 5.6kQ 470Q 0.22Q green blue red gold yellow violet brown gold not applicable green blue black brown brown yellow violet black black brown not applicable 100kQ 82kQ 4.7kQ 470Q 220Q 150Q brown black yellow gold grey red orange gold yellow violet red gold yellow violet brown gold red red brown gold brown green brown gold brown black black orange brown grey red black red brown yellow violet black brown brown yellow violet black black brown red red black black brown brown green black black brown 2.2kQ 390Q red red red gold orange white brown gold red red black brown brown orange white black black brown TRAFFIC LIGHTS SIMULATOR 0 0 0 0 0 0 6 1 1 6 1 1 POINTS CONTROLLER 0 0 32 1 1 SILICON CHIP SILICON CHIP AUSTRALIA'S BRIGHTEST ELECTRONICS MA(iAZINE ENJOY THE WORLD OF ELECTRONICS & COMPUTERS EACH MONT * Constructional Projects For The Enthusiast * The Serviceman's Log * Vintage Radio: Technology From The Past * Articles On Computers & Radio Remote Control * New Circuit Ideas & Techniques * Amateur Radio Projects & Features Subscribe today by phoning (02) 979 5644 & quoting your credit card number, or fill in the form below & fax it to (02) 979 6503. 0 New subscription - month to start._ _ _ _ _ _ _ __ RATES (please tick one) 2 years (24 issues) Australia 0 Australia with binder(s)* 0 $A105 0 $A240 Overseas airmail $A84 0 Renewal - Sub. No. , _____ 1 year (12 issues) Fax or mail coupon to: 0 $A42 0 $A53 0 $A120 Silicon Chip Publications Freepost 25 PO Box 139 Collaroy Beach 2097 .*1 binder with 1-year subscription; 2 binders with 2-year subscription Your Name_ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Signature (PLEASE PRINn Address_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ Postcode_ __ Card expiry date_ _-"/_ __ Card No. FEBRUARY 1993 37 Ever run out of petrol? This simple project reminds you to fill 'er up by lighting a 12V lamp when_ the fuel drops below a preset level. A low fuel indicator for your car By JOHN CLARKE & GREG SWAIN OST LATE-MODEL cars have a low-fuel warning light but any vehicle that's more than about five years old probably lacks this important feature. This means that you have to remember to check the fuel gauge regularly to avoid runn~ng out of petrol Well that's the general theory but if you drive a "gas-guzzler", it's all too M easy to get caught. Result - an empty tank and you're left stranded. Often, this is only inconvenient but running out of petrol can also be dangerous. That's why late-model cars have a low-fuel warning lamp. It's easy to neglect a gauge but a carefully positioned warning lamp ("idiot" light?) is much more visible and consequently harder to ignore. The Low Fuel Indicator described here is easy to build and can be installed in most vehicles. It lights a 12V warning lamp when the fuel in the petrol tank drops below a preset level. If you've ever run out of petrol or have come close to doing so, this project is well worth building. It could save you quite a few dollars , not to mention embarrassment and inconvenience. Types of sensors Apart from the lamp, there are just three external wiring connections from the Low Fuel Indicator: to +12V via the ignition switch, to vehicle chassis & to the fuel sensor lead. The warning lamp lights when the critical point is reached. 38 SILICON CHIP In most cars, the fuel sensor consists of a float-controlled rheostat which is wired in series with the fuel gauge - see Fig, 1. These two components are then connected to a regulated supply rail derived from the battery. As the fuel level varies, the resistance of the rheostat also varies and this in turn controls the current through the fuel gauge (ie, the fuel gauge acts as a milliammeter). Usually, the higher the float level, the lower the resistance of the rheostat and the higher the current through the fuel gauge. Some circuits work in the reverse sense to this though, so our clrcuit has been designed to accommodate both situations. All you have to do is change the location of a single wire link. B_e warned, however, that this circuit is not suitable for cars that have capacitance-type fuel sensors. In this type of sensor, the fuel acts as a dielectric between two parallel plates PETROL TANK METER SENDER r---------, +V FROM IGNITION '' I ______ ":' L _ ___ JI which form a capacitor. As far as we know, only the Ford Falcon (model XD onwards) uses this type of sensor but you should still check to ensure your car has a rheostat sensor before starting this project. How it works Let's now take a look at the circuit of the Low Fuel Indicator - see Fig.2. It works by monitoring the voltage across the rheostat in the fuel sensor. In greater detail, the voltage from the fuel sensor is first filtered by a 47kQ input resistor and a ZZ0µF electrolytic capacitor which combine to provide a 10-second response time. This 10s delay is built in to prevent false triggering near the preset level due to fuel sloshing about in the tank. IC1a, an LM339 comparator, compares the filtered sensor voltage on its pin 8 input with a reference voltage on pin 9. This reference voltage is derived from a regulated 9.1 V rail via a lOkQ resistor and trimpot VR1. It is fed via another lOkn resistor to pin 9 of IC la, to pin 7 of IC1 b and to pin 4 of IC1c. Note that because the LM339 has PARTS LIST Fig.1: in most cars, the fuel level sensor consists of a float-controlled rheostat. This controls the current through a meter which then indicates the fuel level. 1 PC board, code 05203931, 61 x46mm 1 12V panel mount indicator lamp 1 10kQ horizontal trimpot (VR1) 5 PC stakes 1 3mm machine screw and nut open collector outputs, pin 14 ofIC1a is fitted with an external 10kQ pullup resistor. Thus, depending on the fuel level, pin 14 ofICla will be either high or low. The lMQ feedback resistor provides the stage with a degree of hysteresis, so that it switches cleanly at the transition point and eliminates lamp flicker. ICla drives comparator stages IClb and IClc. One of these stages then drives Darlington transistor Ql, depending on whether link LKl or link LKZ is installed. If the fuel sensor voltage increases with decreasing fuel level, LKl is installed and Ql is controlled by IClb. Conversely, if the sensor voltage falls with decreasing fuel level, LKZ is installed and Ql is controlled by IClc. Let's assume initially that the sensor voltage rises with decreasing fuel level (ie, LKl must be installed). Thus, when the tank is full , the sensor voltage will be low and pin 14 ofICla will be high (ie, at +9.lV). Pin 1 of IClb will thus be low and so Ql and the warning lamp will both be off. As the fuel level falls, the voltage on pin 8 of ICla steadily increases. +V FROM I G N I T I O N D - - - - - - - - - - - - - - - - - - - - - - - ---<11--- - - - . SWITCH ZD1 9.IV 1W 100 + 18VW+ 10k 1M 10k .,. FROM FUEL SENSOR 2.2k FUEL LEVEL SET VRI 10k 47k 220 + 18VW+ 47k CHASSIS~ 12V LAMP SW MAX Semiconductors 1 LM339 quad comparator (IC1) 1 BO679 NPN Darlington transistor (01) 1 9.1 V 1W zener diode (ZD1) Capacitors 1 220µF 16VW PC electrolytic 1 100µF 16VW PG electrolytic Resistors (0.25W 1%) 1 1Mn 2 47kn 310kW 1 2.2kn 1 150!1 1 10Q 5W Miscellaneous Automotive hook-up wire, automotive connectors. When the fuel drops below the preset level, pin 14 ofICla switches low and pin 1 of1C1b is pulled high by a z.zkn pull-up resistor. This high turns on Ql and lights the warning lamp. The lamp then remains lit until the fuel tank is filled above the preset level (or until the ignition is switched off). Now let's consider the circuit action where the sensor voltage falls Fig.2: the circuit uses IC1a to compare the voltage from the fuel sensor with a reference voltage set by VR1. When the fuel in the tank drops below the critical level, pin 14 ofIC1a changes state. This then switches on Q1 & the lamp, either via IC1b & LK1 or via IC1c & LK2. Q1 B0879 .,. .,. PLASTIC SIDE rn E B C LOW FUEL INDICATOR .,. FEBRUARY 1993 39 FROM F SENSO 0 c.n ro CHAS 0 w ....w '° Fig.3: install LKl if the sensor voltage rises as the fuel level drops. Alternatively, install LK2 if the sensor voltage falls with decreasing fuel level. Fig.4: check your PC board for defects against this full size etching pattern before mounting any of the parts. with decreasing fuel level (ie, LKZ 05203931 and measures 61 x 46mm. must be installed). In this case, pin 14 Fig.3 shows the assembly details. of IC la is normally low and thus pin 2 Before starting construction, you first of IClc is also low. have to test the sensor to discover If the fuel level now drops below whether link LKl or link LKZ should the preset level, pin 14 switches high be installed. To do this, locate the and so pin 2 of IClc is pulled high by gauge terminal that connects to the the 2.ZkQ pull-up resistor. This then fuel sensor and short it to chassis via turns on Ql via link LKZ and lights a l0Q 5W resistor with the ignition the lamp as before. on. If the fuel gauge reading goes up, The level at which the circuit trig- . install LKl. Conversely, if the reading gers is set by adjusting VRl. Normally, goes down, install LKZ. this would be set so that the lamp The remaining parts can be installed comes on just before the fuel gauge in any order but make sure that ICl, ZDl and the two electrolytic capacineedle dips into the red danger zone. Power for the circuit is derived from tors are correctly oriented. We used the car's battery via the ignition PC stakes at the five external wiring switch. This +12V (nominal) supply points but these can be considered powers the indicator lamp directly to optional. ensure maximum brightness when Ql Ql should be mounted flat against turns on. the PC board with its plastic side facZDl and its parallel lO0µF filter ing upwards. Bend its leads at rightcapacitor provide the regulated 9.1 V angles so that they pass through the supply rail. This supplies ICl and the holes in the PC board before securing voltage divider for the reference volt- it using a screw and nut. Trim away age, and ensures that the circuit is any excess lead lengths after solderunaffected by fluctuations in the bat- ing. tery voltage. ZDl also protects ICl by clipping any voltage spikes that may Installation Because the PC board is so small, it be generated by the electrical system. can be easily wrapped in foam insulaConstruction tion and hidden under the dashboard. All the parts for the Low Fuel Indi- The warning lamp can be mounted cator (except the lamp) are mounted directly on the dashboard and conon a small PC board. This is coded nected to the PC board via flying leads. Alternatively, the board could be fitted inside a small plastic case, along with the warning lamp, and the entire assembly then mounted on top of the dashboard. The remaining connections are to +12V via the ignition switch, to chassis, and to the fuel sensor lead. If you have trouble identifying the sensor lead, check the colour code in the manual or check the lead at the fuel sensor. Use automotive connectors to interface to the vehicle wiring and solder the other ends of the leads to the PC stakes on the circuit board. Calibration The best way to calibrate the unit is to wait until the fuel gauge reaches the critical level and then adjust VRl so that the device just triggers. This critical level will normally be just above the red zone. If want to calibrate the unit immediately, disconnect the fuel sensor lead at the gauge and connect a lO0Q potentiometer between the gauge and chassis. Adjust this potentiometer until the gauge indicates the desired critical fuel level, then adjust VRl on the PC board until the lamp just comes on. That's it. Now there's no excuse for ever running out of petrol. SC RESISTOR COLOUR CODES 0 0 0 0 0 0 40 No. Value _4-Band Code (1%) 5-Band Code (1%) 1 2 1MQ 47kQ 10kQ 2.2kQ 150Q brown black green brown yellow violet orange brown brown black orange brown red red red brown brown green brown brown brown black black yellow brown yellow violet black red brown brown black black red brown red red black brown brown brown green black black brown 3 1 1 SILICON CHIP PIUJdeect 'if:~ 'Reteaae 1te«,, 1:] ·:•:1trn:,if:i:ti: : : :rs1.ttsua:1: s:m:rre:m:<at>:i:e:11::1$;:11it:::· ]11e:1<:ttm:ei11te:s)t:1ama:: : :1 t 1:1:te::s:s.:a1:1;e :s i: :::1 IPOFFERING • EXTRA SIZES 11 MORE ACCESSORIES LOWER PRICES ■ NATURAL or BLACK ANODISED FRAMES • FOREST GREY or BLACK TEXTURE COVER FINISHES READER INFO NO. 6 THE UNIQUE ZIP-RACK DESIGN SIMPLE, FAST & EFFECTIVE THATS ZIP-RACK Twelve lengths of ZIP-RACK hollow section aluminium extrusion are interconnected using black ABS plastic corner connectors. This requires only a rubber mallet or similar tool. The assembly is self aligning and can be further strengthened by 'pop' riviting the overlapping flanges at each corner. TYPE 46 RACK DATA: RACK WIDTH 540mm. RACK DEPTH 460mm. 1U (RACK UNIT) =44.45mm OR 1 3/4". FOR EQUIPMENT/PANEL CAPACITY DEDUCT 90mm FROM TOTAL RACK HEIGHT COVER SET IDENT NO. GREY J:it.ie.k: ; :1 :•:•:•:•.•.•:•.•:•.•.•:•:•:::::::•:•::,:: F04 F06 F09 P.R!dl!M TOTAL RACK HEIGHT t: i ::; C04 C06 C09 268 357 490 F12 F15 F18 624 757 890 F24 F30 F40 1157 1424 1868 ACCESORIES 6/01 t PRICE$ M6 PACK 12 M6 Clip Nuts~ 2 M6 Ph. Screws 12 Nyl Washers 6/01BK 6/02 6/03 6/03BK 6/04 6/04BK As 6/01 in Black 100 M6 Clip Nuts 100 M6 Screws 100 M6 Screws Black 100 M6 Washers 100 M6 Washers Black CT2 CT3 CT4 Cantilever Tray 2U Cantilever Tray 3U Cantilever Tray 4U ZIP-RACK is made by "The ZIP-RACK Company" Factory 2, 7 Michellan Court, Bayswater Victoria 3153. Australia. Under licence to AUTOTRON AUSTRALIA P/L. The ZIP-RACK Designers Beware of illegitimate copies without the ZIP-RACK name. For product sales, wholesale pricing & product literature Phone: {03) 729 7255 or Fax: {03) 729 6017 COMPUTER BITS BY DARREN VATES File back..ups plus a useful utility program for LHA & PKZIP Making back-ups at the end of the working day need not be the chore it seems. With a little programming, you can get your computer to do most of the hard work for you. For many people, the days of backing up their hard disc on a regular basis are all but over. For example, just imagine what's involved in backing up even 80Mb of hard disc space onto floppy discs. For starters, you'd need around 70 1.2Mb floppy disc plus a couple of zillion years sitting in front of the screen waiting for the prompt that tells you when to install memory as possible and then copy them all over in one hit. But what about files that are too big to fit on a single floppy disc? This is now a common problem, especially if you are working with a CAD program, an accounting or spreadsheet package, or page layout software (particularly if scanned images are involved). Of course, you can back up onto mul- The two best known file compression utilities are PKZIP and LHA. Both are capable of compressing files to a fraction of their original size - often 20% or less, depending on the file. the next disc into the drive. But what about the work files you create on a daily basis? Obviously, these need to be backed up at regular intervals to protect against hard disc crashes and executive wrath! Copy&Xcopy So what does DOS have to offer in this regard? DOS has two commands, COPY and XCOPY, for copying files but XCOPY is the more efficient. If you decide to copy a complete directory to a floppy disc, COPY will copy the files across one at a time whereas XCOPY will load as many files into 42 SILICON CHIP tiple floppy discs using the BACKUP command, but the best answer is often to use some form of file compression. File compression is also handy if you are running out of hard disc space. Little used files can be compressed to a fraction of their original size and the original file deleted. When the file is required again, you simply run it through the reverse part of the compression program. This process is generally called "un-zipping" or "extracting" and it gives you the original file, ready for use. It's worth noting that compression programs are not just limited to data or ASCII files. They can be used on other files as well, including .EXE, .COM and binary files. In fact, many computer programs are now supplied with compressed files. When the program is installed, the files are automatically unzipped. LHA&PKZIP The two best known file compression utilities are PKZIP and LHA. Both are capable of compressing files to a fraction of their original size - often 20% or less, depending on the file. However, PKZIP. requires a separate program, PKUNZIP, to restore compressed files to their original condition. By contrast, LHA uses a software switch in the command line to enable it to do both jobs. That said, there's little to choose between the two programs in terms of user convenience, at least for everyday file compression and extraction. So how do they work? Without going into the details, both programs use a series of mathematical algorithms to perform file compression. In either case, it's best to store the program in a utilities directory on your hard disc. This directory should be inserted in the PATH command in your AUTOEXEC.BAT file. That way, the compression program can be run from any directory or subdirectory on the disc. Neither utility is a terminate-stayresident (TSR) program, so you won't run into problems if you're running Windows with limited memory. To create an archive using LHA, you type the following command: Iha a <compfile> <file.ext> where "compfile" is the name you wish to give to the compressed file and "file.ext" is the file that you wish to compress. The "a" switch tells LHA to add the file to an archive (note: earlier versions of the program require you to type "lharc a ... ). When finished, the compressed file will have a ".lzh" extension; ie, a file called compfile.lzh will be created. Note that this is an extra file; the original file (file.ext) remains unaltered on the disc. Alternatively, LHA can also compress and add a file to an existing archive. And it will work with wildcard characters. For example, the command: Iha a <compfile> <* .exe> will compress and add all files with the extension ".exe" to an archive called "compfile.lzh". Having added files to an archive, you can list them using the "l" switch or extract then using the "e" switch. For example, to list all files in an archive called "compfile.lzh", you type: Iha 1 <compfile> Note that there is no need to add the ".lzh" extension to the file name, as LHA automatically assumes this extension. Similarly, to extract a file called file.exe, you type: Iha e <compfile> diie.exe> To use PKZIP, you type: PKZIP <compfile> <file.ext> As before, "compfile" is the name of the archive and "file.ext" is the file that you wish to compress. Note that PKZIP gives the archive a ".zip " extension; ie, it creates a file called "compfile.zip". Not to be outdone by LHA, PKZIP also accepts wildcard commands. For example, the command PKZIP <compfile> <*. *> will compress and add all files in the directory to compfile.lzh. The corresponding command for LHA is Iha a <compfile> <*. *> Zipping up automatically Although LHA and PKZIP are great for backing up and storing compressed files, they do have their limitations. For example, let's say that you wanted to compress 10 large files and back them up onto a floppy disc. Neither program has any problem in automatically compressing all these files into a single archive but what hap- pens if the archive is greater than 1.2Mb (or 1.44Mb)? There's no way you can copy the archive to floppy discs and back again unless you use the cumbersome BACKUP and RESTORE commands. Unfortunately, neither program can take all 10 files and automatically zip them up into separate archives. Of course, you could sit there and type LHA a <filename> <filename.ext> for each file but after you've typed the first few entries, you quickly get sick of it. What's needed is a utility program that will enable LHA or PKZIP to automatically do this for you. By zipping each file up individually, you can then use the Windows File Manager (or another file manager) to select blocks of compressed files (up to 1.2Mb or 1.44Mb) for copying to a floppy disc. Compress.exe As the saying goes, "many an invention has come about through necessity" and that goes triple for computer programs! To solve this inherent problem with LHA and PKZIP, we've come up with a small utility program using QuickBasic 4.5. This utility program is called "Compress.exe" and it will automatically create a separate compressed copy of each file in a specified directory (using either LHA or PKZIP) and store it in that same directory. Of course, it also leaves the original copy of the file in the directory as well. The program works like this: when you run the program (you just type <compress>), a subroutine asks for the name of the directory that contains the files you wish to have compressed. And that's about it from your side of things. The program takes over from here. If you make a mistake and you wish to get rid of the compressed files, go to the DOS prompt in that directory and just type <erase * .lzh> or <erase * .zip> as appropriate. Things to check When using this program, it's important that the first part of each filename be different to every other one in that directory. If they're not, files with the same prefix are compressed into a single archive. If the files are only small, this may not be a bad thing in some cases but it is something you need to be aware of. No files are lost if this occurs - compression programs are smart enough to extract all files. The best part about both LHA and PKZIP\PKUNZIP is that they are "shareware" and can be downloaded from many bulletin boards. For example, both programs are available on the Dick Smith Electronics bulletin board. This operates as a 24-hour service and you can use a modem with anything up to 14,400 baud. There are two lines for the BBS: (02) 887 1146 and (02) 887 2276. Obtaining Compress.exe In a future issue, we'll take a more detailed look at both LHA and PKZIP and check out what other options they have to offer. In the meantime, to obtain a copy of "Compress.exe", just send us a formatted floppy disc plus $5 to cover the cost of return postage. Don't forget to specify whether you have LHA or PKZIP, so that we can send you the correct version of the program. The program will work on all PC-compatible machines running DOS 4.01 or later. SC VIDEO & T.V. SERVICE PERSONNEL TV & VIDEO FAULT LIBRARIES AVAILABLE AS PRINTED MANUALS $85 +P/H BOTH MANUALS T.V. & VIDEO $145 +P/H • OR AS A PROGRAM FOR IBM COMPATIBLES OR AS AN . APPLICATION PROGRAM FORD-BASE 111 PLUS FOR MORE INFO. CONTACT TECHNICAL APPLICATIONS PO BOX 137 KENMORE 4069 OR FAX/PHONE (07) 3781064 FEBRUARY 1993 43 VERY LARGE LCD DISPLAY MODULE SODIUM VAPOUR LAMPS 111 Brand new large 640 x 200 dot matrix LCD displays, made by EPSON - SEIKO, screen size is 120 x 265mm, has built in drivers. Four bit TTL interface, a total of 14 connections are required for signal arid power (+5V, -12V). Capable of displaying characters, graphs, patterns etc. 28 pages of information included. ON SPECIAL for two months :•:::::,;,~\"1!::»f~S'::;"::!%~;,.'::i~\"<;:~.··· A very small but complete IR tele- scope which only needs an EHT power supply, which is provided in kit form. $279 Item No. 0121 A Includes a "Free" 75mm IR filter. Based on an IC with 20dB of gain, a bandwidth of 2Ghz and a noise figure of 2,8db this amplifier kit out performs many other IC's, and is a fraction of their cost. The complete kit of parts for the masthead amplifier PCB and components, and the power and signal combiner PCB and components, is priced at an incredible: $tS (Item No. 0166) Note th;;.1 an LSI surface mount controller IC for this display is available. This IC has a built in character set generator and many other features. It is compatible with 8080 and 6800 MPU's. The IC is available elsewhere for about $35, and we will supply more information upon request. NEW 12 CHANNEL UHF REMOTE CONTROL Brand new 6 volt 1 watt amorphous solar panels. Two of these in series make a great 12V battery maintainer/ charger. Incredible pricing. $10eafor 10 for $85. Fore more information see a novel , extremely popular, and an effective active antenna design which employs this amplifier: MIRACLE TV ANTENNA - E.A. May _1992. LASER GUN SIGHT Item No. 0130 MARINE SEARCHLIGHTS A SmW gunsight at an unbeatable price. $279 Coming soon is our new 12 channel UHF remote control channel that is easily expandable to 16 channels. The system features a SAW resonator locked transmitter, prealigned and assembled receiver "front end" which solders onto the main receiver PCB, and a very compact 2 channel relay driver PCB which can be used in multiples: Up to eight units. As a price indicator, we will be offering a package deal consisting of 2 transmitter kits, plus one receiver kit, plus three relay driver kit$, for a total cost of $200 12V OPERATED LASER BARGAIN . .. .. ,,,, ..,.. ,. Item No. 0108 Includes one "Free" rifle or pistol mount. STEPPER MOTORS $25 ,...-• · - ·· · ,. ' impressive unique, product with many applications. Two used 3mW Siemens HeApproximate weight of pillar Ne visible red laser tubes, and Spotlight is 60KG. and one of our efficient 12V universal laser supply kits. (Ref:XXFEB93101) $129 The $6 P+P charge doesn't apply to this one!! "Ring" Item No. 00105X $1100 Brand new units. Diameter ,S8mm, height 25mm, 5V operation , simple to drive (Two phase - 6 wires), 7.5 egree steps , coil resistance 6.6 ohm: $12 Item No. 0140. Driver IC 9UCN5804B) plus circuit $9. DISTANCE MEASURING WHEEL This brand new instrument consists of a large wheel attached to a handle bar, with two separate mechanical counters. Used for measuring distances: 50mm resolution, 10KM counter. Quality U.K. made instrument at about 1/3 of it's real value. Two only at: $270Ea. (RtifXXFEB93102) Ea. (Ref: XXFEB93103) SOLAR LIGHTNING BARGAIN long ... $5.50 M4 - 3-15V, I No load= 20mA at 12V, main body 31 mm Diam - 22mm long ... $3 M5-3-15V, I No load= 60mA 5700 RPM at 12V, main body 28mm Diam - 40mm (E.A. NOV. 92) This kit has three separate sections that long ... $2.50 are contained on one PCB, M9-12V, I No load= 0.52Abut can be separated: 15,800 RPM at 12V, main (1) A crystal locked ultrasonic ·body 36mm Diam - 67mm movement detector, (2) A long ... $8.50 fluorescent tube inverter M 14 - Made for slot cars, 4(4-20W) with logic circuitry, 8V, I No load= 0.84A at 6V, (3) A solar battery charging at max efficiency I = 5. 7 A regulator, and an incalescent 7500 RPM, main body 30mm lamp switcher - pulser, which Diam - 57mm long... $9.50 employs a mosfet switch, as a Further to the above special package special we are prices, during Feb.:March w.: offering the complete kit for are offering an introductory the three sections plus six package which includes ONE 6V/1 W solar panels for a tot~I OF EACH OF THE ABOVE cost of: MOTORS, and one of the STEPPER MOTORS advertised elsewhere in ttlis (REF: XXFEB93104) ad. (Item No. 0140) . ONLY $99! ULTRASONIC BURGLAR ALARM KIT See S.C. May 88 for this high quality crystal locked ultrasonic design. Can be used as a detector or a self standing alarm, has provision for bonnet/boot protection and flashing light and back up battery. Easily combined with our U.H.F. Remote Control. CLEARANCE PRICED AT ONLY: These new 0.5 metre diameter military grade search li!Jhts were made by LUCAS in the U.K. They are painted grey and are almost totally made of brass, except for a few stainless steel screws and nuts, a mirrored glass parabolic reflector, and a glass cover plate, They have a detachable mounting pillar which brings the total height of the searchlight and the stand to approximately 2 meters. Fully adjustable positioning and focussing. Supplied with a 1000W/240V Mt:i.~;€\?$?::ffZ?!t€tsfr:1 ~~~o~zo ~~~~~~- l~~~~T1 1). $109 Brand new 140W low pressure sodium vapour low pressure lamps. Overall lenght 520mm, 65mm diam., G.E.C. type SO1 /H. We supply data for a very similar lamp (135W). LIMITED QUANTITY. D.C. MOTORS We have good stocks of 5 different high quality JAPANESE DC Motors. These should suit many industrial, hobby, robotics and other applications. Check out the SPECIAL prices, and compare! M1 - 24V, I No load= 50mA 22,000 RPM at 24V, main body 28mm Diam - 40mm $29.90 (Cat. No. GK125) For the P.C.B. and all parts, except the screw terminals. A pair of ultrasonic transducers is included!! DON'T MISS OUT! SIX DIFFERENT MOTORS FOR A TOTAL COST OF $30. Main body has a diameter of 117mm and is 107mm long. The whole assembly can be easily unscrewed to obtain three very large lenses: two plastic and one glass. The basis of the cheapest large magnifier or projection system? Experimenters delight at ONLY $28 MYSTERY LASER Includes 1 12VMK3 universal power supply kit, plus a used laser tube with a power rating in the 1-3mW range. A laser tube and a power supply for a little more than the price of the inverter only: $89 (Item No. 0110) VISIBLE LASER DIODE KIT Brand new 5mW-670nM laser diode, plus a collimating lens, plus driver kit, plus, hardware, plus instructions. $89 Item No. 0164 Used air cooled ARGON laser heads, that produce a BLUE beam! Power output is in the 30-100mW range. Limited stock, at a fraction of their $600-800 ... real value: For the Argon head only. We also provide a circuit for a simple power supply. Item No. 0109 TUNING FORK FILTER PCB's t 1'/~ 1 INDUCTIVE ~~~Jc / Each one of these identical PCB filter assemblies contains six three terminal tuning fork filters (IN-GNDOUT), at different frequencies in the audio range: 1.8-3.1 Khz. These high quality dual fork filters have very narrow bandwidths, and could be used as the basis of a selective call system, high stability oscillators etc. LED DISPLAYS IR FILTER LCD DISPLAYS 1 1 ... ~- J _J___ These industrial quality detectors will detect ferrous and non-ferrous metals at close proximity. Some are " DC powered (10-30VO, some are AC powered (Mains) , am;t all will switch loads directly. All have a three wire for connecting into circuitry: Two for the supply, and one for switching the load. LIMITED QUANTITIES at a small fraction of their real price: $28 EHT GENERATOR KIT ' \\ These are new 16 character by 2 hne alphanumeric LCD display modules , with surface mount control circu itry mounted on the rear of the display. Require a few milliamperes at 5V to operate, information included: $18 5 $80 ea . or for (Item No. 0131) OFFER. CRAZY BATTERY Brand new industrial grade PANASONIC 12V/6.5AH sealed gel batteries at a •educed price. Yes 6.5 AMPERE HOURS! Use them in lighting, ala[ms , communications, laser power supplies, solar systems etc. Dimensions: 100 x 94 x 65mm. Weight of one battery is 2.2KG! The SPECIAL PRICE? ea. (Ref.XXFEB93101) Furthermore, here is the CRAZY OFFER. Buy three of these batteries at the above price, and we .will deliver them to any mail addresses in Australia at no additional costs!! YES $114 TOTAL COST, TO HAVE THREE OF THESE BATTERIES DELIVERED TO YOUR DOOR!! We also have available a suitable overnight charger for these batteries (500mA) ... $25ea. No additional delivery charge applies if the charger/s is/are bought with the above three battery offer. ,. Small PCB Assembly based on a ULN2232IC. This device has a built in light detector, filters , timer, narrow angle lens, and even a siren driver circu it that can drive an external speaker. Will detect humans crossing a narrow corridor at distances up to 3 metres. Much higher ranges are possible if the detector is · illuminated by a remote visible or IR light source. Can be used at very low light levels , and even in total darkness. With IR LED. Full information provided . The IC only, is worth $16! OUR PRICE FOR THE AS~~BLYIS: :ji(j EA, OR 5 FOR $25 Item No. 0163 IIR LASERS A high quality military grade deep infra red (IR) filter. Used to filter the IR spectrum from medium and high power incandescent spotlights and flood lights. It's glass base makes it capable of withstanding high temperatures. Approx. 130m diameter and 6mm thick. Can be used in conjunction infra red night viewers and IR responsive CCD cameras: Many colour video cameras and most monochrome video cameras have good IR response: Check by viewing the LED's in an TV or VCR infra red remote control. Excellent for night surveillance equipment! At a FRACTION OF THEIR REAL PRICE . ON SPECIAL AT ONLY: $38 NATIONAL SEMICONDUCTOR seven segment, Common cathode, 12 digit, multiplexed , LED display with 12 decimal points. Overall size is 60 x 18mm and a pinout diagram is provided. ONLY $2.50 ea.or 5 for $10 . ELECTRON IC KEY KIT .' Based on a brand new, very compact modern EHT flyback transformer which includes an EHT diode rectifier. We supply the transformer, a very simple circuit, and the components to suit. All you need to make a very simple EHT, DC or pulsed AC supply. Powered from 12V DC supply. Great for EHT experiments, EHT testing , plasma displays, etc. Total price for the transformer and the components is ONLY: $20 Use them to activate door ' strikers for entering buildings , car alarms , central locking , the most secure key ever (See E.A. July 92) : ON Item No. 0161 PASSIVE NIGHT VIEWER $49.90 SPECIAL<at> For two keys, and one decoder kit. Cat. No. GK138. VULTURE CAR ALARM E.A. Nov 89. Best value car alarm kit!! Fully adjustable voltage drop and vibration sensor on board, instant and delay inputs, flashing light output, alarm memory, battery back up provision , provision for U.H.F. remote control , etc. INCREDIBLE VALUE at a CLEARANCE PRICE OF ONLY: $29.90 For the cqmplete P.C.B. and components kit: Whilst stocks last. .. (Cat No. GK124) ELECTRIC FENCE KIT Coming soon is our easy to construct electric fence kit. It features very low power consumption, a solar charging/regulating and . indicating circuit, and it can be easily solar powered. The PCB (Screened and solder masked) and all components kit will cost under $50 The first generation (XX1080) passive IR night viewer tube features excellent gain, and when used with a very low light objective lens, it can produce useful images under almost as little as submoonlight illumination. Cal also be IR assisted. We will supply a XX1080 tube, plus a suitable Lens, plus a kit of parts for an EHT power supply (PCB and components only) for a total price of $299 $45 LASER POINTER Th is precision collimator assembly was removed from working laser printers and it is supplied with an extra brand new laser diode-!o suit. A produces a well collimated laser beam at 780nM/5mW. Barely visible. We also supply a PCB and components kit plus instructions , for a suitable digital driver circuit that can be used to complete the laser transmitter. Suitable for communications , data links, perimeter protection , barcode reading, medical , use, etc. $89 (Item No. 0111) We can also supply a similar kit which inciudes a laser diode , unmounted lens, and a driver kit. $45 (Item No. 0111 X) Note that a suitable receiver for use in perimeter protection is the one published in E.A. April 81 . High quality pen sized 5mW laser diode pointer for teachers, doctors, etc . On $199 Special Item No. 0101 DIVERGING LENS SPECIAL ~~ L:., A high quality laser beam diverging (beam expander) glass lens, mounted on an alum inium plate, with mounting screws provided. Dimensions : 25 x 25 x 6mm. Use it to expand the laser beam for Holography. Special Effects , or one of the two lenses required to fine focus a la~er beam , for Surveying and Bar Code Reading . SPECIAL $5.00 ea. MAL-4: Microcontroller Aid for Learning; Pt.3 All the parts for the MAL-4 microcontroller are mounted on a double-sided PC board, so the assembly is straightforward. All you have to do is follow the step-by-step instructions. By BARRY ROZEMA Numerous hours were spent designing, prototyping and programming the MAL-4 microcontroller kit but all this time will have been in vain if you do not take considerable care in the construction. At the very least, read the following instructions thoroughly before starting assembly. If you are an experienced construc46 SILICON CHIP tor, then the steps may be used as a guide on~y. However, if you don't have much experience, then the following steps should be adhered to rigidly. Step 1: check the supplied components against the parts list. Contact the kit supplier immediately if there are any missing components. Step 2: check the copper tracks on the PC board by holding it in front of a strong light. You should spend at least half an hour inspecting the board for breaks, tracks shorted together and holes not drilled. It is easier to spot faults on a bare board than it is on a fully assembled board. Step 3: solder the IC sockets into place. Each IC position has pin 1 marked on the PC board and care should be taken to orient each IC socket accordingly. Note: some readers may wish to use the more expensive ZIF (Zero Insertion Force) sockets for Ul & UZ. Step 4: solder all resistors into place, as indicated on the board and on the wiring diagram (Fig.2). Bend the leads E.S.D. Jf<SRDZEMAYI.'i'll Fig.3: parts layout for the MAL-4 microcontroller. Note that only the bottom layer of the board is shown, which is why some tracks appear to end in mid-air. Follow the instructions in the text when installing the parts on the board. at right angles with long-nosed pliers and fit each resistor with its tolerance band towards the righthand or bottom edge of the board (this will make checking easier later on). Trim the excess wire from the soldered joints on the back of the board. Step 5: solder the capacitors into place, making sure that all tantalum and electrolytic capacitors are correctly oriented (the positive lead is marked by a plus sign on the PC board). Trim the excess wire from the soldered joints on the back of the board. Step 6: install the light emitting diodes (LEDl-18). Most LEDs have a flat spot on their base to mark the cathode (K) lead and this should go to the negative sign, as marked on the PC board. If the cathode is not marked, the cathode lead is the shorter of the two. Note that LED 2 should be a high intensity type. Step 7: install diodes D1-D5 & the bridge rectifier BR1. The cathode terminal is marked by the bar in the diode outline on the PC board. Check that the bridge rectifier is correctly oriented; ie, that its plus and minus pins go to corresponding pads on the PC board. Step 8: install transistors Q1-Q3. Ql and QZ have their base terminal towards the righthand side of the board, while Q3's base terminal is towards the bottom of the board. Step 9: install potentiometers VR1 and VRZ. The PC board has been designed to accept potentiometers with different "footprints". When installing each potentiometer, connect its wiper terminal to one of the two lower holes in the footprint on the board. Step 10: fit the four fuse clips. Note that some brands of fuse clips must be oriented correctly to allow the fuse to fit between them. Fit the two 1A fuses. Step 11: install the 2MHz crystal. Note that this crystal should lie flat on the PC board, as shown in Fig.3. Step 12: install SIP resistors RP1RP3. Pin 1 is marked on each resistor pack and this must be aligned with the pin 1 marking on the PC board. Step 13: install plugs PL1 and PLZ. These should both be mounted with their long pins pointing up. Step 14: install linking terminals LNK1-LNK3 with their long pins facing up and fit the shorting straps. In each case, the shorting strap should be fitted to the upper position (position 1). Step 15: solder the display socket to the PC board. The type of display that has been supplied will govern the type of socket and its position. Display 1 has a 14-pin DIP plug & socket, while Display 2 has a 14-pin SIP plug & socket. After fitting the socket, fit the plug to the underside of the display (the pins are soldered on the top of the display board). Don't plug the display in yet. Step 16: install 5V regulator U9 and its heatsink. To do this, first align the heatsink and regulator assembly with the board by bending the pins of the regulator through 90°. Once the correct location has been found, apply a light film of heatsinking paste to the back of the regulator, then bolt the assembly to the PC board using three 3mm screws, nuts and washers (nuts on the top of the heats ink). Solder the regulator leads and trim away the excess lead lengths. Step 17: install the rightangle PCmount DIN socket (IBM type), then FEBRUARY 1993 47 Table 1: Input/Output Program Address Data · 0030 B6 00 0032 B7 01 0034 BC 30 Table 2: Tone Generator Address Data 0040 B6 00 0042 CD 14 A1 0045 1F 02 0047 B600 0049 CD 14 A1 004C 1E 02 004E BC40 install the 8-way screw connector. Make sure that the wire entry side of the screw connector faces the lefthand edge of the board. Step 18: install the three PC-mount toggle switches (Sl, S2 & S3). Note: if you do not wish to use the switches, Sl must be replaced with a wire link. This link should go betweeri the two lower pads of the Sl terminals. Step 19: install the PC-mount pushbutton switches (KEY5 & KEY6). Careful inspection of the switch pinouts and the PC board is necessary to obtain the correct orientation. Try to fit the switches so that the "RESET" and "IRQ" prinL markings on Lhe board are visible (see the notes supplied with the kit). Step 20: install the keypad. The MAL-4 can accommodate several types of keypads: (1). Keypad 1: 16-key (4 x 4) x-y,, 9pin. (2). Keypad 2: 24-key (3 x 8) x-y, 11pin. (3) . Other: up to 32 keys, hard wired. If you purchased a complete kit, refer to the notes supplied with the kit. If you want to use a socket with the keypad, this should now be fitted to the PC board. The keypad is then fitted by plugging it into the socket or by soldering it directly to the board. If you use Keypad 2, then skip the next step. Step 21: install PC-mount pushbutton switches KEY2, KEY3 & KEY4. As before, careful inspection of the switch 48 SILICON CHIP pin outs and the PC board is necessary to ensure the correct orientation. Try to fit the switches so that the titles on the overlay are visible. Step 22: install the two 8-way DIP switches by plugging them into their sockets. These switches should be oriented so that the "ON" position is towards the bottom of the PC board. This will set the switches so that "up" is high and "down" is low. Step 23: apply 9V AC to the power connector terminals labelled" AC", or 12V DC between the terminal marked +12 and GND (your supply should have a current capability of at least 500mA). Operate switch Sl and check that the power LED (LED 1) lights. Now measure the voltage on the +5 terminal of the screw connector block - it should be between 4.75V and 5.25V. If all is well, disconnect the AC and continue. If not, remedy the fault(s) before moving on to the next step. Step 24: install ICs U3-U8 by plugging them into their sockets. Make sure that each one is correctly oriented (double check this) before applying power. Step 25: apply 9V AC to the power connector terminals, switch on and re-check the +5 terminal on the power connector strip (4.75-5.25V). Check the temperature of the ICs by feeling them with your finger - all should be cool. If all is well, disconnect the AC and continue. If not, remedy the fault(s) before proceeding. Step 26: install the display & the pre-programmed MCU (U2) by plugging them into their sockets. Step 27: re-apply power, check the temperature of the MCU (U2), and check for signs of distress. Re-check the +5V terminal on the power connector. If this voltage is low, switch off immediately and remedy the fault. If all is well, there should be a message on the LCD (note: contrast pot VR1 may need to be adjusted). This message will read "* * * WARNING! *** RAM POWER FAIL" if you have no battery back-up supply, or "M.A.L. Vers 4.XX Enter Mode ... " if you do. If the display reads "* * * WARNING! * * * RAM POWER FAIL" then press the reset key and the display will read "M.A.L. Vers 4.XX Enter Mode ... " The construction of the MAL-4 board is now complete. The next step is check that the various functions built into the unit are working cor- rectly. Assuming that you get the messages described in step 2 7 on the display, you should now perform each of the tests described below. Keypad test (mode 7) Step 1: to enter this mode, press the "7" key at the "M.A.L. Vers 4.XX" prompt. The display should now show "KVAL - KYBIN -" on the first line and "MAL Keyboard TST" on the second line. Step 2: press any keypad key. The display should show the KEYVALUE (the order in which the keys are scanned) and the KEYBINARY (ie; the assigned binary value for a given key). Step 3: press the RESET or IRQ switch key to leave mode "7". This will display the "M.A.L. Vers 4.XX" prompt again. Display test (mode 8) Step 1: press the "8" key at the "M.A.L. Vers 4.XX" prompt. The display should rotate all its characters to the right from a flashing cursor. Step 2: press the RESET or IRQ key to leave mode "8" and display the "M.A.L. Vers 4.XX" prompt again. Keyboard.test (mode D) Step 1: set the DIP switches on PORT D (DIP SW2) as shown below: DIP SW2 7 X E 5 4 3 2 1 0 on on off off off off off Step 2: plug an IBM XT compatible keyboard into the DIN socket on the lefthand side of the board. Step 3: press the "D" key from "M.A.L. Vers 4.XX" prompt. The display should now show "Keyboard Data" on the first line, while the second line will be blank. Step 4: press any key on the IBM XT keyboard. The display should show the data that is sent from the keyboard in hexadecimal format, while the Port B LEDs will display the da,ta in binary. Step 5: press the RESET or IRQ key to leave mode "D" and display the "M.A.L. Vers 4.XX" prompt again. Simple test programs Tables 1, 2 & 3 list some simple test programs for the MAL-4. Enter them using MODE-0 and run them using MODE-1. Table 3: Yes/No Decision Maker Address Data 0060 CD 12 05 0063 AE 10 0065 CD 11 CC 0068 AE 11 006A CD 11 FE 006D CD 13 2E 0070 4C 0071 3D D3 0073 27 F8 0075 A4 01 0077 26 07 0079 AE12 0078 CD 11 FE 007E 20 05 0080 AE13 - 0082 PCB and SCHEMATIC CAD r------·~----------- ·-·?t~ : / TV IF AMPLIFIE - / "I rl-f-t----H.lm,. 1!, ,._ . • ~ C-Uiiiflt• . ·-: j•4 : ..... ~ : CD 11 FE II mllll 1111111•111111111111111 11>1 1111111111 • 1.... '·""''"'lf•Nn,w 0085 A604 0087 CD 14 F3 008A 20D7 0100 54 68 65 20 41 6E 73 77 65 72 20 69 73 20 2D 3E 0110 50 72 65 73 73 20 61 20 48 65 79 20 4E 4F 57 21 • Design Single sided, Double sided and Multilayer boards 0120 2D 2D 2A 2A 20 20 59 45 53 21 20 20 2A 2A 2D 2D • Provides Surface Mount support 0130 2D2D28282020204E4F20202028282D2D • Standard output includes Dot Matrix/Laser/Inkjet printers, Pen Plotters, Photo-plotters and NC Drill Table 1 shows an input/output program. It simply takes the data on the input port (Port A) DIP SW1 and displays it on the output port (Port B) LEDs. Table 2 lists a tone generator program, which generates a variable tone from the external loudspeaker. This tone ranges in frequency from 20Hz to 5kHz and is set by the Port A DIP switch (SW1). Finally, Table 3 shows a program that generates a random YES/NO decision when you press any key on the keyboard. Monitor operation The monitor program, which is in the MC68HC705C8 EPROM, allows the user to access RAM, ROM and all the various registers within the single chip microcontroller. A detailed description of the operation of this monitor program follows. When power is applied or the RE- EASY-PC • Runs on PC/XT/AT/286/386 with Hercules, CGA, EGA or VGA. SET button is pressed, the display will show the prompt; ie, "M.A.L. Vers 4.XX. Enter Mode ... " This means that you may enter a mode of operation by pressing any of the keys indicated in Table 4. A detailed description of each mode follows: Mode "O" - Load, Examine or Modify Memory. Step 1: to enter this mode (Mode 0), press the "O" key when the "M.A.L. Vers 4.XX" prompt is displayed. The display will show "Ad.XXXX". The "Ad." is the ADDRESS prompt and indicates that the next four digits contain an address location. Step 2: enter desired address. If the microcontroller has just been reset, then the "XXXX" may contain anything. Conversely, if the microcontroller has not just been reset, the "XXXX" will contain the last address entered. The address displayed after the • Award winning EASY-PC is in use in over 12,000 installations in 70 Countries World-Wide • Superbly Easy to use • Not Copy Protected Options: • 1000 piece Schematic symbol library • Surface Mount symbol library • Gerber Import facility For full info 'phone, fax or write: BTC PO BOX432 GARBUTT 4814 QLD. PH (077) 21 5299 FAX (077) 21 5930 FEBRUARY 1993 49 Table 4: Monitor Operating Modes Key Mode Of Operation 0 Load, examine or modify memory 1 Run a program from a given location 2 Disassemble program ·froln a given location 3 No function 4 No function 5 No function 6 Keyboard beep on/off 7 MAL keyboard test 8 Test MAL display 9 No function A Print all RAM contents B No function C No function D Test IBM keyboard raw data E Test IBM keyboard characters F Shut down CPU & save RAM ENTER No function INC No function DEC No function "Ad." prompt will be the address that is to have data loaded, examined or modified. While the display shows "AdJOCXX", a 4-digit address may be entered via the keypad. The increment and decrement keys may be used to increment or decrement the 4-digit address by one. Step 3: press the ENTER key when the correct address is displayed. The display will now show "Ad.XXXX Data YY". The last two digits ("YY") contain the data that is in the address location displayed. Step 4: load, examine or modify the data using the keypad. Step 5: increment or decrement to the next address location (use the increment and decrement keys). Step 6: repeat steps 4 & 5 until you are finished. Step 7: press the ENTER key to leave mode "0". The display will show the "M.A.L. Vers 4.XX" prompt again. Note: when the data is displayed, the address location is constantly being interrogated and displayed at a rate of once every few milliseconds. Thus, if the data does not respond to key entries, then the address indicated is "read only". This also means that if the data changes, then the display will show the change almost instantly. This may be useful in monitoring an input port. MODE 1: Run a program from a given location. Step 1: to enter this mode, press the Where to buy the kit Parts for the MAL-4 Microcontroller Aid For Learning are available from E.S.D., PO Box 73, Glenbrook, NSW 2773. Phone (047) 39 4039. Prices are as follows: standard kit (incl. manual but does not incl. speaker or plugpack) - $249.00; standard kit with ZIF sockets plus toggle switches -$306; PC board only- $80; programmed MCU & manual - $48. Please add $10 for postage inside NSW, $15 for postage interstate. Payment should be made by cheque or money order. Note: copyright© of the PC board is retained by Electronic System Designs. 50 SILICON CHIP "1" key when the "M.A.L. Vers 4.XX" prompt is displayed. The display will show "Ad.XXXX Run". The "Ad." is the address prompt and indicates that the next four digits contain an address location. The "Run" prompt indicates that you are in the run mode. Step 2: enter the desired address. If the microcontroller has just been reset, then the "XXXX" may contain anything. If the microcontroller has not just been reset, then the "XXXX" will contain the last address entered. The address displayed after the "Ad." prompt is the address that the program will run from. While the display shows "Ad.XXXX", a 4-digit address may be entered via the keypad. The increment and decrement keys may be used to increment or decrement the 4-digit address by one. Step 3: when the correct address is displayed, press the ENTER key. The microcontroller will jump to the address that was in the display and run from there. The display will have "Ad.XXXX Run" on the first line and "Program Running" on the second line. Mode 2: Disassemble a program from a given location. Step 1: press the "2" key when the "M.A.L. Vers 4.XX" prompt is displayed . The display will show "Ad.XXXX" on the first line and "Disassemble from" on the second line. The "Ad." prompt indicates that the next four digits contain an address location. Step 2: enter the desired address via the keypad, or use the increment and decrement keys to increment or decrement the 4-digit address by one. The address displayed after the "Ad." prompt will be the address of the first instruction that is to be disassembled. Step 3: when the correct address is displayed, press the ENTER key. The display will show the address and a 1, 2 or 3 byte op-code on the first line and the mnemonic and operand on the second line. Step 4: increment to the next address. Step 5: repeat step 4 until you are finished. Step 6: press the enter key to leave mode "2 ". The display will show the "M.A.L. Vers 4.XX" prompt again. MODE F: Shut down CPU &save RAM. Step 1: press the "F" key from "M.A.L. Vers 4.XX" prompt. The dis- Table 5: MAL-4 Subroutines KALEX Reg.Use u. ACC& IX N Make port A an input None y Make port A an output None y IX y IX y LIGHT BOXES CLR LCD. Home cursor. RST AD. None y • Portuvee 4 • Portuvee 6 • Dual Level Home cursor line 1 RST AD.$00 None y TRIMMER e ldeal Description Name Address SETUP $1180 lnit. 1/0. lnit LCD. Set P.V. AINPUT $11BA AOUTPUT $11C3 LDISBUF1 $11CC LDISBUF2 $11FE CLRDISP $1205 HOME1 $120E Load 1st line of LCD with message pointed to by IX Load 2nd line of LCD with message pointed to by IX The UV People ETCH TANKS • Bubble Etch • Circulating HOME2 $1217 Home cursor line 2 RST AD.$40 None y WCTRL $1220 Write ACC to LCD control Reg. Ace y PCB DRILL WDATA $1240 Write ACC to LCD data Reg Ace y • Toyo HiSpeed RCTRL $1261 Read LCD control reg . to ACC Ace y MATERIALS RDATA $1275 Read LCD data reg. to ACC Ace y WAIT1 $1289 Fixed sous delay None y • PC Board: Riston, Dynachem e 3M Label/Panel Stock • Dynamark: Metal , Plastic DELAY1 $1295 100us times the ACC delay Ace y DELAYS $12A3 5ms times the ACC delay Ace y SCANKEY $112E Scans keypad, sets KEYV AL, KEYBIN & KEYASCII None y GETROW $1323 Used by SCANKEY subroutine Ace N CONVTOA $1317 Used by SCANKEY subroutine Ace N * AUSTRALIA'S N0.1 STOCKIST * I VISA I 40 Wallis Ave, East Ivanhoe 3079. Phone (03) 497 3422, Fax (03) 499 2381 LSNCON $13C6 LSN HEX to ASCII via ACC ACC y MSNCON $13D1 MSN HEX to ASCII via ACC ACC y Old Reprinted Electrical Books Beeps speaker 1kHz for 0.25s None y None ? IX y None y All N Ace y Build a 40,000 Volt Induction Coil ............ $9 Short Wave Radio Manual (1930) ........ $23 High Power Wireless Equipment (1911) $16 High Frequency Apparatus (1916) ........ $19 Build Short Wave Receivers (1932) ...... $13 Vision By Radio (1925) ......................... $16 1936 Radio Data Book .......................... $12 How to Become a Radio Amateur (1930) $6 All About Aerials ....................................... $5 Television (1938) ...................................... $5 Shortwave Coil Data Book (1937) ........... $5 . 1928 Radio Trouble-Shooting ............... $24 101 Short Wave Hook-Ups (1935) ........ $14 Vacuum Tubes in Wireless's ................. $21 Construction of Induction Coil ............... $21 Tesla: Man Out of Time (biography) ...... $22 Tesla Said, articles by Tesla 292pp ....... $74 My Inventions, by Nikola Tesla 111pp ... $27 Dr. Nikola Tesla - Complete Patents ..... $93 Tesla Coil Secrets ................................. $13 How to Build a Solar Cell That Works ...... $9 191 4 Catalog Electro Importing Co ....... $14 Electric Arc Furnaces ............................... $6 Experimental Television ........................ $25 BEEP $13DE DISPADD $13F9 Displays address in LCD DISPACC1 $1423 Displays ACC in LCD point.IX 0ISPACC $1420 Displays ACC in LCD fixed SETADD $1447 D10US $1498 D100US $14A1 Delay= ACC times 100us Ace y D1MS $1480 Delay = ACC times 1ms Ace y D10MS $1409 Delay = ACC times 1Oms Ace y 0100MS $14E6 Delay = ACC times 100ms Ace y D1SEC $14F3 Delay = ACC times 1s Ace y 01MIN $1500 Delay = ACC times 1 minute Ace y Displays address in LCD from keyboard Delay = ACC times 10us NB: ACC must be > $02 play will show "uP. in stop mode" on the first line and "SWITCH OFF NOW" on the second line. Step 2: switch off the power to the MAL-4 board. Step 3: check the battery warning LED (LED 2). This is used as an ammeter and indicates the relative power consumption of the MCU. When the MCU is in the stop mode, the LED will not light. If the LED is illuminated, repeat steps 1-3. Subroutines Finally, the MAL-4 has a number of subroutines that the programmer may find useful. Table 5 lists mos~ of these subroutines and their addresses. SC Allow 15 weeks for delivery of some items. Payment can be made by cheque made out to Plough Book Sales, PO Box 14, Belmont, Vic. 3216. Phone {052) 66 1262. F EB R UARY 1993 51 e ALTR.C>~IC: COMPONENTS e ~ jl.--1,, L..JAj-/l l.--&.J&.J AUSTRALIA WIDE . ,~,f-HMLTi■OIII ;· ~ IT ~-:!i11ur·~~ f, W.v~ 1993 /fi'I ~ ELECTRONIC COMPONENTS CATALOGUE YOURS FREE with this month's Silicon Chip and Electronics Australia Magazines OR Send $1.00 to cover P & P to: ALTRO NI CS MAIL ORDER, PO BOX 8350, Stirling Street, Perth WA 6849 Our 1993 Catalogue has even more fantastic new products and greater value than last year's. We still offer the technical help that only a staff of electronic enthusiasts like yourself is able to give. Of course, in addition to this we have our FAMOUS OVERNIGHT DELIVERY Australia wide and Bankcard phone order service to 4pm (E.S.T.) Monday to Friday. All on our quality products at DIRECT IMPORT PRICES that enables YOU TO SAVE UP TO 50% off competitors' prices. Jack O'Donnell Managing Director Rectangular Piezo Tweeter removing small surface scratches and general dirt and grime. A 9220 NORMALLY $1 7- 95 $7·95 Th is Month Only Outside diam eter size of 144mm x 67mm. Rated to IS Watts. Clearout C 6120 NORMALLY $19 This Month Only 50 00 $10· Laboratory Power Supply Super Small PIR (EA May '85)3-50 Volts at up to 5 Amps This supply has been one of our most popular. It inclu d es the latest refinements and is now housed in a tough 'ABS' inStnlment case. This compact version uses a high efficiency toroidal transformer resulting in less heat and weight. Features: • Exclusive to Altronics • Deluxe instrument case • Attractive silk screened fro nt panel • Pre-drilled and punched chassis - No holes to d rill • Front panel drilled for K 3302 option Specifications: • O utput Voltage: 3 to SOV • Max O utput Current: 5 This neat infra-red movement detector fea tures triple pu lse count and will easily connect to most alarm systerns. Ideally suited to the S 5490 alarm opposite. $ S 5302 · S 5315 NORMA LLY $19 This Month Only $ 95 7 Oxygen Free Cable We have a limited supp ly of OFC cables in two varieties. Both 2 RCA to 2 RCA with earth leads. P 0446 900mm in length, Normally This Month Only $16-00 $10 P 0448 1.8m in length Normally $19·50 This Month Only $14 3 Sector Home Alarm wea th er-proof this horn is ideal M 9090 Power Supply & Backu p Battery to Suit $69·•s Sn Ho .. canM Til.oNics('" 1 4~~••~ri~I to ~'!.'t1 With this simple device you can monitor any door in your house. This two piece alarm consists of a Control box and a magnet. The magnet simply onto the door frame w hile the control box is mounted on the door, so that they are opposite when the door is closed. Easy to use on / off switch. Built-in beeping buzzer sounds w hen tripped. Requires 9V battery. This ·alarm control panel features stylish and compact good looks It can be either surface or fl ush mounted to blend smoothly into any decor. Features: • 4 digit PIN code to arm a nd disarm panel • 3 Independent Protection Circuits 24 hour fire/ panic, external and internal (isolatable) • All Sectors are Compatible with NO and NC Switches • All Sectors are Sealed with End-OfLine Resistors • Adjustable Timers for Entry Delay and Siren Duration • Fits Into standard 3 gang wall plate • Plug in wiring harness supplied 00 00 S 5490 Normally $119· , This Month Only · 62 1----------- --t Amps Max • Floating Output • Ripp le: Less than Sm V • Dual Meters Door Alarms Economical and $89 K33oo$195· ______ _J~~~=====--_j..:.:=:.::.::::__:=====:.J Mini Home Teleplwne Exchange Kit 00 Casio Two Colour Printing Calculator • • • • • • • • Black print and red print to subtractions Sub-total total Item counting Average function Save Over 50% 3 digit comma markers Full decimal system O perates on 4 x Aa power supply Includes one roll of 58mm paper and d ust cover 00 X 2125 Normally $149· This Month Only $69·00 This grea t unit allows you to place calls on hold, intercom other extensions, answer calls from any extension and transfer calls. It is expandable up to 10 extensions, and is compatible with all DTMF (touch tone) telephones. Operation is as simple as pressing '* ' to place a call on hold and press the extension number (0.9) and the respective station rings. Once answered you have a two way intercom with which you can announced call. To pick up the incoming call from hold press#. A neat fea ture is at extensions will ring w hen an incoming call is placed on hold fo r 30 seconds so that it won't be forgotten. The basic kit is complete with power supply, case and facili ties for 3 extensions. Extra extension boards allow expansion in multiples of 3. Fantastic for home or small office. No more shouting from room to room. Not Austel approved. 00 95 . Board K 1430 Baste KJt K 1435 Expansion . . $189· $79· PHONE ORDER- FREECALL 008 999 007 AUSTRALIAWIDE Protector Car Alarm Kit What a bargain! This amazing kit comes complete with 2 piezosiren, dash lamp flasher, battery back up, pin sw itches, sticker, case and all components required to assemble the kit. It even has an ignition kille r built in. At this prices they won't last. K4370 NORMALLY $129•00 $59·00 Digital Storage C.R.O. Adaptor for P.C.'s Kit This Month Only - -- - - - - - - - - - - - - i e ~ J l., i- L.J A// 1 l.,v ° This great kit enables a P.C. user lo capture interest then save them lo disc. The unit has 32K of storage memory and a sampling rate of over 600K samples per second . Input level of up to 2.5 Volt. Full sampling rate between 15K s/ s to over 600K s/ s. Inpu t impedance of JM ohm. K 2805 $63·50 . $ 19-95 K 2806 5.25" PC Software to SUII . $ 1 9-95 K 2807 3.5" PC Software to Suit --------------Digital Headphones These superb lightweight Hi-fi Stereo Headphones fea ture • Super comfortable foam ear muffs ~ 29mm samarium cobalt speakers • Sensitivity of l OOdB / 32 ohms / 250mW • Supplied with 2.Sm coiled lead and 3.5mm gold plated stereo plug and 6.35mm gold plated stereo adaptor a t no extra cost. C 9002 NORMALLY $24·95 ALTR.C>~IC:: Desolder Bulbs Video to TV Transmitter Kit COMPONENTS Soldering Iron • 370'C. • Fixed De-Solders with an ciency 1 - - - - - -- - - - - - - -- --i This kit enables you to transmit TV signals from the UHF output of your TV on your VCR to a second TV set in the house. The kit is complete with box and has a range of about 20 metres. Requires 12 Volts DC (p ictured without case-included). K 5860 NORMA LLY $74·95 This Month O nly $49·oo Texas Instruments Book Clearance a waveform and zoom in to segments of e universal Remote Control This Universal Remote Control makes all o ther remotes superfluous. Designed to combine all infra red remo te controls into one handy unit. No more searching through piles of remotes. 95 A 1000 $69· We only have a select few of these high standard Texas Instruments data books left. So be quick as stocks won't last. PCB Moun Blocks $20·00 00 B 1208 TI Linear Applications Vol 2 $20· 00 B 1216 TI MOS Memory Data Book $2600 B ll18 TI Linear and Interface Orruits $20 B U06 TI Linear Applications Vol 1 Just the shot fo r wire termination to PCB for your latest project. Enables easy connection (and disconnection) o f wire and cables to a PCB. 45' type. Available in 2 and 3 way configurations. P 2042 2 WayWAS .~, NOW ONLY ,3041 ea patented heating element • Iron clad, chrome plated, long life interchangeable tips. Tip life expectan cy is many times that of conventional plated tips. Supplied with T 2424 Tip. Energy authority approved. 95 T 2420 $27· Hole Punch Set Cuts holes in metal upto 1.6mm(16 gauge).Set 5 punches tapered rea er. Pun ch sizes, 16 25mmand T2360 NO ThiiiMonth 12V DC at 2 Amps full y regulated. 250V AC inp to 2 x binding posts. Allowing v · These supplies are j bility is in need. M 9050 NORMALL Palm-Grip Series P20433WayWAS ,SSq,NOW ONLY .4541 ea Hand Tools .-------,,-_,..,.., _ _ _ __ _ _ _ _....,__ _ _ _ _ _ _ __ A must for all tool boxes. Handy palm-grip size lea- ;n'i,;;,F.;ro,;~~-' tures spring return and sta struction. T 2710 Flat Nose Pliers T 2720 Needle Nose Pliers T 2730 Curved Needle Nose Pli_ ·e__ rs_ _--, 95 ALL NORMALLY $9· ea .95 This Month Only ea $7 BUYALL FO R $18 High Energy Rack Cases For very high heat dissipation, this design allows the fitting of computer type fans to inside back of rear panel, adjacent to each respective heatsink. 3 Unit Rack Size (130mm x 440mm x 252mm) H 0417 Silver Painted Aluminium Front Panel H 0418 Black Painted Alu minium Front Panel This lightweight, comfortable tool cuts, clinches and burnished compo00 N ow Onl nents leads in one ....;;.;.;;.;.;...;;.;;;;;....i.;=;....--------t single stroke. Rugged aluminium body with durable tool steel mechanism. SPST chassis mount. With Limited stocks! built in 240VAC Neon light. T 2800 NORMALLY $35·oo $ _ . Clearing out at Only 2 0 00 S3218 ea 22· Telephone Type .l Keypad I 3 x 4 wa y matrix, as used with DTMF telephones and some security applications. S 5380 $5·00 .99( L__ _::=::!:..::.:.:. ::::.::.:::::....:::..=-=--i-------=::::::':::::=====~ High Quality Polypropyl.--e_n e_ __, Telep Speakers at 1992 Prices Hurry - Stocks Limit Bell Most 'state of the art' hig h performance speaker systems use either bextrene or polypropylene cone material in their woofers. This development has given significant improvement in bottom end frequency response and cabinet size reductions. 50 C 3045 6.5" Midrange 30 Watts Nom/ 50 Watts Max C 3055 6.5" Woofer 30 Watts Nom / 50 Wa tts Max $2 7$29.95 C 3060 8" Woofer 60 Watts Nom / 100 Watts Max $49.95 C 3065 10" Woofer 60 Watts Nom/ 100 Watts Max $69 .00 C 3070 12" Woofer 100 Watts Nom /150 Watts Max $99 .00 C 3075 15" Woofer 120 Watts Nom / 200 Watts Max $ 1 29 .00 This handy line unit allows you to hear the telephone ringing outside in the shed or even those who have trouble hearing the telephone inside. Simply connects via a double adaptor to the telephone line. Telecom approved. P 0996 Was $29·50 ea, This month only $27·00 Top quality blank panel clearout. All stock must go at t h ese crazy prices. Stock is limited with definitely no backorders. at these 3 Unit-ALL 512·95 H 0423 Nat Alum H0433Grey Heavy Duty Lamp Relays Fully internally fused (30 Amp x 2) double pole 12V relays suitable for headlights, ho rns or any situation where heavy duty switching is a mus t. 50 S 4335 Were $13· Now clearing at $8·00 PHONE ORDER- FREECALL 008 999 007 Silicon Chip BACK ISSUES May 1989: Electronic Pools/Lotto Selector; Synthesised Tom-Tom; Biofeedback Monitor For Your PC; Simple Stub Filter For Suppressing TV Interference; LED Message Board, Pt.3; Electronics For Everyone - All About Electroly1ic Capacitors. June 1989: Touch-Lamp Dimmer (uses Siemens SLB0586); Passive Loop Antenna For AM Radios; Universal Temperature Controller; Understanding CRO Probes; LED Message Board, Pt.3. July 1989: Exhaust Gas Monitor (Uses TGS812 Gas Sensor); Extensibn For The Touch-Lamp Dimmer; Experimental Mains Hum Sniffers; Compact Ultrasonic Car Alarm ; NSW 86 Class Electric Locomotives. July 1988: Stereo Control Preamplifier, Pt.2; Fitting A Fuel Cut-Off Solenoid To Your Car; Booster For TV & FM Signals ; The Discolight Light Show, Pt.1 ; Tone Burst Source For Amplifier Headroom Testing; What Is Negative Feedback, Pt.3. December 1988: 120W PA Amplifier (With Balanced Inputs), Pt.1 ; Diesel Sound Generator; Car Antenna/Demister Adaptor; SSB Adaptor For Shortwave Receivers ; Why Diesel Electrics Killed Off Steam ; Index to Volume 1. August 1988: Building A Plasma Display; Universal Power Supply Board ; Remote Chime/Doorbell; High Performance AC Millivoltmeter, Pt.1; Discolight Light Show, Pt.2 ; Getting The Most Out Of Nicad Batteries; Data On Insulated Tab Triacs. January 1989: Line Filter For Computers ; Ultrasonic Proximity Detector For Cars; 120W PA Amplifier (With Balanced Inputs) Pt.1; How To Service Car Cassette Players; Massive Diesel Electrics In The USA; Marantz LD50 Loudspeakers. September 1989: 2-Chip Portable AM Stereo Radio (Uses MC 13024 and TX7376P) Pt.1 ; AlarmTriggered Telephone Dialler; High Or Low Fluid Level Detector; Simple DTMF Encoder; Studio Series 20-Band Stereo Equaliser, Pt.2; Auto-Zero Module for Audio Amplifiers (Uses LMC669). September 1988: Hands-Free Speakerphone ; Electronic Fish Bite Detector; High Performance AC Millivoltmeter, Pt. 2; Build The Vader Voice ; Motorola MC34018 Speakerphone IC Data; What Is Negative Feedback, Pt.4. February 1989: Transistor Beta Tester; Minstrel 2-30 Loudspeaker System; LED Flasher For Model Railways; Build A Simple VHF FM Monitor (uses MC3362), Pt. 1; Lightning & Electronic Appliances ; Using Comparators to Detect & Measure. October 1989: Introducing Remote Control; FM Radio Intercom For Motorbikes Pt.1; GaAsFet Preamplifier For Amateur TV; 1Mb Printer Buffer; 2-Chip Portable AM Stereo Radio, Pt.2; Installing A Hard Disc In The PC. October 1988: Stereo FM Transmitter (Uses Rohm BA1 404); High Performance FM Antenna; Matchbox Crystal Set ; Electronic House Number; Converting · A CB Radio To The 28MHz Band; Queensland's Powerful Electric Locomotives. March 1989: LED Message Board, Pt.1 ; 32-Band Graphic Equaliser, Pt.1; Stereo Compressor For CD Players; Amateur VHF FM Monitor, Pt.2; Signetics NE572 Compandor IC Data; Map reader For Trip Calculations; Electronics For Everyone Resistors. November 1989: Radfax Decoder For Your PC (Displays Fax, RTTY & Morse); Sensitive FM Wireless Microphone; FM Radio Intercom For Motorbikes, Pt.2; 2-Chip Portable AM ~ereo Radio , Pt.3; Floppy Disc Drive Formats & Options; The Pilbara Iron Ore Railways. April 1989: Auxiliary Brake Light Flasher; Electronics For Everyone: What You Need to Know About Capacitors; Telephone Bell Monitor/ Transmitter; 32-Band Graphic Equaliser, Pt.2; LED Message Board, Pt.2. December 1989: Digital Voice Board (Records Up To Four Separate Messages); UHF Remote Switch ; Balanced Input & Output Stages; Data For The LM831 Low Voltage Amplifier IC; Install A Clock Card In Your PC; Index to Volume 2. November 1988: 120W PA Amplifier Module (Uses Mosfets) ; Poor Man's Plasma Display; Automotive Night Safety Light; Adding A Headset To The Speakerphone; How To Quieten The Fan In Your Computer; Screws & Screwdrivers, What You Need To Know; Diesel Electric Locomotives. l. -------- - ---- -- - - ------------ -- ---- Use this handy form to order your back issues Please send me a back issue for : O October 1988 O November 1988 O March 1989 O April 1989 O September 1989 O October 1989 0 February 1990 July 1990 O December 1990 O May 1991 O October 1991 o March 1992 O August 1992 O January 1993 o O March 1990 o August 1990 O January 1991 O June 1991 o November 1991 o April 1992 O September 1992 0 July 1988 O December 1988 0 May 1989 O November 1989 0 April 1990 O September 1990 0 February 1991 0 July 1991 O December 1991 0 May 1992 0 October 1992 Enclosed is my cheque/money order for $___or please debit my: Card No. ~~I O August 1988 O January 1989 O June 1989 O December 1989 0 May 1990 O October 1990 O March 1991 O August 1991 0 January 1992 O June 1992 O November 1992 O Bankcard '--I~~I '--I~ ___.I l~___.I_·__. Signature _ __ _ _ _ _ _ _ _ _ _ Card expiry date_ _ /_ _ O Visa Card -, O O 0 O O O 0 September 1988 February 1989 July 1989 January 1990 June 1990 November 1990 April 1991 o September 1991 O February 1992 0 July 1992 O December 1992 O Master Card $5.00 each (includes p&p) . Overseas orders _add $1 each for postage. NZ orders are sent air mail. Street _ __ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Detach and mall to: SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROY BEACH NSW 2097 Suburb/town _ _ _ _ __ ________ Postcode _ _ _ _ __ Or call (02) 979 5644 & quote your credit card details. Fax (02) 979 6503. Name L----------------- --- ---------. -------- - -54 SILIC O N CHIP January 1990: High Quality Sine/Square Oscillator; Service Tips For Your VCR ; Speeding Up Your PC; Phone Patch For Radio Amateurs; Active Antenna Kit; Speed Controller For Ceiling Fans; Designing UHF Transmitter Stages. February 1990: 16-Channel Mixing Desk; High Quality Audio Oscillator, Pt.2; The Incredible Hot Canaries; Random Wire Antenna Tuner For 6 Metres; Phone Patch For Radio Amateurs, Pt.2; PC Program Calculates Great Circle Bearings. March 1990: 6/12V Charger For Sealed LeadAcid Batteries; Delay Unit For Automatic Antennas; Workout Timer For Aerobics Classes; 16Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC. April 1990: Dual Tracking ±S0V Power Supply; VOX With Delayed Audio; Relative Field Strength Meter; 16-Channel Mixing Desk, Pt.3; Active CW Filter For Weak Signal Reception ; How To Find Vintage Radio Receivers From The 1920s. May 1990: Build A 4-Digit Capacitance Meter; High Energy Ignition For Cars With Reluctor Distributors; The Mozzie CW Transceiver; Waveform Generation Using A PC, Pt.3; 16-Channel Mixing Desk, Pt.4. June 1990: Multi-Sector Home Burglar Alarm; Low-Noise Universal Stereo Preamplifier; Load Protection Switch For Power Supplies; A Speed Alarm For Your Car; Design Factors For Model Aircraft; Fitting A Fax Card To A Computer. July 1990: Digital Sine/Square Generator, Pt.1 (Covers 0-S00kHz); Burglar Alarm Keypad & Combination Lock; Simple Electronic Die; Low-Cost Dual Power Supply; Inside A Coal Burning Power Station; Weather Fax Frequencies. · Batteries, Pt.2; How To Design Amplifier Output Stages; Tasmania's Hydroelectric Power System. Call Timer; Coping With Damaged Computer Directories ; Valve Substitution In Vintage Radios . March 1991: Remote Controller For Garage Doors, Pt.1; Transistor Beta Tester Mk.2; Synthesised AM Stereo Tuner, Pt.2; Multi-Purpose 1/0 Board F.or PC-Compatibles; Universal Wideband RF Preamplifier For Amateurs & TV ; A Look At The Config.Sys & Ansi.Sys Files. April 1992: lnfrared Remote Control For Model Railroads ; Differential Input Buffer For CROs; Studio Twin Fifty Stereo Amplifier, Pt.2; Understanding Computer Memory; Switching Frequencies in Model Speed Controllers; Aligning Vintage Radio Receivers, Pt.1. April 1991 : Steam Sound Simulator For Model Railroads; Remote Controller For Garage Doors, Pt.2; Simple 12/24V Light Chaser; Synthesised AM Stereo Tuner, Pt.3; A Practical Approach To Amplifier Design, Pt.2; Playing With The Ansi.Sys File; FSK Indicator For HF Transmissions . . May 1992: Build A Telephone Intercom ; LowCost Electronic Doorbell ; Battery Eliminator For Personal Players; lnfrared Remote Control For Model Railroads , Pt.2; A Look At Large Screen High Resolution Monitors; OS2 Is Really Here; Aligning Vintage Radio Receivers , Pt.2. May 1991: Build A DTMF Decoder; 13.SV 25A Power Supply For Transceivers; Stereo Audio Expander; Fluorescent Light Simulator For Model Railways; How To Install Multiple TV Outlets, Pt.1; Setting Screen Colours On Your PC. June 1992: Multi-Station Headset Intercom, Pt.1 ; Video Switcher For Camcorders & VCRs ; lnfrared Remote Control For Model Railroads , Pt.3; 15Watt 12-240V Inverter; What's New In Oscilloscopes? ; A Look At Hard Disc Drives. June 1991: A Corner Reflector Antenna For UHF TV; 4-Channel Lighting Desk, Pt.1; 13.SV 25A Power Supply For Transceivers; Active Filter For CW Reception; Electric Vehicle Transmission Options; Tuning In To Satellite TV, Pt.1 . July 1992: Build A Nicad Battery Discharger; 8Station Automatic Sprinkler Timer ; Portable 12V SLA Battery Charger; Off-Hook Timer For Telephones; Multi-Station Headset Intercom , Pt.2; Understanding The World Of CB Radio ; Electronics Workbench For Home Or Lab. July 1991: Battery Discharge Pacer For Electric Vehicles ; Loudspeaker Protector For Stereo Amplifiers; 4-Channel Lighting Desk, Pt.2; How To Install Multiple TV Outlets, Pt.2; Tuning In To Satellite TV, Pt.2; PEP Monitor For Transceivers. August 1991: Build A Digital Tachometer; Masthead Amplifier For TV & FM; PC Voice Recorder; Tuning In To Satellite TV, Pt.3; Installing Windows On Your PC; Step-By-Step Vintage Radio Repairs. August 1990: High Stability UHF Remote Transmitter; Universal Safety Timer For Mains Appliances (9 Minutes); Horace The Electronic Cricket; Digital Sine/Square Wave Generator, Pt.2. September 1991: Studio 3-55L 3-Way Loudspeaker System; Digital Altimeter For Gliders & Ultralights, Pt.1 ; Build A Fax/Modem · For Your Computer; The Basics Of AID & DIA Conversion; Windows 3 Swapfiles, Program Groups & Icons. September 1990: Music On Hold For Your Telephone; Remote Control Extender For VCRs; Power Supply For Burglar Alarms; Low-Cost 3Digit Counter Module; Simple Shortwave Converter For The 2-Metre Band. October 1991: Build A Talking Voltmeter For Your PC, Pt.1; SteamSound Simulator Mk.11; Magnetic Field Strength Meter; Digital Altimeter For Gliders & Ultralights, Pt.2; Getting To Know The Windows PIF Editor. October 1990: Low-Cost Siren For Burglar Alarms; Dimming Controls For The Discolight; Surfsound Simulator; DC Offset For DMMs; The Dangers of Polychlorinated Biphenyls; Using The NE602 In Home-Brew Converter Circuits. November 1991: Colour TV Pattern Generator, Pt.1; Battery Charger For Solar Panels; Flashing Alarm Light For Cars; Digital Altimeter For Gliders & Ultralights, Pt.3; Build A Talking Voltmeter For Your PC, Pt.2; Error Analyser For CD Players Pt.3; Modifying The Windows INI Files. August 1992: Build An Automatic SLA Battery Charger; Miniature 1.5V To 9V DC Converter; The lnterphone Digital Telephone Exchange, Pt.1 ; Dummy Load Box For Large Audio Amplifiers; Internal Combustion Engines For Model Aircraft; Troubleshooting Vintage Radio Receivers . September 1992: Multi-Sector Home Burglar Alarm; The lnterphone Digital Telephone Exchange, Pt.2; General-Purpose 3½- Digit LCD Panel Meter; Track Tester For Model Railroads; Build A Relative Field Strength Meter; Internal Combustion Engines For Model Aircraft, Pt.2. October 1992: 2kW 24VDC To 240VAC Sinewave Inverter; Multi-Sector Home Burglar Alarm, Pt.2; Mini Amplifier For Personal Stereos; Electronically Regulated Battery Charger (Charges 6V, 12V & 24V Lead-Acid Batteries) ; Internal Combustion Engines For Model Aircraft, Pt. 2. November 1992: MAL-4 Microcontroller Board, Pt.1 ; Simple FM Radio Receiver; lnfrared Night Viewer; Speed Controller For Electric Models, Pt.1; 2kW 24VDC To 240VAC Sinewave Inverter, Pt.2; Automatic Nicad Battery Discharger; Modifications To The Drill Speed Controller. November 1990: How To Connect Two TV Sets To One VCR; A Really Snazzy Egg Timer; LowCost Model Train Controller; Battery Powered Laser Pointer; 1.5V To 9V DC Converter; Introduction To Digital Electronics; Simple 6-Metre Amateur Transmitter. December 1991: TV Transmitter For VCRs With UHF Modulators; lnfrared Light Beam Relay; SolidState Laser Pointer; Colour TV Pattern Generator, Pt.2; Windows 3 & The Dreaded Unrecoverable Application Error; Index To Volume 4. December 1992: Diesel Sound Simulator For Model Railroads; Easy-To-Build UHF Remote Switch ; MAL-4 Microcontroller Board, Pt.2; Speed Controller For Electric Models, Pt.2; 2kW 24VDC To 240VAC Sinewave Inverter, Pt.3; High Voltage Probes - Beware The Dangers; Index To Volume 5. December 1990: DC-DC Converter For Car Amplifiers; The Big Escape -A Game Of Skill; Wiper Pulser For Rear Windows; Versatile 4-Digit Combination Lock; SW Power Amplifier For The 6Metre Amateur Transmitter; Index To Volume 3. January 1992: 4-Channel Guitar Mixer; Adjustable 0-45V BA Power Supply, Pt.1; Baby Room Monitor/FM Transmitter; Automatic Controller For Car Headlights; Experiments For Your Games Card; Restoring An AWA Radiolette Receiver. January 1993: Peerless PSK60/2 2-Way Hifi Loudspeakers; Flea-Power AM Radio Transmitter; High Intensity LED Flasher For Bicycles; 2kW 24VDC "(o 240VAC Sinewave Inverter, Pt.4; Speed Controller For Electric Models, Pt.3. January 1991: Fast Charger For Nicad Batteries, Pt.1; The Fruit Machine; Two-Tone Alarm Module; Laser Power Supply; LCD Readout For The Capacitance Meter; How Quartz Crystals Work; The Dangers When Servicing Microwave Ovens. February 1992: Compact Digital Voice Recorder; SO-Watt/Channel Stereo Power Amplifier; 12VDC/ 240VAC 40-Watt Inverter; Adjustable 0-45V BA Power Supply, Pt.2; Designing A Speed Controller For Electric Models. February 1991: Synthesised Stereo AM Tuner, Pt.1; Three Inverters For Fluorescent Lights; LowCost Sinewave Oscillator; Fast Charger For Nicad March 1992: TV Transmitter For VHF VCRs; Studio Twin Fifty Stereo Amplifier, Pt.1; Thermostatic Switch For Car Radiator Fans; Telephone PLEASE NOTE: All issues from November 1987 to June 1988 plus the August 1989 issue are now sold out. All other issues are presently in stock. For readers wanting articles from sold-out issues, we can supply photostat copies (or tearsheets) at $5.00 per article, including postage. When supplying photostat articles or back copies, we automatically supply any relevant Notes & Errata at no extra charge. F EBRUARY 1993 55 Audio leve meter with LED readout This LED VU meter can be used as an adjunct to the mechanical meters found in older tape decks & in low-cost audio mixers. Its main advantages include a fast response time & a peak hold facility so that you can accurately set recording levels. By BERNIE GILCHRIST When recording audio signals, it's important that input levels be accurately set in order to obtain good results. If the signal level is set too high, the recorded signal will sound distorted due to signal overload. On the other hand, if the input signal level is set too low, the recording will be noisy, will have limited dynamic range and may even suffer from signal dropouts. The traditional way of monitoring signal levels is to use a VU (volume units) meter. In practice, the input signal level is normally adjusted so that peak levels register no more than 56 SILICON CHIP about +3dB. Any more than that and you run the risk of signal overload. Mechanical VU meters have one major disadvantage though - they're not fast enough to respond to fast signal transients. The result is signal clipping and unwanted distortion in your recordings. By comparison, this electronic VU meter can respond to fast transients and also has a peak hold facility to give you sufficient time to observe these signal peaks. Unlike conventional units, this unit displays the signal level using 12 rectangular LEDs arranged in bargraph fashion. The reading is scaled in volume units, which is a logarithmic scale commonly used in audio equipment for displaying dynamic signal levels. Table 1 shows the absolute and relative levels for the LEDs when no input attenuation is used; ie, when the input signal is applied direct to Cl (see Fig.1). The peak hold facility involves the top five LEDs. If the signal peak reaches these LEDs, then the highest LED that lights will be held on long enough for it to be observed, while the other LEDs in the peak hold section turn off. By this means, any peaks that are normally too quick to be observed are captured and displayed. By making a simple circuit modification, two of these VU meters can Below: the LM317 regulator is secured to the underside of the PC board using a screw & nut. The 12 LEDs indicate the signal level. They can be mounted separately & wired back to the main board via a 12-way cable if required. Of TABLE 1 1N4002 +11-40V i CS + 33 3svw-.,. ov°+ C4 + AS 1M 1 sovw- 13 PK OSC -20dB LED1 15 D1 16 .,. -15dB LED2 D2 17 Rt 33k -tOdB LED3 INPUT R2 47k GND°+ 7 VRt 50k .,. .,. D3 18 IN1(·) R4 82k -7d8 LED4 C2 1 SOVW+ 04 19 -SdB LEDS D5 20 ·3dB LED6 IC1 LB1412 LED Input Level Relative Level 1 11mV -20dB 2 20mV -15dB 3 35mV -10dB 4 49mV -?dB 5 62mV -5dB 6 78mV -3dB 7 98mV -1dB 8 110mV 0dB 9 123mV +1dB 10 156mV +3dB 11 196mV +5dB 12 276mV +8dB D6 21 10 ~ AO I -1dB LED7 D7 OdB LEDS R6 4.7k 14 D8 .~. 010 11 D11 I I I 012 + BARGRAPH vu 1 ILED 09 Jf 22 2 3 4 5d8 LE011 5 SdB LE012 K A .,. METER Fig.1: the circuit is based on an LB1412 display driver (ICl ). The audio signal is fed in on pin 7, after which it is amplified & detected before being fed to 12 comparator stages. These stages compare the input level against preset thresholds & operate the appropriate LEDs. share a common peak hold reset li:rie, so that the peak LEDs in each channel switch off at the same time. This enhances the meter display and makes it easier to adjust recording levels in a stereo system. To make the display easy to read, the bottom seven LEDs are all green and these correspond to relative signal levels ranging from -20dB to -ldB. The eighth LED is yellow and corresponds to 0dB, while the top four LEDs are all red and indicate signal levels ranging from +ldB to +BdB. How it works Let's now take a look at the circuitsee Fig.1. It's based on a single LB1412 IC plus a 3-terminal regulator and a handful of minor parts. As can be seen, the audio signal is fed in via an input attenuator consisting of Rl, R2 & VRl. This circuit allows the input sensitivity and impedance to be adjusted (see Table 2). The attenuated signal is then AC-coupled via Cl and R3 to the inverting input of an op amp inside the LB1412 IC. ICl is a complete 12-dot red/green LED level meter on a single chip. It contains two stages of input amplification, 12 comparator stages, an inbuilt oscillator for peak hold reset, two constant current sources, and 12 output driver stages for the LEDs. In addition, there are five RS flipflop stages which function as latches and provide the peak hold logic for the five top LEDs. The gain of the first op amp stage is determined by resistors R3 and R4 and, according to the manufacturer's specifications, must not be made greater than 4. In this circuit, R3 and R4 have been selected to give a gain of 3.7. The output of this first stage is coupled via C2 to the input (pin 9) of the second stage. This stage functions as a half-wave detector with a gain of 2. Its output at pin 10 is filtered by capacitor C3, the value of which determines the attack and decay times of the display. If C3 is made too small, the display will tend to flicker rapidly with low frequency signals. Conversely, if it is made too large, the display will not respond to short peaks or troughs. The 2.2µF capacitor used in this circuit gives attack and decay times of approximately 0.5ms and 250ms respectively. Internal comparators The output of the detector is fed to the 12 comparators (one for each LED). These compare the input level with the preset threshold levels for the display and operate the appropriate LEDs. As indicated above, the peak hold function works by using the internal latches to gate the top five LEDs. This latching circuit holds on the highest LED to be lit until a reset pulse is received. It also ensures that any lower LEDs in the peak hold circuit are FEBRUARY 1993 57 Fig.2: install the parts on the PC board as shown in this wiring diagram, noting especially that IC2 is mounted on the copper side of the board. The LED display section can be separated from the remainder of the circuit by cutting along the dotted line. protection diode and about 2V across the regulator. A relatively large area of copper is provided on the PC board to serve as a heatsink for the LM317. This allows it to operate continuously from a 40V supply without overheating, even with all LEDs turned on. The LM317 has automatic thermal protection but normally only some of the LEDs are on, so even with a 40V supply the power dissipation will be comfortably below its shutdown point. Finally, link J1 (shown dotted) disables the peak hold circuit by pulling the reset line of the internal oscillator to ground. The top five LEDs then function in the same manner as the bottom seven LEDs. Construction turned off (ie, only one of the top five LEDs can be lit at any one time). The reset pulse is supplied by the internal oscillator, the frequency of which is determined by R5 (1MQ) and C4 (1µF). This resets the latches once every cycle; ie, about every 0.9s with the values shown. Because the oscillator is not synchronised to the signal peaks, the actual peak hold time depends on just when the peak occurs within the cycle and may be very short if it occurs just before the reset pulse arrives. In practice though, the varying peak hold time is not all that noticeable since the effect averages out over time. Constant current drivers The two constant current drivers inside IC1 control the current through the bottom seven LEDs. LEDs 1-4 share one constant current driver, while LEDs 5-7 share the other. Resistor R6 sets the current through these drivers to about 11mA. Although the current decreases with an increase in R6, it is not inversely proportional to R6. LEDs 8-12 are individually driven because of their peak hold function, their current being determined by series resistors R7-R11. Because of this, their brightness can vary if the supply voltage to the LB1412 varies but in this circuit, an LM317 voltage regulator provides a fixed supply voltage of 9.6V. Actually, the specified supply voltage range for the LB1412 is 10-16V but tests involving six of these ICs showed that they all worked down to 8.4V without any problems. The LM317 voltage regulator allows input voltages of up to 40V to be used so that the unit can be connected to the positive supply rail of most power amplifiers. The lower supply voltage limit for the circuit is about 11 V, which gives approximately 8.4V across the LB1412 after dropping 0.6V across the All the parts for the LED VU meter are mounted on a small PC board coded ZA-1363 - see Fig.2. You can install the parts in any order but make sure that the IC, diode and electrolytic capacitors are correctly oriented. The LM317 is mounted on the copper side of the PC board and is secured to the board using a screw and nut. If you want the peak hold facility, link J1 should be omitted. Conversely, install J1 to disable the peak hold s ircuit if this feature is not required. As shown in Fig.2, the circuit is configured for a sensitivity range of 600mV to 1.5V and a nominal input impedance of 50kQ (ie, R1 = 33kQ & R2 = 47kQ). This sensitivity range should suit most line level signals; eg, from CD players and tuners. If required, the sensitivity can be increased to suit signals up to 600mV by installing a wire link for R1 and deleting R2. The most difficult part of the construction is getting the ends of the LEDs to line up. One technique that RESISTOR COLOUR CODES 0 0 0 0 0 0 0 0 0 0 58 No. Value 1 1MQ 82kQ 47kQ 33kQ 22kQ 4.7kQ 1.8kQ 560Q 270Q 1 1 1 1 1 1 5 1 SILICON CHIP 4-Band Code (5%) brown black green gold grey red orange gold yellow violet orange gold orange orange orange gold red red orfenge gold yellow vio et red gold brown grey red gold green blue brown gold red violet brown gold 5-Band Code (1%) brown black black yellow brown grey red black red brown yellow violet black red brown orange orange black red brown red red black red brown yellow violet black brown brown brown grey black brown brown green blue black black brown red violet black black brown TABLE 2 R1 (ohms) R2 (ohms) Sensitivity 0 - 110-600mV 15-50k 33k 47k 600mV - 1.5V 50k 100k 47k 1.5V, - 3V 100k 100k 10k 3V-8V 100k 100k 3.3k 8V- 20V 100k 100k 1.2k 20V- 50V 100k can be used is to first carefully solder the two end LEDs so that they are the same distance from the PC board. The remaining LEDs can then be installed and the display pushed against a flat surface to align the ends of LEDs before soldering. It is a good idea to initially solder only one lead of each LED until you are satisfied that they are all correctly aligned. Make sure that the LEDs are correctly oriented - the anode lead is the longer of the two. Use green LEDs for LEDs 1-7, a yellow LED for LED 8, and red LEDs for LEDs 9-12. To allow for different mounting configurations , the display end of the board can be separated from the rest of the circuitry using a fine-bladed hacksaw. The display can then be connected to the main board via flying leads, or directly soldered to it at right angles. If you are soldering the two boards together, lightly solder tack the two end connections first. The angle between the two boards can then be easily adjusted if necessary before the PARTS LIST Input Impedance 1 PC board, code ZA-1363 1 10mm x 3mm-dia. screw, nut & washer 4 PC stakes 1 S0kn miniature vertical trimpot Semiconductors remaining connections are soldered. If two of these VU meters are to be used together in a stereo system, then the following modifications should be included so that the peak hold circuits reset together: (1) disable the p eak hold oscillator on one meter by removing C4 and R5 ; (2) connect pin 13 of ICl in this meter to ground (ie, to OV); and (3) connect the reset pins (11) of the two LB1412 display driver ICs together. The oscillator in one unit will now reset both units simultaneously. Adjustment Trimpot VRl is the only component on the PC board that requires adjustment. If you are using the unit as an adjunct to a mechanical VU meter, adjust VRl so that both meters read the same on a lkHz sinewave signal. If you have access to an audio signal generator, you can calibrate the circuit so that the OVU LED corresponds to a signal level of 775mV at lkHz. SC 1 LB1412 display driver (IC1) 1 LM317T regulator (IC2) 1 1N4002 silicon diode (D1) 7 green LEDs (LED1 -LED?) 1 yellow LED (LED8) 4 red LEDs (LED9-LED12) Capacitors 1 33µF 35VW PC electrolytic 1 4.7µF 25VW PC electrolytic 1 2.2µF 25VW PC electrolytic 2 1µF 50VW PC electrolytic 1 0.1 µF monolithic Resistors (0.25W, 5%) 1 1MQ 1 82kQ 1 47kn 1 33kn 1 22kQ 1 4.7kQ 1 1.8kQ 5 5600 1 270n Where to buy the kit A kit of parts for this project is available from any Dick Smith Electronics store or by mail order from PO Box 321, North Ryde 2113. Phone (02) 888 2105. The price is $24.95 plus $5 p&p. Quote Cat. K-5370 when ordering. Note: copyright of the PC artwork for this project is retained by Dick Smith Electronics. · YOU CAN NOW AFFORD A SATELLITE TV SYSTEM .,,._ For many years you have probably looked at sate IIite TV systems and thought "one day" You can now purchase the following K-band system for only: $995 Here's what you get: • A 1.6 metre prime focus dish antenna, complete with all the mounting hardware. • One super low-noise LNB (1.4dB or better). • One Ku-band feedhorn and a magnetic signal polariser. • 30 metres of low-loss coaxial cable with a single pair control line. • lnfrared remote control pre programmed satellite receiver with selectable IF & audio bandwidth, polarity & digital readout. Your receiver is pre-programmed to the popular OPTUS transponders via the internal memory. AV-COMM Pty Ltd, PO Box 225, Balgowlah NSW 2093. Ph: (02) 949 7417. Fax: (02) 949 7095. All items are available separately. Ask about our C-band LNBs, NTSC-to-PAL converters. video time date generators, FM2 & EPAL & Pay fV hardware. ~ jYES GARRY, please send me more information on K-band I satellite systems. I Name: _ _ _ _ _ _ _ _ _ _ __ I Address: _ __ _ _ _ _ _ _ _ __ : _ _ _ _ _ _ _ _ _ P'code: _ __ 1 Phone: _ _ _ _ _ _ __ __ __ I ACN 002 174 478 10/92 FEBRUARY 1993 59 A-ONE A-ONE A-ONE A-ONE A-ONE ~ 10% off all Bench-Top fustr •• < The GAG-808G is GW Instruments' latest general purpose audio oscillator. Being an AC type oscillator ensures a pure, low distortion sinewave output over the entire frequency range. A switchable output attenuator, calibrated in steps of 10 dB, makes the GAG-808G ideal in teaching as well as service applications. Both the sinewave and square wave outputs can also be varied by a continuous amplitude control. GAG-B0BG 10009 < CAT No. l0008 CAT. No. 10014 • • • • 2CH Input, auto selection. _ • Dual Decimal Points Indication • 0.1 Second Gate Time 2Hz-200KHz (5 Ranges) Sine, Triangle, Square Wave 1 % Typical at 1KHz $304.00 Frequency Range: 10 Hz to 1 MHz, in 5 ranges Sinewave Output: < 20 V pk-pk; Distortion < 0.1 % Squarewave Output: < 10Vpk- pk; Rise timme < 200 ns Output Impedance: 600 ohm Stepped Attentuator Oto -50 dB in 10 dB steps ! FUNCTION GENERATORS $313 & $454 ! GW GFC-F SERIES ► Competitively Priced ► Professional Quality GFC 801G 120 MHz 10012 $313.00 Frequency Range: 1 Hz to 120 MHz Sensitivity: ,;,20 mV 10 Hz to 100 MHz ,;,30 mV 100 MHz to 120 MHz Display 8 digit display and Gate Time 0.1 s, 1s, 10s < CTIC86A UNIVERSAL COUNTER $144.00 CAT No. 10007 • • • ~ < ~ < ~ CTI C550A $199.00 550 MHz FREQUENCY COUNTER $95.00 ~ ~ $304 1 ► Low Distortion Oscillator ~ ~ IAUDIO SIGNAL GENERATOR ECONOMICAL BENCH-TOP INSTRUMENTS 10Hz-60MHz Two Ranges 0-9999999 Counts 25mV RMS Sensitivity • • • CTIC90A 24V 3A DIGITAL POWER SUPPLY $129,00 CAT No. 10212 Precision 60.0V DVM for Monitoring the regulator output voltage/current. Output Voltage: 0-24V Output Current: 3A Current Limit: 20mA, 5DmA, 200mA, 500mA, 1A, 3A. Line Regulation: 0 .1 % against 20% line variation Load Regulation: 0.5% against 10 to 90% load variation. INTELLIGENT COUNTERS $609 ! GWGFC-G SERIES ► Frequency, Period and RPM .Ranges The GFC-813G is an economically priced 1.3 1 Ghz counter. Additional features include a continuously variable Gate Time control as well as adjustable variable Level/Sensitivity. Front panel switches include AC/DC input coupling. LPF and attenuator controls. $609.00 GFC-813 G 10015 Frequency Range: 0.01 Hz to 1.3 GHz, AC or DC coupling Period Range: 0.6 rpm to 7,200 rpm Sensitivity: Input A 10 mVat 80 MHz Input B 50 mVat 1.3 GHz I UNIVERSAL COUNTERS CTIC87A AUTORANGING CAPACITANCE METER CAT No. M0203 $144.00 $592 ! 10 Ranges, fully Automatic with Range Hold. Ftill Scale Value From 99.9pF to 99.9mF. Accuracy 0.5% +/-0.5pF +/-1 Digit. GFC 8055G 5500 MHz 10013 $454.00 Frequency Range: 1 Hz to 550 MHz Sensitivity: lnputA ,;, 20 mVat 100 MHz Input B ,;, 150 mVat 550 MHz Display 8 digit LED and Gate Time 0.1 s, 1sand 10s ' ECONOMICAL LABORATORY GW POWER SUPPLY BASIC FUNCTIONS Continuously variable voltage and current from zero to rated limit with FINE and COARSE controls. Outputs are electronically protected against short circuit or overload conditions. The input is fuse protected, with a true 240V AC input. Automatic Constant Voltage - Constant crossover with LEDs CTIC83B 30V 1A DIGITAL POWER SUPPLY $93,00 CAT No. 10213 Precision 60.0V DVM for Monitoring the regulator output voltage/current. Output Voltage: 0-30V Output Current: 1A (MAX) Current Limit: 10mA, 50mA, 200mA, 500mA, 1A, 2A (Approx.) Line Regulation: 0.1 % against 20% line variation Load Regulation: 0.5% against 10 to 90% load variation. I The GPR-Series includes Floating Output, allowing either side to be linked to ground. FINE and COARSE voltage and current control. Clearly marked analogue panel meters, CLASS2.5 I► GPC-SERIES I TRIPLE Output DC Supplies ► 4 Analogue Panel Meters MODEL $458 ! ► Inbuilt Logic Probe ► 5V DC Power Supply Output GPG-8018I0011 GPS & GPR-SERIES ► SINGLE output DC Supplies ► 2 Analogue Panel Meters, V and A Dual Variable Outputs Switch selectable configurations Independent both outputs controlled separately Dual Tracking provides Master/ Slave control voltages Parallel doubles output current range Series doubles output voltage range Single Fixed Output Each output has an overload indication LED. Both Variable and Fixed outputs are floating. 5 Hzto 2 MHz (CH 8) Period Range: 0.5 µ.s to 0.2s, 5 Hz to 2MHz (CH A) Frequency Ratio Measurement: 11 (CH 8)/12 (CH A) Totalise Range Oto 99999999 (CH A) Time Interval Measurement Range 0.5 µ.s to 0.2s Sensitivity: Input A <150 mVat 175 MHz Input B < 30 mVat 2 MHz Display 8 digit LED I PULSE GENERATORS I $458.00 Frequency Range: 0.5 Hz to 5 MHz Pulse width and spacing independently variable 100 ns to 0.1 s Functions run, Trigger, Gate, One shot, Square, invert Outputs: TTL (Fanout 40) Variable Output (0,5 to 10V) for CMOS Synchronisation Output (Fanout 10) GPS-1830 GPR-1810H GPS-2020 GPR-3060 GPR-6030 GPS-3030D GPR-6030D GPC-1850D GPC-3030D GPC-1850 GPC-3030 RANGE 0-18V0-3A 0-18V0-10A 0-30V0-3A 0-30V0-6A 0-60V0-3A 0-30V0-3A 0-60V0-3A 2x0-18V5A, 1x5V3A 2x0-30V 3A, 1 x5V 3A 2x0-18V3A, 1x5V3A 2xO-30V 3A, 1x5V 3A < ,3 NO-V 3NO-V 3NO-V 3NO-V 3NO-V Escort SPACE SAVER SERIES EUC-2200 175 MHz 10016 Frequency Range: 5 Hzto 175 MHz (CH A). $592.00 L--------------------------------------------------- -------------- - t\ ..____·~O ~N'--""""""E-- - -A==- -., --0 - - -.;=-=N:__L,! E ! !~ A-~O~N~E . _____,A , , _- """"--- ~ E ~ A ""--- - - - "~NE Ji uments & Power Supp T~~§T~FEB'930NLY >. ~ ~ 1FUNctloN CENEAAToAs FROM $4s2 1 GWGFG 2 MHz SERIES GFG SERiES COMMON FEATURES Frequency Range 0.2 Hz to 2 MHz, continuously variable. Output Waveforms sine, triangle, square, TTL pulse and ramp Output Level > 20 Vp-p open circuit, 10 Vp-p into 50 ohms VCF Oto 10V input for 1000:1 output frequency variation DC offset of :±; 10VDC. GFG-8016G l0005 ► Frequency Counter $545.00 & 2 M Hz Function Generator Special Functions Frequency Counter • Internal or External operation • Frequency range 0.1 Hz to 10 Mhz •Sensitivity ,;; 20 m V rms 10 MHz • 6 digit LED display GFG-8017G 10004 ► Sweep $455.00 Function , 2 MHz Function Generator Special Functions Sweep Generator Operation • Auto or Manual sweep ing • Sweep width is 1000:1 ratio • Sweep time is variable from 0.5s to 30s • Sweep modes UN, LOG (Hi/Lo) 1 $626.00 2 MHz Funct ion Generator Special Functions 3 units in 1 • Inbuilt Frequency Counter, same as GFG- 8016G • Inbuilt Sweep Generator, same as GFG-8017G • AM and FM Modulation, internal or external GFG-8020G 10003 ► Digital $452.00 Readout 2 MHz Function Generator Special functions large 0.5 inch, 4 digit LED display for frequency indication . 'OC POWER SUPPLIES Low ripple noise components, typically 0.5 mV rms to 1 mV ms. Excellent line and load regulation, typically 0.01 %. Dual and Quad output suppl ies with SERIES and PARALLEL functions. Guaranteed for 12 months, with 9 years experience in Australia. I GPS & GPR-DIGITAL SERIES ► SINGLE Output, DC Supplies I GPC-DIGITAL SERIES ► TRIPLE Output DC Supplies ► two Cat. No. Model Panel Width Panel Height Box Width Box Height Box Depth UNIT PRICE 80308 80309 80310 80311 80312 80313 80314 80315 80316 80317 80318 4U-10 2U-12 4U-12 3U-14 4U-14 AL-2U-12 AL-3U-14 AL-4U-12 AL-2U -10 AL-3U -10 AL-4U-10 19.00 19.00 19.00 19 .. 00 19.00 19.00 19.00 19.00 19.00 19.00 19.00 7.00 3.50 7.. 00 5.25 7.00 3.50 5.25 7.00 3.50 5.25 7.00 16.50 16.50 16.50 16.50 16.50 16.50 16.50 16.50 16.50 16.50 16.50 6.75 3.25 6.75 5.00 6.75 3.25 5.00 6.75 3.25 5.00 6.75 10.00 12.00 12.00 14.00 14.00 12.00 14.00 12.00 10.00 10.00 10.00 $45.00 $45.00 $52.00 $56.00 $65.00 $82.00 $92 .00 $92.00 $72 .00 $77.00 $82.00 BLACK RACK FRONT PANELS Height Width Cat. No. Model 80416 80417 80418 ► Two 3½ Digit LCD Panel Meter, V or A The GPR-D Series includes Floating Output, allowing either side to be linked to ground. FINE and COARSE voltage control. An inbuilt, autoranging 200V DC Digital Voltmeter (100VA model s). I TopCover ,: Bottom Cover 5 Side Cover '6 Rear Panel Handle Sc rew 0 M3 x O 6 x 5 '9 Screw 0 M4 x 0.7 x 12 3 GFG-8019G 10006 ► Multifunction Front Panel :> Front Mounting Plate I 2U 3U 4U 13¼ DIGIT DMMs FROM <at> 74 3½ Digit LED Panel Meters Switch selectable configurations Independent both outputs controlled separately Dual Tracking provides Master/ Slave control voltages Parallel doubles output current range Series doubles output voltage range Single Fixed Output CAT No. PRICE 10201 10202 10203 10204 10205 10206 10207 10208 10209 10210 10211 $282.50 $732.00 $319.00 $523 .00 $589.00 $437.00 $665.0 0 $742.50 $750.00 $714.00 $714.00 ! GW GDM-SERIES GDM-8034 M0112 Dual Variable Outputs 13.50 16.50 18.50 3.50 5.25 7.00 19.00 19.00 19.00 UNIT PRICE $274.00 3½ digit LCD display. High accuracy 0.5% . Includes CAPACITANCE measurement range. SPECIFICATIONS V DC ± 199.9mVto ± 1000V; ± 0.5% (10Mohm input impedance) V AC ±199.9mVto 1000V; ± 1 %, 40Hzto 500Hz A DC ± 199.9µA to ±20A; ±0.5% A AC 199.9µAto 20A; ± 1 %, 40Hz to 500Hz Ohm 199.9ohm to 20Mohm; ± 0. 75%, 6 ranges Capacitance 2nFto 20µF, ± 0. 75%, 1 pF maximum resolution Diode Test Function Audibility Continuity Check GDM-8135G M0113 3½ digit LED display. All ranges are fully protected . Wide measurement ranges up to 1.2kV and 20A. High resolution extending to 100µVand 100 ± A. Basic accuracy of 0.1 % . CASE HANDLES Cat. No. Model 80501 80502 80503 2U 3U 4U PRICE (PAIR) 6.50 7.50 8.50 SPECiFICATIONS V DC ± 199.9mVto ±1000V; ±0.1 % (10Mohm input impedance) V AC 199.9mVto 1000V; ±0.5%, 40Hz to 10kHz (40kHz, ± 5%) A DC ± 199.9µA to20A; ±0.2% A AC 199.9µAto 20A; ±0.5%, 40Hz to 10kHz (20kHz, ± 1 %) Ohm 199.9ohm to 20Mohm; ± 0.2 % , 6 ranges Diode Test Function ' Audibility Continuity Check !ESCORT s31& 1 SPACE SAVER SERIES EDM-2116 M0114 $316.00 3½ digit LCD display. Fully portable BATTERY or MAINS operation. Includes CAPACITANCE measurement range. SPECIFICATI ONS $393.00 V DC ± 200mVto ±1 000V; ±0.5% (10Mohm input impedance) V AC 200mVto 1000V; ± 1 %, 45Hz to 500Hz A DC ± 200µAto ±20A; ± 1% A AC 200µA to 20A; ± 1.5%, 45Hz to 500Hz Ohm 200ohm to 20Mohm; ± 0. 75%, 6 rang es Capacitance 2nF to 20µF, ±2%, 1p F maximum resolution >. ~ ~ t!NO-V 3NO-V 3NO-V 3NO-V 3NO-V A-ONE A-ONE A-ONE A-ONE A-O g • <I POWER SUPPLY 1 Cat. No. K0008 $17.95 1 g This kit is a basic power supply based on the 7805 series of regulators. Two 7805 are used. One gives a fixed 5V for TTL work. The second shows how the regulator may be used to give a variable voltage output. Heatsinks and box provided. Max 1A output. < I < 0I < OPAIIP FUNCTION GENERATOR Cat. No. K0118 $15.95 Cheap and easy way to generate square, triangle and sine waves in the audio range. Uses QUAD OPAMP IC and passive components. A 1M log potentiometer gives best control over the 6 Hz to 6000 Hz range covered. Sine wave is made by wave shaping circuit. 9V battery operation. Cat. No. K0119 $27.95 1 One of the most important testing and measurement tools is the Logic Probe. This original & modern design can test both CMOS & TTL circuits as well as detect fast pulses. Its operation is fully described. Both visual & audio indication of the logic states found. Power from circuit being tested. . OSCILLATOR BUILDING BLOCKS Cat. No. K0120 $12.95 This kit demonstrates the three basic multivibrator oscillor circuits - the monostable, the bistable and the astable. Multivibrator circuits are everwhere in modern electronics. You must know them. Learn them here. Uses LED's to demonstrate each one. MAINS LIGHT DIMMER CIRCUIR Cat.No.K0357 $17.95 This is a standard thyristor light dimmer circuit. It can be used to control AC motors. Has RF anti-noise circuit. Works better than some commercial units on the market. CAUTION: uses 240V mains voltage, you must know what you are doing. Use care, Build into box before using. CONTINUITY TESTER & 2 YEAR FLASHER Cat. No. K0358 $10.95 NATIONAL SEMICONDUCTOR LM3909 introduces low power (under 3V) IC applications. 2 PCB's plus 7 pages documentation. Use the long life flasher as an imitation car alarm. Over 2 years 1Hz flashing with a 1.5V D cell. Continuity tester sounds buzzer with rising pitch up to about 500 ohm. < Ll,a~!. Koass $30.95 Flashes a Xenon Flashtube exactly like those found on planes signal beacons, fast photo kiosks and discos. Vary flash rate between 1 per second and 10/ sec. Flashtube rated for 2,000,000 flashes. Uses SCR and neon tube. CAUTION : uses 240V mains voltage. Must use care and enclose in box. 9V BAffERY POWERED XENON FLASHER Cat No. K0360 $35.95 Power a high voltage xenon flash tube from a standard 9V battery. Wind your own potcore transformer. It forms part of a modifed Hartley ascillator which feeds a relaxation oscillator. Modify the oscillator with an optional second neon tube. SCR trigger. A lot of electronics in this kit. Many people come back from an overseas trip with audio, video or computer equipment which will only run at 11 0V. They get caught. But all is not lost and some of this equipment will run quite happily via a 11 0V isolation transformer. Pictured is one of a range of 11 0V isolation transformers manufactured by Harbuch Electronics. All are based on the company's toroidal transformers and thus they are compact and have a low residual hum field. Units are available with ratings of 60VA,120VA,300VA,500VA and 625VA. The units up to 300VA are all housed in tt:,e same size case, measuring 125 x 75 x 185mm. This kit uses the popular Harris/lntersil 7106 IC to show you how easy it is to use this chip. Separate area on the PCB provided so you may build your own digital volt meter or other measuring devices. Full instructions and 12 pages of documentation enclosed. 9V battery included. This counter uses only 2 IC's and can be used for event counting. Separate counter unit included using Schmidt NAND gates and debounce c.ircuits to eliminate switch noise. Join two units to make 6 or 9 digit unit. May cut off and relocated display. With data sheets and instructions. XENON FLASHTUBE STROBOSCOPIC 110V ISOLATION TRANSFORMER gF;;;;:;:"n~4,95 I E Cat. No. Rating T0301 300VA T0302 625VA Price $149.50 $199.50 Call for prices of other ratings LED DICE WITH SLOWDOWN$ 23■95 FEATURE Cat. No. K0361 FM TRANSMlffER BUG • THE COMRADE Cat. No. K0408 $12.95 Push the button and the dice rolls. It gradually slows and comes to stop on a value at random. The modern way to play games that use a dice. Excellent Kit to start electronics. Ingenious circuit design using the 14017 decade counter and 555 timer with minimum components. Box, 9V battery included. The most powerful bug possible for its size, 3V supply and number of components. Based on proven design. Uses trimcap for easy tuning in the FM band. 50 meters within buildings, 300 meters or more in open. 4 pages documentation & battery holder included. A-ONE A-ONE A-ONE A-ONE A-ONE I I ' I LIGHT ALARM Cat. No. K0304 $9.95 Detacts the slightest light. Protect your cash drawer, medicine cabinet or lolly jar with this light alarm. Uses Darlington phototransistor MEL12 & 14011. Good introduction to several electronic building blocks especially NANO gate operation and how to get a piezo to sound loudly. 9V battery included. BASIC ULTRASONIC MOVEMENT DETECTOR $37.95 Cat. No. K0305 ■ A matched pair of ultrasonic transducers operating at 40kHz will reliably detect movement 3m to 5m away. Use 8V to 10V supply for best results. Ideal to monitor door opening and movement passed a point. Add your own alarm circuit. Make a crystal locked transmitter circuit for better stability. I ROULETIE LED Cat. No. K0414 Ten LED's arranged in a circle. Pressing the switch turns one LED on in turn to simulate a roulette ball spinning in a circle. A slowdown circuit gradually brings the ball to a stop. Uses the versatile 14017 IC. Plug-in socket provided so you easily change a resistor to alter the spin speed. STAIRWAY TO HEAV~~ No. K04 15 Cat No. K0410 $21,95 Record both speakers of your telephone conversations. It turns on your tape recorder when lift up the handset by detecting the drop in phone line voltage. Note: your tape recorder must have MIC and REMOTE sockets, no battery needed. Educational Kit, not for illegal use. Cat.No.K0411 $10,95 This small but powerful circuit attaches to a phone line & transmits the conversation into the FM band. It uses the phone line itself as an aerial. No battery required since it draws its power from the phone line. Easily adjucted to transmit outside the commercial FM band for greater security. FM TRANSMITIER BUG • THE CADRE Cat. No. 1<0412 $10,95 Uses 9V battery. Oscillator coil buiild into circuit board. Uses trimcap to tune in FM band. Proven design. Transmits over 500 meters in the open. You can experiment by better aerial for greater range. Three pages of documentation provided giving explaination of circuit. 1•5 MINUTE MAINS 240¥ TIMER Cat. No. K0413 $31,95 A up-to-date robust circuit for timing a mains appliance for from 1 to 5 minutes. Has START and RESET buttons. Uses triac, op-amp to control switching and 555 for RESET circuit. Excellent educational Kit. CAUTION: uses mains power. You must know what you are doing. Will switch to 4 Amps. $16195 OPTO•TRIAC MUSIC•TO■LIGHT MODULATOR $14,95 The modern, safe way to make an electrical connection from a low voltage circuit to a high voltage circuit is to use an optocoupler. The opto-triac is a further development. This Kit takes an audio input 1.2-1.5Vand modulates a mains light using an opto-triac & triac. TWO STATION INTERCOM/HARD WIRED 11BUG" Cat. No. K0511 FOX PHONE FM TRANSMlfflR I Build your own gamer of skill. The bi-coloured LED flashes RED & GREEN - press the switch when it is GREEN and the Stairway of 6 LED's starts to light up. But press it when it is RED and you undo all your work. Kit introduces many basic electronic concepts. Box & 9V battery included. Cat.No.K0510 TELEPHONE CONTROLLED TAPE RECORDER SW $18.95 $38,95 A simple but effective 2 station intercom. Each unit contains its own microphone, speaker and audio power amplifier circuit using the LM386. Circuit may be modified to become a hard wired bug. Power can be sent to the remote unit. 10 meters of cable supplied. DIGITAL COMBINATION $31 95 ■ Cheap, versatile and adaptable combination lock. Uses two 14013 quad D flip flops. Set your own secret 4 digit code. Any wrong number or wrong key-in sequence results the lock. Separate touchpad PCB, 3 cable, connectors & 12V relay included. Excellent introduction to security devices. LOCK TOUCH SWITCH & TOUCH PLATE Cat. No. K0306 Cat. No. K0307 $13,95 Both touch switch and touch plate are built into the same kit'. A battery can operate the touch switch. But a mains power supply must be used for the touch plate to operate. Uses the 14011. A 12V relay rated to switch 240V/3A included. SOUND ACTIVATED TAPE RECORDER SWITCHCat. No. K0409 $21.95 Plugs into REMOTE jack of tape recorder. Turns tape recorder on when it detec ts a preselected level of sound. Very sensitive. Once the sound goes away circuit will turn off after a short delay. Uses CMOS 74HC14. Note: Kit does not improve sensitivity of tape recorder itself. ~ FIBRE OPTIC AUDIO LINK Cat. No. K0512 $79,95 Complete Kit to m~_ke an audio link using light guided by 1mm plastic fibre optic cable. 14 feet cable, microphone, speaker supplied. Kit will send signal in over 500 ft of optic cable. 2 PCB. Each requires 9V battery. Uses matched LED emitter/detector from Motolora. Very simple to use. LM386 LOW VOLTAGE AUDIO AMPLIFIER MODUL~at. No. K0611 $11.95 A Kit module designed to be used as a building block in a larger project. The National Semiconductor LM386 is a general purpose power amplifier designed for use in low voltage applications. Gain may be set between 20 and 200. Used in Kit Cat. No. K0511. LM386 Data Sheet included . TDA70521WPOWER AMPLIFIER Cat.No.K0611 $12,95 A 1W power amplifier module designed to be used as a part of a larger project. The Phillips TDA7052 is a general purpose 1Wamplifier ideal for low power battery operations from 3 to 15V. Very few external components required. No heatsink needed. Short circuit protected. Uses 8 ohm speaker. 2 A-ONE~ ELECTRONICS PTY LTD 432-434 Kent Street, Sydney NSW 2000. Phone: (02) 267 4819. Fax: (02) 267 4821. A C.N. 003 882 513. MAIL ORDERS WELCOME: CHEQUE, MONEY ORDER, AMERICAN EXPRESS, BANKCARD,MASTERCARD AND VISA. POSTAL CHARGE $5-$25 ...... $4.50 $51 -$100 ....... $7.00 $26-$50 .... $5.50 Over $100 .... $10.00 Phone or write to us for a copy of your price list. Shop hours Mon-Fri 9-5. Sat 9- 1. All prices include sales tax. ------------------------------------------------------' >. ~~ :flNO·V :flNO-V :flNO-V :flNO-V :flNO ·¥ SERVICEMAN'S LOG A story to support Murphy's Law Traditionally, by Murphy's Law, any servicing short cuts we attempt will always bypass the fault. And conversely, when we find a fault by conventional means, we can see an obvious short cut. But let's not take Murphy too seriously. The truth is, we live on short cuts of one form or another, from recognising the symptoms from previous jobs to the replacement of complete boards in order to save time. Generally, these short cuts work. It is only when they don't work that we blame Murphy (or bad luck). . This story would seem to support Murphy's Law, at least initially. It concerns a Thorn Model 9007 colour TV set, which uses the Mitsubishi G series chassis. This chassis was also marketed as the AWA model C608. These sets are now about 15 years old and this one belongs to a local motel, the owner being a relatively new customer. The owner brought it in with the complaint that it had lost colour and an initial check on the bench confirmed this. However, I found that it was possible to brute force it into colour - of a sort - by deliberately mistuning in the direction of the sound carrier with the colour saturation control wound full up. I used the term "colour - of a sort" because there was something funny about it; that being the only way I could describe it initially. To put it a little more scientifically, I knew it wasn't right but couldn't work out what was wrong with it visually. But there was more wrong with the set than that. The first thing I noticed, apart from the loss of colour, was that the picture was grossly over-scanning; mainly horizontally but also vertically to a somewhat lesser degree. There was also some obvious convergence error. FRACARRO SAVES ••• .. .more than $10. from every UHF television antenna you buy. Fracarro's 4PUN for better performance from weak UHF signals. Peter C. Lacey Services Pty. Ltd. P.O. Box 678 (74Fulton Rd.) Mount Eliza 3930 T el:03 787 2077 Fax: 03) 787 3460 ACN006893438 64 SILICON CHIP Colour bar pattern I fed in a colour bar signal from a TV pattern generator and, by careful mistuning, was able to bring this up in colour. But the degree of mistuning was very critical and it produced a strange effect. While each colour bar displayed the correct colour, it did so for only part of its width, starting with monochrome on the left- hand side and graduating to colour on the right. This probably accounted for the "funny" effect I had observed on program material. . My first reaction to the colour problem was to speculate on a possible front-end fault. Perhaps the tuner or the IF system was upsetting the response curve. However, I put these thoughts aside for the moment and decided to investigate the overscan problem. HT voltage The first thing I check in such cases is the HT rail voltage and this paid off. Normally, the HT for this set is 105V but it was actually sitting on 138V. This was far too high and suggested a fault in the power supply regulator system. This set is made up of a main board ("PCB-MAIN") and a number of auxiliary boards which plug into this via edge connectors. Fortunately, this being an old set, I have accumulated a fair stock of these auxiliary boards from scrapped sets and these prove very useful. First, they can help pinpoint a faulty board quite quickly by simple substitution. Second, leaving the substitute board in place is often the quickest and cheapest solution; an important factor in sets of this age. So I simply fished out a spare "PCBPOWER REG" board and plugged it into the main board. That didn't help much because the HT voltage was virtually identical. This made me suspect that one or both of the power ~~?sr, i"RA't>l1IONAU-'-f, 'B'-f MURPHY'S LAW, A~Y SE"R.V\CIN6 SHO'R.T"CUTS W~ A1TE:M?r W\U... At..WAVS "BVPASS ™e:. FAuL--r.. o regulator transistors , Q901 and Q902 (2SC935), might be leaky. These are mounted off the board, via a plug and socket connection. The plug and socket arrangement makes it easy to check them but I could find nothing wrong. I replaced the original power board and went to the "B-ADJ" pot, VR901, to see if (1) it was still working and (2) whether there was adequate adjustment available. Well, it was working and I had no trouble resetting the HT to the correct 105V with a perfectly reasonable pot setting. In short, all the indications were that there was nothing wrong with the power supply, except that the pot had been incorrectly set. Why this was so was a mystery at that point. And why hadn't the replacement board clarified the problem? It turned out that, for some reason, now lost in history, it was also wrongly set. In fact, I put it back in the set and was able to reset it to 105V as well. So that cured the gross overscan and a minor touch up with the appropriate controls produced a well proportioned picture. But we still had the colour problem. In fact, it was now worse than ever, in the sense that it was much harder to brute force than before (a lesson there, had I but realised it). The next logical board to check was the chroma board, "PCB-CHROMA". I have several on hand and it is a simple un-plug, plug-in operation. But no joy. Remembering how I had been caught with a faulty substitute power board, I tried a second one. But it was no use; this was not the source of the trouble. So what next? Still convinced that the best approach, at least initially, was board substitution, I picked what seemed the next logical one - the "PCB-VIDEO-CHROMA-OUT" board. Again, it was a simple operation, or at least it would have been ifl'd had one in stock. I didn't as it turned out and I finished up borrowing one-from a colleague. Unfortunately, the effort was wasted; there was no joy here either. And that just about exhausted the board swapping approach. All the major and likely sub-boards had been changed, without result. The two suspect areas remaining were the main board and the tuner. Swapping the main board was hardly a proposition, at least at this stage, but I had considered the possi- bility of a tuner problem causing a faulty response curve. Fortunately, I am well set-up to check tuner problems. As mentioned in my last set of notes, I have a self-contained tuner · and power supply which makes an ideal substitute in such situations. It's an old turret type VHF tuner from the monochrome era but it still works perfectly. The substitution was simple. The set's own VHF tuner connects to the IF system, the "PCB-HF" board, via pin 1 of a 4-pin plug (FA). I simply pulled the plug off and clipped the substitute tuner output lead to pin 1. And that disposed of that theory quick smart! There was absolutely no change in the set's behaviour. And it also put paid to the idea of a simple fix by substitution. I was going to have to start working now and track down the fault the hard way. So, harking back to my opening paragraphs, had my short cut attempts been a waste of time? Not at all; they had ruled out a very large part of the set, involving hundreds of components, and forced me to narrow my investigation to relatively few components. That said, I wasn't quite sure where to go from there. The only thing I could immediately think of was the colour burst and/or the associated gating pulse. It was a long shot, because failure here normally means total loss of colour. However, the CRO quickly ruled out that theory, as everything was normal here. What next? So what hadn't I checked? Perhaps I had missed something around the chroma board area and I so I began by checking the supply voltage. The supply to this board is a nominal 20V which is derived from the deflection out board ("PCB-DEFL-OUT") and fed in on pins 1 & 10. This voltage was spot on but I then began wondering about any bypass capacitors associated with this supply. ThE;lre is one on the chroma board (pin 10) but this was ruled out because the board had been changed. Further checks revealed a second bypass capacitor (C579) on the deflection out board, at point "B5". But again I drew a blank as changing it made no difference. I was feeling rather frustrated by now. In desperation, I went over the FEBRUARY 1993 65 a problem. It looked like I would need access to the control board but this, not to put too fine a point on it, is a swine of a thing to remove. What was needed was some other way to conFig.1: the faulty circuit firm my theory before I took such a section in the Thom 9007 colour TV set. Transistors drastic step. Q623 & Q624 are the first & So I tried another tack. By suitably second chroma amplifier juggling the chassis, I was able to reach stages respectively, while the underside of the main board and VR671 (top) is the colour bridge pins 15 & 16 of the edge consaturation control. This pot nector using a clip lead. This was connects to the chroma electrically equivalent to turning the board via a plug connector saturation control fully up which, to the main board (labelled mechanically, was where it had al"MN") & then via pins 15 & ready been set. 15 of an edge connector The result was that the picture imsocket. mediately jumped to full colour saturation. Not only that, but all symptoms of the fault had vanished. I could now bring in colour - albeit oversaturated - on all channels, without resorting to the critical tuning procedure previously required. So at last we had a breakthrough; it physical arrangement. The appropriate part of the cir- was somewhere in the saturation con•ce-•ow~ocus ( cuit is reproduced here as trol circuit. But where? It took only a , ~ I._ Fig.1. The saturation con- moment to shift the clip lead from trol is a soon pot, VR671, pins 15 & 16 on the edge connector to which connects to four pins pins 2 & 4 on the main board, whereon the control board. Pins 1 upon the fault was back exactly as and 3 connect to chassis, before. pin 2 to the moving arm, So what was there between the two and pin 4 to the active end set of pins? Answer: just two copper of the pot. Plug MN fits on tracks, about 70mm long, and the solthese pins and its cable ter- dered joints to them. I went over all minates on a second MN these joints but could find nothing plug which mates with four wrong. Just to make sure, I resoldered ~~i pins on the main board. them anyway but I wasn't really surWith me so far? Right. prised when this had no effect. The saturation control is But I was hot on the trail now. By eventually wired into the pulling the plug off the motherboard chroma amplifier chain pins, I was able to make a resistance aroµnd transistors Q624 measurement from pin 4 to pin 16. and Q625. This is achieved There was no problem there but pin 2 chroma circuit again but without re- by wiring pins 2 and 4 on the main to pin 15 was another story - this sult. Eventually, I finished up near board to pins 15 and 16 of an edge · measured no less than 100!2 And, the top lefthand corner of the chroma connector and this, in turn, carries seeing that I had already cleared the circuit, looking at a 4-pin plug on the the chroma board. Pins 1 and 3 con- soldered joints, this left a faulty copnect to chassis via the main board. per track as the only possibility. main board marked "MN". I had traced out all this circuitry Yet try as I might, I could see nothThis plug connects to the colour saturation control which, along with because I wondered whether the fault ing wrong with it, even with a magnithe contrast, brightness, vertical hold was somewhere in the saturation con- fying glass. Granted, the green lacand horizontal hold controls, is trol circuit. Ifit was, there were plenty quer covering the print didn't help mounted on a sub-board designated of places where it could occur: either and, in any case, I was well past car"PCB-CONTROL". It sits at the front of in the pot itself, in the plugs, between ing about the fine detail. All I wanted the set, beneath the picture tube, and the chroma board and the edge con- was to get the job finished. It was simple enough, of course. A the controls are all connected to the nector, or in the soldered connections appropriate parts of the circuit via to the boards. short length of tinned copper wire plugs, sockets and cables. between the two pins effectively In order to follow what happened Pure speculation wiped out the offending resistance next, it is important to get a clear The trouble was, this was all pure for all time. I then put everything picture of both the circuit and the speculation and proving it presented back together again, satisfied that the SERVICEMAN'S LOG - CTD r 66 SILICON CHIP _____ fault had been positively identif.ied and fixed. Why was the HT high? And that, as far as the job itself was concerned, was that. But there is a little more to the story than just the colour fault. What was the history of the fault and why had I found the HT rail wound up to 138V? As I mentioned at the beginning, this motel is a relatively new customer and this was the first time I had seen this particular set. Prior to that, the motel had employed a serviceman from an adjacent suburb. I know the party concerned. He's a nice enough bloke at a social level and, I have no doubt, is very kind to his mother. But his technical expertise is another matter. In short, I don't have a very high regard for it. So what happened? I can only speculate, of course, but I think it went something like this. The board was probably cracked right from the start but functioned OK while the two edges of the copper track were bright and touching. But eventually the copper corroded and this introduced It had him beaten until he discovered, TETIA TV TIP Panasonic NV-G22A VCR (G mechanism) Symptom: machine won't accept cassette. Capstan motor runs backwards and forwards for 1015 seconds, then machine switches off. If fault occurs while tape is loaded, machine will not eject. Cure: Check for "cut washer" clip on shaft under centre pulley. The pulley contains a spring loaded clutch which has a tendency to push the clip off the shaft. TETIA TV Tip is supplied by the Tasmanian branch of the Electronic Technician's Institute ofAustralia. Contact Jim Lawler, 16 Adina St, Gei/ston Bay 7015. More on computers enough resistance to upset the colour to some extent, at least on an intermittent basis. It was too much for our serviceman friend, although I would be the first to concede that it was a very nasty fault. Electronics Workbench® The electronics lab in a computer! A simple, intuitive and very powerful teaching tool, Electronics Workbench lets students and hol!byists design and test both analog and digital electronic circuits, without the delays and expense of a laboratory. FEATURES • Quick and simple circuit entry • Digital and Analog Modules included, complete with all components • Simulated instruments: dual trace scope, spectrum analyser, function generator, multimeter, digital word generator and logic analyser • Complete control over all component values and parameters • Print: circuit schematics, parts list, instrument readings, macros • Logic conversion - truth table to Boolean formula to logic gates • Customisable hypertext help system probably by accident, that he could cure it by jacking up the HT. So that was what he did, hoping that the resultant overscan would go unnoticed - which it did. Eventually, of course, the corrosion increased and the fault re-appeared, intermittently at first, then permanently. And that's where I came in. Am I being too hard? I don't think so. I would be the first to agree that anyone can be stumped by a stinker and I'm not criticising on that basis. But faking a cure is another matter. Apart from the fact that the customer is being cheated, it simply doesn't pay off in a purely business sense. Sooner or later it backfires and the customer forms his own conclusions. Anyway, I've scored a satisfied cus. tamer. THREE VERSIONS • Professional Version: EGA/VGA colour display; unlimited components • Personal Plus Version: Monochrome display; unlimited components • Personal Version: Monochrome display; limited to 20 components per ... EMONA INSTRUMENTS NSW ......................... (02) 519 3933 VIC ............................ (03) 889 0427 QLD .......................... (07) 397 7427 DISTRIBUTORS Perth ... ........ ..... ......... .. ... (09) 244 2777 Adelaide .. ...................... (08) 362 7548 Hobart .... ..... ........ ....... ... . (002) 34 2233 After my two previous stories about servicing computer monitors, I imagined that that would be the end of it; that I could go back to doing fair dinkum service work. But it was not to be; someone blabbed about my monitor repairs and before long I had EmonaLAB4 Four instruments in one package! The LAB4 has four full function test instruments: ■ DC POWER SUPPLY Triple output; 5V, 15V, 0-SOV ■ DIGITAL MULTIMETER ■ FUNCTION GENERATOR with neatly laid out and labelled front panel controls. Also, the LAB4 is compact and only takes up a small space, compared to four bench-top instruments. Full function, auto-ranging 0.02Hz-2MHz, with SWEEP ■ FREQUENCY COUNT,ER · 1Hz-100MHz input range INDEPENDENT INSTRUMENTS Each instrument in the LAB4 is completely independent and can be switched ON or OFF as required . The LAB4 has only one 240V mains input, saving on multiple power points. Each instrument is clearly defined EMONA INSTRUMENTS NSW ......................... (02) 519 3933 VIC ............................ (03) 889 0427 QLD .......................... (07) 397 7427 DISTRIBUTORS Perth ........................ ..... (09) 244 2777 Adelaide ....... (08) 362 7548 Hobart ......... (002) 34 2233 FEBR{!ARY 1993 67 SERVICEMAN'S LOG - CTD ~ c::=:::::::, ~ c:>C::::.~ another customer appealing for help with a suspect monitor. It turned out to be another Acer MM211 - a fact which made me feel almost cocky about tackling it. After all, I now knew where all the screws were. On the other hand, it seemed to be tempting fate to hope that it would be another power supply fault. ' Even so, the symptoms as related by the customer seemed to support that theory. The fault had first appeared as a collapsed vertical scan, resulting in a bright horizontal line across the middle of the screen. It had lasted only a second or so, the monitor then reverting to a normal display. In fact, the customer at that time wasn't even sure whether there was a fault or whether he had simply observed a brief mains power failure. When the fault subsequently reoccurred several more times, he knew he had a problem. On the other hand, he wasn't sure what to do about it. He knew enough about intermittent faults 68 SILICON CHIP to realise that tracking them down could take days, or even weeks. And as he was using the computer professionally, he couldn't afford to have it out of action for a long period. So he kept flogging it along while ever it would go until, inevitably, it failed completely. And that was the best thing that could have happened really. At least ·I had something to work on. With the cover removed, I went straight to the 12V rail where it emerges from the 12Vregulator. It was dead, so I moved back to the input and measured 20V which, from my previous experience, was spot on. Crook regulator My immediate conclusion was that the regulator had packed it in but I checked the 12V rail for shorts, just to be sure. There was nothing wrong there, which left only the regulator. This was mounted on a 75mm-long finned heatsink which is attached to the PC board by a couple of screws tapped into one end. The regulator IC was mounted near the bottom of this heatsink, with its three leads passing through holes in the board to the copper pattern on the underside. The first problem was to identify the IC. I can't remember the type number but it was a new one on me and so I sought the help of the friendly man behind the counter at the local Dick Smith Electronics store. It turned out that he was quite familiar with the unit and the circuit but not with the regulator IC. No problem, though. A quick phone call to the service department at headquarters and he had the answer. The original type number was not available but it could be replaced by a 7812. This is a regular stock item and he pushed one across the counter. I expected that that would virtually be the end of the story, the repair involving no more than a routine replacement. But not quite. Not being familiar with the faulty IC, I took the precaution of tracing the copper pattern around the pin connections before I removed it. And just as well. Having identified the pin connections, I compared them with the 7812 arrangement and found, as I feared, that they were not the same; two of the pin connections were transposed. This was an annoying development because it meant a messy repair. The IC would have to adopt a crossed leg attitude and I would probably have to attach an extension lead to one leg to facilitate this. I was trying to figure out how best to do this when I noticed an extra set of unused holes adjacent to those for the existing regulator but which had no apparent purpose. When I traced the copper pattern around these holes, it quickly confirmed what I had begun to hope. The makers had anticipated this situation and had provided a second set of connections to suit the alternative pin arrangement. From there on, it was plain sailing. I mounted the IC on the heatsink, soldered its leads to the alternative pads, and put everything back together again. And, of course, it worked and I had another happy customer. But I swore him to secrecy. I don't want any more computer monitors, thank you. And they're making them in colour now, aren't they? Ouch! SC :AR :AR :AR :AR ]!~ ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR m~fR I AYCAR ELE T NI R E TRONICS JAYCAR E TR NI JAY :AR :AR :AR :AR :AR :AR :AR :AR ELEC ELECT ELECT ELECT ELECT ELECT ELECT ELECT ;AR :AR :AR :AR ELECT ELECT ELECT ELECT ]!~ mg ]!~ ~tm ]!~ ~tm :AR ELECT ]!~~tm :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT ]!~ ~t~g :AR ELECT :AR ELECT ;AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR :AR ELECT ELECT :AR :AR ELECT ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT !!~ ~t~~i :AR ELECT ;AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT !!~ ~t~~f :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT :AR ELECT !!~ ~t~~f :AR ELECT ELECTRONICS JAYCAR ELECTRONICS JAYCAH tLtt; I HUNJt;:; JAYL:AH ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR Y E TR NI Y tLtt; 1HUNlt.:~ ELECTRONICS ELECTRONICS ELECTRONICS ~T~g~:~: RONIC RONIC ITRONIC [TRONIC ITRONIC trRONIC trRON IC [TRONIC ■■■liiiiiiiiiiiiiiii Stock is limited, there may not be all items in all stores. If your nearest Jaycar Showroom has sold out of the item you want to purchase, you can phone -(02) 743 6144 and they will advise which stores had that particular product in stock at the beginning of the sale. You can also phone around yourself, or you can place an order with our Mail Order Department on (02) 743 6144, using a credit card and we will do the finding for you and send you the goods (plus post and packing). For full specifications and descriptions on the products listed below check our 1992 catalogue. Be quick, stock is limited and won't last. Description WAS Answering machine/data $1.95 Cassette 60 min 12 cassette carry case $2.50 TV lightweight headphones $9.95 Aviation headset series II $189.00 Push to talk switch for above $29.95 8 ohm 5 watt oval speaker $4.95 6" black metal speaker grille $6.95 CB microphone with lead $24.95 Microphone wired/wireless $45.95 Microphone electret/ $29.95 unidirectional Philips stereo microphone $29.95 22mm microphone wind shield $2.50 BNC - PL259 video cable 1.8m $3.95 PL259 - PL259 video cable 1.8m $2.95 PL259 - RCA video cable 1.8m $2.95 IC OP-amp cookbook $39.95 CMOS cookbook $44.95 TTL cookbook $44.95 IBM personal upgrade $44.95 guidebook Practical digital elect handbook $19.95 Synthesisers for musicians book $19.95 Electronics build and learn book $17.95 Introduction to digital audio book$17.95 How to set up home recording $17.95 studio book Home security electronic $19.95 projects book MS DOS/PC DOS quick $12.95 reference book 386 computer handbook $19.95 1-2-3 for Windows 1st step book $22.95 WordPerfect for Windows book $22.95 Understanding digital $12.95 troubleshooting book 24 SCR projects book $14.95 Understanding automation $12.95 systems book Understanding computer $12.95 science book Relay and their applications book $9.95 51 projects using CD4011 $3.95 IC book Fascinating IC's book $3.95 DigitallC's book $7.95 150 circuits book $9.95 Simple electronics $3.95 experiment book Electronic hobby circuits book $3.95 Simple audio projects book $3.95 Practical audio visual $3.95 projects book Semiconductor diodes book $2.95 Practical electronic games book $3.95 Learn by experimenting CMOS $7.95 IC's book Build your own test $4.95 instruments book Practical electronic projects book$3.95 Practical OP amp pro1·ects book $7.95 Electronic gadgets for you book $3.95 Exciting electronics $3.95 experiment book Using function generators $7.95 and PLLS book NOW $1.50 $2.00 $5.95 $150.00 $20.00 $3.50 $5.00 $18.00 $32.95 $23.95 $19.95 $1.50 $2.00 $1.50 $2.00 $29.95 $34.95 $34.95 $34.95 $7.95 $12.95 $7.95 $12.95 $12.95 $12.95 $9.95 $14.95 $15.95 $15.95 $9.95 $9.95 $9.95 $8.95 $6.95 $2.95 $2.95 $4 .95 $5.95 $2.50 $2.50 $2.50 $2.50 Cat. No. Description WAS BM-2460 Electronic science $3.95 experiments book BM-2461 Understanding & using $3.95 mu ltimeters book BM-2462 Practical electron ic devices book $3.95 BM-2463 Electronic projects for the $3.95 car book BM-2467 Build your own intercoms book $4.95 BM-2468 Versatile electronic circuits book $7.95 BM-2475 Teach yourself DOS $19.95 3.3 & 4.0 book BM-2476 Encyclopedia of $34.95 electronic circuits BM-2480 Thyristor theory app book $12.95 BM-2452 Practical electronic games book $3.95 BM-4556 Inter'! OP amp & Linear IC select $22.95 BM-4558 Inter'! digitallC selector book $14.95 BM-4560 Inter'! diode & SRC index book $24.95 BM-4564 Inter'! microprocessor selector $8.95 CM-2084 Med horn midrange 30W speaker$32.95 CW-2152 10" subwoofer 120W rms $129.50 CS-2480 Studio 3-55L speaker kit $279.00 CX-2610 Minstrel 2 way crossover $29.50 DC-3080 CB quick disconnect ant fitting $13.95 DC-3084 CB lighttension spring 5/16" $12.95 DC-3087 CB mic clip magnetic $2.95 DC-4000 Cellular car phone antenna $49.95 HP-0415 3mm x 25mm R/H bolt pkl 200 $5.95 HP-0419 3mm x 32mm R/H bolt pkt 200 $7.50 HP-0451 4mm x 10mm R/H bolt pkl 200 $6.50 HP-0466 4mm washer flat pkt 200 $5.50 HP-0506 4mm x 12mm C/H bolt pkl 20 $2.95 HP-0622 No6x15mm black spkr $22.95 screw pkl 200 HP-0626 No10 x 30mm black spkr $27.50 screw pkl 200 HP-1177 8mm cable clips pkl 100 $7.95 HB-5480 Alarm control panel box metal $24.95 HB-5935 Vero box $28.95 205(w) x 140(d) x 110(h)mm HB-5948 Black plugpack type box $2.95 HB-6051 Sml quality box $15.95 160(I)x80(w)x44(h)mm HB-6052 Med quality box $16.95 160(1) x 80(w)x60(h)mm HB-6056 Lge quality box $21.95 197(I)x110(w)x86(h)mm HB-6250 Waterproof box $19.95 150(I)x110(w)x70(h)mm HH-8510 1 x T03 heatsink 50x50x25mm $2.95 HG-9901 Copper tape .031 " EZC300311 $5.65 HG-9902 Copper tape .05" EZ300501 $5.65 HG-9909 14 DIL pattern EZ6014 $5.95 HG-9910 16 DIL pattern large EZ6004 $7.25 HG-9918 14 DIL pattern small EZ6013 $7.25 HG-9919 16 DIL pattern large EZ6453 $7.25 HG-9920 40 DIL pattern large EZ6987 $7.25 HG-9931 Tape .031 " 20yd EZ3004 $5.50 HG-9934 Tape .062" 20yd EZC3010 $5.50 HG-9935 Tape .080" 20yd EZC3012 $5.50 HG-9938 Tape .125" 20yd EZC3018 $5.60 HG-9939 Tape .200" 20yd EZC3020 $5.60 HG-9945 Pad 156"0D x 0.031" ID EZD103 $5.60 HG-9948 Pad 250"00 x 0.062" ID EZD109 $5.60 HG-9991 Scotchcal plastic black/white $11.95 KA-1390 Kit - 50MHz freq enter EA12/91 $169.50 KA-1598 Kit - 40 watt inverter EA8/85 $99.50 KA-1610 Kit - 300 watt inverter EA9/85 $269.00 NOW $2.50 Cat. No. KA-1696 KA-1699 $2.50 $2.50 $2.50 $2.95 $4.95 $14.95 KA-1724 KA-1728 KA-1729 KA-1731 KM-3044 KC-5052 KC-5075 $26.95 KC-5076 $9.95 $2.50 $17.95 $6.95 $19.95 $6.95 $19.95 $99.00 $229.00 $22.95 $8.95 $7.95 $1.00 $34.95 $3.95 $4.95 $4.50 $3.50 $1.00 $14.95 $19.95 $3.95 $16.95 $19.95 $1.95 $11.95 $12.95 $16.95 $9.95 $2.00 $3.95 $3.95 $3.95 $4.95 $4.95 $3.95 $3.95 $3.50 $3.25 $3.25 $3.25 $3.25 $3.25 $3.25 $8.95 $139.00 $75.00 $199.00 KC-5077 KC-5082 KC-5085 KC-5088 KC-5096 KC-5100 KC-5111 KC-5114 LF-1260 LT-3180 LM-3846 LM-3850 LA-5012 LA-5018 LA-5020 LA-5022 LA-5023 LA-5065 LA-5160 LA-5187 LA-5270 LA-5272 LR-8850 LA-8922 MB-3520 MS-4004 MT-4710 MT-4720 Ml-5000 ME-6000 ME-6002 ME-6010 NA-1030 NA-1032 NC-4266 PS-0186 PP-0247 PS-0355 PS-0357 PS-0358 PP-0412 PP-0414 PS-0619 PP-0670 PS-0672 PP-0685 PS-0688 PP-0861 PS-0895 PS-0896 Description WAS Kit - Temp probe multi meters $19.95 Kit- Bench amp/signal $44.95 tracer EA4/88 Kit-Voltup 1.5V- 9VDC EA 5/90 $19.95 Kit-VHF powermatch $52.50 Mk2 EA9/90 Kit - RF probe - suit 1728 EA9/90 $7.50 Kit - Trans/FET tester EA10/90 $32.00 Kit- 6000 Mosfet mod AEM7/86 $149.95 Kit - Touch lamp dimmer SC6/89 $34.95 Kit - Capacitance meter $109.00 1pF-9999µF SC5/90 Kit - Reluctor high energy $46.95 ignition SC5/90 Kit- Universal stereo $24.95 preamp SC6/90 Kit - DC offset for DMM SC8/90 $34.95 Kit- Dimmer discolight SC10/90 $39.95 Kit - Fruit machine SC1/91 $24.95 Kit-4 channel lighting desk $329.00 Kit-Talking voltmeter SC10/91 $42.95 Kit - Telephone call timer SC3/92 $29.95 Kit - VHF TV transmitter SC3/92 $89.50 Pot core FX2243 pair $14.95 Outdoor UHF band 4 & 5 antenna$39.95 RF modulator $3.95 Audio/video modulator UHF $34.95 PIR doorway mini alarm $49.95 Pulse count PIR detector $79.00 Hall lens for above $5.95 PIR intelligent pulse count det $99.00 Hall lens for above $5.95 Glass shatter detector $9.95 Alarm digital access keypad $69.95 4 sector expan board Scope 6/30 $45.00 Life guard vapour detector $39.95 GUM-50 life guard vap detector $24.95 4 door centrallocking kit $119.50 Moss hyper car interior detector $99.50 12 volt 4 amp car battery charger$44.95 IEC mains filter 3 amp $9.95 Balanced microphone $37.50 transformer 200/50k Mic line-line transformer 1Ok-10k$37.50 Inverter 12VDC to 240VAC 300W $399.00 Universal electric fence $129.50 Earth stake to suit above $14.95 High efficiency electric fence $139.50 Screen care spray$7.50 monitor cleaner Compuclean spray$10.95 computer cleaner PCB etch resist ER-71 $14.95 6.5mm stereo chassis ski $2.25 RCA plug metal - solderless $1.95 6 pin DIN line ski $1.20 7 pin DIN chassis ski $1.85 8 pin DIN line ski $1.95 2mm plug for multimeters red $0.90 2mm plug for multimeters black $0.90 Rapid wire solderless coupler $3.50 Twinax coax metal plug $9.95 Twinax coax chassis ski $11.95 PL259 rapid plug solderless $3.50 S0-239 bulkhead ski round $2.25 D37 male PC mount connector $2.95 Centronics socket $4.95 Centronics IDC line socket $6.95 NOW $12.95 $39.95 $12.95 $39.95 $3.95 $24.95 $109.00 $27.95 $85.00 $29.95 $19.95 $18.50 $29.95 $14.95 $269.00 $29.95 $19.95 $69.50 $7.95 $29.95 $2.95 $24.95 $34.95 $55.00 $2.95 $79.00 $2.95 $4.95 $49.95 $19.95 $14.95 $10.00 $89.00 $65.00 $34.95 $7.95 $29.95 $29.95 $295.00 $89.50 $8.95 $99.50 $5.50 $6.95 $3.95 $1.00 $1.00 $0.60 $0.80 $0.80 $0.40 $0.40 $1.50 $5.00 $5.00 $1.50 $1.00 $0.20 $2.50 $2.95 [TRONIC. 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TRON IC TRON If TRONIC f~g~:~ TRONICTRONIG TRONI ( TRONll TRON IC TRON IC TRON IC TRON IC TRON IC TAO NIC~ TRON IC:· TRONICi TRON Ic: TRON IC' TRONIC, $2.50 :AR ELECT $2.50 :AR ELECT $3.95 :AR ELECT :AR ELECT $2.95 :AR ELECT :AR ELECT $2 .50 :AR ELECT $4.95 :AR ELECT :AR ELECT $2.50 :AR ELECT $2.50 :AR ELECT :AR ELECT $4.95 :AR ELECT :AR ELECT :AR ELECT~ !11'11!""111Ji[1!11!1!1"'9""1!!1[11!1111~1[191!(1~!1!11!'!19'1ll!llll!I.Pl!lil!!l!ll\l!l!!ll!llll!!!li!l!!lllllll1J!ll[!l"9!'!1!11""1PJ1!11!!!111!11l!'l~-!lll!!i!ll!!llft!!lll!!illll!lllilf!ll!!IIIJ!ll~""'!llll""i!IRl'l!!l~~!l!ll""'·""'l!lllll!ll!!IITRONIC' AR ELECT TRONIC~. AR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONIC~ AR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICi AR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICi AR.ELECIBONI.CS JAYCAR ELECIB.0.NJ.CS_,!fil'CAR Et.ECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR E~~E~ONICS JAYCAR ELECTRO~!£~ ~~~~~~~£!~2~!£~ ~~~£~~ ~~~£~~2~!£: V ORDER FORM · BACK ISSUES* MONTH VEAR MONTH VEAR MONTH VEAR MONTH VEAR *Back issues are $AS each (incl. postage). Overseas orders add $A 1 per issue for postage . BINDERS . Please send me _ _ SILICON CHIP binder(s) at $A14.95 each (incl. postage). Overseas orders please add $A3.00 each for postage. TOTAL PRICE $A SUBSCRIPTIONS 0 New subscription - month to start 0 Renewal - Sub. No. r------------, I I I I I I I I I I 0 Gift subscription l<at>r' 2 years (24 issues) RATES (please tick one) NZ & PNG (airmail) 0 0 0 Overseas surface mail 0$A130 Overseas airmail 0 Australia Australia with binder(s)* 1 year (12 issues) 0 0 0 0 0 $A84 $A105 $A130 $A240 $A42 $A53 $A65 $A65 $A120 *1 binder with 1-year subscription; 2 binders with 2-year subscription I I YOUR DETAILS ,., Your Name (PLEASE PRINT) . Address Postcode Daytime telephone number D Cheque/Money Order Card No. I I I I 0 11 Bankcard 0 Visa Card GIFT SUBSCRIPTION DETAILS Month to start Message Gift for: Name I I I I I I I I I I I- (PLEASE PRI NT) I Address I I I I I I I I State Postcode I IL _ _ _ _ _ _ _ _ _ _ _ _ .JI Signature 0 Master Card I I I II I I I II I I I I Phone (02) 979 5644 Fax (02) 979 6503 9am-5pm Mon-Fri. Please have your credit card details ready Fax the coupon with your credit card details 24 hours 7 days a week Card expiry date I Mail coupon to: Freepost 25 Silicon Chip Publications PO Box 139, Collaroy Beach 2097 No postage stamp required in Australia FEBRUARY 1993 73 I PRODUCT SHOWCASE I 100 watt audio amplifier module Although this amplifier module from A-One Electronics is labelled as a "lO0W pure class A main amplifier", it is technically a class AB amplifier judging from the size of the heatsink and the fact that it has a single 2A fuse. In fact, the circuit information gives details of how to set up the quiescent current. The resultant current of 600 milliamps is much higher than the usual 50-lO0mA one would expect for a typical class AB design and will effectively give class A operation up to about 1 watt RMS into an 8-ohm load. Recommended supply voltages range from ±30V to ±42V although maximum power will naturally be reduced at the lower voltages. A suggested layout of two modules in a stereo amplifier has fan cooling which would be mandatory in view of the standing dissipation ofup to 48 watts in each channel. The module is well made and has a complementary differential amplifier in the input circuit and MS15003/4s as complementary common emitter Digital recorder/ announcer Kingray video combiner amplifier This very handy device is incorrectly named which must cause a lot of confusion to potential buyers. It does not amplify or combine video signals. What it does do is combine the signal from a VHFI UHF antenna with the modulated RF output signal from a VCR. The combined signal is then amplified and fed to a 4-way splitter. Tlie effective gain at each of the four outputs is +6dB, referred to the antenna input. If it was correctly named, it would perhaps be called a "VHF/ UHF/VCR combinei-/splitter" which is still a mouthful and possibly just as confusing to the uninitiated. What the Kingray SA214V does do is enable you to watch off-air programs or tapes from your VCR on four TV sets in 74 SILICON CHIP stages (ie, not emitter followers) in the output circuit. The 100W module(CatS0313) is available for $79 from A-One Electronics Pty Ltd, 432-434 Kent Street, Sydney 2000. Phone (02) 267 4819. your household. It is powered from a 9V DC plugpack which is connected to one of the 75-ohm output sockets via their PSK0l power adaptor. This is supplied together with the 9V plugpack. As such, the SA214V is a very useful accessory and one which will find use in many households with more than one TV set. We're pleased to report that the SA214V is manufactured in Australia and appears to be very well made. The unit is available from David Reid Electronics at $99.95. The MOH330A digital recorder announcer from Eletech uses CVSD compression to provide good quality audio record/play from a compact desktop machine. Originally designed to replace on-hold signal devices such as tape recorders and radio sets, the MOH330A recorder has many other applications. Due to its solid state design with no moving parts the unit is ultra reliable. Good quality speech or music can be recorded on the device using a microphone or the line input. A VU meter displays the record and playback levels. One or two messages can be stored with lengths of up to four minutes and eight seconds. Connections to the unit are via standard audio connectors or phone jacks. An external control can start the playback for use in talking signs, security messages, fire warning systems, etc. For further information contact Zenology Sales Pty Ltd, 7/245 Springvale Road, Glen Waverley, Vic 3150. Phone (03) 802 0599). First High-Speed IEEE 488.2 Controller for Notebook PCs New concept in handheld logic analysers IOtech The "LogicBridge 136" is a new concept in logic analysers. Handheld and battery powered, the LogicBridge performs as an intelligent 3-channel logic probe, yet is also able to store and display waveforms like a logic analyser. Basically it is a dedicated logic instrument for those involved in the design, repair or maintenance of digital electronic circuits and equipment. Fast waveforms can be easily identified by taking a "logical snapshot". Not only can this save hours of lab work but with such a facility, data can be retrieved from memories for later review and analysis. The waveforms are viewed and measured on a high resolution LED display which simulates binary level signal/channel traces as displayed on a logic analyser's CRT. The effective real time bandwidth of the Model 136 is 10MHz but the glitch catcher function allows the capture of pulses down to 50 nanoseconds. The unit may be operated in real time or memory mode. Memory mode allows for the acquisition and storage of up to 100-bit sequences. Waveforms can then be recalled, visually or logically compared (AND, OR, EXCLUSIVE OR) to incoming waveforms or fed to an external source via a serial port. Up to 12 consecutive memories (two waveforms each) can be automatically linked together to store long data sequences. Being a dedicated instrument, the LogicBridge 136 has a range of useful digital debugging, signal identification and tracing facilities. In addition, the audio output may be used for indicating an occurence of trigger and for The Personal488/NB is a compact external IEEE 488.2 interface that enables 170 Kbyte/s IEEE 488.22 control of up to fourteen IEEE instruments from a notebook PC via its parallel port. A virtual PC plug-in board in terms of speed and performance, the Personal488/NB is compatible with both IOtech 's DLL driver for Microsoft Windows and with its DOS subroutinestyle and device driver software. The Personal488/NB also supports third-party data acquisition software packages, such as DADiSP and Labtech Notebook. The Personal488/NB uses FPGA (field programmable gate array) technology to permit simultaneous instrument-control and printer transactions via its connection to a notebook PC's parallel port. The unit can draw power from a notebook PC's keyboard port, a 7 to 15 VDC voltage source, or a standard A/ C voltage source via an included power supply. Portable and Remote Applications. As notebook PCs decrease in price and increase in functionality and power, many engineers are finding them practical, easily transportable alternatives to cumbersome desktop PCs. The Personal488/NB enables engineers to use notebook PCs in IEEE instrument control and data acquisition. It is well suited for vehicle testing, such as aircraft and automobile testing, where physical space is at a premium, and is also ideal for users who require a portable computer, such as test-instrument sales engineers, who can now use notebook PCs to demonstrate IEEE 488 instruments on customer calls. The Personal488/NB is also useful for engineers who need to analyse acquired data away from the test site because it enables the same notebook PC to be used both on-site for data acquisition, and in the Jab for subsequent data analysis. This eliminates the time-consuming data transfer processes and cross-platform incompatibility problems sometimes associated with using one desktop PC for testing and another for analysis. SCIENTIFIC DEVICES AUSTRALIA PTY LTD ~ Melbourne Fax Sydney Fax Adelaide Fax (03) (03) (02) (02) (08) (08) 579 579 344 349 281 281 3622 0971 5200 2602 3788 4194 Product names listed are trademarks of their respective manufacturers' company. FEBRUARY 1993 75 actual waveshape identification. For further information, contact Emona Instruments, PO Box K720, Haymarket, NSW 2000. Phone (02) 519 3933. . . . .. .,. ,...... "' ......... ,. . ............ . . . .. . . .. . . .. " ' ... 4"."-¥ .... «". ...... .> .. ' ......... . .i ... " ,. ~ j .. "' .. " ........ "' ••• • 1ii ......... • If " ..... " . ;jt • •••• . .... . .... " a • • ♦ • • • • • Handy breadboard for small prototype circuits If you want to wire up a circuit with just a few ICs these little prototyping boards are quite handy. They have 29 columns of terminals and so you could insert three 14-pin ICs and one 8-pin IC, or other combinations to take up the space. The board has double-sided foam tape on the back so it can be conveniently mounted on a metal plate and it also comes with a handy little pad of wiring sheets so you can record your layouts. All this costs just $5 .95 (Cat. P11002) from Rod Irving Electronics, 74 Parramatta Rd, Stanmore, NSW or interstate branches. Solar powered musical keychain from Rod Irving Electronics This little keyfob is a bit of a gimmick. When its solar cell is exposed to strong light it plays "Somewhere Over The Rainbow" al though we suspect that noone will be tempted to sing along with it. More useful is the integral lamp which can be lit by pressing the button - handy for finding keyholes in the dark. The unit is completely sealed so we have no way of knowing whether it has an internal cell or not._At the price of only $4. 95 it is quite a useful device. But try to keep it out of sunlight if you don't want to hear that tune again. The solar keychain (Cat. Z19060) is available from all Rod Irving Electronics stores. Philips 21-inch high-resolution computer monitor ANTRIM 'TOROIDAL TRANSFORMERS • Now made in Australia. • Standard range 15VA co 2kVA. • Large ex-stock quantities available. • Competitive pricing available for OEMs & resellers. • Simply the best transformers all round. HARBUCH ELECTRONICS PTY Lm 90 George Street, Hornsby NSW 2077. Telephone (02) 476 5854. Fax (02) 476 3231. 76 S ILICON CHIP Philips has introduced a 21-inch model in its highperformance Brilliance monitor range. The Brilliance 2110 is an autoscan colour monitor that supports resolutions of up to 1600 x 1280 and an extended horizontal scanning frequency range of up to 82kHz. T,rnse high refresh rates are essential to obtain a stable, flicker-free display with such large screen sizes. . The high resolution and display quality of the Brilliance 2110, together with its extensive digital adjustment facilities, make this monitor an outstanding choice for the mos,t demanding applications in areas like CAD, graphic design, DTP and professional pre-press work. Microprocessor-based digital control of all display parameters ensures secure and reliable setting-up. Handling a wide range of display modes is made easy by a IAN J. TRUSCOTT'S ELECTRONIC WORLD 30 Lacey Street, Croydon, 3136. Phone (03) 723 3344; Fax: (03) 725 9443. Now also at: 200 Smith Street, Collingwood. Phone (03) 419 8208 Mail & Credit Card Orders Welcome We now have a range of 5,6,8,9 & 10 pin Ask about our range of E.A.O. precision resistor networks and a comprehensive push button switches, motor start range of micro's and eproms at ridiculous capacitors and Beckman Industrial prices. Quote this ad and receive another multimeters. 5% discount. $l6.80ea. 27C010-15 1 meg eprom 150ns..... $8.IOea. SAB8031 P Romless Micro ........ 2.50ea. MAB8049H Romless Micro ....... $2.50ea. 62256-LP S-Ram ..................... $9.75ea. 41256 D-Ram ................................. $2.60ea. 27C020-15 2 meg eprom 150ns.... FEBRUARY SPECIAL: BECKMAN DM 15XL Multimeter $119 $10.00 ea. 3mw Laser Tube & inverter $99.00 ea. 6 volt 1 watt Solar Panels Infra Red Night Viewing Monocular (kit) $269.00. COMPONENT PHONE ORDER HOTLINE (03) 723 3344 ON SALE NOW First edition Vintage Radio Calendar, in full colour. Featuring a selection of Australia's most photogenic radios. Ideal Christmas gift for friends and .collectors overseas. Available from Resurrection Radi CREDIT CARDS ACCEPTED 51 CHAPEL STREET, WINDSOR, VIC. 3181. PHONE (03) 529 5639. FEBRUARY 1993 77 choice of 22 preset modes; 14 factory preset and the other 8 user-definable. The Brilliance 2110 automatically recognises the horizontal and vertical scanning frequencies of the graphic card to which it is connected, and selects the corresponding display mode. Different modes can be manually selected if desired. Precision colour-matching provides a choice of three colour temperature modes: standard 6500K or 9300K settings, or a user-definable mode with .individual RGB adjustment. This function allows a desired colour balance to be achieved with digital precision; an important benefit in applications where critical matching of external colour references is needed. Also newly introduced is a 20-inch monitor (type number C2082-DAS) fitted with a Trinitron slotted shadowmask tube. This model meets the preference of some users who prefer the Trinitron tube. Other facilities and performance aspects of the C2082DAS are virtually identical to those of the Brilliance 2110, except for the maximum resolution of 1280 x 1024. Distributed in Australia by Clear Technology, the Philips Brilliance 2110 retails for around $5,999 including tax and the C2082-DAS for $5,160 including tax. For further information, contact Philips Components, 34 Waterloo Rd, North Ryde, 2113. Phone (02) 805 4455. 20V/20A power supply with variable output If you want lots of current at up to 20V DC this power supply module is an easy way to get it. The module is completely built and tested; all you LD9000 LP gas leak detector The LD9000 LP gas leak detector is manufactured in Brisbane and uses a "Figaro" sensor. Gas presence is indicated both by an audible alarm and by flashing red lights in the display panel. Red lights also indicate "ON" and "charge". have to do is mount it in a suitable chassis with fan cooling and connect a suitable large power transformer. Essentially, the circuit is a simple series regulator with five TO-3 power transistors connected in parallel to share the output current. At first sight, there appear to be eight power transistors on the large heatsink but two of these comprise the full wave rectifier diodes while the other transistor is Sony's CCD-TR805E camcorder - ctd from page 15 is in telephoto mode. However, such a demonstration really does not show how effective the system is. When Sony released the TR-805E onto the Australian market, they demonstrated the effectiveness of the "steady shot" system by mounting the unit on a motor driven vibrator. With the "steady shot" system switched off, the picture was completely obliterated by the image blurring; with "steady shot" switched on, the picture was normal - a dramatic demonstration. 78 SILICON CHIP With such a plethora of features on a small camcorder, you might wonder whether it is too much for the average user to comprehend. No doubt it is but the beauty of the TR-805E is that you can use as many or as few of the features as you want and just ignore the others. It can be used very simply just by letting the machine do everything automatically or you can intervene as much as you like to get the precise recordings you want. Either way, the results are very good and potentially better than can be The unit is supplied with two battery chargers, one for 240VAC operation, the other for 12VDC from a cigarette lighter outlet. Four rechargeable batteries are fitted inside the unit and these provide up to six hours operation. For further information contact David Hall Electronics, 3/376 Kingston Road, Slacks Creek, Qld 412 7. Phone (07) 808 2777. the driver for the five output devices. The circuit has selectable current limiting as well as short circuit protection. The module appears to be well made and the components are certainly rated for the high current output. It is available at $134 (Cat. SO 005) from A-One Electronics Pty Ltd, 432-434 Kent St, Sydney 2000 Phone (02) 267 4819. SC achieved via any ordinary PAL monitor - you need an S-video monitor to get the best results. In summary then, the Sony CCDTR805E camcorder is a most impressive unit incorporating a host of features, some of which weren't even thought of a few years ago or were only previously available on top of the range units. Recommended retail price of the CCD-TR805E is $2999. For further information, contact your local Sony retailer or Sony Australia Pty Ltd, 3339 Talavera Rd, North Ryde, 2113. Phone (02) 878 9712. SC Introducing the Tektronix 2212 Value Priced at $345 0 * Real Analog - Real Digital Storage No Compromise ■ 60 MHz Bandwidth ■ 20MS/sec Maximum Digitizing Speed ■ Analog and Digital Storage Operation ■ On - Screen Parameter Readout ■ Auto setup ■ 4K Record Length ■ Parallel Printer Interface (STD) ■ 2 1Ox Probes Included ■ Fully Programmable via RS-232/GPIB (Opt) ■ 3 Year Warranty For further information on Tektronix 2212 Portable Oscilloscope Call Toll Free (008) 023342 or contact your local Tektronix office. Tektronix /rest and Measurement Sydney (02) 888 7066 Melbourne (03) 836 3355 Brisbane (07) 394 1155 Adelaide (08) 223 2811 Perth (09) 242 4688 Canberra (06) 251 6111 *Price does not include sales tax. A 2kW 24V/240VAC sinewave inverter; Pt.5 In this fifth & final instalment on the sinewave inverter, we present the assembly details of the chassis and the setting up procedure. Quite a lot of wiring is involved, especially that associated with the DC-DC inverter & H-pack boards. By JOHN CLARKE · The complete kit for the ZkW Sinewave Inverter (from Rod Irving Electronics) will include the assembled DC-DC inverter transformer, Tl. This transformer requires careful construction techniques. The 1-turn copper sheet primary windings must be carefully terminated in order to obtain an 80 SILICON CHIP exact balance between them, while the secondary is quadrifilar wound with 2mm enamelled copper wire. The chassis for the inverter has removable side panels and lid. The DCDC inverter and H-pack PC boards, together with the associated Mosfets, IGBTs and diodes, mount onto the side panels which each have two vertical heatsinks. Rectifier diodes D3D6 are mounted on the rear panel. The assembly procedure given in this article assumes that all metalwork has been drilled. Ifnot, you will naturally have to drill all holes before assembly begins. The wiring involves heavy duty cables capable of carrying 130 amps, plus mains-rated cable and light duty wiring between the PC boards. Because there is such a large variation in the wiring, we recommend that you follow this article and the wiring diagram very carefully. Transformer board We will begin with the transformer board, since this requires a considerable amount of mechanical assembly and wiring. This is a bare fibreglass board measuring 175 x 370mII_l and it accommodates the DC-DC inverter transformer (Tl) and associated components. As supplied, the two Clipsal BP165C12 brass link bars have 12 pairs of screw terminals plus a 5/16-inch bolt at one end. Both these bars are cut to give one block with a bolt and two pairs of terminals and one block with nine pairs of terminals. To do this, remove the two screws at the third pair of terminals (near the bolt) and cut the bar across the centre of these screw holes. Clean up each end with a file. One of the short ends with the bolt, designated LB3, is used to mount fuse Fl. The two 9-pair terminal blocks are designated LB4 and LB5. You will need to drill a mounting hole at the cut end for each of the LB3, LB4 and LB5 terminal blocks. Termina~ strips Three 4-way 30A insulating terminal strips are required for the inverter and these are cut from the 12-way 30A terminal strip (Clipsal BP535 or 593/30) using a sharp knife. If the transformer board has been supplied undrilled, you will need to mark it out and drill it before assembly can begin. To do this, arrange the components as shown on the wiring diagram. The LB1, LB4, LB5 and LB6 terminal blocks are placed with their outside edges about 5mm away from the edge of the board. Note that the LB1 block bar must have its top edge about 40mm from the top edge of the board to allow space for the bank of five l0µF capacitors. LB2 is located 28mm away from LB1. Similarly, the bottom edge of LB6 should be spaced 30mm back from the adjacent edge of the board to provide room for the three lOµF capacitors. A gap of 10mm separates LB7 from LB6. LB2 and LB3 must be correctly spaced to allow fuse Fl to be bolted between them. Transformer Tl is mounted with its righthand bobbin in line with the righthand edge of the board and is secured with two bolts. These bolts pass through a sheet metal retaining clamp which sits on top of the transformer. This retaining clamp also sup- This close-up view shows how inductors L3 & L4 are secured to a fibreglass board using an 8 x 80mm bolt & nut. This board is then mounted vertically on the rectifier board using two right-angle brackets. ports a 4-way 30A insulating connector strip. When you have positioned all the hardware on the board, mark out all the holes and drill them. That done, you can mount the transformer and the associated hardware. The transformer should be mounted with the primary wires close to the board and the red secondary wires directed towards fuse Fl. Four pieces of copper sheet measuring 28 x 60 x 0.6mm will be needed for mounting the 10µF supply bypass capacitors - see Fig.20. These will have to be drilled or punched so that they can be retained by the 5/16-inch bolts on blocks LB1, LB2, LB6 and LB7. They will also need to be drilled to accept the leads of the lOµF capacitors. Five lOµF capacitors mount be- tween LB1 and LB2, while three lOµF capacitors mount between LB6 and LB7. The capacitors are soldered to the copper plates before they are mounted onto the brass terminal blocks. Note that the copper sheet mounted on LB2 is located beneath the lug of fuse Fl. The two copper sheets which mount onto blocks LB6 and LB 7 are each secured with a 5/16-inch bolt and two screws, as shown on the diagram of Fig.20. 130-amp cables Short black and red 130A cables are used to connect LB1 to LB6 and LB2 to LB7. These should be kept as short as possible to minimise any internal voltage drop due to resistance and inductance. If necessary, you will need to strip each end and fit suitable FEBRUARY 1993 81 130A CABLE (BLACK) - X' THERIIAL CUTOUT TH1 TO THERIIAL CUTOUT TH2 y• J SOLDER LUG BOLT TO REAR f'ANEL ........- - - . . - 10uF ,-- COPPER SHEET 10uF TO RECT. PCB 130A CABLE (RED) I 1 Q' FUSE2 FRONT PANEL LB1 ~ ©©© © © E' © <at>F' © <at>G' © <at>H' © <at>I' © DC·DC INVERTER PCB SC11309921 7 TO SINE PCB <at> R<at> TRANSFORMER T1 21r 30A CONNECTOR STRIP CS2 o© TO FRONT PANEL p<at> © © © © © © --~-~-. . . Q8 Q7 Q8 Q9 0 0 0 0 v •s ~T •z *A· ~u ~v *B· \..:..:,w Q1 © B' © A' ©z ©v 0 LBS •c· '-:..::x V • 30A 240VAC INSULATED WIRE 0 0 LB8 0 0 s T w 0 0 FIBREGLASS SHEET 10uF COPPER SHEET 10uF 0 COPPER SHEET 10uF terminal lugs to them using an p.ydraulic crimping press or by soldering them with a blowtorch. If you don't have these facilities, an 82 SILICON CHIP auto electrician will be able to do the job. The main 130A supply leads will also need to be fitted with suitable lugs and battery terminals. These are terminated in a similar manner to the cables described above. Do not connect the battery leads at this stage, since the transformer board MOUNTED ON BACK PANEL - - ....... , 05 06 03 04 T O D C - D C X ' ~ THERMAL INVERTER PCB AND CUTOUT TH1 Y' TH2 Q19 ~ ~ 012 RECTIFIER PCB SC11309924 L4 8x80mm BOLT AND NUT L3 •A •F •C m•B ~•E w•D ~•G ~•H z 1uF 500VAC +365V Cl) o•J 1-.K •L •M •N A• F• H-DRIVE PCB SC11309922 c• B• E• O•~ G• w H•~ I•~ J • =i: K•O IL• M• N• t15A MAINS WIRE DELTA 10DRCG5 EMI FILTER SINEWAVE PCB SC11309923 TO FUSE 5 t15A INSULATED MAINS WIRE has yet to be mounted inside the case. However, you can secure the cables in position between LB1 and LB6 and between LB2 and LB7. Note that the TO EARTH OF GPO TO N OF GPO Fig.20: follow this chassis wiring diagram carefully when wiring up the inverter be sure to use the specified grade of wire for each connection. In particular, note the two 130A cables linking LB1 to LB6 & LB2 to LB7. The two thermal cutouts (TH1 & TH2) are mounted on the side panels immediately adjacent to the heatsinks at the back of the chassis. & FEBRUARY 1993 83 using three short lengths of 15A mains cable. When wiring the CS1 terminal strip, make sure that the secondary wires from bobbin 1 connect to the two lefthand terminals and that the secondary wires from bobbin 2 connect to the two righthand terminals. The blue and brown output wires which connect to the opposite side of CS1 should not be connected until the transformer and rectifier boards have been installed in the case. Chassis side panels The two thermal cutouts are secured to the side panels using machine screws & nuts. If the heatsink temperature rises above 80°C, these cutouts open & switch off the power to the DC-DC inverter circuitry. As mentioned previously, the two side panels of the chassis are used to support the DC-DC inverter PC board and the H-pack PC board. Each board is mounted centrally on its respective side panel on four 6mm metal standoffs. Before going further though, it's a good idea to check that all the mounting holes have been deburred. This will prevent damage to the mica insulating washers that are used to isolate the power semiconductor devices from the chassis. The first step in assembling the side panels is to fit the four heatsinks. To ensure good thermal transfer, apply heatsink compound to the back of each heatsink before attaching it to its respective panel using two screws (one at the top and one at the bottom). The PC boards can now be mounted on the 6mm standoffs. The power semiconductors for the H-pack PC board - IGBTs Q17-QZ0 and diodes D10-D13 - are mounted as shown in Fig.23. Note that two mica washers are used between the tab of each of these devices (Q17-Q20 & D10-D13) and the side panel. This is to prevent Diodes D3-D6 are bolted to the rear panel for heatsinking. Note that they must be insulated from the panel using mica washers & mounting bushes. copper sheets that carry the 10µF capacitors go underneath the cable lugs. Wiring the transformer board The primary wires from the transformer are connected to brass link bars 1B2, 1B4, 1B5 and 1B7 as shown in Fig.20. The four blue primaries connect to 1B4, the four black primaries to 1B5, the four yellow primaries to 1B2 and the four red primaries to 1B7. Cut these leads as short as possible while still allowing a small amount 84 SILICON CHIP of slack when they are connected. They can then be laced together neatly with cable ties. The secondary leads terminate at insulated connector strips CS1 and CS2 (two leads in each terminal). Cut the leads so that a small loop is formed between the transformer and terminal and strip back the plastic sleeving and enamel coating before securing the wires into the terminals. The terminals on the opposite side of connector strip CS2 are interconnected high voltage punch-through of the mica washers. Apply a smear of heatsink compound to all mating surfaces before securing each device with a screw and nut. This done, use your multimeter to check that the metal tab of each device has been correctly isolated from the chassis. The power MOSFETs on the DC-DC inverter board should not be secured to the side panels at this stage. This is because the tabs of these devices are wired to the link bars on the transformer PC board and we're not up to that stage yet. Rectifier board assembly This partly assembled board can w u, ir 31:: <at> ~ ..-z ~~nz ~1~ :c 0 "' - I < w z ~al 0 <at> ~i ~ tw <C ~e -' w z a. 0 ,- :: 0 "' < al iO -' w z a. < a. 0 ,- ,z 0 ff: 0 ,- Fig.21: this diagram shows how the parts are arranged on the rear panel, as viewed from inside the chassis. now be completed. The 4-way 30A terminal strip is mounted on the board with screws and nuts, while the 680µF 400VW filter capacitor is mounted using its integral stud, star washer and nut. The 25µF 370VAC capacitor is mounted with a 45mm-dia. collar bracket. Fig.22: the inside front panel layout. Sleeve the fuse terminals with heatshrink tubing to prevent shock. The toroidal sinewave filter inductors, L3 and L4, mount side-by-side on a vertical piece of bare fibreglass board (100 x 55mm). This board is secured to the rectifier board using two L-shaped brackets. Note that the vertical board has a rubber grommet to allow the wires from L4 to pass through it and thence to the 30A terminal strip. • L3 and L4 are secured to the vertical board with a bolt which passes through their centres. This is fitted with a nut and 45mm washers at each end. The L-shaped brackets are secured to the rectifier board using two FEBRUARY 1993 85 NUT CI:J:l WASHER= - -- - - INSULATING WASHER c:::=========::l CHASSIS HEA TSINK FOR ...__ _ _ _ _ _ __. Q5-Q20, D10-D13 screws which do double duty in retaining two board standoffs). Chassis work Now is the time to assemble the components inside the chassis. As shown in Fig.21 (back panel), the two cable glands are each mounted with the securing nut inside the case. With those fitted, the transformer board, sinewave board and rectifier PC board can all be mounted on standoffs inside the case. The 15A EMI filter can also be mounted at this stage. The front panel hardware can be mounted next. This hardware comprises the front panel label, the two fuseholders, power switch S1, LED1 Fig.23: this diagram shows the general mounting details for the TO-220 devices. Smear all mating surfaces with heatsink compound before bolting the various assemblies together & note that two insulating washers must be used with Q17-Q20 & D10D13 to prevent voltage punchthrough to chassis. and the mains GPO (double power point) - see Fig.22. The positive and negative battery leads are passed through the glands and bolted to the LB3 and LBl terminals on the transformer board. This done, tighten the gland nuts (from outside the chassis) to anchor the leads and prevent any stressing of the transformer board. The O. lµF capacitor associated with LB 1 can now be mounted. One lead is soldered to the copper sheet while the other lead is connected to a solder lug which is fixed to the rear panel of the chassis. Diodes D3-D6 are mounted on the rear panel using insulating bushes and WARNING! The internal wiring of the 2kW inverter is highly dangerous. There are lethal voltages present while the inverter is running and these can remain even after the inverter has been switched off. Before touching any part of the inverter circuitry, always check the DC voltage across the 680µF 400VW capacitor terminals. This capacitor is extremely dangerous when fully charged and can only be regarded as "safe" when the voltage across it is below 20V. This voltage is reached a couple of minutes after the inverter is switched off. As an extra safety precaution, always place the lid on the inverter before powering up. The lid will protect you from flying debris if there are any catastrophic component failures. Don't be rash-this can happen. At the very least, wear eye protection. You should also take considerable care with the battery bank. Ideally, batteries used indoors with inverters or uninterruptible power supplies should have explosion proof vents and should be housed in a separate cabinet. Even so, there is still a risk of explosion since there is a risk of hydrogen being present after charging. Always switch the inverter off before connecting or disconnecting the battery leads to avoid sparks occurring at the battery terminals. Note that a small spark may occur when first connecting the battery leads, even with the inverter switched off. This is due to the charging current into the eight 10µF capacitors connected across the supply leads. 86 SILICON CHIP mica washers. Use heatsink compound on the metal tabs and the mating surface of the rear panel to ensure good heat transfer. Check that the metal tab of each device is isolated from the rear panel by measuring the resistance with a multimeter. Chassis wiring Start by wiring between the DC-DC inverter board and the transformer board. The blue and brown output wires (15A cable) from the DC-DC inverter board to the rectifier PC board are connected using 6mm crimp eyelet lugs. These lugs are secured using screws which thread into nuts that were previously soldered underneath the board. The sources of MOSFETs Q5-Q10 are connected to LB6 on the transformer board, while the source wires from Q11-Q16 are connected to LB1. The source wire connections are made via crimped eyelet lugs which are retained by 4mm screws to the PC board. The connections to the drains of Q5-Q16 are made (using 15A cable) in a similar manner, with the eyelet lugs being placed directly against the metal tab and under the insulating bush of each MOSFET (see Fig.23) . The drain leads from Q5-Q10 go to LBS, while the drain leads from Q11-Q16 go to LB4. Tie the wires into neat bundles with cable ties and then secure the side panel to the chassis. The low current wiring is run mainly using heavy duty (10A) hook-up wire. The exception is the shielded cable that's run between the rectifier PC board and the DC-DC inverter board. Three supply leads run from the DC-DC inverter board to the sinewave generator board, while 14 leads run from the sinewave board to the Hpack drive PC board (refer to the board testing procedure described last month). Finally, there are the leads from LB1 (positive side of fuse Fl) to the front panel switch S1, from LB6 to the DC-DC inverter board, and from the DC-DC inverter board to the thermal cutouts. The thermal cutouts (TH1 and THZ) should be wired before they are secured to the chassis. When running the shielded cable from the DC-DC inverter board to the rectifier board, use heatshrink sleeving • . . ... FLUKE AND PHILIPS - THE GLOBAL ALLIANCE IN TE ST & MEASUREMENT • FLUKE®• • • • J ♦ ♦ • 7 0 • • ♦ ♦ • S E R I E S e PHILIPS ♦ I I We've improved on a winner If you've waited for the next generation · digital multimeter technology, you've made the right choice. 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N.T: Industrial Suppliers & Switchgear J.Blackwoods. PHILIPS • This is the view inside the fully completed prototype. Check all wiring carefully when it is completed & be sure to follow the low-voltage test procedure outlined in the text before applying full power to the inverter. over the cable ends to provide stress relief. High voltage wiring The high voltage wiring involves the rectifier and H-pack drive boards, phis the output to the mains filter, GPO and associated fuse. This wiring must be run using 15A mains-rated cable, much of which is terminated 88 SILICON CHIP using crimped lugs. Use star washers under all the screws to ensure good connections to the wiring lugs. The connections to the 25µF 370VAC capacitor and to the mains filter are made using female quickconnect crimp lugs. Make sure that the earth connections from the mains filter to the chassis and from chassis to the earth terminal of the GPO are made with the correct green/yellow striped mains wire . . The high voltage wires to the Hpack drive board are fitted with eyelet crimp lugs secured with a star washer and screw. Don't forget to install the 1µF 500VAC capacitor between the +365VDC terminal and the 0V terminal. Testing The 2kW Sinewave Inverter comprises a large number of expensive The mains filter at the front of the chassis is necessary to reduce high frequency interference to television & radio reception. components which can be damaged with catastrophic results if there is an error in' the construction or wiring. After you have finished your wiring, we recommend that you check each lead against the wiring diagram and then against the relevant circuit diagram just to make sure that all is correct. If you don't, the bill for blown components can be quite high. We recommend that you follow the testing procedure to the letter. Low voltage test Before testing the inverter fully, it is wise to check that the high voltage circuitry will operate at low voltage. To do this, disconnect the low current +24V lead from 1B3 and connect a clip lead between this lead and the +365V terminal on the H-drive PC board. This done, connect a clip lead between the negative terminal of the 680µF capacitor on the rectifier PC board and the negative battery lead. Finally, remove fuse F4 from the rectifier PC board. This allows the entire circuit to operate at 24V, including all the high voltage circuitry. Now connect a 24V power supply between the negative battery lead and the low current +24V lead (do not connect power to the positive battery lead). This will power the inverter drive circuitry but not the MOSFETs (Q5-Q16). Consequently, the DC-toDC inverter section of the circuit will not be running but the 24V applied to the H-drive circuitry will produce a low voltage sinewave at the mains GPO. An oscilloscope can be used to monitor this sinewave at the GPO. If the power supply you are using is fully floating (ie, neither of its outputs is grounded), you can use one probe to earth one of the GPO terminals. If the power supply is grounded, then the oscilloscope must be used in its differential mode to avoid shorting the supply output. Note that there will some distortion in the output sinewave due to the voltage drop across the IGBTs in the H-drive circuitry. In normal operation, this distortion will not be present since the voltage drop across the IGBTs will be negligible in comparison to the 365V supply. When operation at 24V has been confirmed, a full voltage test can be run. You will require a 24 V battery (or two 12V batteries.in series) which is capable of supplying 120A for at least 15 minutes. Restore the wiring inside the ZkW Sinewave Inverter to its normal condition and re-install fuse F4. Rotate trimpot VRl on the DC-DC inverter PC board so that its wiper is pointing directly upwards. This should set the output voltage at just below 240VAC. Before connecting the inverter to the batteries, it is advisable to install a 15A automotive fuse in the positive battery lead in place of fuse Fl. This will blow well before any damage can occur if a fault is present. This fuse can be supported by two stout lengths of tinned copper wire attached to 1B2 and 1B3. Now replace the lid on the inverter. Make sure that the inverter is switched off, then connect the battery leads (with the 15A fuse in circuit). Connect a digital multimeter set to read 240VAC to the GPO socket and switch on the inverter. The AC voltage should quickly rise to over 200VAC (this can be adjusted later with VRl) and the 15A fuse should remain intact. If a DC clamp meter is available, measure the DC current supplied to the inverter. It should be about 3A for no output load. Switch off the inverter immediately if you smell anything burning and correct the problem before switching on again. Be sure to follow the safety precautions outlined in the warning panel when working on the inverter. For further testing, you will need some loads. Several 100W light bulbs connected in parallel using bayonet holders are useful, while a bar radiator can provide a 2kW load. The inverter will drive a 300W load using a 15A fuse in place of Fl. Measure the AC voltage across this 300W load and note the reading. This done, switch off the inverter, disconnect the battery and remove the lid. Now measure the DC voltage across the 680µF capacitor and wait until it drops to less than 20V. When it does, rotate VRl slightly clockwise if the output voltage was less than 245VAC for a 300W load and slightly anticlockwise if the voltage was greater than 245VAC. This done, check the output voltage across a 300W load again and readjust VRl as necessary. Once the inverter is operating correctly at 300W, disconnect the 15A fuse and re-install fuse Fl. The inverter is now ready for testing at loads up to 2kW. To do this , run the inverter at 2kW and check for excessive l;ieat from the heatsinks at the side of the case. The MOSFETs will normally run quite a lot warmer than the IGBTs. The DC current drawn from the inverter will be about 110A. After operating the unit for a few minutes, switch it off and check the internal components for overheating (be sure to observe the safety precautions). Note that 13 and 14 will normally run quite hot at full load. Finally the sine waveform can be checked using an oscilloscope. The waveforms should be similar to those published on page 30 of the November 1992 issue of SILICON CHIP. SC FEBRUARY 1993 89 ··••"-'"-'IIVL/ 1n•11n.1 CLCVI nVl't/VJ nuu 1nv11•u CLCV1nv, .. 1v.:, nvu 1nv11-.u CLCVlnv, .. ,v.> nuu IM'lll'fU CLC.VI nv1•1\,.,.;, nvu IMVll'IU CLCVI nVl'lf\,.;) nvu lf'1'111NU CU:VIMVl'tlt\,,~ nuu lr1VINU t::Lt::l..,IMUNtt..,.: iNICS ROD IRVING ELECTRONICS ROD IRVING ELECTRON ICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING El ECTRONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONIC! NICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING E. 'cCTRONICS ROO IRVING ELECTRONICS ROO IRVING ELECTRONIC! 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Ten foot extentlon lead. .;~ HUU I HVI N U t:Lt:\.o I hVl"li\,,,'1 11'-'U lMVll"fUI Cl..t;.V inVl"ll\,,,..:J n v u lnVll "IU CLCV I nVl "I I V..> nvu lnVll 'IIU ~LLV I rlV l'ill V-.J rlVL.f 1n v 11 'l1~ c~~ .... , nVl'II I V..> n v v ,n ... ,, .. u c. ~ v I nVl 'III IV..> n vu 1nVll'IIU t:LCV I nV l 'tlV.;J :s ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING E1ECTRONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ..,S ROD IRVIN - - - - - - --· ·· -- ............ ·-• .. ~,..-.. - · _,....,....., ........ ,,.... ...., r-.,..,... ,,.., ,. .. ,...,, ,.., ,-,..,.,.. ...... .. ,..,:,, " "",..,. ,,.,,,. .. ,,- ,-, ,..,....,..,..,...., ,..... c-- nr,..-. ,n,,, ,. ,,... r l"",-..Tnr.. ,,,...c- n r.n 1"''11"..,... ,.., ,.. ,...yn,-,, .. u,...c, "'"""" u·,,t1• ir.- r-LECTAONICS :s :s :s :s :s :s :s :s :s :s :S ROD IRV I ROD IRVI ROD IRVI ~ ROD IRVI • ROD IRVI • ROD IRVI ; ROD IRVIN ROD IRVIN ROD IRVIN TRANSISTOR TESTER ROD IRVIN Have you ever deaoldered • auapect ROD IRVIN trsnsistor only to find that it checks OK? ' :s :s :s :s :s ROD ROD ROD ROD ROD "'S ROD IAVIN trouble shooting exerci- are often IRVIN hindered by Ihle type of false alarm, but IRVIN many of them could beovoided with an IRVIN " in•clrcuit'.' component tester, such ■a the IRVIN EA Handy Teater. (EA Sept. •a3) 83TTII IRVIN K10080............................. $22 .95 ~ ~!::::• :s :s :s :s 'S ROD ROD ROD ROD ROD imr~·.:-· :s ROD IRVI :s ROD IRVI~ ~ ~S ,S :s :s :s ;s ;s ;s ;s , GENERAL PURPOSE PREAMPLIFIER ~ A general purpose atereo preamplifler uaing a single Lt.1382 IC which can be tailored lor use with magnetic plckupa, tape recorders, and microphones by changing• few components (ETI445) (ETI July •1&) m The ETI·569 Solar charger ia deaigned to charge any 111nd1rd 12 V lead acid car ~ttery in any area where maina power ia unavailable. It la ideal for remote data acqulaltlon atatlona. caravana and boata. OI coar• there are 01h er soloar chargers nd arou ' but these are extremely (ETI 480) ~~~~£~~~~~:~:::~::::: ~;~1 ..· '.iclty 11 .•~~:~heapne~: 1 1 1 ~ :••.$ 13 95 • everything•• on the one pcb. . . . ' · · IRVI~ BALANCED INPUT IRVI~ IRVI~ DIFFERENTIAL PREAMP IRVI~ Th' .. r h f IRVI ,a vera1t1 1e ,11 Ie pream11 naa • oat o 1pplicatlon1 In the audlo-and•beyond ROD IRVI range, not the leaat of which would be 18 ROD IRVI I balanced mic preamp. ROD IRVI • ROD IRVI (Ell 461 Dec 82 ETI) ROD IRVI K10070 .............................$19.95 ROD IRVI . . . ROD IRVI DISCOUTE , ROD IRVI ·· ROD IRVI Thla kit makes your ~ I AMPLIFIER CLASS B. One of the handiest "tools" for the electronics experimenter ia a genuine purpose audio amp. Thie module will work from a wide rsnge of aupply voltages, haa very good senaitivity, ia robuat, reliable and easy to build tool (ETI 453) ETI April •so) K10065 $14 95 ··············............... • PLAvMASTER 300W r 100 W AMPUFER MODULE (ETI 480) Similar to the above module but thia one ia 1oow1tta of power. Heataink optional extra K10045............................$32 .95 AMPLIFIER ohm■ tig~~g~:gi LECTRONICS LECTRONIC~ Heatslnk optional extra K10040 .... ........................$27.95 • ···· .. ' ELECTRIC FENCE KIT Main to battery powered, thia electric fence controller ia both inexpensive and ·n B aed on •n auI omoII ve .ign,·1·ion vera, 1e. • coil, it aould prove an adequate deterrent to all manner ol livestock. Additionally it's operation conforms to the relevant clausea ol Auatrslian Standald 3129. (EA Sept..82)82el9 K10110 .............................$23.95 MIKE PRE AMP 300WATTSINT04 LECTRONICS LECTRONICS LECTRONICS LECTRONICS LECTRONICS expenaive. With the ETI-569 the emphaaia LECTRONICS SOW AMPLIFIER MODULE · GENERAL PURPOSE !:::' l K 10055..•.•.•.....................$14.95 SOLAR GENERATOR LECTRONICS LECTRONICS ILECTRONICS ILECTRONICS LECTRON ICS LECTRONICS i' LECTRONICS 1 LECTRONICS LECTRONICS LECTRONICS LECTRONICS • lECTRONICS .LECTRONICS tECTRONICS :LECTRONICS lECTRONICS lECTRONICS J.ECTRONICS lECTRONICS :LECTRONICS :LECTRONICS 1LECTRONICS 1LECTRONICS 1LECTR0N1cs ILEC TRONICS This module will deliver up to 200 watta High quaility tranaformera for matching ;s ROD IRVI lights do amazing into an Bohm load. Comprehensive balanced microphones into unbalanced ILEC TRONICS ;s ROD IRVI things. With 4 llght channels controlled protection ia included and a printed inputs are quite expensive. This simple ELECTRIC FENCE ILECTRONICS 'S ROD IRVI by 4 separate audio channels. Eg. circuit board bringa it all together In• presmplifier will accept balance inputs ILECTRONICS ROD IRVI Forward, reverse, auto reversing chaser rugged 818Y·l 0•build module. It can be directly. CONTROLLER ILECTRONICS ;s ROD IRVI patterns, alternating light pattern■, built in either lully• complementary or (ETI May ·n, ETI 449) Reatore the discipline to the farm or ILECTRONICS 0 19 ;s ROD IRVI adju111ble rate lor light patterns, quaai-complementary ve lona, • output K10060 ............................$11.95 allotment with this new electric fence ILECTRONICS :s ROD IRVI aimultaneoua strobe on all four channels. tranaialor ahortagea should be no controller. It features higher output power ILECTRONICS :s ROD IRVI Plus many more features! (Sil Chip July problem at 111· 1 MORE KITS f and lower current drain than the previoua ILECTRONICS 1 1 :s ROD IRVI 1988) (80pa6) (EA July ·ao) design. ILECTRONICS ;s ROD IRVI K10130............................$155.00 K10085 ...........................$109.00 COMMING SOON! (EA Dec. ·as,a5ef11) 1LECTRONICS 1 ;s ROD IRVI L--- - --------------.J K10115 .............................. $61.95 LECTRONICS ;s ROD IRV1~l - - - - - - - - - - - - - . . . . ; ._ _ _ _ _ _ _ _ _ _ _ _ _....;.- = = = = = = = = = = = = =.....= = = = = = = =- - - - - - - f:LECTRONICS ;s r------------------, ~ :s ROD IRVI ;s ROD IRVI :s ROD IRVI :s ROD IRVI :s ROD IRVI :ss : ;s :s ;s :s :s :s :s :S :s :s :s :s :s :S I l RROODD 1RRVVII 1 ROD IRVI ROD IRVI ROD IRVI ROD IRVI ROD IRVI ROD IRVI ROD IRVI ROD IRVI ROD IRVI RODIRVI ROD IRVI ROD IRVI ROD IRVI ROD IRVI ·-- ~ ,,,.. I Every service man should have I II f th. 1· at eastonero O 1squa1ty "Bene lec" speaker cable in their box. Flat tw·1n f·1gure 8 · :s 1410.14mm ;s RODIRVI ROD IRVI 2C BC xPVC lnsul 50V Go-Go LAMIN ATOR ,-. , la that precious photo of your loved ones in your wallet getting a bit tattery? Don·t lose those precioua memories protect them by laminating them with your own l1mln1tlng machine Important Bualneaa cords, membership cards, recipeaetc.laatallfetimelongerwhen laminated. Now ROD IRVING ELECTRONICS have Imported this laminator that your budget can allord. Don•t pay hundreds of dollar• for some big machine l'aya 1,40 f the price for an attractive compact laminator that ia ao simple to use. up in only 2 to 3 minutes. A911 00 .............................$95 .00 .--7,=::==T71. 1t•s Iha cheapest it has aver bean! Tha famous OKILASER 400 Laser printer at - ~· if==ti1b.. ·:--;: . ~- - · ... !-!~""""~~:~;~J l t~g;~g~:g; only $1299! Reliable and compact, it fits neatly into Iha smallest of offices. Highly reliable dua to its latest LED imaging technology. Tha OL400 offers axcallant print quality, superior paper handling, and a variety of fonts which rivals soma of Iha more expansive laser printers on Iha market 5 year Warranty On LED system head. No moving parts (LED SYSTEM HEAD) recycles its own toner! Approx. 1.Bipercopy. Just $1199 00 WELLER • ~ SOLDERING -~ ST'A' JION ,.._-#'¥" " .,,.. LECTRONICS :LECTRONICS 1LECTRONICS 1LECTRONICS 1LECTRONICS ac · 'I.~ ~••■ : 1!.~I• .·.I.~ ·· ~ · ,'· l1LECTRONICS iLECTRONICS 1LECTRONICS 1LECTRONICS 1LECTRONICS ll ECTRONICS ILECTRONICS ILECTRONICS ILECTRONICS ILECTRONICS ILECTRONICS :LECTRONICS 1 LECTRONICS ILECTRONICS :LECTRONICS ILECTRONICS :s ROD IRVI In 100 metre rolls. Black or Grey ,LECTRONICS :s ROD IRVI (Sorry this has no black polarity with tempersture .~ \ '. LECTRONICS ;SS RROODD IIRRVVII identification stripe down the side controlled aoldering iron. . A tramaformer powered soldering station, complete with a low voltage, temperature :S ROD IRVI of the Wire.) cqntrolled aoldering pencil. The special Wellar "closed loop" method of controlling :LECTRONICS :s ROD IRVI UsuallY, S2a,ee- 1·9 10+ Laminate Shaats.... 95mm x 57mm maximum tip temperature iaemployed, thereby protecting temperature aenlltive :LECTRONICS :s ROD IRVI $ $9 (2.25" x 3.25") component• while the grounded tip protects voltage and current aenaitive components. :LECTRONICS :s ROD IRVI W 11200 .... .. ..... 1O.OO .00 for business cards A91110 .. $18.95 The aolderlng pencil features• atalnleaa ateel heater construction,• non.burning LECTRONICS ;s ROD IRVI silicon rubber cord and a large selection of iron plated tip■ in sizes from 0.8mm LECTRONICS 100 ;s ROD IRVI .pack of diameter to 6.0mm diameter with• choice of tip temperature of 315° C/600°F, 370° LECTRONICS ;s ROD IRVI 50 ohm Ethernet cable c11oc,o F and 430" Ct800"F. LECTRON 1cs ;s ROD IRVI Laminate Shaats.... 156mm x 112mm LECTRONICS ;s ROD IRVI P39502 2 Metre................. $9.95 (4.25" X 6.75") for photos with T12500 LECTRONICS ;s ROD IRVI P39503 3 Metre.................$11.95 punch holes for photo album LECTRONICS ;s ROD IRVI P39505 5 M t $14 95 A91111.. ......... $11,95 pack of 24 ,______ LECTRONICS ;s ROD IRVI e re................. . ... LECTRONICS ;s ROD IRVI P39510 10 Metre...............$24.95 LECTRONICS ;s ROD IRVI P39520 20 Metre...............$34.95 Laminate Shaats ....135mm X 95mm LECTRONICS nd 4 5116 3 ;s ROD IRVI Theae are relldymade cablea to aave you ( 3/ " X S ") for photos a Thie la not your aversge EPROM Ersaerl LECTRONICS rd ;s ROD IRVI time & effort of lnatalling your Networks at ca • Sure tt erssea your El'ROM'• quickly and safely and will erase up to LECTRONICS ;s ROD IRVI school In bualneaa or at home.)NICS RO A91113 ........... ......... .$8.95 pack of 24 9 x 24 pin devicea In about 40 minutea.(leaa for leaa chips). But with thia one you don·t ;s ROD IRVI have to waate your time atanding around -iting lor them. ;s ROD IRVI Laminate shaats .... 110mm x 170mm Thie EPROMe,_, haatlmer to allow you to "set and lorget". By uaingthetimer LECTRONICS ;s ROD IRVI (4.25" x 6.25") A91.112 ....... $10.95 !unction you not only aave money by r11uaing your EPROM's but you alao aave precioua LECTRONICS ;s ROD IRVI time by doing other jobe while the er••• ia working. And you•n never have to worry LECTRONICS ;s ROD IRVI about lorgettlng to tum it off and "cooking" your EPROM'a. LECTRONICS ;s ROD IRVI EPROM SPECIALS Chooaefrom a range of different sett Inga from 15 minutea to 40 minutes depending on .LECTRONICS ;s ROD IRVI 1·9 10+ 100+ the lntenalty of the UV aource. LECTRONICS 1 ;s ROD IRVI 27C64-20 $4.50 $3.90 $3.50 • The chip door haa a conductive foam pad. 1LECTRON ICS ;s ROD IRVI 27C512-15 $8.00 $5.50 $5.00 • High lntenalty at the chip aurlace enaurea EPROM'a are thoroughly erased. LECTRONICS :s ROD IRVI $9.95 2 7e256 •20 $5 •00 $4 50 $ 4 OO • Engineered to prevent UV exposure Save $20 $149.00 LECTRONICS :s ROD IRVI • . :LECTRONICS :S ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS HOD IRVING E:LEC l HONICS HOD IRVING E:Ll::C I HONICS HUU IHVINu t:LECTRONICS ; s ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS 'S BOO IBVING ELECIBONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS ROD IRVING ELECTRONICS "'"c c, CCTDO!IIICC' coo ID\/11,lQ. Cl CCT RONICS COO IRVING ~LECI~ '.t~g;~g~:g~ Heat■ Usually $179.00 This month only $149.00 ""'-1 t~gi:g~:g~ 1--------------~ C. L t: I..,, I HUl 'fl\.,.:, MVU IMVll'f\,.;I C:Lt:.V l nVl'ilVV n.vLJ HlVll'i ...... ,_._,_....,I',...., ,,.,"' ... ELECTRONICS ROD IRVING ELECTRONICS ROD IAVING ELECTRONICS ELECTRONICS ROD IAVING ELECTRONICS ROD IAVING ELECTRONICS ELECTRONICS ROD IAVING ELECTRONICS ROD IA\IIN.G ELECTRONICS , ,...,..., ROD ROD ROO " .. .. . ..... IAVING IAVING IRVING ......................... · ·-~ ELECTRONICS ELECTRONICS ELECTRONICS . ...... · - - - -ROD IAVING ELECTRONICS ROD IAVING E' ECTRONICS ROD IAVING ELECTRONICS ROD IAVING ELE ROD IAVIN G ELECTRON ICS ROD IAVING E ':'CTAONICS ROD IAVING ELECTRONICS ROD IAVING ELE ROD IAV ING ELECTR ON ICS ROO IAVING ELECTRON ICS ROD IAVING ELECTRONICS ROD IAVING ELE - ~ ~ -==='""'...._.._........,....._.._._.._....,.....,.....,.............., EU/ RITRON ~t~ ·•· · RITRON Ifiiiiiiiiil j ,.........== ~~~ EXECUTIVE ·fr•~~~a-\.GI EXECUTIVE oO~~; ►l<-'<:~C~~'/.\ _...,....._....,...,___.,...,,_-:: EL 6 ~L~ Et~ 611 a. \J . . 4{386SX-31 &C~~~~~~►~ ~oa) Slt-~c;O'lc5~o El& ELE , . J1>-~~ ~:.:.-! 386-5~, . . 80386·33 cPu EL& so386sx 25M cPu ELE 2 MEG RAM EXP TO 8 MEG i.:.::=::=..:..:.:.= ELG 3l Mhz LANDMARK SPEED TEST ELG 1.2M JAP F.D.D. 512K VGA CARD EU; 40M HARD DISK DRIVE, .--e-.-=..,.,..,--, EL~ 101 EXTENDED "CLICK" KEYBOARD EL~ MINI CASE & 200W POWER SUPPLY ELE SUPA VGA COLOUR MONITOR 1024 x 768 Res .0.28" D.P E·cE w11>-0t11 --- · RAM! SERIAL PARALLEL GAMES PORT MINI CASE & 200W POWER SUPPLY .___ _ _ _... SUPA VGA COLOUR MONITOR (1024 x 768 Re•) 0.28" DP MEG OF RAM l r-===,=,,:c;::~:=::,_ 64K CACHE ON BOARD MEMORY •• 2 MEG RAM EXP TO 16 MEG • 57Mhz LANDMARK SPEED TEST 40 MEG HARD DISK 1.2M JAPANESE BRAND F.D.D 101 EXTENDED "CLICK" KEYBOARD ~LE SERIAL PARALLEL GAMES PORTS ELE 4 YEAR PARTS & LABOUR WARRANTY IBM' COMPATIBLE I. ELE ELE SPREADSHEET, WORDPROCESSOR .__ _ _ __. ELE & DATABASE SOFTWARE INCLUDED. ELE • SHAREWARE SOFTWARE TAX ELE ASSEMBLED & TESTED INC. ELE IN AUSTRALIA ' EL Add $40 for a 386SX-33/41 ELE;:===================== TAX EX . ~t: gg ::~:~~ ODIAVING EU OD IRVING EU OD :Av:NG EU OD AV NG EU TO CHANGE A 4QM HARD DRIVE TO A oo IAVING Eu 85M HD add $100 126M HD add $210 105M HD.. $175 200m HD add $4!50 170M HD .. $ 275 OD IAVING EU gg ~t: OD IAVING ELE :~:~g OD IRVING ELE OD IRVING ELE OD IAVING ELE 0 0 IAVING ELE SOUND CARDS OD 1AV G ELE SOUND COMMANDER FX $159 IN ........................ OD IAVING ELE SOUNDBLASTER V2 With Speaken... : ..... $149 OD IAVING ELE .·. lM add $59 2M add $118 4M add $236 SOUNDBLASTER PRO $ ............................. 299 FLQPTICAL DRIVE add ........................... "$649 21 M/BYTE DISC TO SUIT...................... $49 CD ROM SOUND BLASTER PACK. ........... $949 PARRADISE WINDOW ACCELERATOR ..... $275 $1 39 9 $1099 · gg ::~:~~~t: J .....:.:-:.:..:.-=-:a EXTRA RAM ( 512K VGA CARD (256 COLOURS) IBM' COMPATIBLE 4 YEAR PARTS & LABOUR WARRANTY SPEADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED. "SHAREWARE SOFTWARE ASSEMBLED & TESTED ' TAX Inc IN AUSTRALIA TAX EX $1 319 . 1~io'-~DRDosa.oADD.................... $75.oo ~.oo-iEtll-'!l(.ENOif.~~CT MSDOS5.0ADD ................... $99.00 ~t-1J..i11.lS~~1.iv-g~3)543ZIG6 MS DOS 5.0 & WINDOW 3.1 .... $179.00 OIS~s -11\\01.f.~.. lM VGA CARD ... .................... $100.00 •• NOW WITH 2 . ..... OD IAVING ELE OPTIONAL EXTRAS ADD PRICE TO BASE SYSTEM COST. Add$25;~r~~~~:~~:r1· •· $1,165 OD IAVING EU 00 IRVING ELE OD IRVING EU OD IAVING EU OD IAVING EU OD IAVING EU MlNI TOWER.$50 FULL TOWER.$200 OD IAVING EU RITRON · [1.111~,, · RITRON. ·· 111 Jr RITRON ill!P~;1!~1t: ~ti EXECUT1?~~1i~tf:$,6&<at> ·'~JIB?UT~~~~~1,,*~!::~~~~).•·•.:.~~A~~t~:::::g;t ! ~ -t~ r 38 6 •65 ·•· · .·•4 a5 75 Slt-►'>:d)\l~l"°~s~ ►l>:o\S~~~~.}{tt911W Add $25 for 128K Cache i~, : LE ~t~ : ~t~ =LE :LE ~LE =LE =L E =LE =LE =LE =LE 11 NOW lij Slt-o\S~s'fl~ .•. 0 \:_ _ _ _ _ _ _ _ _ _ _ 11,~l'- "' 64 CPU K CACHE ON 4 MEG RAM EXP TO 16 MEG 65 Mhz LANDMARK SPEED TEST 40MEGHARDDISK12msACCESS TIME. 1.2M JAPANESE BRAND F.D.D 101 EXTENDED"CLICK" KEYBOARD._______ MINI CASE & 200W POWER SUPPLY SERIAL, PARALLEL, GAMES PORTS 512K VGA CARD, SUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.28" 4 YEAR PARTS & LABOUR WARRANTY SPEADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED. •SHAREWARE SOFTWARE :~=~-: :L E : LE ~t[ ' $1,210 ELE ELE > .· · :'\. . ) TAX INC. TAX EX. ;:(fa,cs ~::~lWI NOW WITH 4 MEGOF RAM! • 80486SX-25 CPU 4 MEG RAM EXP TO 32 MEG 75Mhz LANDMARK SPEED TEST •• 40MEGHARDDISK 1.2M JAPANESE BRAND F.D.D 101 EXTENDED"CLICK" KEYBOARD MINI CASE & 200W POWER SUPPLY ._______ . 4 YEAR PARTS & LABOUR WARRANTY . SERIAL, PARALLEL, GAMES PORTS. 512K VGA CARD SUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.28" DP SPEADSHEET, WORDPROCESSOR & DATABASE • SOFTWARE INCLUDED. 'SHAREWARE SOFTWARE WITH 4 MEG OF RAM! $1 449 c ~ WITH 200 MEG DRIVE . $1 1899 TAXINC. $1,585 TAX EX. <.f.\ .••··.··••·.··• ••••••··.•'!'./ .•...•.•.·.·•·. •._.•· • • ..__.;,..;..;.....;_--'-'---'-'-~-'--"-- • • 80486•33 CPU · NOW ••• 256K ON BOARD CACHE. 4 MEG OF RAM :; 157Mhz LANDMARK SPEED TEST WITH 4 ••• 40MEGHARDDISK MEGOF ••• 1.2M JAPANESE BRAND F.D.D / 101 EXTENDED"CUCK" KEYBOARD RAM' ( SERIAL, PARALLEL, GAMES PORTS " :0 512K VGA CARD. IBM' COMPATIBLE .. SVGA COLOUR MONITOR (1024 x 768 ReM>lutlon) 0.28.. DP MINI CASE & 200W POWER SUPPLY 4 YEAR PARTS & LABOUR WARRANTY SPREADSHEET, WORDPROCESSOR 6 DATABASE SOFTWARE. $ IN AUSTRALIA. $1 ASSEMBLED 469 & TESTED WITH 200 MEGORIVE TAX ·. ' $1,919 TAXINC. $1 1 600 TAX EX. INC. $ 1,225 TAX EX. DDIIRRVVII NNGGE ELLII p.~l'-V'"v,::::.·:;';:::;"';:;;::;;;::::::,p D IRVING ELI $1,870 •• WITH 200 MEG DRIVE 2 ' 249 $2 ' 699 TAX INC. TAXINC $2,245 TAX EX TAX EX. 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SERIAL, PARALLEL, GAMES PORTS TOWER 1 MEG VGA CARD. IBM' COMPATIBLE 1 MEG VGA CARD. IBM' COMPATIBLE CASE ELE TOWER CASE & 220W POWER SUPPLY TOWER CASE & 220W POWE" SUPPLY ~ - - - - SUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.28" DP SUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.28" DP 4 YEAR PARTS & LABOUR WARRANTY· 4 YEAR PARTS & LABOUR WARRANTY ~Li SPEADSHEET, WORDPROCESSOR & DATABASE SPEADSHEET. WORDPROCESSOR & DATABASE 80486-33 CPU 256K ON BOARD CACHE. 4 MEG OF RAM •• 200M gg :: ~:~~ ~t: 200 TIME 1.2M JAPANESE BRAND F.D.D HARD OD IAVIN G ELI 3.5"' 1.44M JAPANESE BRAND F.D.D DRIVE OD IAVIN G ELI 101 EXTENDED "CLICK" KEYBOARD OD IRVING ELI SERIAL, PARALLEL, GAMES PORTS TOWER OD IRVING EU 1 MEG VGA CARD. IBM' COMPATIBLE CASE OD IRVING EU TOWER CASE & 220W POWER SUPPLY .__ _ _ _.... 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While these ancient loudspeakers all sound much the same, some are far more desirable than others. A large proportion of early radio receivers used headphones as a sound reproducer. Users of crystal sets and 1-valve and 2-valve receivers had no other choice; these low powered sets lacked sufficient output to drive a loudspeaker. Radios having three or more valves were a different matter these were capable of loudspeaker performance. Loudspeakers were mostly separate items in the 1920s and the horn speaker was by far the most common type. Cone speakers came into vogue during the latter part of the decade, after which the old horns quickly fell from favour. It was at about this stage of home radio evolution that manufacturers started to tidy up domestic radios by building them into complete self-contained units. Prior to this, radio was a fairly untidy affair with most sets consisting of several bits and pieces. Good points & bad points The old horn speaker had both its good and bad points - mostly bad! These two derelict Amplion Dragons were combined into one unit. The water damaged flare on the left had only two good segments & these were used to replace two broken segments in the flare on the right. 96 SILICON CHIP Perhaps its only good feature was sensitivity, while its worst aspect was a very narrow, peaky, frequency response which resulted in a harsh metallic sound. Horn speakers were also very fragile and just accidentally knocking one onto the floor could do considerable damage. Dangling wires often resulted in a speaker being tipped over. A horn speaker can be described as a large headphone with a trumpet or sound horn atta~hed. In the majority of cases, the driver is constructed in exactly the same manner as a headphone but with the added refinement of a variable air gap between the pole pieces and the diaphragm. This adjustment can increase or decrease the sensitivity, depending on whether the pole pieces are brought closer to the diaphragm or moved further away. On strong signals, it can be necessary to move the pole pieces further away to prevent the diaphragm from rattling against them. Horn speakers came in a range of sizes and varied from quite small units to large floor standing models nearly one metre high. Size did not make a great deal of difference to performance and, generally, one horn speaker sounds much the same as another. If there were any notable exceptions, then I have yet to hear them. It's also worth noting that not all horn speakers look like horn speakers. In some instances, manufacturers built horns into timber or metal cabinets. Never assume that an old speaker box contains a cone speaker. A close inspection may reveal that there is a horn speaker inside the cabinet. Amplion Dragon One of the most sort-after horn speakers is the Amp lion Dragon which a few Dragons around without their drivers and I know of one particular collector who is willing to pay up to $100 for an Amplion driver to fit his junior Dragon. My situation had been the direct opposite. I have had a Dragon driver for some years and had been looking for suitable parts in order to build up a complete speaker. The bits and pieces I had been seeking finally materialised recently when I was lucky enough to obtain two wrecked junior Dragons without drivers. Unfortunately, both flares were damaged and the only way a complete speaker could be built was to combine the undamaged segments of each flare into one unit. Soft iron strips hold the flare together. The oak veneer segments slide into slots in the iron strips & are crimped at each end. An end tab is then folded over for good measure. The oak segments are extremely difficult to remove without damaging them. comes in two sizes: junior and senior. Naturally, the senior is the larger of the two. The appealing aspect of these old Dragons is their timber flares. Most horn speaker flares are made of spun aluminium which, when painted, has nowhere near the same visual appeal of the Amplion Dragon, with its segmented oak flare. Better tone Old advertisements claimed that the wooden flare produced a better tone. Once again, if there is a difference, then my ears cannot detect it. As far as I am concerned, Amplions with oak flares were no better sounding than any other horn speaker from that era. However, they were considerably more expensive than some makes and no doubt there was a bit of "snob appeal" attached to owning one because they looked very stylish indeed! Regrettably, the Amplion Dragons, with their wooden flares, have not survived the shipwrecks of time very well. Although there are still a few good examples around, the majority are in poor condition. Whether Dragons or otherwise, most horn speakers are nearly 70 years old and are showing their age. Damp storage usually results in the Dragon's plywood flare separating and going out of shape. The thin soft iron strips that hold the oak segments together can also give trouble and severe rust problems are difficult to solve. What's more, natural rubber was also used in their construction and this too can cause problems when it deteriorates and goes out of shape. Rebuilding the Dragon It seemed a simple enough task in theory - just dismantle the flares, pretty up all the usable bits and reassemble the pieces. Unfortunately, it's not that easy in practice! The oak flare on a Dragon speaker is not easily dismantled. Each wooden segment is crimped into position at The underside of the base was coated with felt to protect valuable furniture from scratches - especially receiver cabinet tops. Driver attachment This Amplion Dragon driver had been in the author's collection of "junk" for many years. It was still in working order &, judging by the nameplate, has had little use. Often, the dragon emblem is damaged, due to finger wear as the sensitivity control is rotated. The driver on a Dragon speaker is attached to the horn by a rubber bush. It is not uncommon for the bush to perish away to almost nothing, leaving the driver separate from the rest of the speaker. It is for this reason that complete speakers in working order are comparatively rare. There are quite Any "back from the grave" restoration of this nature requires a visit to an electroplater. Re-nickelling helps to bring back that as-new appearance and is often an essential part of the restoration. FEBRUARY 1993 97 individual segments of the horn. This was the case with my rebuild and some of the lighter toned segments were touched up with oak wood stain, making the overall appearance of the flare a little more uniform. I might add at this stage that working on the flare is a delicate operation and one must be careful not to lift the veneer at the .ends of the segments. Old oak veneer is very brittle and splintery and any loose ends need to be glued down before working on the flare. Each flare segment is made of 3-ply and this consists of two outside layers of oak veneer, with another slither of timber in between. The overall thickness of the ply is only about 2.5mm. A tedious task The driver fits onto the end of the horn with nothing to hold it in place but the friction of a rubber bush. As the rubber perishes, it loses its grip & the two sections separate - one reason why so many Amplion Dragons now have no driver attached. . ·,. ." ·,· '· ~\., ,, ', "' '> •·,, ~:~ ; ..... ' Stripping the flare back to bare wood and metal proved to be a long and laborious task. While some would argue that the speaker's originality has been ruined by doing this, one must remember that I have combined parts from three separate speakers in differing stages of disrepair. If the finished article is to have any appeal whatsoever, then it must be refurbished so that it will look as though it is a single unit. Regrettably there are not enough Amplion Dragons in good original condition to go around and combining various bits and pieces was the only way out of my dilemma. Painting the metal strips that hold the oak segments in place was also a tedious job and calls for a steady hand. The inside of the flare was particularly difficult to work on. Semi-gloss finish The electroplating included all nuts, bolts & washers. Attention to such details enhance the overall appearance of the finished restoration. the ends, which makes their removal quite difficult. Great care is required if the segments are to be removed without damaging them. Reassembling the flare also has its problems because once the segments have been removed they do not go back tight enough to hold together. They really need to be glued into place, otherwise the reconstructed flare keeps falling apart. With my particular flare rebuild, one flare had two segments replaced with p1.eces from another flare. I would 98 SILICON CHIP have preferred to completely strip the flare but I didn't want to risk damaging the various pieces and have to go through all the reassembly hassles. Matching the segments One particular problem when combining the flare segments of two or more speakers is that they may not match visually as well as they did originally. The oak veneer doesn't all come from the same oak tree. As a result, there can be significant tonal and wood grain differences between When restoring an antique such as a horn speaker, a much better effect is obtained with semi-gloss finishes. Painting it up so that it is all bright and shiny really does spoil the illusion. A dull lustre is far more appropriate for antiques and a horn speaker is no exception to this rule. The timber flare was not the only part of the speaker that required attention. The pressed steel horn was in need of painting and all the nickel fittings such as the base and various nuts and bolts were packed off to an electroplater to be "re-nickelled". These metallic items looked particularly shabby and really needed the full treatment. Eventually, all the bits and pieces were reassembled and I was rewarded with an excellent example of an Amplion Dragon in working order. It was well worth the effort! A true collector's item ' . The finished loudspeaker, circa 1926. Many hours of work went into restoring the oak flare and painting the metal strips that hold it together. Although horn speakers are terrible things to listen to, this one is a true collectors's item. It was fortunate that the driver I have had for so long was in working order and only required a coat of paint to tidy it up. Some Amplion drivers are not easy to dismantle as there are no convenient screw heads to undo. They seem to be sealed units that were not meant to be tampered with. Listening to the old Amplion confirmed my previous remarks. It sounded no better or worse than most other horn speakers. However, its looks and general appearance are far more appealing to the eye than most and that is what the old Dragon is all about. It is a collector's item in the true sense of the term! An interesting aspect of collecting horn speakers is that although they are primitive by modern standards, they were the pinnacle of technological development at the time they were made. Every invention has to start somewhere and from that point on it is gradually modified and improved until technical excellence is finally obtained. For example, consider how much sound recording and reproduction equipment has improved since the early days of the Edison cylindrical gramophone. Likewise, the loudspeaker has gone through many stages of development during the past 70 years. One does not have to listen to a horn speaker for very long to fully appreciate just how much time and effort has gone into loudspeaker development since the 1920s - a time when the Amplion Dragon reigned supreme. SC TETIA/MITSUBISHI ELECTRIC AWA TECHNICAL LECTURES 13th and 14th March 1993 • WMM,i ►iidW Enjoy a weekend of informative technical lectures and exciting afterhours fun at the luxurious WREST POINT Hotel/Casino. Subjects include VCRs, TVs, CDs, Fax, microwaves & cellular telephones. Fares, accommodation, meals etc. are a legitimate business deduction so why not take a tax free_Q~~ak aw8:_y from the routine? Go on! Be a Devil! - - , :::F= -- Contact Cliff Townsend, 27 Alma Road, Orford, Tasmania 7190 or phone him on (002) 57 1266. FEBRUARY 1993 99 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. Write to:Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. Valiant ignition fights on I have a query on the electronic ignition circuits based on the Motorola MC3334P which have been featured in various issues of SILICON CHIP. I need one for my own car. It is for a Valiant which has a reliable system. One only needs to change the plugs when it gets hard to start on cool mornings. Anyway, the Chrysler unit uses a TIV transistor and the sealant leaks out in the hot weather and it draws about 6A running - double the specifications. My question involves the adaptability of the SILICON CHIP circuit to this one, in respect to the dual ballast resistor which has an auxiliary resistor of 0.5.Q Does the SILICON CHIP design use this auxiliary resistor and does it sink the coil current in the same way? I would like to fit the Chrysler socket Using the inverter with computers I have been reading with interest the articles on the 2kW inverter that began in your October 1992 issue. A couple of days ago, we had a bad electrical storm . that passed through the area where I work and lightning struck a tree in the grounds outside the building. It blacked out our power for a few seconds - just enough to send our main computer system into a spin. We are intending to purchase a UPS for it but a unit that would run our system for about 15 minutes will cost in excess of $4500 (it takes that long to properly power down our system). I was wondering how much modification would need to be done to the inverter to turn it into a UPS, as this project would be a lot more viable for us 100 SILICON CHIP on it so I'd have an emergency plug when on long trips. (R. D., Darwin, NT). • Unfortunately, we do not have any circuit information on the ignition systems fitted as original equipment to motor vehicles. The Chrysler system does appear to have used a sensing resistor to prevent the coil current from exceeding a predetermined value. In that respect, it is probably similar in principle to the circuit suggested by Motorola for the Delco distributor. This circuit was featured in the article on our reluctor-based high energy ignition published in the May 1990 issue of SILICON CHIP. Having said that, it may be possible to adapt our circuit for use in the Valiant system. Generating 240VAC in a remote area The area that I live in is about 2km and would easily run our computer system. (M. R., Toowoomba, Qld). • Essentially, the inverter could be converted to function as an uninterruptible power supply (UPS) by providing an additional circuit which senses mains drop out and then switches over to the inverter. The inverter could either be run continuously or, if a longer changeover period could be tolerated, the inverter could be switched on by the mains changeover circuitry. We do intend to do something along these lines in the longer term but have no plans to do it within the next few months. Mind you, by the time you build an inverter and provide a decent battery bank using explosion proof batteries, you may well find that $4500 is quite reasonable for the UPS you require. from the nearest power pole and to have 240VAC mains installed would be far too expensive. Because of this, we have gone to an alternate lifestyle. We run two battery banks of12V. Each bank consists of two rows of six 2V ex-Telecom batteries connected in series to give 12V, then hooked up in parallel to give twice the amperage. These batteries are charged via two solar panels (one per bank of batteries) which on a good day can deliver up to 4A per panel. To assist charging in winter, we run a generator. Not only does this generator assist charging but it runs a few of our 240VAC appliances as well. I am interested in the 2kW 24/240VAC Sinewave Inverter featured in the October and November issues of SILICON CHIP. My only concern is that this inverter operates at a voltage of 24 V rather than 12V. I would like to know what I would have to do to change it to 12V operation. If this isn't worth doing, then could you tell me of a circuit that could regulate 240VAC at a reasonably high amperage with any starting voltage, as our generator is not regulated and when the revs go up so does the voltage. Because of this, we have to set the throttle at a certain point to give us 250-260VAC, to allow for voltage drop when a big load is connected; eg, our washing machine. If I had such a circuit, I wouldn't have to worry about the starting voltage, or any high voltage that may damage our appliances (which has already been done). When we bought our generator we were told that it was regulated but we found out that this was wrong. The generator started putting out in excess of 390 volts and destroyed. or damaged most of our 240VAC appliances. Any suggestions would be greatly appreciated. (S. J., Walwa, Vic). • It is not possible to modify the 2kW Sinewave Inverter to run from 12V without substantial redesign. Why not use your existing battery bank in series rather than in parallel? You could still use the same charging arrangement of one solar panel for each bank of batteries. Better still, you could connect the two solar panels in series and use them to charge the whole 24 V battery bank in one go. We are surprised that your generator does not have sorne form of regulation which is usually achieved by varying or rapidly switching the field current. We are also surprised that the revs can vary. Normally a 240VAC 50Hz petrol powered alternator is set to run at a fixed speed which is close to 3000 rpm (to obtain 50Hz). The throttle is then automatically governed to maintain the speed, regardless of changes in the load. It seems possible that you have been sold a "pig in a poke". You should have it repaired or replaced to avoid the risk of damaging your appliances again. By the way, the 2kW inverter will run a standard washing machine without any problems. Confusion on diesel sound simulator With lightening heart, I read the project article on the Diesel Sound Simulator (SILICON CHIP, December 1992) only to conclude in a state of confusion. My problem is simple. I wish to use the project in my radio-controlled model boat. The heart of my boat is a 12V 35Ah lead acid battery, so finding a suitable power supply presents no problems. The drive system is two 12VDC motors, independently controlled by two reversible, resistive, variable speed controllers. These each have a maximum resistance of 15Q to drive the screws at very slow speed. How do I modify the input circuit to make the Diesel Sound Simulator operate in my boat? Secondly, if I use the DSE K-2630 audio amplifier to drive a larger speaker, will I have to modify the existing audio amplifier circuit to suit this external amplifier? (N. S., Coolbellup, WA) . • This circuit should be adaptable for use in your boat without any modifications - just connect the input across one of the motors. In addition, the existing small amplifier should be quite adequate to drive a larger loudspeaker. In fact, we would suggest that you try the circuit on its own Solution to masthead amplifier problem a 1.SpF ceramic capacitor and what had been an attenuator became an amplifier. I refer to the Masthead AmpliThis begs the obvious question: fier, published in SILICON CHIP in if it's a design fault, what of the August 1991 and the letter from R. "many hundreds of kits sold"? Are W. in June 1992. I too purchased they relegated to many hundreds one of these kits an d had precisely of junkboxes or are they being used the same results as R.W. in high-signal areas that benefit Because mine was an awkward from an attenuator rather than an mast to access and since we wanted amplifier? Or is there some pecuimmediate reception, I did the liar resonance problem with the same as R. W. and purchased a kits purchased by R. W. and mycommercial unit, consigning the self, perhaps linked to station freqkit to the junkbox. uency? Some time ago, however, a friend . Whatever the answer, I can only required a masthead amplifier, so suggest that if anyone has one of I decided to exhume the kit and these kits in the junkbox, they just see if I could find out why it be- try the above modification. They haved more like an attenuator than too might be pleasantly surprised! an amplifier. All components ex- (R. R., Maclean, NSW). cept the OM350 were either • We are very interested to learn checked or replaced, to no avail. that you were able to make your This only left the OM350 or a de- masthead amplifier operational by sign fault. discarding 14. In fact, if L4 can be I was reluctant to purchase an- discarded, then you really should other OM350 after reading of R. not need the 1.SpF ceramic caW.'s woes, so I took a closer look at pacitor either. the schematic. With the limited In answer to your obvious quesequipment at my disposal, it tion, we don't know how many seemed that 14 (in the LT Telebrite other units would have the same power supply unit) was highly sus- fault. However, any readers who pect. This coil appeared to simply are experiencing problems with shunt the signal to ground, so L4 this unit should try the same apwas discarded and replaced with proach. before building or buying a larger audio amplifier. If you do decide to run another amplifier, you can leave out transistors Q2-Q5. The signal from the Diesel Sound Simulator is then connected to the external amplifier from the junction of the 47kQ and 100kQ resistors; ie, at the base of Q2. of the Triac and its A2 electrode. Notes & errata Studio Twin 50 Amplifier, MarchApril, 1992: the power amplifier stages can become unstable if the polyswitches (TH1) open due to overdrive and disconnect the Zobel networks. To prevent this, replace the two poly- Are Triacs equivalent types? I have been supplied with a Q6040J7 Triac in place of BTA41 600 Triac. Can this substitute be used and if so what alteration is required to the circuit? Note: the physical difference can be taken care of. (I. H., Killarney, Qld). • The Q6040J7 Triac is a suitable substitute for the BTA41 and no alterations to the circuit are necessary. Note that you should check that there is no electrical connection between the tab !\ + GNO GNO + LEFT RIGHT OUTPUT OUTPUT switches on the PC board with wire links and connect them instead between the outputs of the Zobel networks and the speakers. The above diagram shows the wiring details. SC FEBRUARY 1993 101 .......TCENrRE Cash in your surplus gear. Advertise it here in Silicon Chip. r-------------------------7 CLASSIFIED ADVERTISING RATES ANTIQUE RADIO Advertising rates for this page: Classified ads: $10.00 for up to 15 words plus 40 cents for each additional word . Display ads (casual rate): $20 per column centimetre (Max. 10cm). Closing date: five weeks prior to month of sale. To run your classified ad, print it clearly in the space below or on a separate sheet of paper & send it with your cheque or credit card details to: Silicon Chip Classifieds, PO Box 139, Collaroy Beach, NSW 2097. Or fax the details to (02) 979 6503. ANTIQUE RADIO restorations. Your one-stop radio repair shop. Specialising in restoring vintage radios, including chassis rewiring, re-condensing, quality new parts, valves, valve sockets, speakers, power & audio transformers. Secondhand radio dials & parts for most brands & models. About 400 radios in stock for sale, restoration & parts. Every restored wireless is covered by a 2year warranty on parts & labour. We restore damaged woodwork & cabinets & French polish (approx. 40 coats) . Vintage car radios available for sale or restoration. Repairs done on tape decks. Open Sat. 10am-5pm; Sun. 12.30-5pm. 109 Cann St, Bass Hill, NSW 2197. Phone (02) 645 3173 BH or (02) 726 1613AH. FOR SALE Enclosed is my cheque/money order for $._ _ __ D Bankcard D Visa Card D Master Card or please debit my XI I I I Signature_ _ _ _ _ _ _ _ _ __ _ Card expiry date_ _~/_ _ _ I Name _ _ _ __ _ _ __ _ _ _ __ _ __ _ __ _ __ _ I I Street _ _ _ __ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ __ I I Suburb/town _ _ _ _ _ __ __ _ _ _ Postcode_ __ _ __ L _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ JI Card No. 102 SILICON CHIP WEATHER FAX programs for IBM XT/ ATs *** "RADFAX2" $35 is a high resolution, shortwave fax, Morse & RTTY receiving program. Suitable for CGA, EGA, VGA and Hercules cards (state which). Needs SSB HF radio & Radfax decoder. *** "SATFAX" $45 is a NOAA, Meteor & GMS weather satellite picture receiving program. Needs EGA or VGA plus "WEATHER FAX" PC card. *** "MAXISAT" $75 is similar to SATFAX but needs 2Mb expanded memory (EMS 3.6 or 4.0) and 1024 x 768 SVGA card. All programs are on 5.25-inch or 3.5-inch disks (state which) & include documentation. Add $3 postage. Only from M. Delahunty, 42 Villiers St, New Farm, Old 4005. Phone (07) 358 2785. PAY ASIAN PRICES for common electronic components. No minimum. Ask about hard to get items. Local SAE for details. DIY Electronics, GPO Box 904, Hong Kong. FOR SALE: we have a number of Plessey 2001 B-MAC satellite receivers for sale. This model is currently retailing at over $2200.00. These are in good going condition and complete with SURPLUS COMPONENT SALE STOCK QTYS LIMITED, NO BACKORDER$ . 2N3055 $1.20 RESISTORS TIP30C $0.50 MOST VALUES AVAIL. TIP122 $1.20 1I4W MIFILM $31100 2N7000 $1.50 113W CARBON $21100 2SC2240 $0.60 112W CARBON $41100 VN88 $2.00 · 1W CARBON $51100 3N170 $1.50 2W CARBON $8/100 2N5954 $1.50 SW WIREWOUND $0.30 2N3440 $1.20 10W RESISTORS $0.60 2N4392 $0.50 100uF 10VTANT $1.50 LM3900 $0.50 C&K 1201 SW $0.50 27C41 $1.00 SW Oil SW $2.00 68681 $7.00 CD22100 IC $2.50 747CJ $0.80 78L12, 79L12 $0.50 8251 $3.00 8259 $4.00 74122 $0.50 A25 THERMISTOR $5.00 4520 $1.00 MCT275 OPTO $1.20 74HC132 $1.00 MOC3020 OPTO $2.00 74HC14 $1.00 MOC8050 OPTO $1.50 4528 $1.00 74C161 $2.00 7417 $0.50 74HC74 $0.70 9602 $0.50 74S02 $0.70 PHONE OR MAIL ORDERS, CREDIT CARDS ACCEPTED FOR ORDERS $20 & OVER, DISCOUNTS FOR QUANTITY ORDERS SECONTRONICS PO BOX 2215, BROOKSIDE, OLD 4053, PHONE {07) 355 1314 143 GRAYS RD, ENOGGERA, QLD 4051, FAX (07) 8551014 SHOP OPEN SATURDAY 9AM • 4PM AH (07) 8551880 MEMORY & DRIVES Plans Kits and PCBs PRICES AT DEC. 10TH, 1992 SIMM 1Mbx9 1Mbx 3 4Mbx9 4Mbx B DRAM DIP 1 x 1Mb 256 X 4 41256 1Mbx4 70ns 70ns 70ns 80ns $52 $48 $190 $174 70ns 70ns 80ns (stat) $5.50 $5.50 $2 $23 DRIVES SEAG42Mb SEAG89Mb SEAG 107Mb SEAG 130Mb SEAG245Mb 14ms 14ms 15ms 12ms 12ms $240 $310 $360 $398 $770 IBM PS.2 50/55170 70135 90/95 2Mb 4Mb 4Mb $120 $210 $210 TOSHIBA T3200SX T44/6400 T5200 2Mb 4Mb 2Mb $150 $300 $150 MAC 2Mb SI & LC 4Mb P'Book $95 $245 PROCESSORS INTEL 486DX2-66 INTEL 486 DX50 $950 $810 EPROMS 27C 256-150 $3 Sales tax 20%. Overnight delivery. Credit cards welcome. Ring for Latest Prices 100W Valve Amp PCB ............................................... $30 Valve Amp PSU PCB ................................................. $25 Universal PSU (±5/±12V) Dual Supply ...................... $10 Digi 125100W amp/pair ............................................ $10 ETI 1623 PIA for PCs .............................................. $40 Max 1/0 Board ............................................................ $40 Max Kit ............ .. ............... $169 LM380 3.5 amp PCB ................................................... $7 AEM 35W amp kit ........ ................................ .. ........ $20 ETI Audio Toolkit PCB .............................................. $10 AGC Amp PCB ...... .. ................. $7 Z-80 Miniprocessor PCB ............................................ $50 6502 Miniprocessor PCB ......................................... $50 6809 Miniprocessor PCB ........................................... $50 8048/8049 Developers board complete B& T ........... $199 IBM PC Prototype PCB.................. .. ...................... $50 EPROM Programmer .............................................. $299 ESL-1 Electrostatic speaker kit/pair inc manual ...... $899 ESL-1 Assembly Manual ........................................... $50 P.C. Computers (08) 332 6513 36 Regent St, Kensington SA. 1st Floor, 100 Yarrara Rd, PO Box 382, Pennant HIiis, 2120. Tel: (02) 980 6988 Fax: (02) 980 6991 PELHAM FIX-A-KIT KIT REPAIR & CONSTRUCTION remote controls and handbooks. If interested, please make a cash or Bankcard offer to: Long ridge Electronics, PO Box 290, Norfolk Island 2899, or fax to (0011) 6723 22833. THE HOMEBUILT DYNAMO: (plans) brush less, 1000 watt at 740 revs. $A85 postpaid airmail from Al Forbes, PO Box 3919 - SC, Auckland, New Zealand. Phone Auckland (09) 818 8967 anytime. KIT REPAIRS & Construction Service. Fixed price servicing for all kits. No job too small. Ph (02) 649 2134 after 5pm. COMPONENT PACKS, 30 trimpots, Bourns, Beckman etc, mixed values and types including multiturn. 400 metal film ¼W resistors, most are 1% or 2% Beyschlag, mixed values including some E96 and E192 series. 200 carbon film ½W and 1W resistors, most are Beyschlag 1% or 2%. All component packs $12 ea plus $5 p&p. Japanese transistor pack with two each of 2SA1069, 2SC923, 2SC1826, 2SC3157, 2SD381, 2SD667, $15 per pack. Electronic component pack, 400 items including ICs, transistors, diodes, resistors, trimpots, capacitors, relays, fuses etc. All new components, $25 per pack, plus $8 p&p. Valves, CV3998, · 12AX7, 12AY7, 12BY7A, 3A4, 6AM5, 6J7G, all $8 each or 10 for $70 (can be mixed). Open Thursday, Friday 4pm8pm, Saturday 9am-4pm, 143 Grays Rd, Enoggera, Old. Ph (07) 355 1314 or (07) 855 1880 AH. Fax (07) 855 TRANSFORMER REWINDS 3 MONTHS WARRANTY ON REPAIRS 12 MONTHS WARRANTY ON CONSTRUCTION TECHNICAL ASSISTANCE ALL TYPES OF TRANSFORMER REWINDS HVCAL ELECTRONICS TRANSFORMER REWINDS Design. Manufa cture & Re p a i r of El e ctro n ic Reply Paid No.2, PO Box 438, Singleton, NSW 2330. Ph: (065) 761291. Fax: (065) 761003. 1014. Visa, Bankcard, Mastercard available for fax or phone orders over $20. Secontronics, PO Box 2215, Brookside, Old 4053. 8061 MICRO-COMPUTER PROTOTYPING PCB $30 - similar to my ROMLoader EA Jan 92. Provision for 8255 PPI, 9346 EEPROM, 2k-32k SRAM, 2k-32k EPROM, MAX232, DIP switches & expansion header. Send A4 SAE for article. Tantau, PO Box 206, Gordon 2072. AMSTRAD NOTEPAD info disk. IBM 720K format. Includes expansion software drivers and circuits, a full map of all Port addresses, and a short machine language tutorial on the inbuilt Z80 Assembler. $15, or free with the purchase of a unit at $390 incl. post & ins. For promo disk, send a $1 stamp to [---------~=-; INTELSTAT - International Satellite (Television) Receiving System (movies, sport, news). Commercial 4.8-metre solid dish plus system electronics package. Can see operating. $3995.00 ono. Phone Rod (08) 387 03-Z:2. Equipme nt (02) 633 5477 Don McKenzie, 29 Ellesmere Crescent, Tullamarine 3043. Phone (03) 338 6286. MUSIC ON HOLD KIT: SC Sept.1990. This unit is simply connected across · the existing telephone line. Press the "Hold" button and your caller will have music on hold, press the release button to restore the conversation. Captures the line when activated and an inbuilt pulser and a flashing LED remind you that the hold function is activated. Will even release the line after a few minutes in case you forget that you left somebody on hold. Just add an inexpensive radio for a complete system. The radio is switched by this unit to conserve its batteries. On special at $30. For the complete kit without the case, 12V DC plugpack: $12.00. Cat No GK116. * 16 CHANNEL UHF REMOTE CONTROL: see EA Nov 88-Jan 89. One transmitter kit, one receiver kit, & one 4-channel relay driver kit, priced to clear •at a total price of $99. Ref XXFEB9401 . * 1-inch CRO TUBE: new 1-inch CRO tube, plus a connecting diagram, plus a simple experimental circuit. Very limited quantities: $30. Ref XXFEB9402. * FIBRE OPTIC CABLE: high quality fibre optic cable, single fibre <at> $2/metre or 10 metres for $15, dual fibre <at> $4/metre or 10 metres for FEBRUARY 1993 103 * JV Tuners - Repairs Tuner • • • • repairs for T\'s & \'CRs Shorted Turns Tester High \'oltage Probe Degaussing \\'and Remote Control Tester * (02) 7741154 Fax (02) 7741154 Transfonner Rewinds Advertising Index Altronics ... ....................... ...... 52-53 For all t~ pes of transformer rewinds. Antique Radio Restorations ..... 102 (065) 761291 Fax (065) 761003 Autotron Australia ............ .... ...... 41 A-One Electronics ................ 60-63 Av-Comm .... .......... ..................... 59 Breakthrough Computers .. .. ...... 49 Ian J Truscott's Electronic World EEM Electronics \!ail or credit card facilities Printed drrnit hoard assembly. s11itchmode pm1er supplies repaired. Design 1rnrk from start to finish. Ring anytime 9am-9pm \Ion-Sun. (03) 7233344 Fax (03) 4192808 (OJ) 4011393 For sen ice ~'\; re1rnir work David Reid Electronics ............. ... 5 Dick Smith Electronics .......... 10-13 EEM Electronics ..... ................ . 104 Electronic World ................. 77,104 Emona Instruments ................... 67 Ford Motor Company ............ OBC Harbuch Electronics .................. 76 $30. Ref XXFEB9403. * SWITCHED MODE POWER SUPPLIES: compact enclosed ex-Telecom supplies. Dimensions: 300 x 90 x 180mm. Unregulated input: 30-50V, regulated input of 12V<at> 6A or 5V <at> 40A; two different units. Limited stocks <at> $28 ea. P&P $7 (Heavy!). Specify type when ordering. Ref XXFEB9404. * SOLAR LIGHTING BARGAIN: (EA Nov. 92). This kit has three separate sections that are contained on one PCB b!,.lt can be separated: (1) a crystal locked ultrasonic movement detector, (2) a fluorescent tube inverter (4-20W) with logic circuitry, (3) a solar battery charging regulator & an incandescent lamp switcher-pulser, which employs a Mosfet switch. As a package special, we are offering the complete kit for the three sections plus six 6V/1 W solar panels for a total cost of only $99 ! Ref XXJAN93104. * SWITCHES: high quality miniature enclosed, Italian (FEME) 1, 2, 3 & 5pole, 12-position switches: $2.80 ea or 10 for $20. Ref XXJAN93105. Major cards accepted with phone & fax orders. Total cost of certified p&p: Australia $5, NZ (airmail) $10. Oatley Electronics, PO Box 89, Oatley, 2223. Phone (02) 579 4985. Fax (02) 570 7910. MICRO-ELECTRONIC ENGINEER: a Sydney-based computing technical company wishes to permanently appoint a micro-electronics engineer to provide technical support and to develop new products for export markets. Duties will involve to diagnose and repair MP based PCBs (component level); to design and debug MC interface driver using AL & C; to undertake research on the application of MP controlled elec- 104 SILICON CHIP T. A. Mowles Printed cirrnit hoards for the hohh~ ist. For sen ice & enquiries contact: Hycal Instruments .... ... .. ... ........ 103 Jaycar ... .. .. .... ..... . 33-36,69-72,IBC JV Tuners ................................ 104 Kalex .......... .............................. . 51 Oatley Electronics ......... 44-45, 103 (08) 3265590 PC Computers ......................... 103 Pelham ............................... 31,103 tronic equipment; to liaise with manufacturers in H.K. & Taiwan. The ideal person must have:* tertiary qualification in electronics engineering;* advanced skills in electronic hardware (analog & digital) and software (AL & C): * at least 5 years exp. in MP based hardware service, software design and network support; * initiative to work independently and ability to train staff; * proficiency in English and Mandarin; * a member of ACS, IREE or IEAust preferable. Salary range $32,000 - $38,000 p.a. Please send written application with resume and reference to: Managing Director, Keap Technology P/L, PO Box 1604, Chatswood, NSW 2067. Peter C. Lacey Services ............ 64 Philips Test & Measurement ...... 87 Plough Book Sales .................... 51 RCS Radio .............................. 104 Resurrection Radio .................... 77 Rod Irving Electronics .......... 90-95 Scan Audio .. .... .......................... 23 Scientific Devices ...................... 75 Silicon Chip Binders .................. 30 Silicon Chip Back Issues ...... 54-55 T. A. Mowles ............................ 104 Technical Applications .......... .. ... 43 Tektronix ....... ............................. 79 Tetia ...... .. ................................... 99 Transformer Rewinds .............. 104 RC§ RADIO PTY LTD ~ "ifr1ffi RCS Radio Pty Ltd is the only company that manufactures and sells every PC board and front panel published in SILICON CHIP, ETI and EA. RCS Radio Pty Ltd, 651 Forest Rd, Bexley 2207. Phone (02) 587 3491 PC Boards Printed circuit boards for SILICON CHIP projects are made by: • Jemal Products, 5 Forge St, Welshpool, WA 6106. Phone (09) 350 5555. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone (09) 828 5730. • RCS Radio Pty Ltd, 651 Forest Rd, Bexley, NSW 2207. Phone (02) 587 3491. ''BELLMATE'' BURGLAR ALARMS Jaycar Electronics is proud to announce a new range of high quality, feature packed low priced home/ office/warehouse burglar alarm equipment. The Bellmate range is solely represented in Australia by Jaycar. This means that the middleman has been eliminated and that saving is passed on to our customers. They are only available throughjaycar Electronics,Jaycar Dealers &Jaycar appointed installers. The Bellmate range includes: • 3 Alarm Control Panels • 2 Remote Keypads • 3 Passive lnfrared Detectors. See our catalogue in March '93 for all the details. BELLMATE 950 4 SECTOR PROGRAMMABLE CONTROL PANEL BELLMATE 1000 8SECTOR PROGRAMMABLE CONTROL PANEL This will be available mid February. If you compare features per dollar, we believe no other alarm panel comes near. Features include: • Keypad controlled • Easy to programme • Heavy duty 1.5mm thick painted steel cabinet • 4 zones • 24 hour zone • Lockout if incorrect access codes used • Split end of line resistors • 3 sound panic sirens • 1 year warranty • Plus more. CAT. LA5320 This panel incorporates they very latest in alarm technology. Look at the features: • 8 programmable zones plus tamper and panic • Each of the 8 zones can be programmed to any I of the 6 options instant, 1st delay, 2nd delay,handover, 24 hour, two trigger • Can have silent alarm if a telephone dialler is used • 4 separate tampers on panel • Split end of line resistors BELLMATE 100 • Plus all the BELLMATE 100 PASSIVE INFRA BELLMATE 1000 BELLMATE 950 features of the RED DETECTOR 4 sector. See our new catal~ e for Watch out for the two new pairs The "I 00" incorporates the latest available shortly. The Bellmate 200 at full details. CAT LA 5324 design features which offer total peace $34.95 and the top of the line 300 INTELLIGENT of mind to the end user, and few at $69.95 <A ,. . REMOTE i'~:;., -r ·:.:,i return calls for the installer. It has .. , . KEYPAD 'II,\;, ei;1 switchable pulse count operation with BELLMATE · ,.,r ~,~.., ~·· single pulse and three pulse trigger 960 KEYPAD I FOR 1000 The keypad looks exactly which virtually eliminate false alarms. This keypad will remotely control like the control panel on the 1000 See new catalogue for full details. the 950 and 1000 panels. alarm. From the keypads you can arm Two year warranty. CAT. LA5016 and disarm the alarm and fully CAT. LA5321. prog:amme it. CAT. LA5325. ------------- I $149 229 $49.95 MAIL ORDER VIA ~ FREE CALL FOR ORDERS ONLY (008) 022 888 HOTLINE (02) 743 6144. ~ - -~ II =·~ s I' "I -.:::.:..._) V/S4 fit:1,:ri!n $50-$99.99 $6.50 OVER $100 $8.00 $49.95 . ~tl~o~~~:~~ncord 2137 ROAD FREIGHT ANYWHERE IN AUSTRALIA (up to 20kg) $13.50 $55 i• ~, 0 :Et!:s Rhodes 2138. ~ • ~ ~, Telephone (02) 743 5222. "'... ■- , - t~::: Fax (02) 743 2066. :t. iL 1 ADELAIDE SA 190 Wright St (Cnr Selby St) (08) 231 7355. Mon-Fri 9-5.30 Fri 8.30-Sat 9-12. BURANDA QLO 144 Logan Rd (07) 393 Om Mon-Fri 9-5.30 Thurs 8.30-Sat 9-4. COBURG VIC 266 Sydney Rd (03) 384 1811. Mon-Fri 9-5.30. Fri 8.30-Sat 9-4. MELBOURNE CITY Shop 2, 45 A'Beckett St City (03) 663 2030. Mon-Fri 9-5.30 Fri 8.30-Sat 9-2. SPRINIVALE VIC 887-889 Springvale Rd Mulgrave (03) 547 1022. Nr Cnr. Dandenong Rd. Mon-Fri 9-5.30 Fri 8.30 - Sat 9-2. SYDNEY CITY 129 York St. (02) 267 1614. Mon-Fri 8.30-5.30 Thurs 8.30pm - Sat 9-4. BANKSTOWN 363 Hume Hwy Cnr Meredith St (02) 709 2822. Mon-Fri 9-5.30 Thurs 8.30pm - Sat 9-4 - Sun 10-4pm. GORE HILL 188 Pacific Hwy (Cnr. Bellevue Ave) (02) 439 4799. Mon-Fri 9-5.30 T~urs 8.30 - Sat 9-4pm. PARRAMATTA 355 Church St (Cnr. Victoria Rd) (02) 683 337Z Mon-Fri 9-5.30 Thurs 8.30pm - Sat 9-4pm. Sunday 10am-4pm. PENRITH 199 High St. (047) 21 833Z Mon-Fri 9-5.30 Thurs 8.30 - Sat 9-4pm Sun 10-4pm. RHODES 6 Leeds St. (02) 743 5222. Mon-Fri 9-5.30.