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Contents Vol.22, No.5; May 2009 www.siliconchip.com.au SILICON CHIP Features 12 Tech Support: Terror Tales From The Front Line You wouldn’t believe some of the idiotic calls that computer tech support people get; but then again you just might – by Barrie Smith 16 HID Lamps: Out Of The Car & Over Your Shoulder It’s taken a while but high-intensity discharge (HID) lamps are now available in hand-held spotlights. Here’s a look at Jaycar’s ST-3369 – by Ross Tester Dead-Accurate 6-Digit GPS-Locked Clock – Page 20. 70 Why Calibrate Your Test Equipment? If you work in industry, it’s vital that your test equipment is correctly calibrated. Here’s why – by Tony Tong 72 How To Draw Circuit Schematics In Protel Autotrax Here’s an easy way to make your circuit diagrams look good – by Rick Walters Pro jects To Build 20 Dead-Accurate 6-Digit GPS-Locked Clock, Pt.1 Looking for a digital clock that’s always dead accurate? This one is locked to GPS time signals, so it never needs setting or adjusting – by Jim Rowe 36 230VAC 10A Full-Wave Motor Speed Controller 230VAC 10A Motor Speed Controller – Page 36. It gives smooth control from near zero to full speed on electric drills, routers, circular saws & other appliances with universal motors – by John Clarke 62 Precision 10V DC Reference For Checking DMMs Check your DMM’s accuracy with this simple device. It provides a precision 10V DC reference that’s accurate to within ±3mV – by Jim Rowe 80 UHF Remote 2-Channel 230VAC Power Switch Long range (80-metres) unit uses pre-built UHF transmitter & receiver modules to make it easy to build – by Branco Justic & Ross Tester 88 Input Attenuator For The Digital Audio Millivoltmeter Precision 10V DC Reference For Checking DMMs – Page 62. Extend the range of the SILICON CHIP Digital Audio Millivoltmeter with this easy-to-build switched input attenuator – by Jim Rowe Special Columns 30 Circuit Notebook (1) 12V Regulated Inverter Supply; (2) Solar Panel Tracker Uses LED Sensors; (3) Picaxe-Based Solar HWS Boost Control; (4) 3-Stage Dimmer For Mountain Bike Light; (5) Reticulation Valve Locator; (6) Overvoltage Protection For DC Loads; (7) Preamplifier For Speed Controller 57 Serviceman’s Log The real meaning of eternity – by the Serviceman UHF Remote 2-Channel Mains Switch – Page 80. 92 Vintage Radio The Astor Football GR/GRP 3-Valve TRF Receiver – by Rodney Champness Departments   2   4 29 79 Publisher’s Letter Mailbag Order Form Product Showcase siliconchip.com.au   96 Ask Silicon Chip   99 Notes & Errata 102 Market Centre Input Attenuator For The SC Digital Audio Millivoltmeter – Page 88. May ay 2009  1