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Dr Video not good on latest Macrovision I recently constructed two Doctor Video kits from the April 2001 issue and have since tried to use them only to find that although they do help they don’t work fully. I tried to copy my Star Wars trilogy set so as to keep the originals in perfect condition. I found that it helped stop some of the horizontal tearing in the picture but not enough to stop all of the colour and hori- in different places. (R. S., via email). • You can run another IRLED via a separate 220Ω resistor connected to transistor Q1. Ignition circuit runs hot I have built the High Energy Ignition described in the June 1998 issue. It works well but the case gets very hot. I checked the current draw which was around 4A at idle, dropping to 3A when I revved the engine. All this seems OK but I am just a bit con­cerned that it runs so hot; I can’t keep my hand on the case. (P. C., via email). • Paradoxically, it is the current limiting which causes the circuit to run hot. If you want to check that your circuit is running properly. Short out D3 to disable the current limiting. The case should now run just warm to the touch; if it is still hot, you have a fault. Another possibility is that the case is too close to the engine. It is best to Notes & Errata Audio/Video Distribution Amplifier, November 2001: the 12 47kΩ resistors for the audio distribution outputs should be changed to 1kΩ. This is to avoid undue treble loss due to long cables. Though not essential, to ensure an extended bass response down to 20Hz with all six outputs in use, increase the output coupling capacitors from 0.39µF to 1µF. Programming Adapter for AVR Microcontrollers, October 2001: Fig.1 on page 69 shows the optional programming indicator connected to ground. www.siliconchip.com.au zontal problems. Can you help? (P. C., via email). • It sounds like the tape you want to copy has the very latest version of Macrovision which is designed to be much harder to remove than the earlier versions. If so, the Dr Video box won’t be able to give clean enough video. As far as we know, there isn’t any complete fix for the latest Macro­ vision – luckily it hasn’t been used on too many movies yet but that may quickly change. mount the case away from exhaust manifolds and preferably where air can pass over it. MicroZed Computers HAS MADE THESE NAMES FAMOUS IN AUSTRALIA micro Engineering Labs, Inc. NOW WE INTRODUCE Cooler not cold enough for beer I have built the Switching Temperature Controller described in the August 1999 issue but cannot get it to regulate the tem­perature below 10°C; not cold enough for my beer. I am a pommy but not that much. It was built using the Oatley kit. The Esky can cool to -1°C by removing the thermistor from the circuit. Please help! (Andrew, via email). • If the circuit can cool to below 1°C without the thermistor, we suggest you connect a 100Ω resistor in series with trimpot VR1. This will compensate for any tolerance variation in the thermistor. It seems likely that either there is a wide spread in the thermistor tolerances or a different thermistor has been supplied in the kit. The LED polarity should be reversed and connected to +5V. Universal Fast Battery Charger, June & July 2001: in some cases, transistor Q2 turns on slightly even though the unit is not in Refresh mode. The cure is to install a 1N4148 or 1N914 diode in series with Q2’s base (anode toward pin 10 of IC1). This diode can be installed in place of the link connecting pin 10 of IC1 to the base of Q2. Low Ohms Adaptor for DMMs, September 2001: the Circuit Notebook item on page 68 shows a GND terminal on the LM317. It should be labelled ADJ. SC Basic Micro offer ATOM: a Stamp2 lookalike with extended capabilities available in an IC or OEM format. A development board with sockets for IC and OEM version with a breadboard space instead of solder pads. Basic Micro also offer BASIC compilers, programmers and a range of development boards for 18, 28 and 40 pin PIC Chips. MicroZed Computers PO Box 634, Armidale, NSW 2350 (296 North Cooke’s Rd) Tel: (02) 6772 2777 Fax: (02) 6772 8987 Mob: 0438 277 634 http://www.microzed.com.au December 2001  93