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when displaying the full eight bars from white to black. When I switch S4 from grey scale to colour, it tries to change but remains grey scale. Varying VR2 and VC1 made no changes whatsoever to the colour scale when testing it on my small colour TV. There don’t appear to be any obvious solder bridges on the SMD IC10 on the underside of the PC board and all voltages check OK as per the testing procedures specified in the magazine article. (D. S., via email). The lack of colour may be due to the delay time set by the 2.2kΩ resistor between pins 8 of IC11b and 3,4&5 of IC11c. Try changing the 10nF (0.01µF) at the IC11c inputs to a larger value. Also the 270pF capacitor added at IC10’s pin 16 input may need to be made slightly larger in value to obtain colour. • Cranking difficulties with Austin A1300 I have a problem with the High Energy Ignition project described in the June 1998 issue. I have installed it in an Austin 1300 which is used infrequently. The circuit produces no spark while the starter motor is cranking the engine. I can only start the engine by towing/rolling down a hill or changing over to the HEI once the engine is warm when the engine will run once the ignition switch is released to the running position. What can I do? (G. P., via email). We assume you are using points ignition. The HEI should work even if the battery voltage drops to 6V while cranking. How far does your battery drop? Also check the points gap. Rubbing block wear can reduce the gap to nil. We suggest that you use a larger points gap than specified, to ensure a “clean and fast break” in the points current even when cranking slowly. • LiL Snooper Camera switcher I am interested in building the Li’L Snooper camera switcher from the June 2001 issue of SILICON CHIP. I have one question though. The cameras to be used with it are both colour. Is this circuit be suitable for colour cameras; one is CCD, the other is CMOS? If not, can you recommend any mods to make it suitable? (C. L., via email). www.siliconchip.com.au Notes & Errata Multi-purpose Fast Battery Charger: June and July 2001. When charging older cells either singly or in series, it is important to ensure that their contacts are clean to prevent voltage drops across these connections.    High resistance connections will prevent the charger from operating correctly as it will detect a high voltage per cell and simply indicate “no Battery”.    In addition the connecting leads from the charger to the cell or cells must be rated at 7.5A or more and be no longer than necessary to prevent voltage drops. K-Type Thermocouple Thermometer/Thermostat, August 2002: The display reading and the thermostat trip point can be affected by RF signals produced by portable and mobile telephones when these are close to the unit. This problem can be cured with the addition of four 100nF (0.1µF) ceramic capacitors and a 1kΩ resistor. The 1kΩ resistor is placed in series with the probe input connecting to pin 3 of IC1 while one 100nF capacitor connects between pin 3 and pin 4 of IC1. This forms a low pass filter in the input circuit. The second 100nF capacitor connects between pin 3 of IC1 and ground which is the thicker PC track adjacent to the 10µF capacitor The Snooper will work with any •camera which delivers a 1V composite video signal. Low sensitivity in Theremin I have recently built the Theremin project from the August 2000 issue of SILICON CHIP. It works well but I find the sensitivity and range of the pitch antenna low. This is also the same case with the volume disc but this is not such a problem. I have earthed myself to the ground plane of the project and this helps but it is still limiting. I was wondering if there is a circuit modification I could do to improve this? This web site http://www.maxiespages.com has to the left of IC1. The third 100nF capacitor connects between pins 2 and 3 of IC1. The 100nF MKT polyester capacitor connecting between pins 6 and 2 of IC1 (located to the right of IC1 on the PC board) is removed. The fourth 100nF ceramic capacitor connects between pins 2 and 3 of IC2.   To provide for these changes, we have modified the PC board, as shown in this diagram. The modified PC board is coded 04208022 and is available on our website. Atmel AVR ISP Programming Adaptor (October 2001): The software referred to in the article, avr_isp.zip, is no longer available from the Atmel website. A suitable alternative is “Ponyprog”, available for free download from http:// www.lancos.com/prog.html This program also supports Windows NT/2000 and can program many of the newer AVR devices.    To configure Ponyprog to work with the ISP Programmer, set it up for the “AVR ISP (STK200/300) parallel port interface” as described in the included documentation. Digital Storage Logic Probe, August 2002: the outputs of the 4N25 optocouplers on the circuit on page 24 should be pins 4 & 5, not 5 & 6. The PC board diagrams are correct in this regard. many circuit diagrams but none like your unique design. (T. H., via email). Sensitivity to hand movement is dependent on careful tuning of the Theremin adjustments. However, sensitivity is not extreme and is not meant to be. The original Theremins required the hand to be brought very close to the plate or vertical wire for best pitch and volume changes. Note that positioning of the Theremin is important and it should not be located near to metal surfaces. Also attaching the lid of the Theremin onto the box can alter tuning and readjustments may be required on a trial and error basis. A larger diameter plate and larger diameter antenna can also improve sensitivity. SC • October 2002  91