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The design seems very good but would require considerable effort (and probably extra cost) for little benefit for my circumstances. All that I need is a simple, reliable spark. I know that I will have to buy a 12V coil and battery; I just need the electronics to control the spark. I can use the existing trigger but will need circuitry to couple it to the control module. My questions are: 1. Is a PCB available for the December 2005 Universal High Energy Electronic System, code 05112051? 2. Is there a kit available for that project, or would I have to buy components separately? 3. Is a PCB available for the reluctor circuit? 4. Are there any components that are not available now. If so, what are the alternatives? 5. Are the above all available from your Shop? (T. H., Wallington, Vic) ● We do not recommend building the 2005/6 version of the High Energy Ignition system as there are no longer any kits or PCBs available. However, a Advertising Index Altronics.................................33-40 Control Devices............................. 9 Dave Thompson........................ 111 Digi-Key Electronics...................... 3 Emona Instruments.................. IBC Hare & Forbes........................... 107 Jaycar.......................IFC, 11, 53-55, ..................................60-61, 99, 103 Keith Rippon Kit Assembly....... 111 revised version of that project was published in the November & December 2012 issues (siliconchip.au/Series/18), and the PCB is still available; see siliconchip.au/Shop/?article=464 Kits for that project may also still be available. Check with Jaycar regarding their kit KC5513; their website currently says “Limited quantities available in store”, and if available, it is on sale at $19.80. As well as the PCB, we sell the hardto-get parts such as IGBT and programmed PIC, available via the link above. The other parts are commonly available. The reluctor circuitry is catered for on the PCB supplied. Replacement SOT-223 LDO regulators I am in the process of making the PIC/AVR Programming Adaptor Board (May & June 2012; siliconchip.au/ Series/24), but I can’t seem to find any AP1117E33 3.3V low-dropout linear regulators. Can I use an MCP17993302H/DB or LDI1117-3.3H instead? (L. P., Sydenham, NSW) ● There are many different kinds of compatible LDO regulators in SOT-223 packages with 1117 in their part code. The 3.3V version of the LDI1117 you mentioned should work. Another common compatible type is the AMS1117. The MCP1799 will not work without modifying the PCB because it has a different pinout (Vin, GND, Vout rather than GND, Vout, Vin). About power supply in Circuit Notebook I want to build the “Fully adjustable power supply” circuit published in the Circuit Notebook column, March 2004 (siliconchip.au/Article/3427). I assume the 33Ω resistor needs to be rated at 5W. I do not have an 18V supply at 5A. Can I use a transformer secondary rated at 15V 6A, giving approximately 21V when rectified? I could use a 1W 18V zener and dropping resistor to power the TL071. Is there any erratum for this circuit? (R. M., Melville, WA) ● The 33Ω resistor can be a 1/2W or even 1/4W type as its dissipation will be less than 30mW. There will only be a maximum of about 0.7V across it (the base-emitter forward voltage of transistor Q1). Yes, you can use your proposed 20V DC supply to power that circuit. The TL071 can run from a supply of up to 30V, so no extra zener clamp is required. Replacing components on a failed Turbo Timer I have a burnt-out resistor on my Turbo Timer circuit board (November 1998; siliconchip.au/Article/4649). It is labelled “33R [680R]”. Can you please confirm the value of the resistor I have to replace it with? (S. M., via email) ● The resistor should be 33Ω 1/2W. However, zener diode ZD1 and the 555 timer IC are possibly destroyed as well. The burned-out resistor would have been caused by a voltage transient that shorted the zener diode and possibly harmed the 555 timer. Check if there is a short circuit across ZD1. We suspect that it will measure near 0Ω with a multimeter. All three components should be replaced. SC Lazer Security........................... 111 LD Electronics........................... 111 Microchip Technology......... 5, OBC Mouser Electronics..................... 13 Ocean Controls............................. 8 Rohde & Schwarz.......................... 7 Silicon Chip Shop.................88-89 Silvertone.................................... 12 The Loudspeaker Kit.com.......... 10 Tronixlabs.................................. 111 Wagner Electronics....................... 6 112 Silicon Chip Errata and Next Issue LEDsales................................... 111 isoundBar with Built-in Woofer, August 2022: the part code given for the Peerless tweeters should have been BC25SC55-04 instead of BC25SC55-06. Also, the sheet of 19-20mm thick plywood in the parts list is arguably not required as all the pieces can be cut from the DAR pine lengths. Motion-sensing 12V Power Switch, February 2019: it has been reported that the vibration switches can become unreliable (stuck ‘on’) due to contact welding when it closes. To solve this, solder a 100Ω resistor in series with one of the sensor leads (we suggest the thinner one). This value seems to work well but note that it is a compromise as it must be low enough to discharge the capacitor quickly but high enough to avoid contact welding. Next Issue: the December 2022 issue is due on sale in newsagents by Monday, November 28th. Expect postal delivery of subscription copies in Australia between November 28th and December 12th. Australia's electronics magazine siliconchip.com.au