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Advertising Index Altronics.................................. 66-69 Amateur Scientist CD................... 94 Blamey & Saunders Hearing.......... 5 HB Wireless Sales & Service..... IBC Embedded Logic Solutions............ 6 Emona Instruments...................... 57 Front Panel Express..................... 11 Futurlec........................................ 10 Grantronics................................... 95 Harbuch Electronics..................... 59 Hare & Forbes.......................... OBC Ask SILICON CHIP . . . continued from p93 rating by stacking two cores together and winding 0.7 the number of turns originally specified around both cores. The changes for a 24V battery are detailed in the original article in a separate panel. These include changes to the inductor windings. Note that diodes D1 & D2 are only rated for a 100W solar panel, not for 175W. Make sure that any higher-rated replacement diodes are also Schottky types so that the circuit can operate at 32kHz. The low-ESR capacitors need to be increased in number to cope with the extra current. The PCB tracks and fuse are also not suited for the extra power involved and will need to be upgraded. The PCB tracks for the charging section could be beefed up with tinned copper wire. High-energy ignition for old twin-cylinder I have a 2-cylinder Kohler engine driving a wood chipper. Originally it had a “double-ended” ignition coil activated by a conventional set of points from a 12V battery. The coil was damaged beyond repair and a replacement was both expensive and hard to get so I ended up using two conventional 12V coils and condensers wired to the points to get the job we were doing finished. This was some months ago and the decision has been made that the machine should be fixed properly. I thought about using one of your transistor ignition designs but didn’t know if it would handle the two coils. I then went to see my friendly auto-electrician and spoke to him about using a 96  Silicon Chip DOWNLOAD OUR CATALOG at www.iinet.net.au/~worcom WORLDWIDE ELECTRONIC COMPONENTS PO Box 631, Hillarys, WA 6923 Ph: (08) 9307 7305 Fax: (08) 9307 7309 Email: worcom<at>iinet.net.au Notes & Errata High-Energy Electronic Ignition System, Nov-Dec 2012: readers building the coil tester version of the High Energy Electronic Ignition System, as depicted in Fig.10 on page 50 of the December 2012 issue, should be aware that there is a risk of failure in the LM2940CT-5 regulator and the PIC microcontroller due to high voltage spikes superimposed on the common positive lead from the battery to the coil and the ignition module. To avoid this risk, the coil tester should be built exactly as we have configured it for the Jacob’s Ladder in this issue, including the added protection components for the regulator: 10Ω resistor, 13.6V TVS and 1000µF 25V DC input capacitor. These additional components are not required for the other versions of the High Energy Electronic Ignition System. Commodore ignition coil (which he gave me) but he says that they need a special driver. Jaycar has a number of electronic ignition kits but the people in the Port Macquarie shop were unsure as to what would be needed. (D. H., via email). • If you only have one set of points Instant PCBs................................ 95 Jaycar .............................. IFC,45-52 Keith Rippon................................. 95 Kitstop.......................................... 10 LED Sales.................................... 95 Linkwell........................................ 11 Low Energy Developments.......... 95 Microchip Technology..................... 3 Mikroelektronika............................. 7 Ocean Controls............................ 37 Quest Electronics......................... 95 Radio, TV & Hobbies DVD............ 87 RF Modules.................................. 96 Sesame Electronics..................... 95 Silicon Chip Binders..................... 70 Silicon Chip Bookshop................. 79 Silicon Chip Order Form............... 89 Silicon Chip Partshop................... 88 Silicon Chip Subscriptions........... 21 Splat Controls............................... 95 Star Components......................... 95 Television Replacements............. 95 Tenrod Pty Ltd.............................. 19 Truscotts Electronic World............ 95 Wiltronics..................................... 8,9 Worldwide Elect. Components..... 96 driving a coil with two HT output terminals then a Commodore coil driven by our High-Energy Ignition System (SILICON CHIP, November & December 2012) is the way to go. In fact, if you read the Jacob’s Ladder article in this issue, you will see that we are using a version of our High-Energy Ignition. For your application, build the points version of the kit. Altronics or Jaycar SC can supply the kit. siliconchip.com.au