Misc Circuits: 555 Ignition Coil Driver with Jacob’s Ladder

There are many 555 timer circuits on the Internet for driving ignition coils, but this one seems a bit better than most.

The circuit schematic and PCB template are here:
http://chemelec.com/Projects/Car-Coil/Car-Coil.htm

I was able to make a printed circuit board by taping a piece of paper on the monitor, sizing the image to actual size by using the browser zoom function, and tracing the template off my monitor screen. Then I transferred the template to a bit of PCB material, drilled and etched as usual. (I find it easiest to drill first, then lay down the traces and pads with a Sharpie marker, then etch with Ferric Chloride as usual.) The circuit is running at about 145 Hz and is making a very hot set of sparkies. The trimpot adjusts the duty cycle. I tried first with an IRF830 mosfet, it works fine, but it works better with the IRFP260N. I also substituted BYV26E diodes for the 1n4004s and raised the frequency by changing the 100nF timing cap to 47 nF.

Thanks, GL Chemelec!

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