I needed a buzz coil for a little Stove Pipe Domestic I just got from a friend (the Herder engine casting set, with about 4" flywheels). One of the things I always loved about my good friend George Luhr's models what how he hid the coils in a relatively small base and used 2 AA batteries for ignition so you could walk around with his tiny models.
Well, I wanted to hide the ignition in the small coil box on this engine, so I was looking at how others used the standard auto relay's and a regular coil for a buzz coil. The complaint occasionally is that the 12v relay needs 12v for the ignition. Enter George's use of the Modelectric 3v model aircraft coils. I thought why not get a cheap 3v coil relay and try the same setup. Well, I must say so far it looks great! I need to hook it up to the engine and test longevity, but it seems to throw a wonderful healthy spark!
https://youtu.be/tcSCLNZwuL0