RE: Scratch Built Ignition???
what chip they use isn't that important, most microcontrollers can easily handle the simple timing operation needed on these engines. they simply count the RPM and vary the amount of delay.
the important part is the code that needs to be written to program the chip. without that it is a worthless piece of plastic with metal legs. for some people the needed code is super simple and for others (like me) it is totally incomprehensible. the most basic PIC project is making a LED blink and after failing at it too many times i simply gave up. i'm better with wrenches and machining....
dave