The toroid coil is used on the circuit board, along with some other components, to step up the 4.8 volts to somewhere around 300 to zap the spark coil...The circuits used on the other ignition are not CD ignition, and only control the voltage to the Modelectric spark coil..These coils were used about 50 years ago for the spark ignition engines with points...The coils work fine when used as designed, but the insulation won't hold up for long to the 300 volts from a modern CD ignition system....