Ignition Coil: Description and Operation

The ignition coil houses two circuits: the ignition coil primary and ignition coil secondary circuits. The ignition coil primary circuit uses battery current to create an electromagnetic field that will induce voltage on the ignition coil secondary windings. The ignition coil secondary windings receive an induced voltage of approximately 28,000 volts. This high voltage, low amperage pulse is necessary to generate a spark across the gap of a spark plug.