Ignition Coil: Description and Operation

PURPOSE
An ignition coil is a voltage step-up transformer that is used to raise upwards of 50,000 volts to jump the spark plug gap.

OPERATION
The ignition coil has a primary and secondary winding on a common core with a common terminal at one end of the windings. When the primary windings in the ignition coil are energized, a magnetic field builds up around the primary and secondary windings and is reinforced by the core. When the primary circuit shuts off current to the coil, the field quickly collapses, inducing a high tension current into the secondary winding through the ignition coil to distributor high tension wiring, to the distributor cap, and out to the appropriate spark plug.