Ignition Coil: Description and Operation
PURPOSE/OPERATIONThe ignition coils transform battery voltage into ignition voltage and deliver it in the form of a high voltage surge to the secondary ignition components.
Current flow through the primary winding is stored as a magnetic field. When current flow in the primary winding is interrupted by the power transistor breaking the circuit ground, the magnetic field collapses inducing a voltage surge into the secondary windings.
There are two ignition coils contained in a single unit, each composed of two windings of copper wire around a soft iron core. The primary windings are made of a hundred or so turns of wire. The secondary windings contain several thousand turns of wire wound directly onto the iron core. The ratio of the number of wraps in the secondary winding to the number of wraps in the primary windings determines the output voltage of the coils.
The primary winding is connected directly to the ignition switch (+) and the power transistor (-). The secondary windings are connected to the output towers of the coils through the iron core.