An Ignition Coil is an electrical transformer. It converts low voltage to high voltage through a process called induction. There are various designs, but all ignition coils do the same basic job.
Parts of the Coil
An ignition coil is made up of an iron core surrounded by coils of copper wire.
Around the outside of the coil is the primary winding. It is usually a larger wire coiled a few hundred times.
On the inside of the coil, next to the core, is the secondary winding. It is usually a smaller wire coiled a few thousand times.
The coil is then filled with oil or epoxy to help with cooling.
The coil also has a primary (input) terminal, a negative (ground) terminal, and a secondary (output) terminal.
How does it work?
- Electrical current flows into the primary terminal and the primary winding.
- This builds a magnetic field around the iron core.
- When triggered, the current to the primary winding is stopped.
- The magnetic field collapses.
- This induces a high-voltage surge in the secondary winding.
- The high-voltage current leaves the coil through the output terminal.
- The current is sent to the spark plug.
Depending on the design of the ignition system, the current may pass through the distributor or go directly to the spark plugs.