An ignition coil, which is also known as a spark coil is an induction coil in an automobile’s ignition system. It transforms a storage battery’s 12 volts to the thousands of volts needed to spark the spark plugs.
This particular form of the autotransformer (an electrical transformer with only one winding and it has at three electrical connection points called taps), together with the contact breaker (a type of switch found in the distributor of the ignition systems of non diesel powered internal combustion engines) will convert the low voltage from the battery into the high voltage that is required by the spark plugs in an internal combustion engine. The purpose of the contact breaker is to interrupt the current flowing in the primary circuit of the ignition coil.
In the coil on plug system, each spark plug will have its own individual coil that sits right on top of it. This is a so called Direct Ignition module.
The waste spark system is better than having a single coil, and it is cheaper than having a coil on plug. The disruptive discharge tesla coil is an earlier coil of the ignition coil in the ignition system. It also used the same principles of the ignition coil that is used in today’s vehicles.