Analysis of high-requency ignition circuits

THE modern high-voltage magnetos installed on a 2,000-horsepower aircraft engine may not resemble externally the crude induction coil used by Lenoir in 1860 to provide ignition for his gas engine. Yet, both make use of the same method to generate a transient voltage high enough to fire the spark plug. A current is first established in a primary winding surrounding a core of magnetic material and then suddenly interrupted. This interruption produces a high rate of change of flux through a secondary coil wound with a large number of turns, thus inducing a high voltage that is transmitted to the spark plug.