Fig. 89. Induction Coil.
A Simple High Tension Sparking System.—With such a coil, of proper size, and adapted to receive the required current, several things are necessary in order to produce a sparking effect.
Condenser.—One of these is a condenser, which, while a spark can be produced without it, is nevertheless an important element. The office of a condenser is to absorb a certain amount of current. It will be remembered that the drawing apart of the points in a conductor, produced a spark. Now in the secondary current, of the high tension system, is an interrupter, a mechanism that makes and breaks the circuit continuously.
Interrupter.—Whenever the interrupter opens the circuit, the condenser absorbs the surging current produced by the break, so that it acts like a storage battery in the system.
Fig. 90. High Tension Circuit.
The interrupter may be made something like the mechanism of an electric bell, in which the current is interrupted as the clapper moves back and forth.
By referring to Fig. 90 a comprehensive idea may be obtained of a high tension system for igniting the compressed fuel in a gasoline engine.
Arrangement of a High Tension System.—The dynamo A, or the battery, as the case may be, is connected up with the primary coil B, by means of the circuit wires C. The secondary coil D, which is, of course, wound around the primary B, in practice, has one of its terminals E extending to what we shall call the spark plug F.