Nikola Tesla Books
HOW THE CURRENT IS PRODUCED 15 of apparatus, a simple modification of the condenser discharge principle is available. This method utilizes what is known as a "kicking coil." A kicking coil is a solenoid of coarse copper wire wound upon a laminated iron core. If a direct current be sent through this winding, and the circuit broken suddenly, a pronounced flash will occur at the break of contact. The high potential represented by this flash is induced by the self-induction of the coil wound on the iron core. Under favorable circumstances the instantaneous voltage generated may reach from several hundred to considerably over a thousand volts. This potential is, of course, quite sufficient to charge a condenser, and it is only necessary to provide some suitable means for rapidly making and breaking the circuit with condenser and inductance in series in order to generate a high frequency current quite similar to that produced with the apparatus described in the preceding section. Experiment has shown that a substantial vibrating interrupter with heavy silver contacts serves the purpose admirably. The vibrator is actuated by means of the magnetism in the core of the kicking coil.
