Circuit Simulator - Tesla Coil

This is a tesla coil circuit. A transformer steps the input voltage up 100x to create a high voltage. After a few seconds, the voltage is high enough to fire the spark gap. The capacitor and the primary coil of the second transformer then form a resonant circuit. The secondary transformer coil is attached to a toroid, represented here by a capacitor connected to ground. It also forms a resonant circuit with the same resonant frequency, about 200kHz The energy is gradually transferred from the first circuit to the second, and then the spark gap stops conducting, leaving all the energy in the toroid circuit.

Once the spark gap stops conducting, it takes a while for the voltage to build up enough for it to fire again. The simulation speed is slowed down quite a bit so that the 200kHz oscillations can be seen. You might want to reload the circuit instead of waiting.