<P> A Tesla coil is an electrical resonant transformer circuit designed by inventor Nikola Tesla in 1891 . It is used to produce high - voltage, low - current, high frequency alternating - current electricity . Tesla experimented with a number of different configurations consisting of two, or sometimes three, coupled resonant electric circuits . </P> <P> Tesla used these circuits to conduct innovative experiments in electrical lighting, phosphorescence, X-ray generation, high frequency alternating current phenomena, electrotherapy, and the transmission of electrical energy without wires . Tesla coil circuits were used commercially in sparkgap radio transmitters for wireless telegraphy until the 1920s, and in medical equipment such as electrotherapy and violet ray devices . Today their main use is for entertainment and educational displays, although small coils are still used today as leak detectors for high vacuum systems . </P> <P> A Tesla coil is a radio frequency oscillator that drives an air - core double - tuned resonant transformer to produce high voltages at low currents . Tesla's original circuits as well as most modern coils use a simple spark gap to excite oscillations in the tuned transformer . More sophisticated designs use transistor or thyristor switches or vacuum tube electronic oscillators to drive the resonant transformer . </P> <P> Tesla coils can produce output voltages from 50 kilovolts to several million volts for large coils . The alternating current output is in the low radio frequency range, usually between 50 kHz and 1 MHz . Although some oscillator - driven coils generate a continuous alternating current, most Tesla coils have a pulsed output; the high voltage consists of a rapid string of pulses of radio frequency alternating current . </P>

Where does a tesla coil get its power
find me the text answering this question