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A Tesla coil is an electrical resonant transformer circuit invented by Nikola Tesla around 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. Tesla used these coils 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,〔〔, ( archive )〕〔"''Unfortunately, the common misunderstanding by most people today is that the Tesla coil is merely a device that produces a spectacular exhibit of sparks which tittilates audiences. Nevertheless, its circuitry is fundamental to all radio transmission''" 〕 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.〔 ==Operation== 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. These are described in later sections. 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. The common spark-excited Tesla coil circuit, shown below, consists of these components:〔〔( Denicolai, 2001, ''Tesla Transformer for Experimentation and Research'', Ch.2, p. 8-10 )〕 *A high voltage supply transformer ''(T)'', to step the AC mains voltage up to a high enough voltage to jump the spark gap. Typical voltages are between 5 and 30 kilovolts (kV).〔 *A capacitor ''(C1)'' that forms a tuned circuit with the primary winding ''L1'' of the Tesla transformer *A spark gap ''(SG)'' that acts as a switch in the primary circuit *The Tesla coil ''(L1, L2)'', an air-core double-tuned resonant transformer, which generates the high output voltage. *Optionally, a capacitive electrode (top load) ''(E)'' in the form of a smooth metal sphere or torus attached to the secondary terminal of the coil. Its large surface area suppresses premature corona discharge and streamer arcs, increasing the Q factor and output voltage. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tesla coil」の詳細全文を読む スポンサード リンク
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