Research & Development The development of the Tesla coil
The inventor Nikola Tesla experimented at the end of the 19th century with different configurations of two or sometimes three resonant circuits. These experiments resulted in the Tesla transformer, better known as the Tesla coil.
At the end of the 19th century, Tesla experimented with different configurations of two or sometimes three resonant circuits. He used these devices to conduct novel experiments in the fields of electrical lighting, phosphorescence, X-ray generation, high-frequency alternating current phenomena, electrotherapy or wireless transmission of energy.
Tesla coils can generate output voltages ranging from 50 kilovolts to several million volts in large coils. The alternating current output is in the low high-frequency range, usually between 50 kHz and 1 MHz.
Although some oscillator-driven coils produce a continuous alternating current, most Tesla coils have a pulsed output; the high voltage consists of a fast series of pulses of high-frequency alternating current.
Power without cables
The test arrangement in the picture above - the Wardenclyffe Tower built-in 1901 - was to become a prototype for a worldwide energy transmission. However, it was never completed and demolished in 1917 due to a lack of money.
There are no really relevant technical applications for the apparatus other than entertainment and educational institutions. Smaller Tesla coils are used to detect gas leaks in high-vacuum systems. The principle of wireless energy transmission propagated by Tesla is used today to transmit very low power in the range from microwatts to a few milliwatts, but does not require high voltage.
Applications of the principle
Application examples include wireless charging cups for smartphones. Also, RFID chips and sensors that are powered by a high-frequency electromagnetic field. The field is generated by ring coils, which are approached to the sensors and at the same time serve to receive the signals from the sensors. There are also attempts to generate a correspondingly high field in an entire room in order to feed low-power sensors in it.
In the gaming scene, Tesla coils are known from the classic game Command & Conquer Red Alert, in which Tesla coils play an essential role as a defensive weapon against approaching troops.
The largest Tesla coil in the world today is a 130,000-watt unit, part of a 12-meter-high sculpture, and is currently located in a private sculpture park in Auckland, New Zealand.
This article was first published in German by Konstruktionspraxis.