singing Tesla coil

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File:MOStesla.ogv's coil]]

The singing Tesla coil, sometimes called a zeusaphone, thoramin or musical lightning, is a form of plasma speaker. It is a variety of a solid state Tesla coil that has been modified to produce musical tones by modulating its spark output. The resulting pitch is a low fidelity square wave like sound reminiscent of an analog synthesizer. The high-frequency signal acts in effect as a carrier wave; its frequency is significantly above human-audible sound frequencies, so that digital modulation can reproduce a recognizable pitch. The musical tone results directly from the passage of the spark through the air. Because solid-state coil drivers are limited to "on-off" modulation, the sound produced consists of square-like waveforms rather than sinusoidal (though simple chords are possible).

Image:singingteslacoil.jpgThe term "singing Tesla coil" was coined by David Nunez, the coordinator of the Austin, Texas chapter of Dorkbot, while describing a musical Tesla coil presentation by Joe DiPrima and Oliver Greaves during DorkBot's 2007 SXSW event. The term was then made popular by a CNET article describing the event.{{cite web|last=Terdiman |first=Daniel |url=http://news.cnet.com/8301-17938_105-9696332-1.html |title=The singing tesla coils |publisher=Crave - CNET |date=2007-03-10 |accessdate=2013-10-28}} They had been doing public performances with the technology since March 2006.[http://austinist.com/2006/03/27/art_outside_the_pulse_of_austins_creative_community.php] {{webarchive|url=https://web.archive.org/web/20120309132842/http://austinist.com/2006/03/27/art_outside_the_pulse_of_austins_creative_community.php|date=March 9, 2012}} Shortly after that, DiPrima named their performance group "ArcAttack" and became the first musical group to ever use this technology in live performance.{{cite web|last=Terdiman |first=Daniel |url=http://news.cnet.com/8301-13772_3-9921650-52.html |title=ArcAttack brings singing Tesla coils to the masses |publisher=Geek Gestalt - CNET News |date=2008-04-17 |accessdate=2013-10-28}}

Early versions of musical Tesla coils generally used zero crossing threshold detectors as a method of producing music through their spark output. Scott Coppersmith was the first person to design a complete MIDI-based Tesla coil system.{{cite web|url=http://www.pupman.com/listarchives/2006/Apr/msg00667.html |title=Fwd: MIDI (68HC11) controlled DRSSTC - TeslaPhonic Organ Project |publisher=Pupman.com |date=2006-04-27 |accessdate=2013-10-28}}

MIDI is the most common method of music production. It works by means of a microcontroller that is programmed to interpret MIDI data, and output a corresponding Pulse-width modulation (PWM) signal. This PWM signal is coupled to the Tesla coil through a fiber optic cable, and controls when the Tesla coil turns on and off.