Instruments where sound is produced using electronics to create an audio signal.
The theremin is an early electronic musical instrument controlled without physical contact by the thereminist (performer). It is named after the Westernized name of its Russian inventor, Léon Theremin, who patented the device in 1928.
The instrument's controlling section usually consists of two metal antennas that sense the relative position of the thereminist's hands and control oscillators for frequency with one hand, and amplitude (volume) with the other. The electric signals from the theremin are amplified and sent to a loudspeaker.
Theremins are also used in concert music (especially avant-garde and 20th- and 21st-century new music) and in popular music genres such as rock.
- from Wikipedia
The singing Tesla coil, sometimes called a zeusaphone, thoramin, or musical lightning, is a form of plasma speaker. It is a variation 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.
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The Ondes Martenot is an early electronic musical instrument invented in 1928 by Maurice Martenot.
The ondes, in its later forms, can be controlled either by depressing keys on the six-octave keyboard (au clavier), or by sliding a metal ring worn on the right-hand index finger in front of the keyboard (au ruban). The position of the ring corresponds in pitch to the horizontal location along the keyboard. The latter playing method allows for unbroken, sweeping glissandi to be produced in much the same manner as a Theremin.
Moog synthesizer (pronounced /ˈmohg) refers to any number of analog synthesizers designed by Robert Moog or manufactured by Moog Music, and is commonly used as a generic term for older-generation analog music synthesizers. The Moog company pioneered the commercial manufacture of modular voltage-controlled analog synthesizer systems in the mid 1960s. The technological development that led to the creation of the Moog synthesizer was the invention of the transistor, which enabled researchers like Moog to build electronic music systems that were considerably smaller, cheaper and far more reliable than earlier vacuum tube-based systems.
- from Wikipedia