The Theremin (710502) has no keyboard, but was (and still is) used as an instrument for live performance. An earlier instrument, Thaddeus Cahill's Telharmonium, which began operation in New York City in 1906, was a huge electromechanical installation operated by a musician playing piano-like keyboards. With the invention of vacuum tubes a few years later, amplifiers and tone generators (or oscillators) were built. They were much simpler and smaller, and used much less electric power. They also produced louder sounds. These were used by Russian scientist Leon Theremin in the 1920s in the design of the first Theremin.

Leon Theremin with his electronic music device. The rod and loop sensors are attached to induction coils and amplifying electronics. (Big Briar Inc.)

To play the Theremin, the musician controls pitch with one hand and volume with the other by changing the hands' distance from two rods protruding from the instrument. It is an exciting instrument, opening new sound possibilities. It produces ethereal visual and sonic effects as the performer's hands wave and flutter in the air. The instrument was commercially manufactured by RCA.