An electronic instrument named after Paul Tanner, who invented it in the 1950s, and sometimes referred to as an 'electro-theremin'. Unlike a theremin, a Tannerin uses a complex mechanically controlled oscillator.

A Tannerin produces a pure sine wave, variable over 3 or 4 octaves. It is played by sliding a knob along the length of the instrument in front of fixed reference points on a mock keyboard. On some models the tone can be started and stopped with a contact switch located on the pitch knob and operated by the forefinger.

A slide theremin is a more general term for an instrument that sounds like a Tannerin, but has a different mechanical/electrical configuration. A Tannerin is a slide theremin, but a slide theremin is not necessarily a Tannerin.