An electro-mechanical keyboard instrument that was a precursor to the Mellotron. It was developed and patented by Iowa, Wisconsin inventor Harry Chamberlin from 1949 to 1956, when the first model was introduced. Various models and versions of these Chamberlin music instruments exist. While most are keyboard-based instruments, there were also some early drum machines.

The basic Chamberlin has a piano-style keyboard. Underneath each key is an individual tape-playing mechanism. Each tape is pre-recorded with various musical instruments or special effects. When the player presses down a key, a pressure pad pushes the tape on to a tape head and a pinch roller beneath the key catches the tape and pulls it forward into a storage box or on to a roller mechanism. As this occurs, the sound of the tape is heard through an amplified speaker. When the player releases the key, the sound stops, and the tape rewinds by either metal spring rods (as on the early models) or by a return roller mechanism (as on the later models). Each tape is only a few seconds long.