Chamberlin

Chamberlin — Concert Photography by Wayne Dennon

The Chamberlin is an electro-mechanical keyboard instrument that was a precursor to the Mellotron. It was developed and patented by the American inventor Harry Chamberlin from 1949 to 1956, when the first model was introduced. There are several models and versions of the Chamberlin. While most are keyboard-based, there were also early drum machines produced and sold.

Summary source: Wikipedia