The Printed Circuit Keyboard was designed in 1962. It was operated by the conductivity of the performer's finger using conductive material evaporated onto an insulator-backed sheet.

The 1967 version of the Printed Circuit Keyboard.

When the key was contacted, a small current was transmitted through the performer's finger from one conductive section to another. The pitch was amplified and played through speakers.

Printed Circuit Keyboard as module for studio use.