The Dubreq Stylophone is a miniature electronic musical instrument invented in 1967 by Brian Jarvis. It consists of a metal keyboard played by touching it with a stylus - each note being connected to a cheap voltage-controlled oscillator via a different-value resistor - thus closing a circuit. Some three million Stylophones were sold, mostly as children's toys. Rolf Harris appeared for several years as the Stylophone's advertising spokesman in the United Kingdom.
Here is how it works and sounds:
Hexstatic - Stylophone