Stylophone

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

Ondes Martenot

The ondes Martenot (French for "Martenot waves"; also known as the ondium Martenot, Martenot and ondes musicales) is an early electronic musical instrument with a keyboard and slide, invented in 1928 by Maurice Martenot - a French cellist, a radio telegrapher during the first World War, and an inventor. The instrument is originally very similar in sound to the Theremin. They both used the vacuum tube oscillator as a sound source and were both monophonic, where the Theremin had a sliding scale and no fixed preset notes the Ondes-Martenot had a keyboard and a strip control for glissando and vibrato and an appearance that was familiar to any keyboard player.

The instrument also had a bank of expression keys that allowed the player to change the timbre and character of the sounds. A later (1938) version of the instrument featured microtonal tuning as specified by the Hindu poet Rabindranath Tagore and the musician Alain Danielou.

The Ondes-Martenot was quickly accepted and eventually had a wide repetoire, works were written for the instrument by composers such as Edgard Varèse, Olivier Messian, Darius Milhaud, Arthur Honegger, Maurice Jarre.

Here you can see how it works.

Here is a great video of Claus Simon performing Olivier Messiaen works on Ondes Martenot.