The Stylophone was a small stylus-operated keyboard, sold mostly as an annoying children's toy. Invented in 1967, it entered production in 1968. It consisted of a tiny metal keyboard played by touching it with a live stylus - each note being connected to a voltage-controlled noise via a resistor - closing a circuit.
The only other controls were a power switch and a vibrato control on the front panel beside the keyboard, and a tuning control on the rear. Some three million Stylophones were sold. They played only at full volume with an ear splitting shrieking sound making them an ideal present for people you hated who had kids.
There was a larger version called the 350S with more notes on the keyboard, a horrific 'wah-wah' effect that was controlled by moving one's hand over a high voltage photo-sensor.
In the mid-1970s a new model appeared which featured genuine pseudo-wood on the speaker panel and a volume control. (Previous Stylophones had been notorious for being too loud in quiet situations. This was shortly before the Stylophone ceased production altogether in 1975.
The now disgraced Rolf Harris appeared frequently on T.V. looking like a "Beatnik" or Open University Geek as the Stylophone's advertising spokesman in the United Kingdom, and appeared on many "play-along" records sold by the manufacturer.