The physical form of a digital piano

The physical form of a digital piano can vary considerably. Most vaguely resemble a low upright piano (but usually lacking a fully enclosed lower section). Others, notably Yamaha's "GranTouch" range are based on the casework of traditional upright or grand instruments. An opposite and recent trend is to produce an instrument. Telegraph" was a chance by-product of his telephone technology when Gray accidentally discovered that he could control sound from a self-vibrating electromagnetic circuit. In 1970, Moog designed the Minimoog, a non-modular synthesizer with a built-in keyboard. The analogue circuits were interconnected with switches .