The clavinet uses hammers to hit strings, the vibrations of which are then picked up by a magnetic pickup similar to that of an electric guitar. It can therefore be viewed as an electronically amplified clavichord, hence its name.
Its predecessors, the Cembalet and Pianet, worked by a different principle, using a plucked reed.
The archetypal Clavinet sound can be heard on Stevie Wonder's track Superstition.