infra-red stereo transmitter

Headphones have long been popular with hi-fi enthusiasts, since they provide good-quality reproduction at a fraction of the cost of loudspeakers, and can be used to listen to music at full blast without disturbing other members of the household. However, they do suffer from one drawback, namely the connecting cable, which invariably becomes entangled with the furniture, and prevents the listener from moving freely about the room. Recently, however, several manufacturers have introduced `wireless` headphones using infra- red radiation as the transmitting medium. This article describes an infra-red transmitter that is compatible with many of these ` and which may be connected into most hi-fi systems. The circuit of this transmitter is a design provided by Sennheiser, who market headphones fitted with a suitable infra-red receiver.