Hard-of-hearing loudspeaker controller - sets signal frequency and sound volume, with duration controlled by timers

摘要

Efficient signal transmission to hard-of-hearing people in such cases as door or telephone bell is ensured by a control circuit connected to a signal transmitter. The unit comprises a loudspeaker (11) connected to the supply and the signal transmitter. The assembly is held in a box (13) featuring control push-buttons (132-135) for setting the frequency and sound volume, as well as the duration of the signalling. The push-button (135) controls the duration of blink from a flash light (136) indicating that the unit is in the operative state. A stabilised voltage unit feeds timers and an oscillator, while the non-stabilised supply drives a low frequency amplifier and the control light emitting diode.