Abstract: A circuit for providing a plurality of distinguishable audible signals from an audible tone generator includes at least two gates wherein the output of one of the gates determines the type of audible signal produced by the audible tone generator in response thereto. The circuit further includes a single control terminal for controlling the logical state the output of the one gate and for controlling the type of audible signal produced by the audible tone generator. The absence of an electrical potential at the control terminal when power is applied to the circuit results in a latching of the output of the one gate and the production of a continuous audible signal by the audible tone generator. The presence of an electrical potential at the control terminal when power is applied to the circuit results in a periodic changing of the output of the one gate and the production of an interrupted audible signal by the audible tone generator.

Abstract: An audible signalling system utilizes a piezoelectric transducer to produce a chime tone audible signal. The system includes audible signalling circuitry, circuitry for driving the audible signalling circuitry to provide a pulsed audible signal, and circuitry for exponentially decaying the pulsed audible signal to produce a chime tone audible signal.