MULTIPLE TONE SIGNALING DEVICE

摘要

MULTIPLE TONE SIGNALING DEVICE A multiple tone signaling device provides a piezoelectric transducer, first, second and third oscillator circuits, a first input terminal for enabling either or both of the first and second oscillator circuits, circuitry coupling the third oscillator circuit to the first and second oscillator circuits for disabling either the first or second oscillator circuits in response thereto, and a second input terminal coupled to the third oscillator circuit for allowing control of the output of said third oscillator circuit.