ELECTRONIC TONE RINGER

摘要

EMBREE-13 ELECTRONIC TONE RINGER An electronic tone ringer responds to ringing signals on a telephone line while being unresponsive to dialing pulses or other signals on the line. Powered directly from the telephone line the ringer uses current sources to provide a high impedance to the ringer circuitry and an insensitivity to line voltage variations so that reliable operation of the ringer is maintained on long loops and with multiple ringers terminated on the line. A multitone signal for activating an electroacoustic transducer is provided by frequency modulating a single oscillator within the tone ringer.