Telephone ringer circuit

Details Telephone ringer circuit Telephone ringer circuit

1981-07-22

1987-04-14

Dwyer, James L.

Telephonic communications

Supervisory or control line signaling

Signal reception at substation

340384E, H04M 100

Patent

active

046584196

ABSTRACT:
A telephone ringer circuit having a ring signal detection network serving to detect ring signals utilizing an R-C network and operating in conjunction with a threshold responsive detection device. Upon the detection of a valid ring signal, the resistance component of the R-C network is by-passed to permit low impedance passage of electrical energy into the ringing components of the circuit. Drive for a piezoelectric crystal driven audio output is provided by two push-pull amplification stages, configured as integrators, so as to effect crystal drive with trapezoidal shaped waveforms wherein high harmonics are not evolved. Improved loudness and sound quality are achieved with the circuit.

REFERENCES:
patent: 3867585 (1975-02-01), Morstadt
patent: 4157459 (1979-06-01), Bush et al.
patent: 4214131 (1980-07-01), Bush et al.
patent: 4346265 (1982-08-01), Boss et al.

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