Telephone ringer circuit

Details Telephone ringer circuit Telephone ringer circuit

1976-04-26

1977-08-16

Claffy, Kathleen H.

H04M 126

Patent

active

040427862

ABSTRACT:
A telephone ringing circuit responds to both conventional high voltage 20Hz ringing signals and low voltage tone alerting signals. A conventional electromechanical ringer is connected across the telephone line and is responsive to high voltage 20Hz ringing signals. A high capacitance capacitor is charged by the dc voltage present on the telephone line and is discharged across the electromechanical ringer when a tone detector circuit connected across the line detects a tone alerting signal, thereby activating the electromechanical ringer.

REFERENCES:
patent: 3471651 (1969-10-01), Saia
patent: 3603740 (1971-09-01), Cambridge
patent: 3688038 (1972-08-01), Hugyecz
patent: 3808379 (1974-04-01), Lind
patent: 3904833 (1975-09-01), Beene

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