Frequency selective ringer circuit

Details Frequency selective ringer circuit Frequency selective ringer circuit

1985-07-26

1987-03-24

Dwyer, James L.

Telephonic communications

Supervisory or control line signaling

Signal receiver

379180, 328138, H04M 100

Patent

active

046530932

ABSTRACT:
A frequency selective ringer circuit which utilizes a constant current source in conjunction with an array of resistors and switches for developing a frequency selective window with which to detect an incoming frequency at the tip and ring inputs of a telephone system. The incoming frequency is doubled and converted to a d.c. level which is utilized as the converted level which is evaluated by the circuit. Where the converted voltage level falls within the established window, a drive circuit is energized for actuating a transducer such as a piezoelectric crystal or loudspeaker. Frequency selection is made by the simple expedient of closing one of a plurality of SPST switches. The circuit also may include a circuit for automatically deactivating the mechanical bell of an existing telephone set without the removal thereof.

REFERENCES:
patent: 4273965 (1981-06-01), Cowpland et al.

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