Telephone line monitoring circuitry and apparatus

Details Telephone line monitoring circuitry and apparatus Telephone line monitoring circuitry and apparatus

1990-10-29

1991-10-08

Schreyer, Stafford D.

Telephonic communications

Diagnostic testing, malfunction indication, or electrical...

Monitoring

379 27, H04M 124, H04M 324

Patent

active

050561316

ABSTRACT:
A telephone line monitoring circuitry apparatus which is used to continuously monitor the telephone line and causes a light emitting diode to flash on and off and further causes an auditory sounder to sound loud and soft to provide both a visual signal and an auitory signal if the telephone line becomes inoperative. The light emitting diode is a self-flashing type which serves to modulate the auditory sounder. The monitoring circuitry and apparatus is energized by a DC battery, or by an AC power source with DC battery back-up. The monitoring circuitry and apparatus is designed to have acceptable input impedance and ringer-equivalence and complete isolation to prevent interference with the telephone network.

REFERENCES:
patent: 3951248 (1976-04-01), Feiner
patent: 3976849 (1976-08-01), Champan
patent: 4002861 (1977-01-01), Putt
patent: 4373120 (1983-02-01), McDonald
patent: 4513176 (1985-04-01), Fostveit
patent: 4544807 (1985-10-01), Sers
patent: 4564728 (1986-01-01), Romano
patent: 4588862 (1986-05-01), Grabowy
patent: 4600810 (1986-07-01), Feldman
patent: 4827498 (1989-05-01), Ross
patent: 4841559 (1989-06-01), Curtis
patent: 4969178 (1990-11-01), Chen et al.
patent: 4969179 (1990-11-01), Kanare et al.

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