Telephone line monitoring circuit for providing a visual and auditory signal if the telephone line becomes inoperative

摘要

A telephone line monitoring apparatus which is used to continuously monitor the telephone line and provide both a visual signal and an auditory signal if the line becomes inoperative. The circuit is designed to be plugged into a conventional telephone jack and monitor the line voltage so that if the line voltage falls below about 6 volts DC or if the line is short circuited or becomes disconnected, the telephone line monitoring apparatus will cause a light emitting diode to flash on and off and further will cause an auditory sounder to emit an audible signal. The light emitting diode is a self-flashing type which serves to modulate the auditory signal.