High voltage message waiting circuit

Details High voltage message waiting circuit High voltage message waiting circuit

1997-04-02

1998-06-16

Zele, Krista

Telephonic communications

Substation or terminal circuitry

Visual signalling

379164, 379373, 379396, H04M 900

Patent

active

057683662

ABSTRACT:
A message waiting circuit comprised of a pair of electrical leads which carry a message waiting signal, a capacitor for storing electrical energy extracted from the message waiting signal, a transistor for allowing the capacitor to charge when the message waiting signal is within a predetermined range; a Darlington transistor for causing the capacitor to discharge; and a light emitting diode (LED) which emits light when the capacitor discharges. The flashing LED indicates that a message is waiting for a user of the telephone set associated with the message waiting circuit. Approximately ten to twenty-five message waiting circuits and associated telephone sets can be connected to a single telephone line.

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patent: 5557666 (1996-09-01), Kim
patent: 5664008 (1997-09-01), Bossi et al.

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