On-hook control circuit for answering machine

Details On-hook control circuit for answering machine On-hook control circuit for answering machine

1987-08-04

1989-05-23

Brown, Thomas W.

Telephonic communications

Audio message storage, retrieval, or synthesis

379 82, 379373, H04M 165

Patent

active

048337030

ABSTRACT:
Control circuit for an answering machine having an electrical unit in parallel therewith including a controller for causing a first photocoupler to be conductive for a predetermined time period to discharge a capacitor when the machine goes into an on line state and, thereafter, causing the voltage across the telephone lines to charge the capacitor via a rectifier unit; a second photocoupler for detecting a voltage drop across the telephone lines caused by picking up said unit while the machine is in its on line state while using the voltage across the capacitor as a reference, whereby the controller returns the machine to its standby state after a predetermined time from the occurrance of the voltage drop.

REFERENCES:
patent: 4074081 (1978-02-01), Humm
patent: 4444999 (1984-04-01), Sparrevohu
patent: 4484036 (1984-11-01), Lyle et al.
patent: 4496797 (1985-01-01), Price

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