Line coupling controller for facsimile machine - has circuit sensing incoming signals disconnecting answer-phone or facsimile machine and returning connection tone

摘要

The facsimile machine (1) and answer-phone (3) are connected in parallel across a telephone line (2). The interface from the line passes to a bridge rectifier (20), and through a transformer (4) to a high impedance circuit, so that only a small current is monitored, on the surveillance unit (10). A microprocessor (16) detects the type of signal, and switches the facsimile machine via the switch (12) or the answer-phone via a double throw switch (54, 55) and returns the correct connection tone to the line. ADVANTAGE - Avoids need for modem and takes only small signal allowing answer-phone to be connected to same line.