Telephone line interface

Details Telephone line interface Telephone line interface

1983-10-14

1985-08-20

Rubinson, Gene Z.

179 616, H04M 172

Patent

active

045366187

ABSTRACT:
A telephone line interface for direct connect telephone line connections characterized by low cost and minimal package size requirements. The telephone line interface utilizes a small signal transformer with a primary winding couplable to the line by actuation of a relay. A secondary winding of the transformer is coupled to an integrated circuit which performs the functions of ring detect and dial tone detect, and separation of the received signal and the transmit signal when transmitting and receiving simultaneously. Ring signal detection on the secondary side of the coupling transformer substantially reduces the size and cost of the ring detect circuitry, as the secondary of the transformer may be provided with over-voltage protection, whereas the line side of the transformer must survive particularly high surge voltages, thereby requiring high voltage isolation not obtainable by way of conventional integrated circuits. Other aspects and features of the invention are disclosed.

REFERENCES:
patent: 3603740 (1971-09-01), Cambridge
patent: 4390752 (1983-06-01), Jacobson

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