Telephone line loop current regulator
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United States of America Patent
Stats
-
May 28, 1991
Grant Date -
N/A
app pub date -
Jul 7, 1989
filing date -
Jul 13, 1988
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A telephone line loop current regulator combines the functions of current regulation, current detection, loop disconnect signalling and speech switching. It comprises a gyrator circuit formed by resistor (R1), capacitor (C1), transistor (T1) and resistor (R3). Loop current is regulated by transistor (T1) and resistor (R3) while loop current detection is achieved by monitoring the voltage across resistor (R3) by an opto-diode which forms part of an opto-electronic coupler (OP2). Speech switching is performed by transistor (T3) which also monitors the voltage across resistor (R3) so that speech is switched onto the line via transformer (TR1) when d.c. loop current is present. Line seizure and loop disconnect signalling are carried out by switching the opto-coupler (OP1) to turn the transistor (T1) on and off.
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Family
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Cited Art Landscape
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