Telephone line loop current regulator
US5020100A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 7, 1989 |
| Grant date | May 28, 1991 |
| Priority date | — |
| Expiry date | Jul 7, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H11/42
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.