Detector circuit for sensing battery polarity and loop closure
US4126765A · kind A · utility
13Cited by
1References
9Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Dec 12, 1977 |
| Grant date | Nov 21, 1978 |
| Priority date | — |
| Expiry date | Dec 12, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M7/0096
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A detector circuit for use in conjunction with a trunk circuit of a PABX telephone system interfacing with a central office providing for constant monitoring of normal or reverse battery application by the central office during the high impedance idle state or the low impedance busy state. In addition, the circuit provides for detection of: proper loop closure, electrically shorted tip and ring leads, open circuit condition of tip and ring leads or a grounded ring lead. Furthermore, the circuit indicates when current flow of proper magnitude is sensed during normal or reverse battery conditions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.