Circuit for telephone set comprising a light-emitting diode power supply
US5742676A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 27, 1996 |
| Grant date | Apr 21, 1998 |
| Priority date | — |
| Expiry date | Sep 27, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M1/6025
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A circuit comprising a transistor (T1) is connected in series to a resistor (RM) for measuring the line current; the whole is connected to the terminals (1,2) of the line. According to the invention, a light-emitting diode (18) is connected in series to a variable current source (20), the whole being connected in parallel to the emitter/collector path of the transistor (T1), and the variable current source, which receives a monitoring signal that represents the line current, produces a current that varies between a zero current and a maximum current for an average line current that varies between a low threshold and a high threshold.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.