Telephone installation
US4734937A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 3, 1986 |
| Grant date | Mar 29, 1988 |
| Priority date | — |
| Expiry date | Nov 3, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M19/008
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
The invention relates to an overvoltage protected high-voltage integrated circuit and a low-voltage integrated circuit with switching control for a hybrid circuit connected peripherally to a telephone exchange for serving telephone instruments. In particular it serves to provide battery feed, ringing voltage generation, and voice signal transmission. Essentially the circuit includes a transformer for transmission of high-frequency energy to the high-voltage circuit, which incorporates transfer of signal currents through four high-resistance, pair-organized symmetrical voltage dividers. The circuit further includes a ringing signal generating arrangement that is activated by means of a voltage increase applied to the high-voltage circuit supply voltage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.