Telephone line interface circuit with voltage control
CA 2131295 C · Owner: Rosch, Reinhard Werner · Inventors: Rosch, Reinhard Werner; Rosenbaum, Stanley Daniel
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A telephone line interface circuit comprises two unity gain d.c. amplifiers (132 134) having outputs d.c. coupled via feed resistors to the line wires. Currents in the feed resistors are monitored via a digital control circuit (152) which can be, programmed to provide desired operating conditions. The control circuit controls via D-A converters (158, 161), currents passed by current sources (142,148) through resistors (140,146) at inputs of the d.c. amplifiers thereby determining voltages at the amplifier inputs and hence on the line wires. These d.c. voltages are smoothed by capacitors (136,138) used for coupling an a.c. signal to the d.c. amplifiers. The voltage control facilitates …
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed March 17, 1993 and granted February 24, 1998. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 17, 2013.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 17, 2015.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.