Electronic hold and hold-release circuit for a telephone set in a multiple extension single line telephone system
CA 1096077 A · Owner: Northern Telecom Limited · Inventors: Laing, Graham S.; Rousseau, Barry A.; Overdulve, Adriaan D.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Abstract of the Disclosure, An electronic hold and hold-release circuit for a telephone set in a multiple extension single line telephone system has an indicator in either the tip or ring line an electronic, switch, such as a SCR, across the lines and a manually operated momentary hold button which, when operated after picking up the handset of the telephone, switches the electronic switch device to a conducting state and provides a hold current on the lines the hold, current maintained after replacing the handset. The hold condition is indicated by the indicator. An electronic device in one of the lines prevents current flow when the line voltage drops to about 10 volts, when another …
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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
- Granted February 17, 1981. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended February 17, 1998.
- 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.