Telephone test set
CA 1263776 C · Owner: Durston, Thomas W. · Inventors: Faith, Richard W.; Durston, Thomas W.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An improved telephone test set is disclosed which may be operated with low voltage line conditions. Transmitting and receiving voice communication circuits are connected in parallel with leads which are adapted to be connected to the tip and ring lines of a subscriber's telephone line to isolate the voice transmitting and receiving circuits from the voltage drop of a polarity guarding bridge which is connected to the signalling circuits of the telephone test set. A polarity indicating circuit to indicate the direction of current flow between the tip and ring lines of a subscriber's telephone line is connected in series with the voice transmitting and receiving circuits.
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
- Granted December 5, 1989. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended December 5, 2006.
- 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.