Constant current line circuit
CA 1231480 A · Owner: Meier, Rolf G. · Inventors: Barsellotti, John A.; Meier, Rolf G.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A constant current line circuit for connection to balanced tip and ring leads of a telephone line and unbalanced transmit and receive leads of a PABX. A differential amplifier receives and applies incoming audio signals carried by the tip and ring leads to the unbalanced transmit lead and, detects D.C. loop current flowing through the tip and ring leads and generates a D.C. signal in response thereto. A voltage controlled feed current supply connected in a circuit to the differential amplifier generates a constant current D.C. voltage to the tip and ring leads in response to receiving the D.C. signal and an integrator circuit is connected in a feedback path from the output of the …
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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 January 12, 1988. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended January 12, 2005.
- 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.