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Expired Canadian patentCanada

Active clamp circuit with immunity to zener diode microplasmic noise

CA 2033236 C · Owner: Eccleston, Rex James · Inventors: Eccleston, Rex James; Bator, Philip Mark; Rutkowski, David John

CIPO record

Overview

Drawings and full text

Its claims, description and drawings are in the Canadian Patents Database.

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Abstract From the Canadian patent

An active clamp circuit for an inductive load switching circuit includes a zener current control resistor to set the breakdown current in a zener diode of the clamp circuit. The zener breakdown current is set at a sufficiently high level to ensure that the zener diode is operated at a point beyond its "knee" region and therefore does not generate interfering levels of microplasmic noise (MPN). The zener current control resistor is provided in addition to a circuit speed control resistor such that there is substantially independent control of the switching circuit operating speed and the breakdown current of the zener diode of the active clamp circuit.

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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

  • Filed December 27, 1990 and granted April 29, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended December 27, 2010.
  • A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 27, 2012.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledDecember 27, 1990
GrantedApril 29, 1997
Term endedDecember 27, 2010
Patent numberCA 2033236 C
Classification (IPC)H03K17/60 +2 more

Timeline

Timeline From CIPO dates

1991199319951997199920012003200520072009Application filedDec 27, 1990Patent grantedApril 29, 1997Term endedDec 27, 2010

Sources & verification

Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.