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Expired Canadian patentCanada

Electronic bipolar interface circuit

CA 1266305 C · Owner: Union Switch & Signal Inc. · Inventors: Darrow, John O.G.; Campbell, Richard D.

CIPO record

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

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Abstract From the Canadian patent

Case No. 8254), ABSTRACT OF THE DISCLOSURE An electronic bipolar interface driver circuit for interconnecting a microprocessor to an electromagnetic relay load. The driver circuit includes a peripheral adapter circuit having a pair of outputs connected to a respective one of the two inputs of a pair of NAND gates. A source of square-wave signals connected to the other inputs of the two input NAND gates so that a.c. signals are supplied to one of two switching amplifiers. The a.c. signals are transformer-coupled to a pair of rectifiers. The rectified d.c. voltage is supplied to either one of two switching transistors which establishes a given polarity of voltage on a pair of output terminals …

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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 27, 1990. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended February 27, 2007.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledOctober 20, 1986
GrantedFebruary 27, 1990
Term endedFebruary 27, 2007
Patent numberCA 1266305 C
Classification (IPC)G05B11/12 +2 more

Timeline

Timeline From CIPO dates

1987199019931996199920022005Application filedOct 20, 1986Patent grantedFeb 27, 1990Term endedFeb 27, 2007

Sources & verification

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