Negative feedback system servo control and its application to amplifiers and servomechanisms

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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 August 29, 1990 and granted July 27, 1993. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended August 29, 2010.
• A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by August 29, 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.