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Direct current motor speed control

  • US 4,893,067 A
  • Filed: 05/06/1987
  • Issued: 01/09/1990
  • Est. Priority Date: 05/06/1987
  • Status: Expired due to Term
First Claim
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1. A DC motor speed control circuit comprising:

  • a DC motor inducing a back EMF;

    a sample and hold means coupled to said motor for developing a signal having a 1-χ

    relationship to the back EMF of said motor where is χ

    the back EMF;

    a means for measuring and comparing said developed signal with a predetermined reference signal indicative of the desired motor speed;

    a means for producing a gating signal indicative of the relationship of said developed signal to said reference signal;

    a gated control means coupled to regulate electrical power to said motor;

    said control means being responsive to said gating signal to permit power flow to said motor when said developed signal is at one relationship to said reference signal and to restrict power flow to said motor when said developed signal is at a second relationship to said reference signal.

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