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Metallic article discriminator

  • US 4,754,862 A
  • Filed: 12/23/1985
  • Issued: 07/05/1988
  • Est. Priority Date: 01/04/1985
  • Status: Expired due to Term
First Claim
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1. Coin discrimination apparatus comprising means defining a path for passage of coins under test;

  • sensor coil means for forming an inductive coupling with coins under test during their passage along the path;

    a resonant circuit in which said sensor coil means is connected, said resonant circuit exhibiting a resonant frequency which varies in dependence upon the inductive coupling between the sensor coil means and the coin under test during the passage of the coin along the path;

    variable frequency oscillator means for energizing said resonant circuit;

    control means for varying the frequency of the oscillator means such that it tracks the varying resonant frequency of the oscillator means during passage of the coin along the path past the sensor coil means; and

    amplitude response means responsive to changes in amplitude of an oscillatory signal developed by the resonant circuit during said passage of the coin past the sensor coil means, whereby to provide a signal indicative of characteristics of the coin.

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