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Coin validation apparatus

  • US 4,460,080 A
  • Filed: 03/04/1982
  • Issued: 07/17/1984
  • Est. Priority Date: 03/19/1981
  • Status: Expired due to Term
First Claim
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1. A method of validating a coin comprising providing only a single feedback oscillator having a tuned electrical coil permanently connected in its feedback loop, positioning a coin adjacent said electrical coil, operating said single feedback oscillator and monitoring its frequency, selectively including a phase shifting network in said feedback loop of said single feedback oscillator, operating said single feedback oscillator and monitoring its frequency when said phase shifting network is included in its feedback loop, deriving from said monitored frequencies two parameter signals characteristic of the effect of said coin on the inductance and loss factor of said coil, and comparing said two parameter signals with reference values to determine if said coin is valid.

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