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Coin examination apparatus employing an RL relaxation oscillator

  • US 4,416,365 A
  • Filed: 08/21/1981
  • Issued: 11/22/1983
  • Est. Priority Date: 08/21/1981
  • Status: Expired due to Term
First Claim
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1. A coin testing apparatus comprising means to subject a coin to an electromagnetic field and to produce a digital signal indicative of the degree of interaction of the coin with the field, and means to determine whether said signal corresponds to that for an acceptable coin, wherein said means to subject a coin to an electromagnetic field and to produce a digital signal comprises a coin passageway and a resistor-inductor type relaxation oscillator having an oscillation frequency determining inductor adjacent the coin passageway, the inductor producing the electromagnetic field in the coin passageway, said resistor-inductor relaxation oscillator having a substantially linear frequency change with respect to change in the effective inductance in the oscillator over a range of inductance suitable for testing coins and producing an output signal which is digital in nature and requires no amplitude discrimination or shaping to be suitable for counting, and said means to determine whether said signal corresponds to that for an acceptable coin comprises counting means for counting the digital output signal.

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