LIGHT SENSITIVE SECURITY SYSTEM

  • US 3,811,046 A
  • Filed: 01/22/1973
  • Issued: 05/14/1974
  • Est. Priority Date: 01/22/1973
  • Status: Expired due to Term
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First Claim
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1. A light sensitive control circuit comprising a source of DC power;

  • a series network formed of a first resistor and a capacitor, said series network being effectively coupled in series across the DC power source;

    a series voltage divider network effectively coupled across the capacitor, said voltage divider network being formed of a first resistor and said light sensitive element;

    a discharge circuit coupled to discharge the voltage retained by the capacitor, said discharge circuit including a light sensitive element which registers a change in resistance upon exposure to a source of light, said light sensitive element being coupled to vary the rate of discharge of the voltage charge on the capacitor in response to the rate of light exposure of the element; and

    means coupled to the discharge circuit for producing an output signal when said rate of discharge exceeds a predetermined value representative of a predetermined variation of light incident upon the light sensitive element.

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