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PROXIMITY DETECTOR

  • US 3,829,850 A
  • Filed: 12/17/1971
  • Issued: 08/13/1974
  • Est. Priority Date: 12/17/1971
  • Status: Expired due to Term
First Claim
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1. A protector device comprising a capacitive balancing circuit, means for coupling an antenna located adjacent an area to be protected electrically into said balancing circuit, said antenna having a capacitive reactance which causes said balancing circuit to be normally unbalanced, means coupled to said balancing circuit for exciting it with alternating electrical energy, a demodulaTor coupled to said balancing circuit for producing a DC output indicative of unbalance in said balancing circuit, a pair of electrical windows having maximum and minimum limits coupled to the output of said demodulator, and a pair of relays coupled to said windows for actuation when the output of said demodulator is greater than the maximum limit or less than the minimum limit of either window.

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