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Concealed electrical conductor detecting system

  • US 4,427,942 A
  • Filed: 04/21/1981
  • Issued: 01/24/1984
  • Est. Priority Date: 04/29/1980
  • Status: Expired due to Term
First Claim
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1. A detection system for concealed current carrying conductors such as underground pipes or cables, comprising two parallel, spaced first and second coils, respective first and second channels through which the coil outputs are directed, a comparator receiving said coil outputs via said channels to produce its own output corresponding the difference in the coil outputs, an indicator, a further channel from the first coil to the indicator, and gating means in said further channel responsive to the comparator output to pass the first coil output to the indicator only when the signal strength in the first coil is greater by a predetermined amount than that in the second coil.

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