METAL DETECTOR Russian patent published in 1999 - IPC

FIELD: physics, geophysics, detection o current-carrying and ferromagnetic objects with use of induction coils forming variable magnetic field. SUBSTANCE: metal detector has reference and tunable generators, indicator manufactured in the form of network of n light-emitting diodes arranged in ring or line and creating effect of " traveling lights ", counter-decoder with n outputs to which light-emitting diodes are connected, scale-of-n divider and flip-flop. Output of scale- of-n divider is connected to reset input of R flip-flop which direct output Q is connected to common wire of light-emitting diodes and forms light inhibition circuit. Inverse output of flip-flop is connected to input of inhibition of EC reading of counter-decoder. Indicator additionally has first and second frequency dividers, phase detector and stereo sound alarm. Tunable generator is fitted with input of tunable frequency. Outputs of tunable and reference generators are connected to counting inputs C of first and second dividers correspondingly. Output of reference generator is also connected to counting inputs C of scale-of-n divider and counter-decoder. Output of first divider is linked to setting input of S flip-flop, reset input R of counter-decoder and first input of phase detector. Output of second divider is connected to reset input R of scale-of-n divider and second input of phase detector which output is linked to input of tunable frequency of tunable generator. Inputs of stereo sound alarm are connected to input and output of phase detector. EFFECT: minimization of load on attention and memory of operator while determining type of metal ( ferrous or nonferrous ). 2 dwg