| 摘要 |
PURPOSE:To detect the back member of a wall and, at the same time, to judge whether said member is a metal by simultaneously operating a sensor searching for the back member of a wall and a sensor for searching for a metal. CONSTITUTION:A metal searching part is constituted of an oscillation circuit 1 as the first sensor for forming an alternating magnetic field to the circumference to detect the presence of a metal on the basis of he variation of said magnetic field, an operation control circuit 10 sending out contact output when the output level of the circuit 1 reaches a predetermined value or less and a light emitting diode LD1. When a metal is present in the magnetic field of an oscillation transformer T, the output of the oscillation circuit 1 lowers and the light emitting diode LD1 lights. A back member searching port is constituted of an electrode plate 2 constituting a time constant circuit becoming a sensor emitting the signal corresponding to the dielectric constant of the circumference along with resistors R2-R5, an operation control circuit 20 and a light emitting diode LD2. When a back member is present in a wall and the electrostatic capacity detected by a main electrode plate 2a becomes large, the output pulse width of a monostable multivibrator 21 becomes large and the light emitting diode LD2 lights.
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