| 摘要 |
PURPOSE:To detect the short circuit part of a printed wiring board, etc., by providing a probe circuit with an element detecting a magnetic field with the aid of a low frequency current and comparing the phase of the output electrical signal of the element detecting said field with that of a current generated by a power source circuit. CONSTITUTION:The magnetic probe 10 is provided with the magnetism detecting element on its tip, and the power source circuit is composed of a low frequency oscillator 12. The signal detected by the probe 10 is amplified by an amplifier 11, and its output is impressed on one input terminal of a phase comparator 13. On the other hand, the output of the oscillator 12 is transmitted to the other input terminal of the comparator 13, and phases of both signals are compared. When they have the same phases, the signal detected by the probe 10 is pressed. Whereas they have phases reverse to each other, the signal is insured against passing. Thus the short circuited place can be easily detected.
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