| 摘要 |
PURPOSE:To obtain simultaneity between flaw detection signals obtained from a differential system and an absolute system by using the coil of the former system as a detecting coil of the latter system, and making different the flaw detection frequencies of flaw detectors of both systems. CONSTITUTION:Since the frequency of a flaw detector 10 is set at f1, and the frequency of a flaw detector 11 at f2, the voltage of f1 is applied to a coil 2 and the voltages of f1 and f2 are applied to the coil 3. The selecting amplifier 45 of the detector 10 is set at the frequency f1, and the output thereof is applied to a phase detecting circuit 46, which outputs the results of the flaw detection of a differential system. A compensation circuit 43 is provided in order to make minute with the input voltage of the amplifier 45 of the detector 11. This amplifier 45 is so arranged as to amplify only the voltage of the frequency f2 and outputs the results of the flaw detection of an absolute system. Since one coil 3 of the coils 2, 3 of the differential system is used as a detection for the absolute system, the signals of both systems generate at the same time. |
