| 摘要 |
A instrument for detetcing stray metal in e.g. ham, sausage etc. The magnetic field is detected by coils which generate induced voltages abd the difference between the induced voltages is applied to a tuning and phase-shift circuit. An output signal having a phase, generated from the tuning and phase-shift circuit, is detected and the peak level of the detected output signal is held in a peak hold and comparing circuit. A number of the peak levels are stored in a memory circuit and are processed by a CPU to determine the preferred phase of the output signal. The tuning and phase-shift circuit is so switched as to apply the preferred phase to the output signal.
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