| 摘要 |
A probe for sensing movement of a body of magnetic material comprises a magnetically energisable pole piece, a closed loop electrical circuit having a first end which is wound around the pole piece and forms a pole piece coil inductively coupled to the pole piece, the arrangement being such that movement of a body of magnetic material relative to the pole piece induces a current in the closed loop circuit, and a second end, remote from the pole piece, which forms a transformer primary coil. A transformer secondary coil is inductively coupled to the primary coil, and terminated by a load resistance and means for measuring an output signal from the secondary coil. The primary and secondary coils form a transformer such that a current in the primary coil induces a voltage across the secondary coil. One or more shorting turns of a conductor are inductively coupled to the primary and secondary coils.
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