| 摘要 |
A fail-safe magnetic sensing arrangement including a first and a second object relatively movable in relationship to each other. The first object includes a magnetic structure having a permanent magnet and a pair of pole pieces to develop a magnetic field. The second object includes an a.c. oscillator which is coupled to an amplifier by a saturable reactor transformer and the amplifier feeds a negative d.c. maker which normally energizes a relay except when the saturable reactor transformer is saturated by the magnetic structure which signifies that the second object is in the vicinity of the first object.
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