1,249,402. Magnetic switches. C. Z. BESSKO. 22 Sept., 1969 [8 Oct., 1968], No. 46605/69. Heading H1N. [Also in Division G1] A magnetic proximity detector has a pair of magnetic flux sources such as permanent magnets 4, 5, a relatively high permeability yoke 6 between opposite polarity poles of the sources which are such that the yoke is not magnetically saturated when the gap between the other poles of the sources is not magnetically bridged but is saturated when the gap is bridged by a magnetic member 8 or a suitably poled further magnetic flux source (not shown). A flux sensor such as a magnetic reed contact unit 7 or flux sensitive semi-conductor device (not shown) adjacent the yoke 6 will respond to the external flux when the yoke is saturated. The flux sources may be electromagnets.
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