Abstract: Ultrasonic type motion detector which highly reliably detects presence of moving object without being mis-operated by any other physical phenomena in detecting area. Respective frequency levels of transmitted and received wave signals are detected by a detecting section of a quadrature detecting circuit and phase difference detecting circuit, one of the level-detected signals is inverted and combined with the other, both signals are connected through an integrating circuit to a standard voltage source, and a pair of comparators are connected to the standard voltage source in parallel to each other so that an output signal indicative of the presence of object to be detected will be provided in either case when ouptut voltage of the standard voltage source becomes high or low.

Abstract: A switch employing such magneto-sensitive switching element as, for example, reed switch or the like and generally used for crime prevention purpose with a high reliability, wherein the switching element is initially set in either one of its ON and OFF states by a permanent magnet disposed adjacent the element and rotatably about its central axis perpendicular to its longitudinal axis and such initially set state of the element is turned to the other state to actuate an alarm device when another permanent magnet mounted, for example, to a door approaches the rotatable magnet and magnetically varies initial relationship of the rotatable magnet to the element.