GB1091040A - - Google Patents

Abstract

1,091,040. Electric motors. SIEMENSSCHUCKERTWERKE A.G. May 31, 1966 [May 31, 1965], No. 24307/66. Heading H2A. [Also in Division H1] An electrical signalling device comprises three magnetic sensitive semi-conductor resistors positioned between fixed and rotatable parts of a magnetic circuit, the rotators consisting of three disc sectors at 120-minute intervals so that on rotation, concentrated magnetic field successively penetrates the resistors. In Fig. 1, rotatable cams 3, 4, 5 are positioned between pole shoes 6 and 7 to lie over magnetic sensitive resistors 8, 9 and 10; magnetic screens 13 prevent field interference. The resistors may be connected in the base-collector circuits of three transistors, the collectors of which supply three load impedances (Fig. 4, not shown). In a modification, the three resistors consist of tracks extending like comb teeth from a common electrode strip (Fig. 3, not shown) and are connected in the base emitter circuits of three transistors; the collectors supply the loads and thermistors (R11, R12, R13) may be included in the base collector circuits to compensate for temperature variation of the magnetic resistors. The resistors may consist of indium antimonide or indium arsenide, if desired with needles of nickel antimonide to form an anisotropic body, and may consist of deposited layers ground and etched to the desired thickness (e.g. 5 to 25Á) and pattern. The arrangement may be used to serve as a contactless commutator in a D.C. motor circuit.