GB867999A - - Google Patents

Abstract

867,999. Inductors. PHILIPS ELECTRICAL INDUSTRIES Ltd. Jan. 30, 1958 [Jan. 30, 1957], No. 3142/58. Class 38 (2). An inductor having a magnetic core 5 is provided with one or more permanent magnets which provide magnetic fields in two opposite directions in the core so that this is saturated by both positive and negative current in the winding 2. As shown, the permanent magnets are annular and magnetized radially, each magnet comprising two halves of opposite magnetization. Alternatively a single annular magnet of three sections providing inner poles S-N-S, may be used. Rod shaped magnets parallel to the core may also be provided. In a further arrangement the core is tubular and surrounds a rod-shaped permanent magnet polarized N-S-N- along its length. The or one of the magnets may be movable relatively to the core which may comprise a manganese-zinc ferrite. An auxiliary magnet disposed on the axis of the core may be provided to affect the permeability of the whole core. The winding 2 may be provided with tappings and the device may be associated with a coil having an inductance independent of current.