An electromagnetic transducer which generates signals on the basis of the Barkhausen effect under periodically alternating externally applied magnetic switching fields. Prior to use, the magnetic sensor element, for example a ferromagnetic wire, is pre-magnetized by undergoing a program which subjects the wire to a coercive applied field substantially higher than the alternating interrogation field. The coercive field places different zones of the wire into magnetic saturation with varying relative polarity, thereby creating two or more zones of different magnetization. When subjected to the alternating, low intensity interrogation field, sensor coils detect a high level, bipolar output signal.

A Wiegand wire is placed within the magnetic field generated by a first and second permanent magnet. The first permanent magnet has a field strength exceeding that of the second permanent magnet and the polarity of its magnetic field is opposite that of the second magnet. A rotor having segments of magnetic shielding alternating with slots is rotated between the Wiegand wire and the first magnet. When the magnetic shielding is between the first magnet and the Wiegand wire, the latter is exposed only to the magnetic field of the second permanent magnet. In a second position of the rotor, the Wiegand wire is exposed to both magnetic fields. Since the second permanent magnet generates a stronger field than the first, the direction of magnetization in the Wiegand wire changes abruptly causing a pulse to be generated in pick-up coil 4.

An electric motor operating on the reluctance principle employs spaced rotor discs presenting rings of inwardly fcing poles of alternating polarity, typically by means of permanent magnets, and an annular stator between the discs consisting of a ring of H shaped cores, with the stems of the H's extending peripherally. Two sets of windings on these cores are energized alternately so as to provide alternating polarization of pole pieces presented by the cores to the rotor discs, with a timing such as to produce continuous rotation at a controlled rate, of the discs as their magnets seek a minimum reluctance position.

A motor comprising an axle adapted to rotate about an axis; a wound armature fixed to and concentric with the axis; two segmented wheel commutators adapted to conduct electricity across a set of tracks and fixed on opposite ends of the axle concentric with the axis, a motor casing surrounding and enclosing the armature; and a pair of permanent magnets attached opposite one another on the sides of the casing. A pair of bearings with a plurality of wire channels may be fixed to the axle and adapted to rotate with the axle in each casing end cap, each wire channel adapted to pass a wire electrically connected to a segment in one wheel commutator, running across the armature, and connected to a segment of the opposite wheel commutator. Each wheel may consist essentially of conductive segments separated by nonconductive epoxy, with a non-conductive bushing centered therein to receive the axle.

An alternating electric current generator comprises an armature rotatably carried by a drive shaft and positioned between stabilized, non-moving magnetic elements. The armature has first and second magnetic field transmitting sections with a magnetized section sandwiched therebetween. As electric load is applied to the generator, a countermagnetic field is generated through the armature to increase speed of the drive shaft and thereby lessen torque required to rotate the drive shaft.