Abstract: A speed sensor for a moving member (8) comprises means (27; 34) for constituting a magnetic singularity on a portion of the moving member, and a sleeve slidably receiving said portion and including at least an annular coil (20, 21) and an annular permanent magnet (22, 23) disposed on a common axis between annular pole pieces (24, 25).

Abstract: The invention relates to a dual-coil electromagnetic valve actuator having a permanent magnet and an actuator member (11) movable between two extreme positions under the effect of a resilient member and two electromagnets each comprising a core having a T-shaped first core portion (18) with a base (19) connected to a central branch (20) with a coil (21) disposed thereabout, the first core portion (18) being placed in a U-shaped second core portion (22) having a base (23) connected to outer branches (24) which extend parallel to the central branch (20) of the first core portion (18), a permanent magnet (25) being interposed between the base of the first core portion (18) and the base of the second core portion (22).

Abstract: A speed sensor for a moving member (8) comprises means (27; 34) for constituting a magnetic singularity on a portion of the moving member, and a sleeve slidably receiving said portion and including at least an annular coil (20, 21) and an annular permanent magnet (22, 23) disposed on a common axis between annular pole pieces (24, 25).

Abstract: High-energy permanent magnetic materials are characterized by exposing the material to sequential pulsed fields of respectively different rates of change of magnetic field strength, sensing the total magnetic field strength, sensing the total magnetic field generated in the sample by the respective pulses including eddy currents induced therein, and eliminating eddy current components from the said fields, whereby the net magnetic fields relate to the magnetic characteristics of the sample. Preferably the pulsed field is capacitor-generated via a solenoid and the rate of change of the magnetic field strength is produced by holding the waveform constant and altering the pulse duration, for example by providing taps on the solenoid together with an inductor and a balancing resistor, to enable the ratio of resistance to inductance to be maintained substantially constant across the range of taps utilized.