A magnetic pickup sensor which includes a sensor assembly 11 and a molded resin housing 12 disposed around the assembly. The sensor assembly has a pickup coil 15 wound around an iron core 14 for detecting a change in the magnetic flux of a magnet 13, and a support unit including a coil bobbin 18 and a spacer 20 for supporting the magnet and core assembly. The iron core has one end 14a projecting outwardly from the molded resin, and the spacer of the support unit has a positioning recess 23 for engagement by a positioning pin 30 of a mold die. Therefore, the sensor assembly can be accurately positioned and held within the mold die during molding of the housing.

A device for detecting the speed of rotation and/or an angle of rotation of a shaft having a motion transmitter which rotates with the shaft, the device consisting of a magnetic-field-dependent sensor which receives a signal from the motion transmitter. A permanent magnet is arranged in the vicinity of the sensor with an evaluating circuit, the sensor being an integrating component of the evaluating circuit. The arrangement of the permanent magnet with respect to the sensor and of the permanent magnet and sensor with respect to the motion transmitter, on the one hand, and the construction of the sensor as a saturable-core probe (fluxgate effect), on the other hand, make it possible to detect even very slow rotational movements such as occur, for example, with antiblocking systems or forward drive control systems in motor vehicles.

A variable reluctance sensor is shown for determining the speed or position of a moveable target object. The sensor has a magnet which is coupled to a pole piece. A wire coil is located annularly around the pole piece. The magnet generates flux in the coil which is changed by the movement of the target object. A second bucking magnet is annularly located around the coil and generates a flux field to reinforce the flux in the coil and to prevent flux from leaking from the wire coil and pole piece. In this manner, the voltage output from the coil is increased due to the decrease in flux leakage. A processor unit is coupled to the wire coil. The processor unit measures the reluctance generated in the coil from the movement of the target object.

To increase the output amplitude obtained from Wiegand wire transducers, for example of the type used in contactless ignition breaker systems, a flux concentration or flux guide element (3) of highly permeable material, for example high-frequency ferrite core material, is provided surrounding the Wiegand wire (1) and, at least in part, the pick-up coil (2) coupled thereto.

A detector detects a rotational speed of a rotating object. The detector includes a closed magnetic circuit having a magnet therein, and detects the rotational speed according to a magnetic flux alteration in the closed magnetic circuit. The detector comprises a cylindrical rotor switch, which rotates together with the rotating object, and a fixed sensor device having a magnet, an electromagnetic coil and claws constituting a magnetic switch. At least two magnetic switches are provided in the closed magnetic circuit in order to increase the flux alteration in the circuit and thereby to enhance a detection accuracy.