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BASED OK THE RECENT ADVANCEMENTS made in application techniques a new “shunt activated” pulser has been developed using the “Wiegand Effect”. Unlike the more typical moving magnet Wiegand pulsers wherein the pulses are produced in response to the passing of external magnets, a “shunt activated” pulser contains its own magnetic circuit. The internal magnetic fields, to which the Wiegand wire is exposed, are altered by the presence of ferrous objects and thereby cause Wiegand pulses to occur. Although the concept of a Wiegand pulser which is activated by the passage of a ferrous object is not new, development of a balanced bridge magnetic circuit has allowed its evolution into a viable product for industrial or automotive use. Previous designs, while functional under laboratory conditions, were plagued with difficulties in manufacturing and setup.

This paper is presented to explain and demonstrate the most recent gains made in application techniques of the Wiegand Effect. “Wiegand Wire” is a small diameter wire drawn from a magnetic alloy such as Vicalloy and secondarily processed by cold working so as to cause a gradient of magnetic hardness from its center to exterior. When exposed to magnetic fields of proper orientation, intensities, and sequence, substantial flux jumps will occur within the wire. These flux changes may be converted to an electrical pulse by interposing an inductive pick up-coil. Being a bistable magnetic threshold device with a firing point of approximately 20 oersteds, the Wiegand Effect may be used to create self-powered pulsers which are essentially insensitive to speed and immune to most ambient magnetic field disturbances.