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Unformatted text preview: ield of the permanent
magnet contained in the sensor is changed. This field change is detected by the
magnetoresistor and converted into an output signal. The sensor responds only to
ferromagnetic materials. © Festo Didactic GmbH & Co. KG • FP 1110 173 11. Physical fundamentals Wiegand effect A wire-shaped ferromagnetic material with one single magnetic domain is used as a
sensor medium. Magnetic polarisation can only take up one of the two directions
parallel to the wire. The soft magnetic core is enclosed by a hard magnetic shell. In
the presence of an external magnetic field, a magnetic reversal takes place along the
entire length of the wire. A voltage signal is created in a coil which is wound around
the wire. Voltage signals of 2 – 8 V amplitude are provided with a sensor length of
15 – 30 mm.
One characteristic feature of Wiegand sensors is that no external voltage supply
is required to operate the sensor. These operate at a temperature range of
-196 – +175 °C. 15 - 30 mm ~ Ø 1 mm 2 3 4
Single or multiple layer coil with concentrated windings...
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This note was uploaded on 11/01/2012 for the course CHEMICAL 102 taught by Professor Jamesrodriguez during the Spring '12 term at Universidad Politécnica de Cartagena.
- Spring '12