This preview shows page 1. Sign up to view the full content.
Unformatted text preview: Resistor strips (e.g. Wi- or InSb, Wi=Wismut, In=Indium, Sb=Antimon) change their
electrical resistance in magnetic fields. This effect, i.e. magnetoresistive, can be
used for various sensor types. Hall proximity sensors If a semiconductor (e.g. InSb) is exposed to a magnetic field, a voltage is created
perpendicular to the direction of the current, i.e. the so-called Hall voltage. Certain
physical dimensions apply in this particular case, i.e. the thickness of the plate must
be small in comparison with the dimensions of length and width. Voltages of up to
1.5 V can be created.
The underlying physical effect is described as the Hall effect after the American
physicist, E. Hall. 42 © Festo Didactic GmbH & Co. KG • FP 1110 3. Magnetic proximity sensors Wiegand proximity sensors The Wiegand sensors consist of a wire which is made from a ferromagnetic alloy of
vanadium, cobalt and iron. The direction of magnetisation of this wire changes
spontaneously when an approaching magnetic field exceeds a certain value. If a coil
is wound around this Wiegand wire, a voltage pulse of up to 3 V is induced.
In principle, Wiegand sensors do not require any external voltage supply. 3.2.2 Technic...
View Full Document
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