Hall-effect is used within sensors and probes to measure magnetism.
It was discovered in 1879 by an American physicist, Edwin Hall, although, the work was ahead of its time so no one had a use for it until decades later when semiconducting materials became better understood.
Hall Effect sensors are becoming more popular as they can be used in many applications including sensing position, velocity or directional movements.
As they are non-contact, they are wear free and have virtually unlimited life.
Hall Effect sensors are made up of a piece of semiconductor material which passes a continuous current through itself. When placed in a magnetic field, the magnetic flux lines will exert a force onto the semiconductor which will deflect the charge carriers, electrons and holes, forcing them to the edge of the semiconductor. As the electrons get forced to the sides, a difference in voltage is produced between the two sides of the semiconductor by the build-up of the charge carriers. The size of the voltage is directly proportional to the size of the current and the strength of the magnetic field.
In a Rotary Hall Effect Sensor, the semiconductor material is mounted in an X format and the magnet rotates above them, as the magnet rotates, the magnetic field will impinge on each of the sensors and produce an electrical output in each one. Hence the output of the X-hall-Element will have sine and cosine characteristics. In the subsequent digital signal processing, both signals are converted back into a linear signal across angular position using the arctan algorithm.
This enables a full 360 degree electrical output with either an analogue or digital interfaces.
Rotary Hall Effect Sensors can be used in Mobile Vehicle applications, Aerospace, Automotive, Test, and General Machine Tool.
The measuring range can be expanded to actually up to 16 x 360 degrees by combining Hall technology with GMR technology.
The same Hall devices than used for measurement of rotary position can be used in a different configuration to measure the linear position of a magnet. This makes sense in a measurement range of 5mm up to up to ca. 50mm.
Instead of using a Hall Effect sensor you could choose a standard linear or rotary potentiometer which would be cheaper. A Hall Effect sensor would be preferable; they are mechanically guaranteed as they are non-contact. There is no part of the sensor which can fail due to wearing. This makes them more expensive but highly reliable.
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You could also take a look at these useful articles;
Explain that stuff http://www.explainthatstuff.com/hall-effect-sensors.htmlElectronics Tutorials http://www.electronics-tutorials.ws/electromagnetism/hall-effect.html
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Article date: 05 / May / 2016
What is Hall Effect?
Published by: Variohm EuroSensor
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