Hall Effect Sensor - Working & Its Applications

What is Hall Effect Sensor?

The Hall effect is named after Edwin Hall, who discovered in 1879 that a voltage potential develops across a current-carrying conductive plate when a magnetic field flows across it in a direction perpendicular to the plate’s plane.
The underlying physical concept supporting the Hall effect is the Lorentz force, which is seen in the upper panel. The Lorentz force, which is orthogonal to both the applied field and the current flow, is experienced by an electron as it moves in a direction that is perpendicular to the applied magnetic field, B.
A sensor known as a Hall effect sensor (or simply a Hall sensor) makes use of the Hall effect to determine the presence and strength of a magnetic field. The output voltage of the Hall sensor varies in direct proportion to the field’s intensity.

A type of Hall Effect sensor is a magnetic sensor. A transducer called a Hall Effect sensor alters its output voltage in response to variations in a magnetic field.
It is an electronic device that detects the Hall effect and translates its results into electronic data that can be processed by an integrated computer, used to turn a circuit on and off, used to measure a changing magnetic field, or shown on an interface.
A current-carrying conductor’s electrons are forced to one side when a magnet is positioned perpendicular to it, creating a potential difference in charge (i.e. voltage). The Hall effect thus indicates the presence and strength of a magnetic field close to a conductor.

A thin rectangular p-type semiconductor material, such as gallium arsenide (GaAs), indium antimonide (InSb), or indium arsenide (InAs), conducts a steady current through itself to create a Hall effect sensor in a Hall effect sensor.
When the device is placed in a magnetic field, the magnetic flux lines exert a force on the semiconductor material, diverting the charge carriers, electrons, and holes, to either side of the semiconductor slab.
Charge carriers move because of the magnetic force they experience as they travel through the semiconductor material.
As electrons and holes move sideways due to the accumulation of charge carriers, a potential difference is created between the two sides of the semiconductor material.

The passage of electrons through a semiconductor material is then impacted by the presence of an external magnetic field at right angles to it; the influence is greater for flat, rectangular-shaped materials.
Using a magnetic field to produce a measurable voltage leads to the Hall Effect.
To produce a potential difference across the device, magnetic flux lines must be of the proper polarity, often a south pole, and perpendicular (90o) to the current flow. The magnetic field strength and type of magnetic pole are both revealed by the Hall effect.
For instance, a south pole influences the output of voltage while a north pole has no effect.
Hall Effect sensors and switches should be set to “OFF” when there is no magnetic field (open circuit status). They become “ON” when exposed to a magnetic field with the proper polarity and strength (closed-circuit condition).

Applications for hall sensors include proximity sensing, positioning, speed detection, and current sensing.
To time the speed of wheels and shafts, such as for tachometers or timing the ignition of internal combustion engines, hall sensors are frequently utilized.
In brushless DC electric motors, they are utilized to locate the permanent magnet.
Frequent use is the replacement of a mechanical limit switch with the detection of a moving element. Another frequent application is the indexing of rotational or translational motion.