Hall Effect Sensor

Sensors and transducers are used to check the practical behaviour and magnetic behaviour of any electrical equipment. There are so many sensors available in market, but here we would discuss about Hall effect sensors.

What is hall effect?

Hall effect was discovered by Edwin Hall in 1879. This effect is better understood by an experiment: suppose we have thin conductive plate and then set a current through it with the help of battery. The charge carriers would flow through it in a straight line. If we bring magnetic field near it, then the flow of charge carriers would deflect from straight line due to Lorentz force. The electrons would deflect to one side and holes to the other side of plate. This would result in voltage between these charges. This production of voltage difference across conductor is transverse to current and also to magnetic field and this effect is called Hall effect.

Hall effect sensors

Principle of hall effect sensors are totally based on Hall effect. Output voltage of hall effect sensors are quite low, usually of few micro volts. That’s why it is employed with amplifier to increase its sensitivity. The output voltage, called the Hall voltage, (V_H) is directly proportional to the strength of the magnetic field passing through the material (output ∝ H). There are two types of hall effect sensors- analog and digital output sensors.

Analog output Hall effect sensor

Analog output sensors- linear or analog sensors gives a continuous voltage. It increases with strong magnetic field and decreases in weak magnetic field. At a very high magnetic field it attains saturation. These types of sensors are suitable for measuring proximity.

Digital output sensors- it has two output states either ON or OFF. These type of sensors have additional element in their circuit called Schmitt Trigger. When magnetic flux passing through the Hall sensor exceeds a pre-set value the output from the device switches quickly between its “OFF” condition to an “ON” condition without any type of contact bounce. They are often used as limit switches, mostly used in CNC machines, 3D printers and in automation systems.

Digital output hall effect sensor