Hall Effect Sensors Basics Tutorial
Understanding Hall Effect Transducer:
While doing electronics based hardware projects which may be used in industrial control applications, electrical sensors/transducers come in to the picture.
In this post, we will see about the fundamentals of hall effect transducer.
History of Hall effect sensor:
The hall effect was discovered by Edward H. Hall at John Hopkins University at 1879. He used a piece of gold to produce the hall effect. But now a days a piece of semiconductor material is used. Because the semiconductor material works better and it is less expensive. The Hall effect sensor is also called as Hall generator.
Principle of Hall effect:
When a transverse magnetic field B is applied to a specimen( a piece of semiconductor or metal) carrying current I, an electric field E is induced in the direction perpendicular to both I and B.
This phenomenon is called as Hall Effect. The voltage induced in the hall effect sensor is usually refered as hall voltage.
- Technically speaking, the hall effect transducer requires four connections - two to provide current through the device and two to provide the output voltage.
- However the negative current supply line and the negative output line are internally connected together.
- Thus it becomes three terminal device that looks similar to a transistor as shown in the above figure.
A Hall effect measurement confirms the validity of the concept that it is possible for two independent types of charge carriers ( ie, electrons and holes) exists in the semiconductor.
The polarity of the voltage produced by the hall generator ( Hall effect sensor) is determined by the following two factors:
- The polarity of the magnetic field used to deflect the current.
- The direction of current flow through the semiconductor material
The amount of voltage produced by the hall effect sensor is determined by
- The strength of the magnetic field used to deflect the current path
- The amount of current flowing through the semiconductor material.
Advantages of Hall effect Sensor:
- It is a solid state device. so does not have moving parts, contacts to wear out.
- As they are made up of semiconductor material, it is very easy to implement signal conditioning circuits on the same piece of material.so it is possible to make a device that will detect a magnetic field and provide a linear output voltage proportional to the strength of the field, all on a piece of silicon no larger than a transistor.
- It is not affected by dirt, oil, vibration.
Applications of Hall Effect Sensor:
- The hall effect is used to find whether a semiconductor is N type or P-type. In addition to that it is useful to find the carrier concentration.
- Hall effect concept can be used to measure the ac power and the strength of magnetic field. It is used to sense the angular position of static magnetic fields in the magnetic field meter.
- This Hall effect multiplier instrument is based on hall effect concept. This instrument gives the output proportional to the product of two input signals.
- It is used in measurement of velocity, rpm, sorting, limit sensing and non-contact current measurements.
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