Hall Effect Sensor

As-Salaam-Alaikum, Welcome to my blogger "World of Knowledge".Here we discuss the topic Hall Effect Sensors.

Points to be discuss in this Article are given below :

• Hall Effect Sensor
• How its Operates
• Uses of Hall Effect Sensor
• Working Principle
• Application of Hall Effect Sensor

Hall effect sensor:

A Hall effect sensor is a transducer that varies its output voltage in response to a magnetic 

field. 

How Hall Effect Sensor Opertes:

In its simplest form, the sensor operates as an analog transducer, directly returning a

voltage. With known magnetic field, its distance from the Hall plate can be determined.

Using groups of sensors, the relative position of the magnet can be deduced.Frequently, a

Hall sensor is combined with circuitry that allows the device to act in a digital (on/off) mode

and may be called a switch in this configuration. 

Uses of Hall Effect Sensor:

Hall effect sensors are used for 

        Switching 
Positioning
Speed detection
Current sensing applications.

Commonly seen in industrial applications, they are also used in consumer

equipment;for example some computer printers use them to detect

missing paper and open covers.When high reliability is required, they are

used in keyboards.

Working Principle:

When a beam of charged particles passes through a magnetic field, forces act on the 

particles and the beam is deflected from a straight path. The flow of electrons through a

conductor is known as a beam of charged carriers.When a conductor is placed in a

magnetic field perpendicular to the direction of the electrons, they will be deflected from a

straight path. As a consequence, one plane of the conductor will become negatively

charged and the opposite side will become positively charged.The voltage between these

planes is called Hall voltage.When the force on the charged particles from the electric field

balances the force produced by magnetic field, the separation of them will stop. If the

current is not changing, then the Hall voltage is a measure of the magnetic flux density.

Basically, there are two kinds of Hall effect sensors. One is linear which means the

output of voltage linearly depends on magnetic flux density; the other is called threshold

which means there will be a sharp decrease of output voltage at each magnetic flux density.

Working

Circuit Symbol

Applications of Hall Effect Sensor:

Position sensing:

Sensing the presence of magnetic objects (connected with the position sensing) is the most

common industrial application of Hall effect sensors, especially those operating in the switch

mode (on/off mode). The Hall effect sensors are also used in the brushless DC motor to

sense the position of the rotor and to switch the transistors in the right sequence.

•         Smartphones use hall sensors to determine if the Flip Cover accessory is closed.
•         Direct Current (DC) transformers

Hall effect sensor may be utilized for contactless measurements of DC current in current

transformers. In such a case the Hall effect sensor is mounted in the gap in magnetic core

around the current conductor.  As a result, the DC magnetic flux can be measured, and the

DC current in the conductor can be calculated.

Automotive fuel level indicator:

The Hall sensor is used in some automotive fuel level  indicators. The main principle of

operation of such indicator is position sensing of a floating element. This can either be done

by using a vertical float magnet or a rotating lever sensor.

In a vertical float system a permanent magnet is mounted on the surface of a floating object.

The  current carrying conductor is fixed on the top of the  tank lining up with the magnet.

When the level of fuel rises, an increasing magnetic field is applied on the current resulting 

in higher Hall voltage. As the fuel level decreases, the Hall voltage will also decrease. The

fuel level is indicated and display by proper signal condition.

In a rotating lever sensor a diametrically magnetized ring magnet rotates about a linear hall

sensor.The sensor only measures the perpendicular (vertical) component of the field. The

strength of the field  measured correlates directly to the angle of the lever and thus the level

of the fuel tank.