Hall Effect Sensor Working and Applications.

Hall voltage is discovered by Edwin Hall in 1879. Hall Effect is caused due to the nature of current in a conductor. Many inventions used this Hall Effect theory. This theory is also used in current sensors, pressure sensors, Fluid flow sensors etc…  One such invention that can measure magnetic field is the Hall Effect sensor.

Hall Effect Sensor Definition

Hall-effect sensors are the linear transducers that are used to measure the magnitude of the magnetic field. Working on the principle of Hall Effect, these sensors generate a Hall voltage when a magnetic field is detected, which is used to measure the magnetic flux density.

Linear sensors can measure the wide range of magnetic fields. Besides magnetic fields, these sensors are also used for detecting proximity, position, speed. For these sensors output voltage is directly proportional to the magnitude of the magnetic field.

Working Principle of Hall Effect Sensor

The principle of Hall voltage is used as a working principle of the Hall Effect sensor. On a thin strip of a conductor, electrons flow in a straight line when electricity is applied. When this charged conductor comes in contact with the magnetic field which is in a perpendicular direction to the motion of electrons, the electrons get deflected.

Some electrons get collected on one side while some on another side. Due to this, one of the conductor’s plane behaves as negatively charged while the other behaves as positively charged. This creates potential difference and voltage is generated. This voltage is called the Hall voltage.

The electrons continue to move from one side of the plane to other till a balance is achieved between the force applied on charged particles due to an electric field and the force that caused magnetic flux that caused this change. When this separation stops, the hall voltage value at that instant gives the measure of magnetic flux density.

Based on the relation between hall voltage and magnetic flux density, Hall Effect sensors are of two types. In the linear sensor, the output voltage is linearly related to magnetic flux density. In the threshold sensor, at each magnetic flux density, the output voltage will have a sharp decrease.

Hall Effect sensors can be viewed as linear transducers. To process the sensor’s output these require a linear circuit that can provide a constant driving current to the sensors and also amplifies the output signal.

Applications of Hall Effect Sensor

The applications of Hall-effect sensors are as follows:

• When combined with threshold detection they act as a switch.
• These are used in ultra-high-reliability applications such as keyboards.
• Hall Effect sensors are used to time the speed of wheels and shafts.
• These are used to detect the position of permanent magnet in brushless electric DC motors.
• Hall Effect sensors are embedded in digital electronic devices along with linear transducers.
• Sensing the presence of the magnetic field in industrial applications.
• Used in smartphone to check whether the flip cover accessory is closed.
• For contactless measurement of DC current in current transformers, Hall Effect sensor is used.
• This is used as a sensor to detect the fuel levels in automobiles.

Examples

Some of the examples for the application of Hall Effect sensors are the current transformers, Position sensing, Galaxy S4 Accessories, Keyboard switch, computers, Proximity sensing, speed detection, current sensing applications, tachometers, anti-lock braking systems, magnetometers, DC motors, disk drives etc…

Hall Effect sensors are available in the form of different IC’s. Many of the Hall Effect sensors in the market contain a sensor element along with a high gain IC amplifier. These are safe from environmental changes due to their protective packaging. Which of the Hall Effect sensor IC have you used?