Hall Effect Transducer

The Hall effect transducer is an essential tool in modern electronics due to their ability to detect and measure magnetic fields with great precision. In many cases, the terms “Hall-effect sensor” and “Hall-effect transducer” are often used interchangeably. This is because Hall-effect sensors are a common type of Hall-effect transducer.

The phenomenon ‘Hall-effect’ was discovered by American physicist Edwin Hall in 1879.

What is the Hall effect?

The Hall- effect refers to the emergence of an electrical potential difference in an electrical conductor when it is placed in a magnetic field and through which an electric current flows.

The Hall effect necessarily implies a conductive material through which electric current passes and on which magnetic force is exerted perpendicularly. In practical terms, a voltage is applied to the conductive pate at its ends, so electrons begin to flow linearly from the negative pole to the positive pole.

However, when a magnet is placed perpendicular to them, the positive and negative charges are sent towards the transverse ends and transverse Hall voltage (VH) is produced. This potential difference is called “Hall voltage.”

A conductive material with the thickness (d), conducts a current (I) and is subjected to a magnetic field (B) applied perpendicularly. As a result, Hall voltage is obtained, whose magnitude is given by


Where RH = the Hall constant of the material.

The Hall effect can be used to find out the type of semiconductor (P-type or N-type).

The Hall effect can occur in both conductors and semiconductors. In conductors, electronics are the primary charge carriers responsible for the effect. In semiconductors, both free electrons and holes are the charge carriers responsible for the Hall effect. The type of charge carriers depends on p-type or n-type semiconductors. In a p-type semiconductor, the current flow is due to the holes as majority carriers, whereas in an n-type semiconductor, it is free electrons.

Principle of Hall Effect Transducer

The principle of operation of the Hall-effect is simple; the Hall-effect occurs when an electric current flows through a metal conductor in the presence of a magnetic field perpendicular to the current. The resulting transverse voltage across the conductor is known as the Hall voltage.

This voltage is then measured and processed to produce an output signal, which can be analog or digital, depending on the specific design of the sensor and the application for which it is intended.

principle-of-hall effect-transducer

Types of Hall Effect Transducers:

Hall-effect devices are available in two types

  • Analog Hall-effect devices
  • Digital Hall-effect devices

Analog Hall-effect devices

Analog Hall-effect devices are typically integrated with an amplifier and circuitry to enhance the linearity of the output. These devices’ operating output voltage range is often limited by the amplifier circuit rather than the Hall-effect sensor.

Analog Hall-effect devices are used to detect a magnetic field, temperature, current, pressure, position, and other parameters. To make a Hall-effect temperature sensor, for example, a magnet is mounted on a material that contracts or expands in response to a temperature change. As the magnet moves, it changes the magnetic field in a nearby Hall-effect device and therefore generates a voltage across the Hall-effect device.

The same effect can be used to measure pressure or other parameters using a material that expands or contracts when pressure or another parameter changes.

Current flowing through a wire generates a magnetic field that surrounds the wire. For this reason, the Hall effect can be used to make an ammeter that can be mounted near, as opposed to in the path of the current.

Digital Hall-effect devices

Digital Hall-effect devices contain the Hall-effect sensor integrated with additional circuitry, such as a comparator, to produce a digital output. These are used as switches or as buttons on a keyboard. If a small magnet is mounted on a button, a Hall-effect device can be used to detect when that magnet is pressed near the Hall-effect sensor. Hall-effect sensors can be utilized as proximity sensors to detect the presence of ferromagnetic objects.

Applications of Hall Effect Transducer

A Hall-effect transducer is a simple device that has many applications. It is essentially a piece of semiconductor with wires attached and calibrated for use. For this reason, Hall-effect devices are inexpensive, small, and readily available. These devices, like most integrated circuits, are durable and long-lasting because they have no mechanical moving parts.

The Hall effect is used to manufacture both switching and linear sensors. Switch-type Hall sensors find extensive applications in position, displacement, and velocity measurement, while linear Hall sensors are commonly employed in magnetic fields, current, and voltage measurements.

Speed Measurement

One of the most common applications of Hall-effect devices is in tachometers, which are used to measure rotation speed.


The Hall-effect sensor is placed near a rotating component, such as a gear. The gear is connected to the shaft, and as the shaft rotates, the gear also rotates. Hence the magnetic field near the sensor changes as shown in the above figure. The change in the magnetic field induces a potential in the Hall-effect sensor.

The induced voltage (potential) is directly related to the magnetic strength, and this, in turn, is influenced by the rotation of the gear teeth. With each rotation, as gear teeth pass by the sensor, there are fluctuations in the induced voltage. The fluctuations result in a pulse signal. By counting the number of pulses, the speed of the motor can be calculated.

Displacement Measurement


The Hall-effect element is used to measure the displacement of the structural element. For example – consider the ferromagnetic structure that has a permanent magnet. The Hall-effect transducer is placed between the poles of the permanent magnet. The intensity of the magnetic field through the Hall-effect element changes by changing the position of the ferromagnetic field, hence displacement can be measured.

Current Measurement


The current measurement often employs a Hall-effect transducer, which enables the measurement of current without any physical connection between the conducting circuit and the meter.

Inside the sensor, a small element acts as the conductor through which current passes. This element is exposed to a magnetic field, which is directly related to the current to be measured.

In its operation, when an electric current passes through the conductive element in the sensor, a magnetic field is applied. Due to the Hall effect, a voltage is generated across the conductor. This voltage is measured and used to calculate the amount of current that is flowing through the conductor.

Current sensors are of two types.

  • Open loop current sensor
  • Closed loop current sensor


  • They have no moving parts; they have no wear and tear.
  • They are reliable and can operate in extreme temperature environments.
  • They offer a fast and accurate response.
  • Hall sensors are utilized in a variety of applications, with digital and analog devices, each serving distinct purposes.


  • They require a magnetic field to function.
  • They can be affected by electromagnetic interference in environments with a lot of electronic equipment.

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