Hall Effect

Brief History:

It was Prof. Edwin Hall an American physicist while experimenting in his Lab; Hall used a thin Gold foil and in 1879 discovered for the first time that an electric potential acting perpendicularly to both the current and the magnetic field. The effect has since been known as the Hall Effect. Hall discovered that charge carriers moving along the conductor experience a transverse force and tend to drift to one side and this movement of charge carriers induces a voltage on the conductor known as Hall voltage. VH

What is the Hall Effect Sensor/Device

A device which converts magnetic or magnetically encoded information into electrical signals is called HALL EFECT SENSOR. A Hall Effect device/sensor is a solid state device that is becoming more and more popular because of its many uses in different types of applications. Hall Effect devices are immune to vibration, dust and water.

A Hall effect sensor is a transducer that varies its output voltage in response to a magnetic field. Hall effect sensors are used for proximity switching, positioning, speed detection, and current sensing applications. In its simplest form, the sensor operates as an analog transducer, directly returning a voltage.

Conventional Hall effect Current Sensor :

How Hall Effect Sensor works

The Basic Principle of Hall Effect is the activation by an external magnetic field. As we are familiar that there are two important characteristics of a magnetic field.

 Flux density, (B) and polarity (North & South Poles).

When the magnetic flux density around the sensor exceeds a certain preset threshold, the sensor detects it and generates an output voltage called the Hall Voltage, VH. The following diagram shows a basic function of a Hall Effect Sensor. 

Why use the Hall effect? 

The reasons for using a particular technology or sensor vary according to the application. Cost, performance and availability are always considerations. The features and benefits of a given technology are factors that should be weighed along with the specific requirements of the application in making this decision.

 General features of Hall effect based sensing devices are:

 • True solid state

 • Long life (30 billion operations in a continuing keyboard module test program) 

• High speed operation - over 100 kHz possible

 • Operates with stationary input (zero speed)

 • No moving parts • Logic compatible input and output

 • Broad temperature range (-40 to +150°C) • Highly repeatable operation