Hall Effect Sensor

A Hall Effect sensor is a device that detects the presence of magnetic field. It is based on the Hall Effect. The Hall Effect was discovered by Edwin hall in 1869. When current is passed through the conductor and the same conductor is placed in magnetic field perpendicular to the current flow then a voltage called the hall voltage is generated perpendicular to both the current and magnetic field. This is known as Hall Effect.When no magnetic field is applied to the current carrying thin semiconductor material(hall element) the hall voltage(Vh) is zero. When an external magnetic field is applied to the current carrying hall element perpendicular to the current flow a Lorentz force acts on the current due to which a voltage called hall voltage(Vh) is generated perpendicular to both the current and the magnetic field. This voltage is very small (in uV) and needs amplification.

Application

Hall effect sensors are activated by a magnetic field and in many applications the device can be operated by a single permanent magnet attached to a moving shaft or device. There are many different types of magnet movements, such as "Head-on", "Sideways", "Push-pull" or "Push-push" etc sensing movements. Which every type of configuration is used, to ensure maximum sensitivity the magnetic lines of flux must always be perpendicular to the sensing area of the device and must be of the correct polarity.
Also to ensure linearity, high field strength magnets are required that produce a large change in field strength for the required movement. There are several possible paths of motion for detecting a magnetic field, and below are two of the more common sensing configurations using a single magnet.Head-on Detection and Sideways Detection