The magnetic piston (1) in this pneumatic cylinder will cause the Hall effect sensors (2 and 3) mounted on its outer wall to activate when it is fully retracted or extended.

Clutch with Hall Effect sensor.

A Hall effect sensor is a transducer that varies its output voltage in response to changes in magnetic field. A transducer is a device usually electrical, electronic, Electro-mechanical, Electromagnetic, Photonic, or Photovoltaic Electrical tension (or voltage after its SI unit, the Volt) is the difference of electrical potential between two points of an electrical In Physics, a magnetic field is a Vector field that permeates space and which can exert a magnetic force on moving Electric charges Hall sensors are used for proximity switching, positioning, speed detection, and current sensing applications.

In its simplest form, the sensor operates as an analogue transducer, directly returning a voltage. An analog or analogue signal is any continuous signal for which the time varying feature (variable of the signal is a representation of some other A transducer is a device usually electrical, electronic, Electro-mechanical, Electromagnetic, Photonic, or Photovoltaic With a 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.

Electricity carried through a conductor will produce a magnetic field that varies with current, and a Hall sensor can be used to measure the current without interrupting the circuit. Typically, the sensor is integrated with a wound core or permanent magnet that surrounds the conductor to be measured.

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. A switch is a mechanical device used to connect and disconnect an electric Circuit at will Commonly seen in industrial applications such as the pictured pneumatic cylinder, 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. There are many types of keyboard, usually differentiated by the Switch technology employed in their operation

Hall sensors are commonly used to time the speed of wheels and shafts, such as for internal combustion engine ignition timing or tachometers. The internal combustion engine is an engine in which the Combustion of Fuel and an Oxidizer (typically air occurs in a confined space called a An ignition system is a system for igniting a fuel-air mixture A tachometer is an instrument that measures the rotation speed of a shaft or disk as in a motor or other machine They are used in Brushless DC electric motors to detect the position of the permanent magnet. The statement Brushless DC electric motor may be misleading and controversial among professionals because it's actually an 3 phase AC motor driven by a DC source In the pictured wheel carrying two equally spaced magnets, the voltage from the sensor will peak twice for each revolution. This arrangement is commonly used to regulate the speed of disc drives. Disk storage is a general category of a Computer storage mechanisms in which data is recorded on planar round and rotating surfaces ( disks, discs, or

See also

• Hall effect
• List of sensors