Hall effect sensor
Hundreds of millions of Hall sensor integrated circuits (ICs) are sold each year[2] by about 50 manufacturers, with the global market around a billion dollars.
The current's charge carriers are deflected by the Lorentz force in the presence of a magnetic field perpendicular to their flow.
The vacuum tube amplifier technology available in the first half of the 20th century was too large, expensive, and power-consuming for everyday Hall effect sensor applications, which were limited to laboratory instruments.
Even early generation transistor technology was unsuited; it was only with the development of the low-cost silicon chip-based integrated circuit (IC) micro-technology that the Hall effect sensor became suitable for mass application.
Hall sensors are called linear if their output is proportional to the incident magnetic field strength.
Schmitt trigger filtering may be applied (or integrated into the IC) to provide a clean digital output that is robust against sensor noise.
[16] Hall effect devices (when appropriately packaged) are immune to dust, dirt, mud, and water.
[17] Magnetic flux from the surroundings (such as other wires) may diminish or enhance the field the Hall probe intends to detect, rendering the results inaccurate.
While a single Hall element is susceptible to external magnetic fields, a differential configuration of two Hall elements can cancel stray fields out from measurements,[18] analogous to how common mode voltage signals are canceled using differential signaling.
Common applications are often found where a robust and contactless alternative to a mechanical switch or potentiometer is required.
Hall effect sensors are used to detect whether a smartphone's cover (that includes a small magnet) is closed.
Hall sensors are used in some automotive fuel-level indicators by detecting the position of a floating element in the fuel tank.
This has several advantages; no additional resistance (a shunt, required for the most common current sensing method) needs to be inserted in the primary circuit.
This configuration also provides an improvement in signal-to-noise ratio and drift effects of over 20 times that of a bare Hall device.
If used in a permanent installation, a split sensor allows the electric current to be tested without dismantling the existing circuit.
As there are no moving parts involved within the sensor or magnet, typical life expectancy is improved compared to traditional electromechanical switches.
the Hall Effect sensor is used as a direct replacement for the mechanical breaker points used in earlier automotive applications.
Hall sensors in 3 or 4-pin brushless DC motors sense the position of the rotor and to switch the transistors in the right sequence.
The thrust produced is extremely small, with a very low mass flow rate and a very high effective exhaust velocity/specific impulse.
This is achieved at the cost of very high electrical power requirements, on the order of 4 kW for a few hundred millinewtons of thrust.
[29] Hall effect switches for computer keyboards were developed in the late 1960s by Everett A. Vorthmann and Joseph T. Maupin at Honeywell.
[30] Due to high manufacturing costs these keyboards were often reserved for high-reliability applications such as aerospace and military.
Hall effect sensors can also be found on some high-performance gaming keyboards (made by companies such as SteelSeries, Wooting, Corsair), with the switches themselves containing magnets.
[31] Although Sega pioneered the use of Hall effect sensors in their Sega Saturn 3D controller[32] and Dreamcast stock controller[33] from the 1990s, Hall effect sensors have only started gaining popularity for use in consumer game controllers since the early 2020s, most notably in analog stick/joystick and trigger mechanisms,[34] for enhanced experience due to their contactless, high-resolution, low-latency measurements of position and movement and their longer lifespan due to lack of mechanical parts.
[4] That pattern can then be decoded to provide both the speed and direction of movement or simply counted up and down to determine the position or angle.
