will cause the Hall effect sensors (2 and 3) mounted on its outer wall to activate when it is fully retracted or extended. Hall effect sensors may be used in various sensors such as rotating speed sensors (bicycle wheels, gear-teeth, automotive
speedometers, electronic ignition systems), fluid
flow sensors,
current sensors, and
pressure sensors. Hall sensors are commonly used to time the speed of wheels and shafts (see Figure 1), such as for
internal combustion engine ignition timing,
tachometers and
anti-lock braking systems. Common applications are often found where a
robust and contactless alternative to a mechanical switch or potentiometer is required. These include: electric
airsoft guns, triggers of electropneumatic
paintball guns,
go-kart speed controls,
smartphones, and some global positioning systems.
Position sensing One of the most common industrial applications of Hall sensors used as binary switches is in position sensing (see Figure 2). Hall effect sensors are used to detect whether a smartphone's cover (that includes a small magnet) is closed. Some
computer printers use Hall sensors to detect missing paper and open covers and some 3D printers use them to measure filament thickness. Hall sensors are used in some automotive fuel-level indicators by detecting the position of a floating element in the fuel tank. Hall sensors affixed to mechanical gauges that have magnetized indicator needles can translate the physical position or orientation of the mechanical indicator needle into an electrical signal that can be used by electronic indicators, controls, or communications devices.
Magnetometers Hall effect magnetometers (also called tesla meters or gauss meters) use a "Hall probe", with a Hall element, to measure magnetic fields or inspect materials (such as tubing or pipelines) using the principles of
magnetic flux leakage. A Hall probe is a device that uses a calibrated Hall-effect sensor to directly measure the strength of a magnetic field. Since magnetic fields have a direction as well as a magnitude, the results from a Hall probe are dependent on the orientation, as well as the position, of the probe.
Ammeters integrated into ferrite ring Hall sensors may be utilized for contactless measurements of
direct current in
current transformers. In such a case the Hall sensor is mounted in a gap in the magnetic core around the current conductor. As a result, the DC
magnetic flux can be measured, and the DC in the conductor can be calculated. When electrons flow through a conductor, a magnetic field is produced. Thus, it is possible to create a non-contacting
current sensor or
ammeters. The device has three terminals. A sensor voltage is applied across two terminals and the third provides a voltage proportional to the current being sensed. 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. Also, the voltage present on the line to be sensed is not transmitted to the sensor, which enhances the safety of measuring equipment.
Improving signal-to-noise Integrating a Hall sensor into a ferrite ring (as shown) concentrates the flux density of the current's magnetic field along the ferrite ring and through the sensor (because flux flows through ferrite much better than through air),
Hall-effect thruster A
Hall-effect thruster (HET) is a device that is used to propel some
spacecraft, after the spacecraft gets into
orbit or farther out into space. In the HET,
atoms are
ionized and accelerated by an
electric field. A radial magnetic field established by magnets on the thruster is used to trap
electrons which then orbit and create an
electric field due to the Hall effect. A large potential is established between the end of the thruster where neutral propellant is fed, and the part where electrons are produced; so, electrons trapped in the magnetic field cannot drop to the lower potential. They are thus extremely energetic, which means that they can ionize neutral atoms. Neutral propellant is pumped into the chamber and is ionized by the trapped electrons. Positive ions and electrons are then ejected from the thruster as a quasineutral
plasma, creating thrust. 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 tens of kW per Newton of thrust.
Integrated digital electronics Hall sensor ICs often integrate digital electronics. This enables advanced corrections to the sensor characteristics (e.g. temperature-coefficient corrections),
digital communication to microprocessor systems, and may provide interfaces for input diagnostics, fault protection for transient conditions, and short/open-circuit detection. Some Hall sensor ICs include
DSP, which can allow for more processing techniques directly within the sensor package. The
ESP32 microcontroller even has an integrated Hall sensor that hypothetically could be read by the microcontroller's internal
analog-to-digital converter, though it does not work.
Two-wire interface Hall sensors normally require at least three
pins (for power, ground, and output). However, two-wire ICs only use a power and ground pin, and instead communicate data using different current levels. Multiple two-wire ICs may operate from a single supply line, to further reduce wiring.
Human interface devices Hall-effect switches for
computer keyboards were developed in the late 1960s by Everett A. Vorthmann and Joseph T. Maupin at
Honeywell. Due to high manufacturing costs these keyboards were often reserved for high-reliability applications such as in aerospace and the military. As mass-production costs have declined, an increasing number of consumer models have become available. 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. Although
Sega pioneered the use of Hall-effect sensors in their
Sega Saturn 3D controller and
Dreamcast stock controller 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, 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. Applications for Hall effect sensing have also expanded to industrial applications, which now use Hall effect
joysticks to control hydraulic valves, replacing the traditional mechanical levers with contactless sensing. Such applications include mining trucks, backhoe loaders, cranes, diggers, scissor lifts, etc.
Dual Hall sensor ICs Some ICs include two Hall elements. This is useful for counting a series of increments (an
incremental encoder) to make a
linear or
rotary encoder, whereby a moving or rotating arrangement of magnets produces an alternating magnetic pattern sensed as a
quadrature encoded pattern. in which case the magnetic pole-to-pole pitch should ideally be two times the Hall element-to-element pitch. == See also ==