What is a Hall Effect Sensor?

A Hall effect sensor is an electronic device that is designed to detect the Hall effect, and convert its findings into electronic data, either to switch a circuit on and off, provide a measurement of a varying magnetic field, be processed by an embedded computer or displayed on an interface. In 1879, scientist Edwin Hall discovered that if a magnet is placed perpendicular to a conductor with a steady flow of current, the electrons flowing within the conductor are pulled to one side, thus creating a potential difference in charge (i.e. voltage). The Hall effect, then, is indicative of the presence and magnitude of a magnetic field near a conductor.

Using magnetic fields, Hall effect sensors are used to detect variables such as the proximity, speed, or displacement of a mechanical system. Hall effect sensors are non-contact, which means that they do not have to come in contact with a physical element. They can produce either a digital (on and off) or analog (continuous) signal depending on their design and intended function.

Hall effect switches and latches are either on or off. A Hall effect switch turns on in the presence of a magnetic field and turns off when the magnet is removed. A Hall effect latch turns on (closes) when a positive magnetic field is applied and remains on even when the magnet is removed. When a negative magnetic field is applied, the Hall effect latch turns off (opens) and remains off even when the magnet is removed.

Linear Hall sensors (analog) render precise and continuous measurements based on magnetic field strength; they do not switch on and off. Within the Hall effect sensor, the Hall element sends the electric potential difference (voltage brought about by the magnetic interference) to an amplifier in order to make the change in voltage large enough to be perceived by the embedded system.  

Hall effect sensor diagram.
Hall effect sensor diagram. (Electronics Hub)

Hall effect sensors can be found in cell phones and GPS, assembly lines, automobiles, medical devices and many IoT devices. The market for Hall effect sensors is expected to grow by more than 10% annually, reaching $7.55 billion by 2026.