Back to the Basics: Hall Effect Sensor

A Hall effect sensor is a solid-state component that varies its signal in response to a magnetic field.  The Hall effect is named for American physicist Edwin Hall.  In 1879, Hall discovered that when an electric current is placed in a magnetic field, it causes a potential difference to be created.  The strength of the potential difference can be measured, from which the strength of the magnetic field can then be determined.

By nature of their operation, Hall effect sensors can be designed so that they are completely sealed from environmental conditions and, because they have no internal moving parts, they can be very reliable.  By using other solid-state electronics, they can be used to measure distance or relative positions.  The output can be designed to vary with intensity of the magnetic field, so the closer the magnetic field, the higher or lower the output voltage will be.  They can also be designed to operate as a switch; output voltage will alternate between a high or a low voltage based on the position of the magnetic field.  Because of these advantages over traditional mechanical sensors, their use on outboard motors has increased significantly.

Hall effect sensors are used in a variety of locations.  Camshaft position sensors, throttle position sensors inside of electronic throttle valves, accessory tilt limit sensors, and inside paddle wheel sensors are just some examples.