The Hall Effect: Explained

In this blog we are going to discuss the science of Hall Effect, how it works, why the effect is important, what products the effect is used in and what the advantages are.

What is the Hall Effect?

Hall Effect is named after American physicist Edwin H. Hall who first introduced the theory to the world in 1879 when he was doctoral candidate at Johns Hopkins University in Baltimore. Hall discovered that when a conductor or semiconductor with current flowing in one direction was introduced to a perpendicular magnetic field a voltage could be measured at right angles to the current path, this measurable voltage is the Hall Effect.

How does it work?

The Hall Effect takes place when you set current flowing through a conductor which is a material such as copper or silver that permits electrons to flow freely across the entire surface area. The electrons begin to flow in a straight line from one side of the conductor to the other. If you were to then introduce a magnetic field near the conductor, it would disturb the flow of the electrons due to the force applied. This is called Lorentz Force, which is the force on a charged particle due to electric and magnetic fields.

The magnet’s north pole pulls the negative electrons to one side of the conductor and deflects the positive electrons to the other side of the conductor. If you then put a voltage tester between the two sides you will be given a voltage reading because there is current between the positive and negative electrons, by retrieving this measurable voltage you are putting the Hall Effect principle into practice. In a semiconductor such as silicon or germanium, the drift velocity of electrons is a lot quicker due to the material used. This results in a stronger Hall Effect which corresponds to a larger voltage reading being detected and therefore a more precise reading taken.

Hall Effect is used in several different products such as sensors, joysticks and switches. We will now discuss the different products to understand what they are, their benefits and their applications. At Live Electronics we work with several manufacturers that produce Hall Effect products, we will also discuss the different manufacturers and their products.

Hall Effect Joysticks

Hall Effect joysticks are devices that use non-contact sensors to change the physical movement from an operator into an electrical signal which can be understood by a computer system. Hall Effect joysticks are extremely robust and have a very long mechanical life due to there being no psychical contact with the sensor. A Hall Effect joysticks mechanical life can range from 1 million cycles (also known as actuations) to 15 million cycles.

There are several types of joysticks being used today, one of them being the Potentiometer joystick. The Potentiometer joystick is a device that has been around for years and they contain several components that increase or decrease the level of resistance within the electronic circuit. Potentiometer joysticks do still offer great performance but in terms of long-term durability these joysticks may be susceptible to reliability issues due to the wearing of moving parts and minor vulnerability to electromagnetic interference or radio frequency interference. As mentioned previously, Hall Effect joysticks have a very long mechanical life due to there being no physical contact with the sensor and they are designed to withstand excessive shock or vibration giving them an advantage over the Potentiometer joystick.

Live Electronics work with a joystick manufacturer, Ruffy Controls. They have a large portfolio of joysticks, several of them being Hall Effect. The HE3 series from Ruffy Controls is a Hall Effect joystick that is designed with built in redundant sensors to provide an extra level of safety. Ruffy Controls joysticks can be designed specifically to meet customer needs and the HE3 series is no different. The HE3 series are available in 2 or 3 axis, provide options for push buttons on the joystick handle, a choice of limiters (square, guided feel, round limiter), the output voltage you require and they are available in different colours. The benefits of the HE3 series include being IP67 rated, extremely rugged, a mechanical life of 5 million actuations in all directions and excellent return to value. The HE3 series are the perfect joysticks for applications such as industrial machinery, agricultural machinery, CCTV control systems and automation systems.

Hall Effect Switches

Hall Effect switches are devices that turn on in the presence of a magnetic field and turn off when the magnet is removed. They are designed with contactless sensing to ensure maximum ruggedness, reliability and mechanical life.

There are several different style switches available one of them being a pushbutton switch. A pushbutton switch requires downward pressure to be applied to activate or deactivate a circuit. They provide an on-off functionality, but different variants are available. Their switching action can be maintained (staying in one position after pressure has been applied) or momentary (returning to their original position once pressure is removed). Due to electromechanical Pushbuttons requiring physical pressure to be applied to function, they experience a lot of physical wear and tear resulting in a shorter mechanical life of around 50 thousand cycles. Physical contact is largely reduced with a Hall Effect switch due to them having contactless sensing, which gives them a much longer mechanical life of around 1 million to 15 million cycles.

Advantages of Hall Effect

Hall Effect devices have many advantages, they are immune to dust, dirt and water and due to their frictionless operation, they have extremely long mechanical lives. They are robust, rugged and can withstand intense vibration and shock. Hall Effect devices can offer high speed operation and they can operate in a wide temperature range.