The Hall effect sensor detects and measures the presence of magnetic fields by exploiting the Hall effect. The Hall effect is when a conductive element is integrated within an electromagnetic field, a force proportional to the field and the current appears.
The sensor generates a voltage in the image of the current which is due to be visualized or measured and gives a signal when it is in the presence of a magnetic field that passes through the material or a metal part. The hall effect sensor is very sensitive, but also very solid despite being very thin.
Hall-effect Sensor: Technical specifications
The high sensitivity of the Hall Effect sensor is not its only characteristic as it also has a very high mechanical resistance. Protected against polarity reversal and insensitive to the environment, it offers a reliable, compact and fast detection technique. A hall effect sensor can be bipolar, unipolar or omnipolar and the output on an amplifier is linear. Generally, it consists of plastic housing and three to eight pins.
Main Technical Characteristics
- Polarity : unipolar or bipolar (sensitivity to North or South pole or both),
- Magnetic sensitivity (in Gs or T) : at 5V – min : 0,75 mV/gauss – max 1,72 mV/gauss. Gauss is the sensitivity range for linear output sensors and T is the switching point for on/off sensors,
- Output type : linear or on/off,
- Output resistance : 50 ohms,
- Supply voltage (in V): 4.5 to 6 V, a wide range that facilitates its use,
- Supply current : 9 mA,
- Magnetic flux density: unlimited,
- Operating temperature: -20°C to +85°C.
Industrial Applications of a Hall Effect Sensor
The hall effect sensor is intended for various applications. It allows one to determine the motor control, the battery management or the rotation direction of an element. It is thus very present in various sectors such as the automotive and aeronautics industries and precision mechanics.
Different Types of Hall Effect Sensors and their Applications
Digital Hall effect sensors
In addition to the great flexibility they offer and their use for precise detection requirements, digital Hall effect sensors can also be programmed to activate at a given magnetic field tolerance. For high-speed sensing applications, they are very popular in white goods such as dryers and washing machines.
In automotive safety applications, digital Hall sensors are also particularly useful. They are reliable in transmission tooth speed detection and seat belt buckle tightening detection.
Analog sensors
While analog Hall-effect sensors were previously used to measure the flux density of magnets while being strongly influenced by the temperature value of the application, they have now improved significantly and can measure the angle of the flux field, making them less sensitive to temperature variations. This improvement allows the sensors to provide a more stable output.
Rotating Hall Effect Sensors
The use of rotary Hall effect sensors as an alternative to resistive potentiometer or film devices has become very popular. They can be used for dial position sensing in appliance and household applications. They are also used in automotive applications to detect the position of the EGR valve on engines, for example.
Linear Hall sensors
Linear Hall sensors can be used to detect the gear change of automotive transmissions in a more complex design. They can also be used to detect the location of the moving float as liquid level sensors.
To enable their use in industry, it is essential that the sensors are inspected, assembled and tested.
Assembly, Inspection and Testing of the Sensors
In order to assemble the electronic sensors, it is necessary to use a versatile automatic line from which different configurations of the sensors are possible, depending on the customer’s needs.
When the sensors are intended for an industrial application, they are usually delivered in strips of hundreds or tens of components. It is then essential to prepare them before their assembly by laser welding on electronic circuits. This preparation consists in cutting and shaping them with a cutting and bending machine. This is a machine specially designed to allow the sensors to be cut to the required dimensions.
Two types of cutting and bending machines can be seen on the market: manual and automatic. The first one is generally present in institutes or schools for tests or training. The second type of machine is used to meet a large quantity demand and to obtain high quality bending.
When the sensors are to be used as speed sensors, they are tested in the laboratory. A dedicated test bench is then required to characterize the sensors at speeds ranging from 100 to 10,000 Rpm.
In the automotive industry, hall effect sensors used to detect the position of a vehicle’s gearshift are electrically controlled and programmed from a dedicated test bench.
