A basic magnetic speed sensor, also known as a magnetic proximity sensor or magnetic hall sensor, is a device used to measure the speed of a moving object by detecting changes in a magnetic field. It typically consists of three main components:
Magnet: A permanent magnet or a magnetized ferromagnetic material is attached to the rotating part of the object whose speed needs to be measured. As the object moves, the magnet generates a magnetic field around it.
Hall Effect Sensor: The Hall effect sensor is a semiconductor device that responds to changes in magnetic fields. It is typically placed near the path of the rotating object, close enough to detect the magnetic field variations.
Signal Processing Circuitry: The sensor's output is a small voltage signal that needs to be processed to obtain the speed information. The signal processing circuitry amplifies and processes the signal to make it suitable for further interpretation.
The operation of a basic magnetic speed sensor is as follows:
Magnetic Field Detection: As the object with the attached magnet rotates, the magnetic field around the magnet changes with respect to the position of the Hall effect sensor. This change in magnetic field intensity is detected by the Hall effect sensor.
Hall Effect Principle: The Hall effect sensor works based on the Hall effect principle, which states that when a conductor or semiconductor carrying current is exposed to a perpendicular magnetic field, a voltage is induced across the material's width. In the case of a Hall effect sensor, the magnetic field from the rotating magnet causes a voltage to be generated across the sensor's output pins.
Signal Generation: As the object rotates faster, the rate of change in the magnetic field detected by the Hall effect sensor increases, resulting in a higher voltage output. The voltage signal generated by the Hall effect sensor is directly proportional to the speed of the rotating object.
Signal Processing: The voltage signal from the Hall effect sensor is often very small and needs to be processed and amplified to be used effectively. The signal processing circuitry, which may include amplifiers and filters, boosts the voltage signal to an appropriate level for further analysis.
Speed Calculation: Once the processed voltage signal is obtained, the speed of the rotating object can be calculated based on a known relationship between the voltage signal and the speed. The speed can then be displayed, recorded, or used for control purposes in various applications, such as in automotive speedometers, industrial machinery, or other speed-sensing systems.
Overall, a basic magnetic speed sensor provides a simple and reliable way to measure the rotational speed of an object by utilizing the Hall effect principle and detecting changes in the magnetic field caused by the rotating magnet.