The Hall Effect Sensor is a transducer that detects the presence of a magnetic field and converts it into an electrical signal. It works on the principle of the Hall Effect, discovered by Edwin Hall in 1879. When a conductor or semiconductor carrying current is placed perpendicular to a magnetic field, a small voltage (Hall voltage) is generated across the material, which can be measured and used for sensing. Working Principle A thin piece of semiconductor is supplied with current. When exposed to a magnetic field, the moving charge carriers (electrons or holes) experience a force (Lorentz force) that pushes them to one side. This creates a voltage difference across the sensor known as the Hall voltage. The magnitude of this voltage is proportional to the strength of the magnetic field. Construction Semiconductor material (e.g., gallium arsenide, indium antimonide, silicon). Current source to bias the sensor. Hall element where the voltage is produced. Signal conditioning circuit (amplifier, comparator, regulator) to process the weak Hall voltage. Types of Hall Effect Sensors Analog Hall Sensors – Output is a continuous voltage proportional to the magnetic field. Digital Hall Sensors – Output is ON/OFF (high/low) depending on whether the magnetic field exceeds a threshold. Applications Position sensing – Detects linear or rotary movement. Speed detection – In tachometers, fans, and wheel speed sensors in ABS. Proximity sensing – Door sensors, brushless DC motors, smartphones. Current measurement – Hall-effect current sensors measure AC and DC currents without direct contact. Magnetic field sensing – Compasses and scientific instruments. Advantages Contactless operation → reduces wear and tear. Can detect both static and dynamic magnetic fields. Reliable and durable in harsh environments. Wide range of applications (automotive, industrial, consumer electronics).