A Hall Effect sensor detects magnetic fields and converts that information into an electrical signal.
When a magnetic field is applied perpendicularly to a current-carrying conductor or semiconductor, it causes the charge carriers (electrons or holes) to be pushed to one side due to the Lorentz force. This creates a voltage difference across the other side of the conductor. That voltage is called the Hall voltage.
A basic Hall sensor has:
A thin piece of semiconductor (like gallium arsenide or silicon)
A constant current passing through it
Electrodes on either side to measure Hall voltage
Usually some amplification and filtering circuitry
When a magnet is near the sensor:
The magnetic field changes the Hall voltage
The sensor outputs an analog or digital signal based on field strength and polarity
A continuously variable analog voltage proportional to the magnetic field strength.
Functionality:
The output voltage changes smoothly as the magnetic field changes, allowing for precise measurement of field strength and position.
Applications:
Ideal for applications requiring accurate and continuous measurement of magnetic field intensity, such as automotive position sensing or current measurement.
Example:
A sensor might output 2.5V when no magnet is present, 3.5V when a magnet is close with its south pole facing the sensor, and 1.5V when a magnet is close with its north pole facing the sensor.
A discrete high or low voltage signal, often 0V and 5V.
Functionality:
The output switches between high and low states based on whether the magnetic field strength exceeds a pre-set threshold.
Applications:
Suitable for applications requiring simple detection of a magnetic field, like detecting the presence of a magnet or counting rotations.
Example:
The output might be low (0V) when a magnet is far away, and switch to high (5V) when a magnet is brought close enough to trigger the sensor.
Magnetic field strength
Magnetic field direction (depending on the sensor type)
Proximity of a magnet (for switches or encoders)
Angular position or speed (like in motors or pendulums)