Many of the sensors around you are really just a magnet and a tiny chip working together. The magnet moves, the chip senses the field, and suddenly a phone, car or factory machine knows position, speed or direction — without any physical contact.
How a magnetic sensor works
A Hall sensor or magnetoresistive chip measures the magnetic field nearby. When a magnet passes, the field changes and the chip turns that change into a voltage. Electronics then convert the voltage into a position, a speed, or a simple on/off signal.
Where you meet them every day
- Car pedals and throttle — a magnet on the pedal shaft reports its angle, replacing mechanical cables.
- ABS wheel speed — a toothed ring and a sensor count wheel rotation for the brakes.
- Smartphone flip covers — a magnet in the cover wakes the screen when it opens.
- Factory cylinders — a magnet in the piston tells the controller where the cylinder is.
Why magnetic sensing wins
Because nothing touches, there is nothing to wear out. Magnetic sensors work through plastic and paint, shrug off dust, oil and moisture, and never need adjustment. They are also fast enough to track spinning parts in real time, which makes them a favorite in cars, phones and industrial machines alike.
Practical tip
For speed and angle sensing, multipole rings — thin rings with many alternating poles — give finer resolution than a single magnet. Pair one with the right sensor and you can measure fractions of a degree.
Read on: Hall sensors explained → · multipole rings →