Door sensors detect door position (i.e., open or closed) based on the precise gap between the magnet and the reed switch.

When you’re driving your car, you’re probably regularly looking at the speedometer to make sure you comply with the local speed limits. The method by which it works is simple enough: ...

If you need to measure a distance, it is tempting to reach for the ubiquitous ultrasonic module like an HC-SR04. These work well, and they are reasonably easy to use. However, they aren’t without ...