DigitalExperience

There are a lot of different magnetic reed switches but by far the more common is the normally open version. Normally it’s on open circuit that closes when you put a magnet near it, and the led shines. The north-south axis of the magnet should be parallel to the axis of the reed and placed near the center.

One day I needed one that acted the opposite way: Normally it must be a closed circuit that opens when a magnet comes near. You can buy it right away but i didn’t want to wait.

By placing a second magnet oriented the opposite way the switch opens because it cancel out the magnetic field in the middle. So one magnet must be fixed to close the switch and when the other magnet comes near, it cancel the field and open the switch. Day saved. Zaion.