Frequently Asked Questions Magnet Sensor FAQs

How do I select a magnet to use with my FX51 Magnet Sensor?

Tips and Tricks:

1. Magnetic field is not linear

Its works more like a flashlight against a wall. The closer you get, the brighter, but at a faster rate than the distance [inverse square relationship]. What this means is that as a magnet gets closer to the sensor, the magnet field gets much larger than the distance. Here is a quick table of our 1/2″ cylindrical magnet.

Distance between sensor and magnet (closest surface)Magnet Field
1.25″68 Gauss
1.00″93 Gauss
0.75″231 Gauss
0.50″549 Gauss
0.25″1751 Gauss

We have this all outlined in a Google Doc for you. Or if you want to experiment more, K and J have a nice calculator.

2. Don’t get them too close or too far away from the sensor

Based on the above information, we can see that the sensing distance is important. Think of the magnet as the signal to the board. You don’t want a weak signal (like under 50 Gauss) and you don’t want to overpower it (1000 Gauss is the sensor limit).

3. Use the appropriate magnet size

This brings us to the last bit. If you are not happy with the range a particular magnet gets you, use a different magnet! A smaller magnet of the same type (there are different types, so please consider what kind you are using) will be weaker up close. If you need more range, get a larger magnet and move it away further.

The newest versions of the FX51D have a built in feedback mechanism to show you when you are too weak or over powering it.