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Michael P C
Michael P C • Feb 5, 2016

How to Detect Steel Door Presence with U-Shaped Electromagnet

Hi guys,

I'm using an electromagnet to detect the presence of a steel door through analog pins on an Arduino. This works great if the magnet itself isn't under power, but once I'm running 12 volts through it, the sensitivity of the readings get so small that it's hard to read. I'm using a resistor based voltage divider to bring that signal back in. Is there another way to get a more sensitive reading under power? Perhaps a module that might sit between the EM and Arduino to amplify resolution?
Michael P C
This works great if the magnet itself isn't under power, but once I'm running 12 volts through it
If it works if the magnet is without power why use 12 V? May be one can try a mechanical solution. A permanent magnet at the end of a levered micro-switch can operate the lever when near a steel door. This can be sensed. Probably a Hall effect sensor may also work if the magnet is on the door. We are using this for checking if the door on a steam sterilizer is properly closed.

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