Gate Position Sensor R&D

My back gate is an electric swing arm gate. Great for getting in and out of the back driveway without getting out of the car, but occasionally the gate doesn’t close. Most of the time it is my own fault, but it happens.

When I first started playing with Arduino microcontrollers one of the first projects to occur to me was to be able to detect if the gate were open, sound an audible alarm for a while, if nothing is done try to close the gate (a signal can be sent to the controller), and if the gate still doesn’t close, send notification to my alarm monitoring service so they can call me.

I finally went out to the gate this spring to do some R&D. My plan was to read the status of the mag lock. According to the docs, if the lock is correctly engaged, it will close a circuit. Well, I wasted a few hours trying to get the mag lock to act like it should and finally gave up in frustration and put this project on the back burner.

This summer it suddenly popped into my head ‘Why use the mag lock – I can put a simple reed switch near the hinge and sense if the gate is open that way.

Tonight I built a little bracket and used a hose clamp to position it. I then mounted the reed switch/magnet and got a simple sensor running just fine.


I rotated the magnet on the bracket so that it is just within range of the reed switch. Once the gate opens just a little, the reed sensor disengages.

I’m not quite ready to begin implementation, but R&D was finally a success!

This entry was posted in c-arduino, Gate Sensor. Bookmark the permalink.

3 Responses to Gate Position Sensor R&D

  1. Arduino says:

    Nifty. One problem with reed switches is that they can magnetize and eventually ‘stick’ and remain closed. If that happens to you you may consider a roll switch or a Hall detector

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