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detect switch state in a garage door opener
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detect switch state in a garage door opener

by markb on Mon Aug 31, 2009 11:05 pm

I'm trying to design a circuit to detect the limiter switch states in my two garage door openers. One uses 8 VDC on the switches, and the other uses 4.5 VAC. I'd like to use these switches to signal the digital inputs on an Xbee. I'm interested in any opinions on the best way to do that? I know just enough about circuits to be dangerous.

One option would be to feed the DC voltage directly into the Xbee's input, and use a bridge rectifier and smoothing capacitor to convert the AC voltage to DC. I could put voltage regulators in, but I'm not sure that would be necessary. My concerns with this option is that the circuits are not isolated, and I'd be assuming everything shares the same ground. I can certainly verify that assumption, but intuitively, it doesn't seem like particularly robust design.

I could potentially isolate the circuits with relays, but I don't know how much current I can rely upon from the switches.

Any guidance?

Thanks!

markb
 
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Joined: Mon Aug 31, 2009 10:50 pm

Re: detect switch state in a garage door opener

by eil on Tue Sep 01, 2009 9:18 pm

It sounds like an optoisolator would be perfect for this, but I'm afraid I can't offer much more detail than that since I've never really used one before (apart from soldering one into the x0xb0x).
eil
 
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Joined: Sun Aug 31, 2008 11:09 pm

Please be positive and constructive with your questions and comments.