garagedoor openers

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jcole

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Lawrenceburg, Kentucky
Hey guys and gals.

Just wondering how the saftey sensors work for a garage door opener. I just assumed it was a RF signal because the wiring just provides power for the reciever and transmitter. Right??

Had a friend whose dog chewed the wires off the transmitter to point of no splicing. So I told him to get another set of sensors and I would help him set then up. He bought genie brand and his lift is liftmaster. I told him I didnt think it was compatiable. Not sure though.

Thats what got me wondering how they work. If it was RF wouldnt it affect another lift close by? As far as I know you dont program them like you do the remotes. I am sure the wires are just for power and not the fault signal. So how does the unit recieve the signal?

He has access to another set of sensors that go to another lift that is the same brand and model number of his lift. He asked if he could take that set of sensors off and put them on his and it work? I told him I was not sure!!?

Anybody with knowledge on this subject that they would like to share? Thanks in advance.
 
I don't know much about gdo sensors. I always understood there to be an IR beam that is reflected across the door opening. If something blocks the light, the door doesn't open.
 
CHWflorida said:
I always understood there to be an IR beam that is reflected across the door opening.
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Not exactly reflected, sent and received

But the communication back to the opener is not RF it is done over the same wires that power them.
 
maybe you can get the installation instructions for the original unit and find out for sure ? then use the exact replacements ?
 
But the communication back to the opener is not RF it is done over the same wires that power them. - Iwire

That never crossed my mind Iwire. Makes alot more sense. I guess that would mean the sensors with same model # would work.

Thanks for the response.
 
iwire said:
Not exactly reflected, sent and received

But the communication back to the opener is not RF it is done over the same wires that power them.
Click to expand...

I understand, I think. I guess I was getting confused with a laser. I bet most are compatible with different brands though.
 
Yes, the two boxes are an IR transmitter/receiver pair, and yes, they use the same wires for power and signal.

In fact, they're wired in parallel, like the interior wired remote control's switch contacts and its bulb or LED.

jcole said:
Had a friend whose dog chewed the wires off the transmitter to point of no splicing.
Click to expand...
Did you look to see if the box can be opened so you can replace the wires?
 
CHWflorida said:
I bet most are compatible with different brands though.
Click to expand...

I doubt that as there are any number of ways to combine the signal and power on one set of conductors.

For that mater there is no reason to believe they even use the same voltage.
 
oh yeah, forgot to add this. tell your friend to put red pepper on the new wires. It should help with the chewing the wires problem.
 
There are 2 types of phote eyes available for Liftmaster operators, through beam, and retro-reflective. most common is the through beam, with an emitter, and a receiver, the receiver is normally open, when it looses contact with the emitter, it closes, and initiates a reversing relay within the control box to stop the motor, then open the motor. Since it is a 12 volt device, and most of them are, as long as you replace both the emitter and the receiver, you should have no problems.

For parts at a good price, try these guys, they have almost any brand you may ever need. http://www.mmtcinc.com/ ( first post I hope I am not offending offering this website, but these guys are a great resource)

good luck!
 
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