Garage Door Sensor


Active Member
I acquired my house with installed Liftmaster garage door openers, but some time ago I disconnected them. The prior owner had managed to get it working without the IR beam security sensor.

I would like to add an IR, but, must I install and original one? I already have a spare IR beam relay that would be perfect for the situation but I dont know if the this would be electrically comptible. Do the regular IR beams work as simple open/closed circuit or have a different method (resistance, electrical pulse, ryv.).

I have checked a few GDO sites, but they do not provde much delails.
Mine has a sender and receiver. The sender is probably just the required voltage to send the beam.

The receiver is definitely more complicated... There is only a single pair to it. Obviously this supplies power to receiver, but I don't know how the "beam has been tripped" signal goes back. It might pull down the supply voltage or send a some form of pulse back.

I believe they work on resistance similar to the way the multi function door opener switches operate.