Garage door safety eye control theory

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carranoelectric

Member
Location
Ct
On a typical safety eye installation on a garage door there are only 2 wires. In parallel from the 2 screws on the operator to both sensors. Does any one know how this circuit works? a loose wire or a shorted wire will prevent door operation.As well as a blocked sensor.The 2 wires also provide power to the light source. Is there an electronic board that monitors current?
 
Rick Christopherson

Rick Christopherson

Senior Member
This is only an educated guess and I have no direct experience with door openers, except that my opener is the same way.

The two wires to the sensors are providing power to the sensors for their operation. I believe the receiving sensor modulates its input resistance when it is detecting the beam. The control board in the opener sees this as a change in voltage on the output lines to the sensors.
 
6

6sunset6

Member
Location
United States
I am guessing as well. I think there may be digital code overlaid on the 24vac that the system runs on. Because you cannot just stick anything in there as a replacement.
 
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hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
I know Genies use a digital signal modulated on a VLF carrier, older GDO's were simple series optical switch's and could be jumped, but that is no longer possible for safety, if GDO's electronics does not see the correct signal it will not function.

Also I have found that strong AM broadcast radio stations in close proximity to the dwelling can render the system useless, I had a customer try three Genie GDO's and even had a factory tech come out 4 times but no one could figure it out, then the builder called me to meet with the Genie tech, I took a toner receiver (telephone) placed it next to the eye wire and out came the radio station that was less then 1200 feet from this house, went to my truck got a telephone RFI trap and put it on the terminals and the problem went away, Genie tech looked quite puzzled as they said they have never ran into this before.
 
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