I'm hoping that someone can appreciate what I'm trying to accomplish.
My son and I have been discussing safety and one of the things we
discussed was the safety sensors on the garage door that cause it to
reverse when something is in its path. He wants me to use a spare set
of sensors I purchased to help him build a science fair project to
demonstrate this in class using a simple electrical circuit with a
light connected say via a relay so that each time the beam is broken
the light goes on or off and a buzzer will sound.

Here's the problem, I'm pretty good with electricity and wiring but I
don't get the wiring for the sensors. There are only 2 screws on the
transmitter and 2 screws on the receiver with nothing identifying a
voltage or polarity. I also don't see how a connection is being broken
or made when I was expecting to see a contact closure.

For the sake of keeping dad hero image thing going, help.

Many thanks

JE

depending on the sensor in question for a photovoltaic cell the power
is dc and polarity does not matter.

One is simply a focused light and the other is a resistor.
When light falls on the reciever it goes either high or low resistance
and the control circuit detects that.

You should be able to see whats happening with a voltmeter.

I have them functioning but still not able to detect when the beam is
broken. I have tried the volt/ohm meter but still not seeing a change.

On 22 Dec 2005 16:41:42 -0800, wrote:

I'm hoping that someone can appreciate what I'm trying to accomplish.
My son and I have been discussing safety and one of the things we
discussed was the safety sensors on the garage door that cause it to
reverse when something is in its path. He wants me to use a spare set
of sensors I purchased to help him build a science fair project to
demonstrate this in class using a simple electrical circuit with a
light connected say via a relay so that each time the beam is broken
the light goes on or off and a buzzer will sound.

Here's the problem, I'm pretty good with electricity and wiring but I
don't get the wiring for the sensors. There are only 2 screws on the
transmitter and 2 screws on the receiver with nothing identifying a
voltage or polarity. I also don't see how a connection is being broken
or made when I was expecting to see a contact closure.

For the sake of keeping dad hero image thing going, help.

Many thanks

JE


JE. To make this simple Imagin the space between the 2 sensors as
being invisable wires. When you break the wire the ccurrent stops.
This is sort of the principle on the sensors ability to detect motion
or blockage.
Answer to 2nd question is there is on the lift master sensors a white
w/black stripe and a solid white if you can't find that look for
printing on each wire and connect those together black stripe to black
stripe and white to white. That makes the circut complete to make the
sensors work properelly. Hope I helped
anthony --anthonys door systems




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