GENIE Garage door sensors used elsewhere

Discussion in 'General Electronics Chat' started by circuitbob, Sep 26, 2011.

  1. circuitbob

    Thread Starter New Member

    Aug 29, 2011
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    I have a set of Genie STB garage door safety sensors. I would like to use them to sense a tractor going by. They are 12vdc units. what I can't figure out is how they work. Looking at the wiring diagram shows transmitter and receiver connected to 12 volts. I have the same units on my garage door and they both have 12 volts on them at all times. Does anyone know how to make these work in my application?
     
  2. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    They will both have 12 volts going to them since that is how they are powered, but one of them will have more wires/connectors than the other one..... any pictures or diagrams you can post of the devices?? Most of the time, these types of sensors just have either a Normally Open connector to connect to other devices that can use those types of sensors or a normally closed contacts, so maybe a little more info on the devices will help....
     
  3. circuitbob

    Thread Starter New Member

    Aug 29, 2011
    15
    0
    they both only have 2 terminals and are parallel connected.
     
  4. colinb

    Active Member

    Jun 15, 2011
    351
    35
    Do you know which is the emitter (transmitter) and which is the detector (receiver)? If not, once easy way to check is to use a digital camera or cell phone camera to look at the optical port on them when they are connected to power -- if it's a simple always-on transmitter, you'll see the infrared light appear as a bright white spot on the digicam. If you can't figure it out at this point, no problem.

    Now measure the current through the detector unit (or try each in turn if you haven't identified the receiver). Measure the receiver current when the beam is blocked and when it is not blocked. Use a multimeter in ammeter mode, in series with one of the 12 V dc supply wires to the detector. It may be that the receiver has a phototransistor that alters the current draw of the detector from the 12 V dc input when the beam is obstructed versus when it is unobstructed.
     
  5. colinb

    Active Member

    Jun 15, 2011
    351
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    When you say they are parallel connected, do you mean that each terminal on both the transmitter and receiver are connected? So there are only two wires going out from the garage door opener? That's interesting, but my suggestion about current consumption varying based on whether the beam is obstructed would still be viable: the transmitter would use a constant current, but the receiver's current would vary based on obstruction status.
     
  6. Meixner

    Member

    Sep 26, 2011
    116
    21
    Those newer remotes have only + 12 V. and ground terminals on both the emitter and receiver. Thats to make it easier for untrained people to install. The way they work is the receiver adds a very narrow pulse train to the 12 V. line when it is detecting the emitter. The circuitry inside the door opener detects this signal.
     
    Last edited: Sep 26, 2011
    Tonyr1084 likes this.
  7. VoodooMojo

    Active Member

    Nov 28, 2009
    503
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    by tractor, are you referring to a semi tractor entering through a door or gate or an agricultural tractor reaching a fixed point?

    Is this close to the diagram for your opener?

    [​IMG]
     
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