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  1. #1
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    Stop voltage on a sensor??

    Ive attached a normal PIR motion sensor to a URC contact sensor. One would think when motion sensed, the contact closure on the motion sensors opens, the URC sensor detects this, thus executing the macro. Not so.

    If i unplug the URC sensor, my meter clearly shows me the motion sensor is working: no motion = closed circuit. motion = open circuit. Perfect. Just as it should. If i plug URC sensor in, the state is ALWAYS open.

    Turns out the URC contact sensor outputs 5.6v ! This apparently is mucking up the contact sensor in the motion sensor. Think I on the right track here lol.

    So, what I need to do is add some resistors or something to the URC sensor to stop the 5+volts from going back to the motion sensor. I have no idea what that formula is or what parts are needed.

    FYI for those that may not know, URC has a contact sensor sensor. It plugs into their control system to monitor the state of open/closed. This URC sensor has an LED on it, green for open, red for closed. Its putting 5.6volts back on the line that goes to the motion sensor. Im guessing this is why the motion sensor is not responding correctly and always showing open and never closed.

    Any help much appreciated! Im guessing a simple solution of some resistors in series or something. Hope so!

  2. #2
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    Re: Stop voltage on a sensor??

    I have no idea how their sensor inputs are used but, if you are trying to prevent voltage from being fed from the URC device to the PIR sensor, then you would want to use a diode to prevent the flow of voltage.
    ---Steve---

  3. #3
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    Re: Stop voltage on a sensor??

    If you put the diode in 'reverse state' then yes, that stops the current. Then HOW is the URC going to work? That is why the voltage is there, to sense a change from open to close. That is how contact closures work. No voltage = no current = no work.

    The problem is most likely the PIR you have chosen (Make & model please). Buzz was 1st with the response on RC, and probably will turn out to be the right one.
    Brad
    "I'm not arguing, I'm explaining why I'm right"

  4. #4
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    Stop voltage on a sensor??

    Quote Originally Posted by Ghost View Post
    If you put the diode in 'reverse state' then yes, that stops the current. Then HOW is the URC going to work? That is why the voltage is there, to sense a change from open to close. That is how contact closures work. No voltage = no current = no work.
    Yeah, I didn’t quite think that part trough 🤣
    ---Steve---

 

 

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