PIR sensor problem...

Discussion in 'General Electronics Chat' started by shezza, Sep 4, 2014.

  1. shezza

    Thread Starter Member

    Mar 19, 2014
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    So I have this sensor. I wanted the sensor to be further from the control module than the existing wires allowed for, so I added an extension. There were 3 insulated wires and a 4th one wrapped around the three wires.
    I suppose the non-insulated wire insulates the 3 wires from magnetic fields?
    So the extension has the insulating wire connected (from the PIR to the module), but doesnt wrap around the 3 wires the length of the extension.
    I didnt really think it through and just connected it all up. Come testing time, the lights switched on and then off 30 seconds later as I expected. Though then it started randomly switching the light on and off. Hanging around for a bit, I noticed it kept happening. So then I began to think about the insulating wire and where I had run the wire. It happens to run right next to the houses main electrical wires to the fuse box where I mounted the module.

    I happen to have a spare PIR sensor and module and decided to try and isolate the problem. The same thing happened with the other module and an unedited PIR sensor. So now I am completely lost! Kind of throws the whole "interference" idea out, doesnt it?
     
    Last edited: Sep 4, 2014
  2. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    the third wire wrapped around the others was a grounded "shield" not for insulating, but shielding from magnetic and electrtic fields. by running it paralell with the others, it dosn't shield.
     
    shezza likes this.
  3. shezza

    Thread Starter Member

    Mar 19, 2014
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    0
    So there was no point in me connecting it in other words? Seems like its not an insulation (or lack of rather) problem. I edited my above post.
     
  4. shezza

    Thread Starter Member

    Mar 19, 2014
    45
    0
    Well to close this thread up, I rerouted the wires away from the fuse box and it seems to have fixed the problem. Thanks for all the replies!
     
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