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Simple relay hack - but noise from long cable run

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Discussion in 'General Electronics Discussion' started by c64, Sep 3, 2021.

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  1. Sep 3, 2021 #1
    c64

    c64

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    Oct 11, 2018
    I am trying to remotely trigger a gate release, by wiring a relay across the gate release switch. The controlling relay is located downstairs and I have hijacked some of the existing unused house (unshielded multicore bell) cabling, so the cable run is about 15m. I think I am getting a lot of (induced?) noise from the length of the cable run and neighbouring wires, so the gate release triggers intermittently. I guess the solution is to place a 2nd relay inside the intercom, but I wondered if there was a simpler solution? Thanks!

    IMG_0496.jpg IMG_0497.jpg
     
  2. Sep 3, 2021 #2
    Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Wire it this way:
    upload_2021-9-3_13-45-24.png
    The relay coil is comparatively insensitive to noise on the lines leading to the coil.
     
    c64 likes this.
  3. Sep 3, 2021 #3
    Kabelsalat

    Kabelsalat

    175
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    Jul 5, 2011
    The circuit you've drawn doesn't look correct.
    According to that, the switch (missing reference designator) short the relay coil - so that you probably ending up burning the internal circuit.

    A relay is not sensitive to normal noise.
     
  4. Sep 3, 2021 #4
    Harald Kapp

    Harald Kapp Moderator Moderator

    12,330
    2,930
    Nov 17, 2011
    The switch/pushbutton seems to be in parallel to the relay contacts, not the coil. It isn't shown where and how the coil is connected.
     
  5. Sep 3, 2021 #5
    c64

    c64

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    Oct 11, 2018
    The relay is part of an automation system so I cannot move it. But I think you are suggesting the best solution is to use a relay closer to the pushbutton. Many thanks.
     
  6. Sep 3, 2021 #6
    Kabelsalat

    Kabelsalat

    175
    31
    Jul 5, 2011
    Ah, thanks - I missed out on that :oops:
     
  7. Sep 3, 2021 #7
    73's de Edd

    73's de Edd

    3,294
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    Aug 21, 2015
    If this is carrying running power . . .STOOPID SITUATION . . . . . and the ensuing wire resistance then would be of consideration.
    Just a thought . . . . . of the resistance of the wires consideration.
    I can see an unused :
    Black-White twisted pair
    Blue-White twisted pair
    Brown-White twisted pair

    Join the BLACK-BLUE-BROWN to the presently wired in GREEN wire connection.
    Join all of the WHITES for the presently wired in White wire connection .
     
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