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Simple relay hack - but noise from long cable run

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

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  1. c64

    c64

    5
    0
    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. Harald Kapp

    Harald Kapp Moderator Moderator

    12,330
    2,930
    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. Kabelsalat

    Kabelsalat

    175
    31
    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. 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. c64

    c64

    5
    0
    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. Kabelsalat

    Kabelsalat

    175
    31
    Jul 5, 2011
    Ah, thanks - I missed out on that :oops:
     
  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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