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Ground loop

Discussion in 'General Electronics Discussion' started by turbogt16v, Sep 19, 2017.

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  1. turbogt16v

    turbogt16v

    173
    4
    Mar 27, 2015
    Hy
    I have put out some Bluetooth speakers with active amplifier. I get noise from ground loop.
    How can i remove it.

    The power goes from ac 220v to 12v 1a converter to amp, and from that same converter to step down converter 5v,that is used to power Bluetooth doongle.

    I have read that isolated power module from 2 converter 5v to doongle would solve my problems, is that true, and is therr some other solution.
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    10,025
    2,138
    Nov 17, 2011
    Is this definite?

    The noise can also come from a noisy power supply as you are using a switch mode regulator. Try to power the blue-tooth dongle and the amplifier from a separate, preferably isolated, power supply, e.g. a USB power bank and a good benchtop power supply.
    • If the source of noise is from a ground loop, it should vanish when using this setup.
    • If the noise persists, it comes from teh step-down regulator or the 220 V to 12 V converter. You can try to minimize the noise by adding addditional filter capacitors to teh power supplies.
     
  3. turbogt16v

    turbogt16v

    173
    4
    Mar 27, 2015
    what would be the value of the filter capacitors
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

    10,025
    2,138
    Nov 17, 2011
    A ballpark figure is 1000 µF per 1 A of current.
     
  5. turbogt16v

    turbogt16v

    173
    4
    Mar 27, 2015
    ok .ty i tried to put cap after 12v regulator and it did give some less noise.do i need to put one before the regulator,
    on 220v current
     
  6. Harald Kapp

    Harald Kapp Moderator Moderator

    10,025
    2,138
    Nov 17, 2011
    Definitely not. The noise is produced within the switching regulator. This is a normal effect of a switching regulator's operation and needs to be filtered well.
    A better filter uses an LC combination. You can get them at low cost for filtering car audio power supplies.Ask your favorite search engine, use search terms like "car audio power filter".
     
  7. turbogt16v

    turbogt16v

    173
    4
    Mar 27, 2015
    i putted mobile charger 5v to charge bluetooth ,and it is good now no noise,ty
     
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