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Chokes on DC power supplies?

Discussion in 'General Electronics Discussion' started by macsrwe, Sep 30, 2017.

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  1. macsrwe


    Mar 5, 2010
    I use a lot of 24VDC power. Often I have to ship it over a bit of a distance, and sometimes when I get to the other end, I have to split it. (Think security cams or WiFi interfaces.)

    At first glance, it seems simple to split it at the destination using a distribution or terminal block and pigtails with the necessary device plugs. However, I have noticed that unlike the 24VDC wall-wart transformers, which have a simple cable output, the larger amperage 24VDC power bricks all have a choke near the plug end of the 24VDC output.

    These pigtails have no chokes. Frankly, I'd rather not have to deal with the chokes, because they get in the way. But I'd like to understand why those chokes are universally there on these brick transformers, and what problems I might be opening myself up to if I just split my power at the destination end with a terminal block, pigtails, and no chokes. Or is the existing choke at the end of the head-end transformer all that is needed to ensure smooth power from there on out?
  2. davenn

    davenn Moderator

    Sep 5, 2009
    Hi there

    this makes no sense at all ???

    The choke's primary purpose is for filtering of the high frequency signal of the switching circuitry. No chokes would allow lots of noise through to the gear being powered
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    You would be best off sending a higher voltage to the remote location and regulating it there.

    How do you ship power? I'm imagining you turning up at a post office with a padded bag full of electrons.
    Arouse1973 likes this.
  4. macsrwe


    Mar 5, 2010
    In other words, I have a long, heavy gauge cable running some distance, then several units to power at the end of the run, so each will be powered by a pigtail connected in parallel to the end of the cable.

    OK. So if the chokes are to squelch artefacts of the power brick, then the existing choke at the end of the brick's own output cord should handle that issue, and I won't need chokes on each of the leads on the far end for any reason.
  5. macsrwe


    Mar 5, 2010
    The destination point is a lot of nothing out in the middle of nowhere. Desert, with a mast on it. Reducing the complexity of the equipment at that location (to zero, if possible) is a prime goal.

    Maybe I'm just too old. I and my colleagues commonly used the expression "shipping power (or data) over a cable" since the early '70s. But I do receive a monthly package of live fly eggs at the PO every month, so out here maybe that's not so far-fetched. :)
  6. AnalogKid


    Jun 10, 2015
    Still not enough words.
    How long?
    How heavy?
    How many units?
    What power?

    Distance, wire gauge, total current.

  7. macsrwe


    Mar 5, 2010
    Thanks, but I have all that part handled.
  8. Alec_t


    Jul 7, 2015
    A long cable will act as an antenna to pick up interference, so putting the filter at the destination will help to suppress that. You may well need a filter at both ends of the cable.
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