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A/C adapter for DC blower fan

Discussion in 'General Electronics Discussion' started by Scott Hanson, Aug 27, 2015.

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  1. Scott Hanson

    Scott Hanson

    7
    1
    Aug 27, 2015
    I'm trying to power the following fan:
    http://www.amazon.com/gp/product/B001O0DE8K?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

    ...off an A/C outlet. I've read numerous projects where guys have used this fan in this manner but can't find how/what power supply they used. I tried this one first (after cutting to the wires)
    http://www.amazon.com/gp/product/B003TUMDWG?psc=1&redirect=true&ref_=oh_aui_detailpage_o02_s00

    The fan runs for a second, then stops for a second, runs for a second, stops for a second. And so on and so on.

    Am just not sure what I'm missing or what I'm doing wrong. The adapter seems to have enough power but I don't know why it keeps stopping?

    Any help greatly appreciated, thanks--
     
  2. Minder

    Minder

    3,092
    661
    Apr 24, 2015
    I suspect it may be inrush shutting the SMPS supply down?
    I would obtain a linear supply for it, confirm it by testing on an automotive battery.
    M.
     
  3. Scott Hanson

    Scott Hanson

    7
    1
    Aug 27, 2015
    Last edited: Aug 28, 2015
  4. Minder

    Minder

    3,092
    661
    Apr 24, 2015
    A linear supply is unregulated the one you show is SMPS, Switch mode.
    Linear is usually a simple transformer, bridge and capacitor.
    Better suited to motor function.
    M.
     
  5. Scott Hanson

    Scott Hanson

    7
    1
    Aug 27, 2015
    Thanks for the help! After searching around on eBay, I'm still pretty unsure what I should try to buy. Searching for "Linear Adapter" and "Unregulated Adapter" is bringing up mostly international results on eBay - and on Amazon I'm getting things with digital readouts ... am I using the wrong search terms to find this?

    Thanks--
     
  6. Minder

    Minder

    3,092
    661
    Apr 24, 2015
    AC adaptors that are old style linear are hard to find now, just pick up a small 120v/12v secondary transformer and a rectifier bridge and you are away.
    M.
     
  7. Scott Hanson

    Scott Hanson

    7
    1
    Aug 27, 2015
    Hmm. Have to come clean that I don't really understand any of that...
     
  8. HellasTechn

    HellasTechn

    1,556
    215
    Apr 14, 2013
    As a power source you should get a 120 to 13 volt step down transformer rated at least 4 amps and then use a bridge rectifier (same amps rating) and at least one 3300mf 16volt smoothing capacitor (or even better two of them in paralel).

    Though the PSU on the link you provided should be enough to run this fan. I dont know maybe it is damaged ?

    I dont think this is an inrush current situation. theese are desinged for high loads.
     
    Last edited: Aug 28, 2015
  9. Minder

    Minder

    3,092
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    Apr 24, 2015
    This what the old style wall warts looked like.
    Basically for a motor load you can do without C1
    D1-D4 comes in a block of 4.
    M.
    [​IMG]
     
  10. Minder

    Minder

    3,092
    661
    Apr 24, 2015
    He says it works OK on a battery, 13vac will result in 18v smoothed.
    M.
     
  11. HellasTechn

    HellasTechn

    1,556
    215
    Apr 14, 2013
    Not that much besides under load it will drop to 13 again

    Keep in mind that devices that run on 12v battery can also run on 14-15 volt
     
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