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Modding Which Fans from USB?

Discussion in 'Modding' started by antiHero, 26 Jun 2007.

  1. antiHero

    antiHero ReliXmas time!

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    I am looking into building a Laptop cooler and I want to run 2 fans from USB. I know that USB can give out 5V and 500mA. All fans I have at home need more amps, so I would like to know if somebody knows of fans who run with about 200mA each.
    Thanks
     
  2. doryakov

    doryakov What's a Dremel?

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    you can use resistor .
    the formula is V=R*I . V=5 I=0.5 . V=voltage R=resistor I=current .
    5=0.5R . R=10 ohm . buy
    very simple electronic . you dont need to spend your money on new fans .
    just take a look of electronic guides before .
     
  3. AJB2K3

    AJB2K3 What's a Dremel?

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    Hang on don't fans need 12 V?
     
  4. Nexxo

    Nexxo * Prefab Sprout – The King of Rock 'n' Roll

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    They can work at lower voltages, which is how you can make fans run more quietly. But 5V is a bit low for undervolting fans and they risk of stalling.
     
  5. antiHero

    antiHero ReliXmas time!

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    Thanks for the reply`s guys.

    I know that 5V is a bit low as most fanbus use 7V as low setting. Thing i was wondering is which kind of fans Zalman & co use in there cooler which run of USB. Or do they use a transformer to get the higher voltage?
     
  6. Fozzy

    Fozzy What's a Dremel?

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    THEY JUST USE REALLY SMALL FANS oops if you manually spin them they won't stall lol
     
  7. dragon2309

    dragon2309 techie

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    They use 5v fans, and yes they are typically smaller... I remember seeing a mod on a site, i think it was an undervolting guide, but he made up a circuit that rev'd the fans up a bit every so often to avoid stalling, this uncluded upon startup aswell (when they are most likely not to start up)

    Cant find the link now
     
  8. Butcher9_9

    Butcher9_9 What's a Dremel?

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    i have made one of these to cool my external hdds
    [​IMG]
    most 25mm wide fans will runs at 5v but a fan at around 300mA works best

    i have found it hard to find fans that need more than 500mA (what fans are you looking at) thermaltake 80mm fans only use 480mA at 4800rpm which is really fast

    i have found that most 80mm fans use between 140-300mA
     
  9. saltynay

    saltynay What's a Dremel?

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    get some 120mm delta focus flow fans underneath lol then you will be able to easily hear whether they have started up or not...
     
  10. Tulatin

    Tulatin The Froggy Poster

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    Depends on the fan. I know that sunon, evercool, and adda's mid-speed offerings will usually spin up at 5v.
     
  11. antiHero

    antiHero ReliXmas time!

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    I thought about Cooltek fans as i get them cheap in a shop around the corner. And it seems like there fans use only 100mA, just dont know if the work good with 5V
     
  12. RickDawson

    RickDawson Minimodder

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    just try them if they are cheap:duh:
    You will never know unless you try.
     
  13. Warrior_Rocker

    Warrior_Rocker Holder of the sacred iron

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    A 12v fan should normally run on a voltage as low at 5v with a low speed and virtually no noise. Just be aware of how much air it is actually pushing at such a low setting.

    You can find tons of small 5v ones that are around 40mm, get 2 or 3 of those at various locations and that should be all the airflow you need.
     
  14. cpemma

    cpemma Ecky thump

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    The silence freaks at SPCR often run their fans on 5V but as said, not all fans will start reliably. Nexus Silent won't, I think they're already under-volted.

    The other point is, a 200mA @ 12V fan will draw under half that current at 5V once running, but there is a starting surge.
     
  15. antiHero

    antiHero ReliXmas time!

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    How much damage can I do to my laptops USB ports if the fans need more power then they can handle? Burn them out or would the fans just not work?
     
  16. saltynay

    saltynay What's a Dremel?

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    it should come up with a warning saying this usb port has overloaded due to a power surge etc.....
     
  17. Shadowed_fury

    Shadowed_fury Minimodder

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    Interesting, i've got 3 Papst (L1As?) running at 5v in mine, have been for well over a year, with no problems!
     

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