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    12V fan on USB?

    Discussion in 'Accessories' started by Apex84, Aug 21, 2010.

  1. Apex84

    Apex84 Notebook Consultant

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    Could I damage my laptop if I connected a 12V 80mm fan to the USB port? I know USB only carries 5V so the fan would spin slower, if at all but that's not the point.
     
    Apex84, Aug 21, 2010
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  2. granyte

    granyte ATI+AMD -> DAAMIT

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    i think you would need to add a resistor so that the fan do not dain more power then the usb let out
     
    granyte, Aug 22, 2010
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  3. thundernet

    thundernet Notebook Deity

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    thundernet, Aug 22, 2010
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  4. Apex84

    Apex84 Notebook Consultant

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    Thanks for the replies. I didn't have the patience to wait for replies so last night I wired an 80mm fan to a USB connector and plugged it into an old laptop that I don't use, just in case it would damage the port immediately. I want to replace the 5V fan that I have in my laptop cooler because the 12V fan seemed to move quite a bit more air when connected to the same USB port. But if it could damage the laptop in any way I won't do it.

    PS. I read that any unit connected to a USB 2.0 port can draw at most 500mA. The 12V 80mm fan I connected was 280mA. Could this lower amperage prevent damage on the USB port?
     
    Apex84, Aug 22, 2010
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  5. afya

    afya Newbie

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    i don't think 12v fan would damage the usb port.
    i think there is just not enough power for the fan to operate at full speed.

    and resistor won't help anything except drawing more power away from the already "slowered" fan(it's not drawing more power from the usb, but shares the 5v with the fan).

    ps. sry for my bad english~
     
    afya, Aug 22, 2010
    #5
  6. kent1146

    kent1146 Notebook Prophet

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    No, you won't damage the USB port. If anything, you will damage the fan. Just because something doesn't break , doesn't mean it's a good idea. Get a 5V fan instead, or build a small circuit that converts 12V to 5V.
     
    kent1146, Aug 22, 2010
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  7. lainx

    lainx Notebook Consultant

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    I was actually thinking of this myself.

    I know some fans comes with adapters (like noctua's) that's namned LNA (low noise adapter) and ULNA (ultra low noise adapter). I was wondering if these adapters basically just sets the fan to different voltage.
     
    lainx, Aug 22, 2010
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  8. jackluo923

    jackluo923 Notebook Virtuoso

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    That's what those thing do. It's essentially a resister to reduce the voltage.
     
    jackluo923, Aug 22, 2010
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  9. lainx

    lainx Notebook Consultant

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    Yeah i figured as much. Thanks for confirming it though :)
     
    lainx, Aug 22, 2010
    #9