power 12v dc motor with 5v dc source

Discussion in 'General Electronics Chat' started by Mohamed Bouakoura, Sep 1, 2015.

  1. Mohamed Bouakoura

    Thread Starter New Member

    Aug 26, 2015
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    hello everyone, .. i have a fan (12v , 0.16A) and i would like to power it using the USB port , which provides almost 5v
    so any ideas how i can make it.

    I tried to connect the USB source to a battery (9v) and the battery to another USB , it means two USB sources with the battery in between, (they are connected in series ) but this doesn't give nothing !

    thanks a lot for your answers in advance.
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    You likely killed one or both of the USB ports!
     
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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  4. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    eh?o_O

    Just buy a 5V fan.
    Otherwise, with that kind of logic, this will be very hard work.
     
    PeterCoxSmith likes this.
  5. dl324

    Distinguished Member

    Mar 30, 2015
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    This is a bad idea. You don't mention which USB protocol you're using, so this is worst case... USB 1.0 specs state that a device can draw 100mA from the port without negotiating for more, up to 500mA. Unintelligent devices that can't negotiate with the host are called client decorations and are limited to 100mA. You can't get 12V @ 160mA from 5V @ 100mA.
     
  6. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    I forgot USB 1.0 is only 100mA... been so long since I've seen USB1 ports.. But who knows what the OP has
     
  7. dl324

    Distinguished Member

    Mar 30, 2015
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    It's 100mA for USB2 and 150mA for USB3. The max current for USB2 is also 500mA, but went up to 900mA in USB3. However, clients need to be able to negotiate with the host for current greater than 1 "load". Voltage tolerance also changed with each USB version...
     
  8. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Yeah I though thats the "per unit/load" (or non-negotiating unit) current rating.. With negotiation (if you ask the host permission) you can pull more.. seen 1.5A up to 5A
     
  9. Dr.killjoy

    Well-Known Member

    Apr 28, 2013
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    Is that good to push that much current threw the USB and is it safe or can be used a long time ??
     
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