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CPU Fan to Wall

Discussion in 'Beginner Electronics' started by Kbalz, Aug 19, 2008.

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  1. Kbalz

    Kbalz Guest

    Hello, I am very interested in powering 3 computer case fans by my
    home wall plug. I'm very electrically challenged, but have a few
    buddies who have tools I can use.

    Here is an example fan

    The fan seems to have a simple power IN and a ground attached. I would
    like to be able to switch the amount of volts that go to the fan. It
    runs at 12 Volts, but I would like to switch between 9, 10, and 12
    volts (to change fan speeds essentially). I've been reading a Wall
    Wort can do something like this, but I haven't come accross a full
    explaination of how to get everything working together.

    Also, say I wanted to have of these fans running through this switch/
    wall wort.. do I need 12 * 3 Volts, or can they be daisey chained..?
  2. PCPaul

    PCPaul Guest

    You'll probably find that won't change the speed all that much. Many
    people running fans slower to make them quieter run 12V fans at 5V.
    You can get wall warts which have adjustable output voltages - usually
    there's a small slide switch on them somewhere to select what it runs at.
    You need to connect them in parallel - i.e. all the ground wires
    connected together and all the +V wires connected together. That way they
    all get the same input voltage *but* the overall current taken from the
    wall wart will be three times what one fan is rated at, so make sure it's
    big enough.

    Also, with your level of (almost no) electronics experience, wiring up
    the fans with 12V or so won't be a safety issue, but please don't try
    doing anything with mains until you know a lot more about it!...
  3. Kbalz

    Kbalz Guest

    Thanks for your response, can you explain this a bit more? If one fan
    needs 12 volts, and 400 mA and 4.8 W, and I would like to run three of
    them at max speed.. I would need to solder all three ground wires
    together and all three +V together and into the wort.. so does the
    wort have to be 12 volts * 3, or 400mA * 3, or 4.8 W * 3, or all?
    Which part of the wort must be 'big enough'? Thanks.
  4. Jasen Betts

    Jasen Betts Guest

    12V 400mA*3 4.8W*3

    1.2A (or more)
    14.6W (or more)
  5. You've already got a power supply in there providing a range of DC
    voltages, why not use it?

    Nicholas Sherlock
  6. Kbalz

    Kbalz Guest

    I'm building a sort of laptop station that will be mounted with fans,
    blowing at the laptop.

    Sorry for the incorrect spelling.
  7. Kbalz

    Kbalz Guest

    Thanks for the numbers. I've found a wort that is big enough. Now what
    do I do to id to hook the three fans to the wort..? I was thinking cut
    the end off of the wort, and solder the Red cord of the fans to the
    wort.. but what about the grounds..?
  8. Jasen Betts

    Jasen Betts Guest

    do the the same but to the other terminal.

    all the red wires from the fans go together and connect to the
    positive output wire of tht 12V supply

    all the black wires from the fans go together and connect to the
    negative output wire of the supply.

    if you get the wires backwards it won't work and may damage the fans.

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