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How to run 3 PC fans without a pc power supply? for new grow box.

Discussion in 'Grow Room Design & Setup' started by mr.notsogreenthumb, Nov 17, 2010.


    mr.notsogreenthumb Active Member

    So I am building a new PC grow box and I want to add 3 pc fans to the mix. Now I’m not the worlds greatest electrician but even I know that powering those three pc fans cant be done directly from the wall sockot.
    The question is, “What sort of adapters and things will I need to make them work?” and no I am not willing to run an actual pc power supply just for three little 12v fans.

    NewClosetGrower Well-Known Member

    find an old cell phone charger, or something along those lines thats closest to the voltage rated for your fans without going over and wire em up
    mr.notsogreenthumb likes this.

    Jefferstone Well-Known Member

    Close...you already know the voltage is 12. You need to take a look at the fan(s) and find either the watts or amps. You need to find a 12v adapter that matches those total amps as closely as possible. For instance, I have three PC fans that draw .160 amps each. If I wire them together I get .480 amps total, so I hook them up to a .5 amp 12v adapter and I'm good to go.

    Saerimmner Well-Known Member

    yup what he said, there are a couple of articles on this very subject in most areas of this forum

    mr.notsogreenthumb Active Member

    I have got stacks of old phone chargers so that fits the bill well. But can I just cut the end off and put the fans directly on them? and do I have to get a charger for each fan or can I link them all to the same one? and if I link them all to the same one does the charger need to put out 12v or 36v in order to acomidate all three?

    brownbearclan Active Member

    Yep use a cell phone charger or 12v cordless tool charger, anything that has nothing higher than 12v. http://www.rollitup.org/general-mar...-desperate-help-computer-fan.html#post4911328

    If you're running 3 fans though a spare PC power supply would be ideal, you can get one for super cheap off newegg.com, craigslist, etc. etc. Then you just run a paper clip from the green wire to a black on the Motherboard plug to keep it turned on and just use a timer or whatev; http://www.youtube.com/watch?v=u0OKmIuNtmI

    Jefferstone Well-Known Member

    Volts is Volts....if you have something that is 12Volt then no matter how many of them you have wired together they are still 12Volt. Like I said in the earlier post, get a 12V adapter that closely matches your total amps and connect the fans together.

    mr.notsogreenthumb Active Member

    Thanks. I have some old P2 and P3 power supplies lying about that I can use but I will try the charger thing first. Nice video link by the way.

    Jefferstone Well-Known Member

    Not that you shouldn't use a PC power supply, but they are usually a couple of hundred watts. You really only need 10 or so. If you are watching your electric bill, every little bit counts.

    iforgotagain Member

    Go to your local electronics store and purchase an AC to DC adapter with variable DC output.

    Find the amperage of each fan, lets say the fans draw 300mA or .3 Amps. Since you are running three fans off the single transformer, each pulling 300mA, you would need 300mA * 3 or 900mA. In that case, I would purchase a variable AC DC transformer with at least 1000mA or 1 Amp output (Personally I would go for 3Amps to be safe, too many amps doesn't hurt).

    This configuration would allow you to change the DC output from the transformer between usually about 1.5V to 12V, which is a poor mans speed controller :)

    cannabutt Well-Known Member

    i know a lowryder grower who runs 6 pc fans the quite ones, she bust 2-3 power packs getting them working lmao.. got it sorted now though, anyway i'm going to email my friend later i will report back after with more info :leaf:

    jondamon Well-Known Member

    I always hear people shouting about cell phone chargers.

    Most Cell Phone chargers are 5v too little to run a PC fan at its optimum.

    If you have an old internet Router that has its own little power supply then these usually are 12v DC 1000mA rated supplies.

    This would be a better choice for running your PC fans. I personally use old Router power supplies or Print server power supplies. They are all rated at 12v DC usually 1000mA as already mentioned.

    Other than that you can go into any electrical store such as RadioShack if you're in the US or Maplin in the UK and purchase a 12v DC supply.

    Depending on the types of PC fans you choose they will usually have 2 or 4 wires on the block for connecting.

    2 wire fans will usually be RED WIRE BLACK WIRE red is live black is neg. You would cut the end off your Power supply so that you have 2 wires. You bare them and connect them up to the fan and turn it on. If it does not spin the fan then change the wires around.

    4 wire fans will usually have YELLOW WIRE BLACK WIRE GREEN WIRE BLUE WIRE.
    Yellow is LIVE
    Black is Neg
    COnnect these 2 wires to your supply if it doesnt spin switch them around.

    The GREEN wire is the sensor wire for the PC you do not need this wire.
    The BLUE wire is the speed control for the fan. If you connect this wire also to your LIVE wire on your supply then this will slow the fan speed down to half speed. This is good if you want to control the noise level of your fans.

    Hope this helped.

    fortheloveofgrow likes this.

    NewClosetGrower Well-Known Member

    i used an old heat/back massage roll up blanket gimic that i had laying around, and an old power wheels charger for mine...cell phone chargers are weak as hell but will work if needed

    mr.notsogreenthumb Active Member

    I have managed to salvage an old keyboard power adaptor cable with a 12v output from a pawn shop, the ampage and everything looks like it might be the one. Unfortunately I am away in business and won’t be back home till the first of December . Once back home I will post my results.

    Thanks for all the help and if you have any other thoughts please don’t hesitate to add.

    cj7420 Active Member

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