Computer Fan Wiring

use a pot to control speed of the fan (via voltage limiting) and DONT PLUG THE FUCKER INTO A WALL PLUG wall plugs are AC comp fans are DC.. hit a thrift store for an appliance that runs off a dc powersource.. anything that has a big black box that plugs into the wall instead of just a normal cord.. and READ.. MAKE SURE IT SAYS DC thoes fans will take up to 14 ish volts.. if you find one that is higher you can use resisters.. (or a POTentiomiter) to reduce voltage to a usable voltage but double check it says DC not AC

Newtious said:

use a pot to control speed of the fan (via voltage limiting) and DONT PLUG THE FUCKER INTO A WALL PLUG wall plugs are AC comp fans are DC.. hit a thrift store for an appliance that runs off a dc powersource.. anything that has a big black box that plugs into the wall instead of just a normal cord.. and READ.. MAKE SURE IT SAYS DC thoes fans will take up to 14 ish volts.. if you find one that is higher you can use resisters.. (or a POTentiomiter) to reduce voltage to a usable voltage but double check it says DC not AC

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No!! Resistors are current limiting devices. A pot *can* drop voltage as can 2 resistors.
for a pot to reduce voltage wire it up like this.

------------------POS
|
|
\
/
\
/
|
|<----------------> to pos on fan (this is the divided voltage)
|
\
/
\
/
|
|
------------ GRND


Just get a pot or resistors that are rated for the power the fan is going to use.

Now if you notice, in this simple voltage divider, the resistors are not in series with the power, but strung across the rails.

would a 15v adaptor from an old laptop work to runn two 12vs safely? or would it fry it? it's definatly a DC adaptor?

You can buy a 12v adapter at Wal Mart for like $10. Just hook it up to the computer fan and you can plug it into a wall outlet. Don't use the 15v, it is too much. Spend the $10 and do it right.
I use 2 130cfm computer fans in veg, and they are both connected to the same 12v adapter.

wow, i been doing some search on a way to move air @ my friends 10x10 room grow area.

i was looking for a balance of price/performance/noice

now the idea is to run an air duct from a romm into this room and yet the same thing from this room out to an other.

i been looking at all kinds of fans, blowers, wall fans, air inline duct fans, cpu fans, ...

since i am a home depot kind of guy, they sell a inline air duct fan for 50 bucks that moves 120 cfm and is pretty loud

online hydrodealers sell fans that are similar but cost a shit load more.

and theirs 120mm computer fans that move over 100cfm are smaller, quiter for as low as 10.00 each.

so seems like a computer fans for the win.

so am i missing something, or are these lil fans the best bang for the buck. im not talking about moving air out of a box, but a whole room.

for 40 bucks i could have two fans breathing air in and two out. thats has to be at least 100 cubic feet of air per minute going ou/in .

in a 10x10x10 room thats 1000 cubic feet. thats a matter of having the fans run for what? 3 times a day for 25 mintues at a time to play it safe. ???

If its a 10'x10' room, to light it properly, you will need like 4000watts. If you are running 4000watts, you are going to need a lot more than 100cfm. More like 1,000cfm. The fans not only bring in fresh air, but also keep the temps down. With 100cfm on 3 times a day for 25 min, you are going to have dead plants in no time. If you have no idea what you are doing, don't go so big. Start with a nice small 400watt or even 250watt grow, then work your way up. You'll be happy you did.

bongrippinbob said:

If its a 10'x10' room, to light it properly, you will need like 4000watts. If you are running 4000watts, you are going to need a lot more than 100cfm. More like 1,000cfm. The fans not only bring in fresh air, but also keep the temps down. With 100cfm on 3 times a day for 25 min, you are going to have dead plants in no time. If you have no idea what you are doing, don't go so big. Start with a nice small 400watt or even 250watt grow, then work your way up. You'll be happy you did.

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yeah for sure, im no where near 4000watts of light juice. i am going small and working my way up, by small im talking about 6 plants and cfls for lighting and keeping them at a 24 inch height through out growth.

but my main point was to how strong those lil fans are, and for the price.

12 VDC vs 12 VAC is a totally different animal. Please read labels before killing items.

My fans say DC12V, and my adapter says universal AC 12V adapter. They have worked fine for over a year on 24/7.

I didn't read the whole thread, so this may have been mentioned, but since a pc psu is ideal, but most these days are ATX, and have no switch.. You can turn on an ATX psu by shorting the green wire on the mobo connector to ground (black).. Install a switch.. Then yellow wires are 12V, red are 5V, and the rest are low current voltages.. dc fans can be run at any voltage to desired speed/sound fine, ac fans are more dangerous to tinker with..
I heard a phone charger mentioned, thats probably really low output.. I use wall adapters too, they have their rated outputs printed on them.. Overloading them will burn them out eventually, but I've never seen anything dangerous with my own eyes..

I bought a CPU fan for £5.00 and found an old 15v adaptor, i ve wired them to a switch for easy off-on-ige and it works a treat! i never realised it was that easy, it's like join the dots, Just one question? 12v fan 12v plug can it be ran 24/7?

ToKeRtHeMoNkEy said:

Just one question? 12v fan 12v plug can it be ran 24/7?

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I've been running mine 24hrs for a long time now with no problems. So I would assume you shouldn't have any either.

You'd kill the adapter, not the fan.. I've used the method quite a bit for years, and rarely killed them without brutally over-drawing them.. If the adapter gets really hot, its probably too much load.. Your fans, and adapters should have current ratings you should stay reasonable to.. I wouldn't run more than one 3-4" fan off the typical 500mA wall adapters though.. PC PSU's on the otherhand can supply alot of amps at 5 & 12V.. They actually need a minimum load to function properly because they are switch-mode psu's.. A fan or forty does that nicely..
You can switch a modern psu on by shorting the green wire on the mobo connector to gnd, or better yet, add a switch between green&ground..
Black=Ground
Red=+5V
Yellow=+12V
Ignore other colors.. They aren't designed to throw out much current..

Newegg.com - MASSCOOL FD08025S1M4 80mm Case Fan - Case Fans

buy 10 for only $1.29 each and free shipping!!

bbqchip said:

Newegg.com - MASSCOOL FD08025S1M4 80mm Case Fan - Case Fans

buy 10 for only $1.29 each and free shipping!!

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Those fans are CRAP!! They are only 31cfm. The ones I am talking about are 130cfm. So they are 5 times more powerful and only like $5 more. Don't buy those fans. Look at the CFM rating before you buy a fan. There is no point buying a fan that small. I had to use 2 130cfm fans for my 200watt veg cab. So you would need all 10 of those to equal what I got from 2 fans. Plus, having 10holes in your cab, with 10 pieces of duct is going to take up so much space in your cab.
DON'T BUY THAT FAN!!

bongrippinbob said:

Those fans are CRAP!! They are only 31cfm. The ones I am talking about are 130cfm. So they are 5 times more powerful and only like $5 more. Don't buy those fans. Look at the CFM rating before you buy a fan. There is no point buying a fan that small. I had to use 2 130cfm fans for my 200watt veg cab. So you would need all 10 of those to equal what I got from 2 fans. Plus, having 10holes in your cab, with 10 pieces of duct is going to take up so much space in your cab.
DON'T BUY THAT FAN!!

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too late

There is no way you are going to be able to hook up all 10 of those fans in your cab. And there is really no point to it. When they get here, send them back and order some real fans that will do the job. ANd if you can't return them, at lest you're only out $10.

im only gonna use six. i got 10 for the free shipping and its cheaper. imma cut six holes in the back of the box 3 in the middle and 3 on top. the middle to suck in and the top to suck out.

Depending on how many watts you are using, it will not be nearly enough. With 3 for exhaust, that is only 93cfms. This isn't much. Plus any ducting that is connected with lower the amount of air the fans can exhaust as well. With only 200watts of CFLs, I needed both of my 130cfm fans to cool the cab.
If you are using these fans for flower as well, you will not want the same amount of air going out as coming in. You want to have some negative pressure. If you are going to exhaust using 3 of them, only hook up 2 for intake and make some passive intakes. Without negative pressure, the smells and whatnot just leak out of the cab and into your house.
You really don't need any intake fans if you can have enough holes cut in the cab to allow enough air to flow in. The exhaust fan needs to get its air from somewhere, and will pull in fresh air through the holes.
You will not be able to use a carbon filter with those fans, or any other computer fan for that matter. If stealth is an issue, you will need a carbon filter. YOu wont need it during veg, but you will need it flower.

do you think it would be possible to put 2 fans on one 12v AC adapter?