Introduction: Simple USB Fan

Picture of Simple USB Fan

This simple fan is designed to keep your wireless internet router cool!

Step 1: Construction

Picture of Construction


-Cable with male USB end
-12v computer fan
-Electrical tape


Strip the ends of the USB cord to revel 4 wires. Strip only the ends of the blue and green wires. Strip the ends black and red wires on the fan too. Solder the Green wire to the black one and the green to the red. Wrap electrical tape around the connections. Now wrap electrical tape all around the exposed wires. Plug it in to your computer's USB and Place on a vent on the router. This simple fan will keep it from over heating during long uses and will prolong its life.


knexfreak32 (author)2012-02-03

I just want to let you know that when you talk about soldering it basically sounds like you are saying + connected to - which = short circuit.But your probably not saying that.

hsarode1 (author)2011-07-19

I dont noe what is the voltage that comes from USB red n blac wires pls can eny1 tell me what is the voltage running in a usb port

dog digger (author)hsarode12011-07-20


colorex (author)2011-06-30

Dude you have the same router as I. Mine also gets hot... It's a WRT150N... :)

Justins210 (author)2011-04-24

Nice instructable and stuff, but I am not rly all for simple passive USB projects like this. Guess what happens if you short out or pull to much current from the USB port....boom your port is fried ( yes this has happened to me.). I'm just saying u have to be really careful and have experience to do this stuff ( from the looks of it your not because you are using a wood burner to solder.). ;)

dmonday (author)2011-03-06

POE uses 15 volts, the fan should be able to handel 3v difference

evan1123 (author)2010-09-12

The correct connection should be black to black and red to red. White and green are the lines for data transfer, red and black provide power.

iProton (author)2009-07-12

Would this mod be enough to keep an HDD cool?

Hakimi (author)2009-07-05

How come 5V power from USB... powering 12V Computer fan?? Is it become slower? Why not just taking a parallel power from same DC power jack that supply to router since the power from DC adapter is 12V?

DBLinuxLover (author)2008-09-30

I had a ghetto-er version. I have a Linksys WRT54G, so there's lots of room to play around with inside. Mounted a 40MM fan inside, and soldered the wires on to the power connectors.

jgeekw (author)DBLinuxLover2009-06-12

pretty ingenious. keeps it covert. How were you able to take apart your router. Last linksys I tried to get into, i had to basically crack the shell cause there we no screws. I even looked under the rubber feet.

DBLinuxLover (author)jgeekw2009-06-12

Okay, before I start, doing this will void your warranty. You have to pull the blue front away from the black shell. It's probably attached with a sticker of some sort. Press down on the black shell while pulling away on the blue, It may seem destructive, but there are no screws.

jgeekw (author)DBLinuxLover2009-06-13

cool. thanks for the info

Xellers (author)2008-03-13

Do you know if it would be possible to use one of the cables that plugs into the router for power? Could it be used instead of a USB connection? I want to know because I have a computer that's not always on, and a hot router that's always on because we have a Skype phone (definitely worth buying). I want to see if I can get the router to power its own fan. Thank you.

jgeekw (author)Xellers2009-06-12

Check out DBLinuxLover's Post. You could do it that way.

Charger_06 (author)Xellers2008-03-13

Yea, that would work. I don't know witch terminals have power and ground though? I'll look in to that. You'll also have to get the etherheart connector.

Xellers (author)Charger_062008-03-14

I have many of those router cables, so I guess I can cut one to see what wires there are. If there are power leads they will probably be red and black, and some poking around with a voltmeter will probably determine everything for sure.

Yerboogieman (author)Xellers2008-07-23

maybe red/white

dylanwinn (author)Xellers2008-06-01

Use any old wall wort you have lying around. I didn't have a spare usb cable, so I used a 120 volt AC - 5.4 volt DC transformer with an 80cm CPU fan, and it works well.

Xellers (author)dylanwinn2008-06-04

I know I can do that, and I have plenty of them laying around, but I want to know if I can use the router's own power.

roelor (author)2008-05-11

only got a black red white and green cable. I think i should use the white and green

updown789 (author)roelor2009-05-26

no use the black to black(black usb to black on fan) and the red to red, thats the power for the usb cable

roelor (author)roelor2008-05-11

O wait i get it the green and black ones,

animal0307 (author)2008-09-19

umm yea thats not really a smart idea because a usb port doesnt put out 12v of power and if you try to draw to much from you usb you could fly the port or worse your computer... you are better off splicing you fan wires into the power pack of you router

martini161 (author)animal03072008-10-28

not true, itll just only draw 5v from the usb to keep the fan quiet ;p

bigt4616 (author)martini1612009-04-09

ya, i agree with martini on this. your computer would only let 5 volts come out and if it overloads it, the computer is smart enough to shut off the port.

Sk8erCk4Life (author)2008-12-15

I added a twenty five foot audio cord onto it. So will it mess my PS2 up.

MrSmartGeek (author)2008-12-06

umm, u should really use a 5.1 volt computer fan

dylanwinn (author)2008-06-01

Should the fan point up or down? (Blowing into or sucking out of the router)

dylanwinn (author)dylanwinn2008-06-01

[Update] Never mind, I pointed the fan down (blows into router) and cranked the transmitter up to 70 DB up from the 42 DB factory default (Using the Tomato Custom Firmware), and after 5 minutes, the router is no warmer than my keyboard. [/Update]

Eeeeeeeeeekz (author)dylanwinn2008-11-04

how were you able to adjust the db signal?

dylanwinn (author)Eeeeeeeeeekz2008-11-04

In the tomato firmware, go to wireless > advanced. Find transmitter power, then change it to anything you want. Then hit save. A little warning though, setting it any higher than 150 could reduce the life of your router and/or cause upstream connection issues (the device gets a powerful signal from the router, but the router gets a very weak signal from the device). You can safely set the power at about 70 DB without a fan, higher with one, though 255 is the physical limit.

DBLinuxLover (author)dylanwinn2008-09-30

Its better to have it blowing out of the router. (remember in science there is no such thing as "suck". lol). Its better to have it pull cool air up from the bottom, drag it over the components, and blow it out. But it should work either way.

Nameless37 (author)2008-10-10

Doesn't usb only give 5V and the fan is 12V BTW where did you get the fan?

Charger_06 (author)Nameless372008-10-15

yup it keeps the rougher cool though. and i got it off a heat sink out of an old computer. you can buy them just about anywhere though.

power (author)2008-06-22

there's a problem with mine. it always say unrecognized driver when I plug the usb into it what can I do?

kraM (author)power2008-09-02

if you have red and dlack wires on the cable attach the fan to those red to red, blk to blk, if thaat dos not workt just try different combos

power (author)kraM2008-09-02

tried all combos. still doesn't work even though the cable is still new

kraM (author)power2008-09-03

check this site out if this dos not help you mite be sol

Nirjuana (author)2008-01-05

Youknow, USB gives you just 5v so I guess the fan don't spin as fast as it could.

uberchoob (author)Nirjuana2008-05-15

two sockets going to one device??

Nirjuana (author)uberchoob2008-05-15

It wouldn't work since we don't have any problems with the amount of load (USB max. load is about 500mAh). You'd need a boost converter to convert 5v to 12v. Connecting two 5v sources won't double the voltage to 10 volts, if you try, you'll probably just short circuit them and fry your motherboard. :P

uberchoob (author)Nirjuana2008-05-20

Yeah, throw it through a transformer that doubles the voltage. It'll give you 10v with the same 500mAh right?

Nirjuana (author)uberchoob2008-05-20

Yes, and this seems like a good circuit for the job. It's extremely simple, no microcontrollers, not even induction coils just a cheap 555 timer and few resistors and capacitors. I bet it isn't the best possible choice for everything though, since it's current output isn't too high and I'm not convinced how stable the voltage is but I'd say it'd do the trick with this one.

Charger_06 (author)Nirjuana2008-01-05

it spins pretty fast but ive never put max voltage on it though

dylanwinn (author)2008-05-11

Great Idea! Could this be modified to work with POE (Power over Ethernet)?

Nirjuana (author)dylanwinn2008-05-15

I'd be pretty careful with that kind of things, phone lines don't probably have enough voltage to make this spin and since phone lines definitely aren't meant for power supplying fans, it might overload and fry your modem.

dylanwinn (author)Nirjuana2008-05-17

POE supplies up to 38 volts and up to 5 amps, so you could get the fan to work. The question is weather the fan would need logic to request the correct amount of power...

"An obvious requirement of the spec is to prevent damage to existing Ethernet equipment. A "discovery process", run from the Power Sourcing Equipment (PSE), examines the Ethernet cables, looking for devices that comply with the specification. It does this by applying a small current-limited voltage to the cable and checks for the presence of a 25k ohm resistor in the remote device. Only if the resistor is present is the full 48V is applied, but this is still current-limited to prevent damage to cables and equipment in fault conditions."

I guess if the above quote is correct, a 25k ohm resistor, a 12 volt voltage regulator, and a pair of filtering capacitors could be used to power the fan...

Nirjuana (author)dylanwinn2008-05-17

Well that certainly changes things. I haven't read much about POE before now and it amazes me that it can supply even 5 amps. =)

According to that article you can use pins 4 and 5 as positive and 7 and 8 as negative but I wonder that how the 25k was planned to be installed, parallel to the load?

And yeah, you still have to check that your modem supports this. Otherwise things can get ugly :P

emoll (author)2008-03-16

You normally have separate power, normally a round male connection from a separate power source, black transformer connected to your poweroutlet... check the voltage on that one... and add resistance as/if needed... maybe a switch as well...

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