Say, considering the warm weather.

mp3guy

I've 3 spare 80mm fans and 1 spare 120mm fan, is there anyway i can mount them on my desk and get power to them to keep me cool?

jozi

It's possible trough a usb port, some modding etc involved. Seen a guide how to do it online at some time. Try googling for usb fanor something

Wigertoods

connect the fans to a 12v battery
or a combination of batteries to make
up the rated voltage.

Endurance Man

Do u have a spare 300w powersupply lying around, something old?? U can just put that on your desk, get some power to it and plug the fans, very easy .

SouperComputer

connect it to the mains :eek:

djmarkus

id be more converned with keeping your rig cool as the warm weather takes its tool on that too!

mp3guy

eh, i've got two 2900RPM fans, its cool enough in there.

g5hn710m4xpdwy

or you could just by THIS or get one of these sumwhere :eek: THIS
hehe it looks eays to mod get a usb lead extender, cut of the female end and strip it ( ull enjoy that want ya.... there shud be 4 wires under the silver stuff. stick the green and white ones out of the way or cut them after striping the wires( there data ones) and then connect the red and black wires to the fan's wires and then plug it into the usb port and ta da it may work. you could al ways put in a switch or speed controller sum where along the line.
flunk

sionnach

got the two 120mm fans that came with my case sellotaped to my desk blowing on me at around 1800rpm. Loud but effective

g5hn710m4xpdwy

ugh lucky you :rolleyes:

Lump

You could just buy a 17 inch fan for £15

John

g5hn710m4xpdwy

you no what thats a brilliant idea :rolleyes:

stevenmu

Great idea, I think I'll be picking up a USB cable on the way home. Seeing as this is the tweaking/modding board, I've been thinking of putting a few spare case fans in a little enclosure with some kind of reverse radiator that I could fill with ice-cold water to try and boost it's cooling ability. It'd probably not have much effect but sure it's worth a try. The only thing is I can't think of anything suitably sized to act as a heat exchanger, can anyone think of something that might do the job ?

(not as good as Lump's 17" fan idea, but where's the fun in that )

po0k

Endurance Man wrote:

Do u have a spare 300w powersupply lying around, something old?? U can just put that on your desk, get some power to it and plug the fans, very easy .

No.
The PSU will burn.

You'd need to put some resistors across the un-used rails to bring up the load to the minimum spec.

g5hn710m4xpdwy

heheh i have a usb lead in front of me( did when i wrote the solution and ta ta im going to cut it up (hehehe its my brothers but hes in america for the summer so who cares???) oh im going to enjoy screwing up my comp... :rolleyes:
can you get them in maplin usb extender leads)?

Giblet

Go outside.

po0k

USB: Voltage 5V, Current 500mA per root hub port.
You aren't going to drive a fan off that without damaging your machine.

Just get a random power brick of 7V or higher, strip the head off the lead and wire it into the fans that way, use whatever pots or varistors you like.

Endurance Man

No.
The PSU will burn.

What do u mean the psu will burn?? Im doing this as we speak and have been doing it for about 4 months, psu seems fins :rolleyes: .

g5hn710m4xpdwy

while ye were talkin i tore apadrt a usb lead and a lil fan put a hole in the fan stuck the cable thru and connected it to the thingys for pwer and then plugged it into the usb port and flicked the on butten (it kinda hurt it wudnt move) and tada it was working very nice ly but very ludly. think im going to maplin on saturday im going to pick up a new lead or 2 and a quite case fane. well later

g5hn710m4xpdwy

is there anyway i can turn down the ammount of power thats comin gout of the usb port?

Capt'n Midnight

Flunked wrote:

is there anyway i can turn down the ammount of power thats comin gout of the usb port?

Not really. It supplies 5 Volts. If the device draws too much current then the USB port should shut down before it fries. So on/off only.

To change the speed of a fan you could add a resistor in series. But it would have to be a only a few ohms and able to handle a watt or so.

DemonOfTheFall

No offence, but it really isn't safe to mess around with electricity if you dont understand it. If you don't understand "turning down" the power from you usb port you may be likely to fry your computer/house.

Not trying to slag you, just saying be very careful...

g5hn710m4xpdwy

DemonOfTheFall wrote:

No offence, but it really isn't safe to mess around with electricity if you dont understand it. If you don't understand "turning down" the power from you usb port you may be likely to fry your computer/house.

Not trying to slag you, just saying be very careful...

well i knew that i was giving 5v to a 3v motor but it was sooo nice for about 5-10 mins and then the motor died so im just going to buy a 5v motor in maplin and do what ever. BTW I'm only 12 so aint a tecno genius. so its not my fault i didnt know that(well it is but why shud i im only 12???

Capt'n Midnight

Capt'n Midnight wrote:

the USB port should shut down before it fries..

OT
Marxcomputers even have a USB coffee cup warmer for a tenner :rolleyes:

DemonOfTheFall

Where did you find a 3v fan ? Computer fans are all 12volt (that I know of)

It'd really be a lot less hassle to buy a power brick with a voltage adjusting switch for a fiver somewhere. Like one that can switch between 3v and 12-13v. Very handy for comparing how loud different fans are, and they dont involve the risk of nuking your motherboard

po0k

SyxPak wrote:

USB: Voltage 5V, Current 500mA per root hub port.
You aren't going to drive a fan off that without damaging your machine.

Just get a random power brick of 7V or higher, strip the head off the lead and wire it into the fans that way, use whatever pots or varistors you like.

*cough*

Also, Flunked, step away from the PC.

Seriously.

Sincerely,
SyxPak B. Eng. Electronics

Endurance Man

Syxpack, u still aint told me why my psu is going to burn, if i run a few fans off it ??? :eek: . I have been doing this for ages and all is well, please explain???

WizZard

From http://www.epanorama.net/links/psu_computer.html

Gotten from Google

Using PC power supply as general laboratory power supply
Many people seem to have nowadays many old PC power supplies from old comouter aroudn them and seem to want to use them for some other applications. The PC power supplies supplies many voltages (+-12V, +5V etc.), but using those power supplies successfully takes some knowledge. The PC power supplies are generally switched mode power supplies that do not like run without a load (power supplies usually automatically shut down themselves then they see no load). The AT standard power supplies do not have any special signalto stay on. They are designed to work on certain power loadsrange correctly. If they are loaded less or more than they are designed to work they will shut down themselves. Generally you need to load the +5V output enough (usually 1 amprere to many ampreres minumum load needed depending onpower supply unit, youy might need to test this).The motherboard or old hard disk connected to power supplytakes at leas this minimum load, so keep the power supplyhappy. If you do not want such devices near you, you need to have some other type of load you can use, for examplewell cooled power resistor to +5V output or a 12V car headline bulb connected to +5V output (12V bulb willglow red/yellow when powered with +5V and take enough powerto guarantee that minimum needed load). The minimum load on +5V is needed, because PC power suppliesare generally regulated at +5V output. The controllign loopon the switching power supply works well on normal load conditions, but in case of too little load causes generally the+5V output to rise to too migh voltage, which leads to theshutdown of the power supply when it detect the overvoltage. Whatever power supply you want to use the best approach is tocheck the PSU spec: some require a minimum current draw on some rails. It is quite easy to provide this by means of a power resistor or power resistors. What is said above is usually valid for most other computer power supplies as well.All modern PC power supplies are nowadays built to match the newer ATX standard. Those power supplies have more signals on their connector for example for turning them on and off. If you plan to use this kind of power supply, you need to take care of the minimum load details told above. In addition to this you need to find out the details how you are supposed to turn this kind of power supply on. To activate ATX power supply, only PS_ON is needed. PS_ON can be activated by connecting ATX power output pin 14 (PS_ON) to pint 15 (ground). Some ATX PSUs also require a load on the main +5V to start (could be even damaged without enough load). Most but not all require a load on +5V to regulate properly, a few require aload on +12 as well. PWR_OK signal has nothing to do on ther controlling of ATX power supply operation. PWR_OK is an output from the supply. "PWR_OK is a "power good" signal. It should be asserted high by the power supply to indicate that the +12 VDC, +5VDC, and +3.3VDC outputs are above the undervoltage thresholds.

DemonOfTheFall

woops, forgot you'd mentioned the power brick already syxpak

duridian

I've got a 1280mm fan above me going at approx 2000RPM, tis f€ckin' luvverly.

edibility

There should be a little message on everything anyway potentially dangerous saying "Don't bloody mess around with this if you don't understand it....."