3 Pin To USB?

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apt403

apt403

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Oct 14, 2006
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Are there any 3 pin to usb power converters? I ask because i want to take a couple 120mm case fans and make a USB powered super fan (atleast it'll be big.) I think a single USB port can only supply about 5v, so i couldnt run a fan at full speed, but that doesnt matter much.

I know i could just buy a table fan for like $10 at walmart, but im bored and a fan made out of like 10 usb case fans would look awesome. It doesnt really HAVE to be USB powered, but it would be fitting for the theme of the fan, and i figured a USB to 3 pin would be more common then, um, wall outlet thing to 3 pin.
 
Completely, totally, 110 percent serious. At first i was thinking about chopping off the power cable from a lamp or something and soldering the wires together, but then 2 thoughts crossed my mind: I dont want to die, and a wall outlet can put out about 125v, so i would probably kill the fan instantly.
 
the only thing i can think of if you get a ac to 12v dc converter link to power the fans. the only thing is you have to watch how many amps the fans draw, those converters can only handle so much
 
Its might be possible, but you really need to do some test with the power output and the minimum to operate the fan. You might just burn it up with to little power. Maybe a rig to double the power with two USB ports would be a more likely solution.
Hope it works out.
 
Why not just get power cable extenders and use your computer's PSU to power the fans?


Cut a hole in one of the back plates for the wires and house as many fans as you want (all being powered by the internal PSU). You could make your own plug external to the case for about 3$ in parts at walmart.
 
It's totally possible to do.. USB provides up to a maximum of .5A of 5V. So you COULD hook it up to a fan using 2.5W or less at 5V.. good luck finding one of those. :)

On the USB plug, the 5V is supplied by pin 1 - the far left side when the 'open' part of the plug is on top.
 
Why not just get power cable extenders and use your computer's PSU to power the fans?


Cut a hole in one of the back plates for the wires and house as many fans as you want (all being powered by the internal PSU). You could make your own plug external to the case for about 3$ in parts at walmart.
Click to expand...

Hmmm, that seems the most feasable, i was planning on hooking together 2 colums of fans, 3 fans high, and 6 fans deep, for a total of 36. All of them with LEDs of course, then i would house them all in some sort of box. I wonder if my psu would be able to handle 36, 120mm fans?
 
My system came out to 512w with a healthy oc of 2.4ghz and 30 fans, but i figure ill get an another cheap psu to be safe, mabye a small form factor one so i can house my creation in a case. Im assuming ill need moltex to 3 pin power adapters, but are there any with like...36, 3 pin connecters? that way i dont have to buy 36 seperate adapters, the fans cost enough already.
 
Sorry, but that's not totally exact 🙂
You can draw 500mA only if you connect a regular USB device, correctly recognized by the USB host and its firmware asks the host for the 500mA current requirement during the enumeration and configuration phase.
If you only connect two wires to +VBUS and GND without attaching any real USB device the host controller limits the maximum output current to 100mA.

That's totally compliant to USB specification. Only a few very low quality mobo don't feature current sensing and limiting, but it's better not to rely on it because serious damage can occour to the mobo.
 
Yes, it could be the current limiting... but usually USB charger have a small IC with limited USB device capability in order to request the full current.
The ports are connected to the USB hosts in pairs... try to connect the charger to an host where it's the only device connected, for example if you connect it to USB1 dont' connect nothing to USB2.
 
Not enough power to run a large fan array off USB. Some 12v fans won't even start spinning at 5v either. Only 500ma per USB port per spec. A compliant USB controller won't even let you draw more than 100ma without requesting it.

Just use an old brick DC adapter (like the kind you use for charging your cell phone) that supplies 7-15v, you can pick them up at second hand stores ussually.
 
oh, also, you won't be using all three pins on the fan. Just two. The third one is the RPM sensor. Not sure what would happen if you connected it to a power source... probably not much.
 
Go to goodwill. I've been to several of them where they have a basket with like ~50 AC-DC brick adapters for like $1 each (cell phone chargers is what I'm ussually looking for because I don't like paying $20-$50 for them when other people are throwing theirs away). Bring a multi-meter with you.

And next time you want to get rid of power bricks you donate them to a charity second hand store (like goodwill) or offer them for free on craigslist or freecycle (freecycle uses this convoluted mailing-list system run by list-nazis that drives me crazy, but sometimes there is good stuff to be had/gotten rid of on there). Either that or you can pay to have them disposed of properly; they likely contain lead, mercury, and/or cadmium or other toxic materials and should not be throw away.
 
Huh, well, i guess i shouldnt have incinerated them then fed the burnt remains to endangered animals. Eh, they'll be fine. Of course ive set fire to a dozen or so electrolytic capacitors just to see what would happen, i probably have lung cancer or something now.

Im a real eco-nut.
 
Huh, well, i guess i shouldnt have incinerated them then fed the burnt remains to endangered animals. Eh, they'll be fine. Of course ive set fire to a dozen or so electrolytic capacitors just to see what would happen, i probably have lung cancer or something now.

Im a real eco-nut.
Click to expand...

cute...
 
You could just buy a cheap USB powered laptop cooler and use the converter that is underneath. I have one and it is very small and would save you a lot of time.
 
29a?! Wow, i guess im going to HAVE to get a seperate psu for the fans. I think ill get this psu, that way ill have a psu for the fans, and a temporary backup if my Enermax psu ever dies.
 
Interesting so far, but one question that no-one has asked to dat eis WHY are you building this?

If all you're after is a big fan, go buy a desktop fan that'll cost you WAAAY less. If its just for the sake of building it... then thats all and good, but I could thnk of better things to spend the cash on.

Still, if you DO manage to make it without burning your house down, then post pics. I would be interested to see how much the PSU glows 😀
 
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