voltmod for 24v?

hey i got a fan that can run 24v, and im wondering how i can do that with my psu, something with 12 and -12 lines or something. thanks.

and oh btw...newb question but the 4 pin power thignyes are those 3.3 or 5v or 12 or whatever...im confused lol.

and 1 last question:

my freind's dad works at some scanner place with scanners the size of a garage, and he brought one home with a truck and me and my freind took **** apart. well it had like 10 psus 1 of whihc was a 1500w psu. only had 3.3 and 5v i think anyways i took it apart and got a fan form it with a 2 pin connector. how do i make it so that the 2 pin can connect to the 4 pin thing coming form my psu, with a 24v mod??

thanks,
david.

Wow, that's a little confusing. Can you post some pics of what you have? It would be easy to swap around the connectors but upping the voltage to 24v would require a transformer I think. Anyway, try to get some pics up and I think I can help you.

Connect +12V to the red wire of fan and -12V to the black wire. That gives you 24V potential. You can find -12V from the ATX-connector. But first look on your fan and see how much current it takes. If it takes too much, you can't use it on your PSU.

I have one of those 24v fans, i run mine at 12 or 7v via a switch. you could probably run 17v by using the 12v line and the -5v line...you could also make a voltage doubler using an op-amp or diodes w/capacitors...though a lot of current is going to be passing through it so make sure the parts are rated for it (Diodes will be hard to come by i think).

ok hmm, this is my question i guess:


what plugs are 3.3 volt, what plugs are 12v and what plugs are 5v?

check your mobo manual or search yahoo for ATX form factor, you should be able to find a diagram of pin assignments and color codes of an ATX PSU

ajrettke said:

check your mobo manual or search yahoo for ATX form factor, you should be able to find a diagram of pin assignments and color codes of an ATX PSU

Click to expand...

k i did it and so now i need to know this:

i need a splitter to make the 4 pin connect 2x4 pin connectors...then i have to connect 2x4 pin connects to my fan, right?

fan is onyl 2 pin, one negative 1 positive...now what is up with the 2 middle pins on the 4 pin connector? com whatever...i dont need those do i?

I'm not sure if this will help but here goes. The 4 wires running out of the psu to the molex are the 12v positive and negative and 5v positive and negative. If I remember right the 12v is the yellow and the 5v is the red, the negative for each is the wire next to it.

Don't take my word on it but this is what I would do to 12v the fan, first make sure your psu can produce the current needed for the fan to run. Second get a molex plug and run the positive wire from the fan to the 12v side of the molex and the negative to the 12v negative wire on the molex. There you have it a 24v fan running at 12v. I say it is like this because to me it seems 12 volting that fan and 7 volting another fan should work the same way. Good luck

The wires in 4-pin connectors are:

Red: +5V
Yellow: +12V
Black: +0V (ground)

Ok, since this thread seems to be a bit of a mess:

1) molex connectors: As breez said,

The wires in 4-pin connectors are:

Red: +5V
Yellow: +12V
Black: +0V (ground)

Click to expand...

There are no negative voltages in a molex connector.


2) 24V fan: You need to connect the red fan wire to the +12V line and the black wire to the -12V line. This gives you 12-(-12)=24V. Now, you can get the +12V from a molex or the 20-pin ATX connector. You can get the -12V only from the ATX connector. You have the pinout guide on the ATX connector, so you should know which wires you need. The thing to be concerned about here is that the -12V line usually has a very low current rating. Check how many amps that fan uses and make sure it doesn't exceed the current rating of the -12V line.


3)fans from old power supplies: The best way to hook up a fan with bare wires is to remove the appropriate individual pins in a molex connector and attach the wires to the crimp, then reinsert the pins into the molex. To get the pins out, you have to bend in small pieces of metal that are jutting out, and then the pin will simply fall out. A good tool for bending the metal is an open safety pin or a small screwdriver. Simply bend the metal pieces back out before you reinsert the pins, and the pins will lock back into place when you put them back in the molex.

Yeah, depending on the amperage draw of that fan, the -12v side of the PSU might not be able to handle it - most have a really weak -12v.

I'd just see if the fan runs at 12v - would be quieter.