24V to a case fan?

Solari · Sep 28, 2003

Ok, here's the deal: I have this Papst 4114 N (24V according to the specs on the fan) 120x120x38mm case fan in my Sonata (front). I am running it at 12V obviously, thus really quiet. Almost too quiet to be honest, and that means weak airflow. My question to you is: what's the easiest way to krank the fan up to 24V?

CrashOveride · Sep 28, 2003

Well I think you just hook up 2 12v wires, however I am not totaly sure so wait for somone else, however, I would not do this. It WILL shorten the life of your fan, if it doesn't just kill it. Maybe a LITTLE more voltage would be ok, but not double!

If you need a fan w/ more CFM, I suggest you just break down and buy one. :/

Solari · Sep 28, 2003

Yeah, buying another one would be an option too, but that may not be the cheapest way out either.

How about some home-made rheobus, can I get one to give ~20V to the fan?

L337 M33P · Sep 28, 2003

Heh unless you built a DC-DC converter I don't think there will be any way to get that fan to reliably run on 24v from a computer PSU. There is a -12v rail on a PSU so if you got one end of the fan and plugged it inot +12v and the other end and plugged it into -12 then it would run at 24v. However the -12v line can only take so much current - 0.8A is typical so you may fry your power supply.

Solari · Sep 28, 2003

Well I'm no electrician, so I thought it would be a better to ask.

So how about this converter thingy.. is there a 12-->24V converter? A 220V-->24V would work too wouldn't it?

martindemon · Sep 28, 2003

The easiest way is to make a ac/dc converter (120V ac to 24V DC). But you need to make a little circuit, and it will cost more than a new fan, and need time to do it. And it is risky to play with 120V if not done properly.

Lithan · Sep 28, 2003

Just buy a new fan.

L337 M33P · Sep 28, 2003

Actually for 3W I think it would work - Rig it with the + side to 12v and the -ve side to -12V. What PSU do you have? It needs to be able to handle at least 300mA on the -12v rail.

Restorer · Sep 28, 2003

L337 M33P said:
What PSU do you have? It needs to be able to handle at least 300mA on the -12v rail.

That's 0.3A as you read it from the chart on the side of the power supply. Looks under the -12V column - if it can't handle 0.3A or more, you shouldn't even try to use the fan this way.

Don't worry at all about killing your fan, it's designed to take 24V. The only thing you need to worry about killing is your power supply.

CrashOveride · Sep 28, 2003

Restorer said:
Don't worry at all about killing your fan, it's designed to take 24V.

Where did you see this?

madcow235 · Sep 28, 2003

on the fan it says 24v and then the tolerance is 12v-30v

L337 M33P · Sep 28, 2003

CrashOveride said:
Where did you see this?

He had a link in the first post

CrashOveride · Sep 28, 2003

Oh, lol. Now I feel stupid =P

pby5cat · Sep 28, 2003

here is an idea.

Solari · Sep 28, 2003

Hmmm, very interesting pby5cat.. That's the product I was looking for. But I wonder how much noise the fan will have when I crank the voltage up to 24... I wonder if they sell products like that here in Finland at that price. Might just be cheaper to buy a new 12V fan.

Koooler King · Sep 29, 2003

Solari said:
Ok, here's the deal: I have this Papst 4114 N (24V according to the specs on the fan) 120x120x38mm case fan in my Sonata (front). I am running it at 12V obviously, thus really quiet. Almost too quiet to be honest, and that means weak airflow. My question to you is: what's the easiest way to krank the fan up to 24V?

Other than buying new fan for 12.0V (probably best bet), depending on your power supply, you could try putting the 12 and 5 volt lines in series to get to 17 volts to your fan, then adjust speed with a reohstat. Maybe same thing could be done with 12 V + 12 V = 24 V if you have a power supply with a floating ground and multiple + / - 12 V taps? Caveat emptor on either idea. Good luck!

KK

Restorer · Sep 29, 2003

Because they share a common ground, the +12V and +5V lines cannot be connected in series to produce 17V. Draw a schematic where the +12V and +5V share the same ground, and try to put them in series without shorting one. You'll see what I mean.

vonkaar · Sep 29, 2003

You don't need to buy a new power supply just for a single fan. Unless you have some blower from hell, there is just *NO* justiying that. You can get a good Comair, Boxer, NMB or Pabst 120mm 12v fan cheaper and more practical than that. You could find some VERY small 24v PSU's on ebay, since that thing hardly draws any current... but it really doesn't make much sense IMO. Just keep it running at 12v for a quiet operation, or buy a real fan rated for 12v.

RCtruckguy · Sep 30, 2003

well also try the -5v line that would give you around 17V depending on how the -5v is.

~RCTG

adrian nelson · Oct 1, 2003

if its only 3.4w or 145mA and if you have a spare AT psu lieing round
ill be easy,
i infact have 2 24v fans on the frount of my case now, between the +12v and -12v rails of a 200w AT psu which powers other things as well
it can take 500mA on the -12v rail
even my hardout 94w ps2 psu dose 420mA
as for 2 12v lines going to it that idea is silly (12v-12v=0v)

24V to a case fan?

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