Yo, I could get his really awesome Papst fan, but it`s specs are as follows : 24V DC 4W ( 12 - 28V DC ) 933 4310 007 Is there a possibility to get this thing working in my PC ? Cheers [DE]FreD_S
If you want to run at full 24v, then you'll need to use a line off the ATX connector. Looking at it head on, with the tab up, the second pin on the left is -12v. Using that as the negative, and +12v as the positive will net 24v for the fan. There are a variety of ways you could do this (wire taps, soldering wires on the ATX connector of motherboard, opening up PSU), which one you want to do depends on how big your cojones are.
im thinking of doing the 24v thing on a couple of my fans, with a rheobus to vary the speed. i know little about electronics, what rheostat/potentiometer would i use? (a maplin stock codeor link would be extremely useful).
Re: Re: Is there some way ? It`s a radial fan. looks like a trubine. I couldn`t find it on the papst site either, but that`s all the info that was on the back of the fan and of course a big fat papst logo I`ll try letting it run at 12V and then if that doesn`t work I`ll try 24V. How can I make sure I won`t overload the lines before I start working around ? As I wrote the fan draws 4W @ 24V. Howmuch Amps is that ? I`m useless in electronics Cheers [DE]FreD_S
4 / 24 = 0.16 amps. It should be ok to run that of the -12v line without overloading anything as most are rated at around 0.5 amps or higher.
Deca, it depends on the operating specs of the fan. FreD couldn't get his 24v to work at 12v, so let's work with a 18-24v range. Now, since you didn't exactly tell us what you're trying to control, I'll make up an amperage value of 200mA. To drop 6v, the resistance would need to be 6 / .2 = 30ohms. The closest value you'll find is 50ohms most likely, which will bring the voltage down to 14v ((24v - 14v) / 50ohms = .2A). At 50ohms, the pot will need a power rating of at least .2A^2*50ohms = 2w. Of course, like I said earlier, I just made up the figures. You'll need to get the specs off of your fans and do the following: *Voltage drop (how far below the normal operating voltage you want the fan to go down) / Current = Resistance needed (or Resistance * Current = Voltage drop) *Current^2 * Resistance = Watts dissipated
thanks, i really cant get my head round that type of stuff unless someone lays it out clearly like you have. in your example, would the 6v drop be when a variable resistor is at its highest resistance, or lowest?
lol thanks, i couldnt get my head round that either u have my permission to call me an idiot or whatever u like edit: what does the ^ in this bit mean: "Current^2 * Resistance = Watts dissipated"
O.k. I found out that the fan is a 6120 according to our SAP system at work ( yeah o.k. it "fell" into my bag .... ) plus I was able to test it today with an old AT PSU. The fan runs at 5, 7, 12 and 24 V without a problem. Really shuvels that air at 24V ... more than an 80mm Delta screamer with about half the noise. But I'll have it at 7 V ... still shuvels a hell of alot of air and is near silent ! Oh, here's a pic of it in the mount I built for it: Cheers [DE]FreD_S
