Reducing Fan Speed Through Rheostat

[Guest]

I got a Delta 80mm 80.1 CFM 5200 RPM Fan that I'm using as a processor cooling device. Anyways, as you all probally already know, or are thinking, this fan is =-*LOUD*-=!! Anyways, I want to find some way to reduce the speed of it, and one of the ways I have found is by the use of a Rheostat. I have found guides to complete this and make it possible, the only problem is, my fan is 10.8 watts!! I can't use a 3 watt nor a 5 watt Rheostat for this, the thing would be dissipating toooo much heat and would melt. It's becoming hard to find a 25 ohm 15 watts Rheostat, so if any of you electricians out there have some advice for me to reduce my speed, please be my guest and share the info. I went to #Electronics on irc.dal.net, they laughed when I said the guide called for a 3-5 watt Rheostat, or 1/4 ratio, Cpu Wattage to Rheostat. They believe a 1.5 ratio is best, for example for a 10 watt fan, a 15 watt Rheostat. They also came up with 25 ohms for me. Anyways heres the specs of the fan incase you do not know them. Btw I would like some form of way so I can atleast change it from high to low, I don't want to just decrease the speed permanently, I want it like low at night, and high when I'm playing games.

Specs:
- 80mm x 38mm
- 12v
- .90 amp
- 10.8 watt
- 5700 RPM
- 80.16 CFM
- 52.5 dBA
- 3 pin connector (must used adapter to 4 pin)

 

[phsstpok]

How about miltary or broadcast industry surplus parts? I don't know of any place to get it but all that stuff is definitely over-engineered and more than adequate for your task.

<b>I have so many cookies I now have a FAT problem!</b>

 

[svol]

You can use a Rheostat in combination with a resistor, so the resistor takes most heat.

<b>THGC:</b> before: :frown: , after: .

 

[Lars_Coleman]

With a rheostat rated at 5w it's only going to resist 5w. So if you have a 10w fan on a 5w rheostat it will resist 5w at the lowest setting which will in turn make the fan operate at 5w. If you had a 10w rheostat and a 10w fan, at the lowest setting the fan would turn off because you are resisting all 10w.

Why don't you get this Rheobus <A HREF="http://www.pcmods.com/details.asp?ProdID=4" target="_new">http://www.pcmods.com/details.asp?ProdID=4</A>

This has switches rated at 17watts.

<font color=red>People and hard drives are like bandwagon fans and sports!</font color=red>

 

[Guest]

Way cool, about time something like the "ReoBus" turned up. I have been messing around with reo's/pots for a while and never come up with a happy solution.

(Crashman would like this post)

Ps: some experienced posters replied here.



<font color=orange>CAN WE</font color=orange><font color=green> FIX IT?</font color=green><font color=blue> yes we can! (Bob the Builder)</font color=blue>