View Full Version : rheostat/rheobus question
01-30-03, 11:50 AM
Anyone know if it were possible to run multiple fans off of one rheostat? if it is, could someone post the stats for it... thanks :D
01-30-03, 12:51 PM
Most rheostats allow you to hook up many fans, sometimes more than one per channel, as long as you aren't hooking up 2 tornado's to one channel (so, you could hook up say 2 12v to the rheostat if it allows for 24v, i'm pretty sure).
As for posting stats, their is more than one rheostat available. Is their any one in particular you are looking for?
01-30-03, 08:11 PM
Rheostats are rated by wattage. Watts=amps*volts
Computer fans usually have their electrical rating on their hub. Sometimes it's in watts...sometimes it's in amps. You can figure out their wattage with the above formula (nearly all computer fans are 12 volts).
Just buy a rheostat that has a wattage rating high enough to handle the number of fans you want to use. You can use as many fans as the wattage of the rheostat can handle.
01-30-03, 08:15 PM
oh...one more thing.
The amount of resistance the rheostat has is measured in ohms. The higher the ohms of the rheostat, the more resistance to electrical flow...and thus, the slower your fan will turn.
It can be difficult to find rheostats in exactly the rating you're looking for. Radio Shack has a 25 ohm, 3 watt rheostat that is just about right for most applications. I've had very good luck with these.
If you get a rheostat with a much more ohms, the fan speed control will be coarser, and you won't be able to use the whole range of the rheostat (as the rheostat will offer so much resistance at just a small turn of the dial, that the fan will not be getting enough electricity to work at all...and it will stop spinning completely).
01-30-03, 08:44 PM
Thanks for the info guys:D ... I'm basically building a custom two-rheostat rheobus that would fit in a 3.5" bay (hopefully:D )... I want one rheostat to control two rear fans and the other to control two front fans...
01-30-03, 09:01 PM
Why build one? Buy a Vantec. (http://www.googlegear.com/jsp/ProductDetail.jsp?ProductCode=142408-2) It works great!:D
Opps....I just read the 3.5" part!:o
01-30-03, 10:25 PM
I was considering buying the 3.5" rheostat that xoxide is selling (I looked into the Nexus one too) but where would the fun be in that?... I haven't tried soldering anything before and this sounded like an okay project to do over the course of a month or so (gotta spend time with the wife and kids too:D )... plus I'd have the satisfaction of knowing that I built the darn thing with my own two hands :D
01-31-03, 12:52 AM
plus I'd have the satisfaction of knowing that I built the darn thing with my own two hands
I totally agree! I built mine, too...built it twice, actually, as I changed cases and wanted it to look a little different than the first one. It was kind of a PITA, and I'm not sure if I would do it again...but hats off to you for wanting to build yours!
This site (http://www.fanbus.com/) was a BIG help. This guy Cliff hand makes and sells baybuses, and has lots of info on his site on building your own.
01-31-03, 12:32 PM
whoa!... cliff is the man!!!... plenty of good information about rheostats and how to build a baybus with 'em... thanks for the info 'zilla... I'll post pics of my finished project as soon as its complete :D
01-31-03, 01:58 PM
Most rheostats are "Single Post Single Resistor" but it is possible to find them with more than one resistor.
Now the second image is one that I found doing a quick search through google but it should get the point across. It allows you to control 2 resistances using a single dial. This would allow you to conect 2 fans and have them isolated from each other.
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