building a rheobus

[ssspy007]

i wanna build my own rheobus since i got a couple of 172mm majors (the ones on sale cyber deal
n e ways the spec sheet says the min watts a 235cfm fan puts out is 26w! and the more i was thinkin bout wirin these up i wanted a rheobus more and more but the strongest one i found was the sunbeam unit but that can only handle 20w per channel. so i wanna build my own. i found a guide to doin it and i understand how fanbus.com but i am not sure on the wattage and the ohms needed to support 2 of these fans and a handfull of cheap 80mm ones. i found these rheostats and they r cheap but i am not sure if they can handle a "major"
and heres another site that sells alot of rheostats (although its expensive) alltronics.com

ok so what do u guys think? u think the cheap rheostat will handle it or should i just give in and buy the sunbeam ??

 

[trdsw20]

Usually I would tell you to go with the project. But to get 4 nice Rheostats and knobs would cost maybe over 20.00 And there are a few nice premade ones out there. So for this one I might have to advise you to buy one instead of make one.

 

[stool]

You'll probably want to look in the range of 25-100 ohm rheostats, depending on how much you want to slow the fans down. The 2ohm listed at All Electronics might fill the bill for the 172mm's, but wouldn't be too good for the rest

 

[cmcquistion]

Take a look at this website. This device is actually a sort of voltage regulator, but very easy to build.

http://www.cpemma.co.uk/sdiodes.html

I built a couple of these for very little money (2 of them for about $10) and they work GREAT! I used 12-position switches and designed mine for voltage control from 12-5V. (I didn't integrate lights into mine, either.)

 

[John LA]

Based on a fan that uses 26 watts at 12 V, the current draw is about 2.167 amps. So the resistance of the fan is approx. 5.54 orms. So if you use a 6 ohm pot you will be able to adjust the voltage from 12 to approximately 6.3 volts. This should slow the fan down considerably.

LA

 

[ssspy007]

wow, thanxs for the help guys , so many options. time to do some more research