SOLVED which rheostat??

[lightning]

err....just now went to radioshack.com and do some research on rheostat, most of them are rate on 5W but Y S tech fan are rate on 7.92W!! would it be a bit low to use 5W?? and they also hv 10ohm@5W, 100ohm@5W, [email protected] so on!! what ohm should i use???

 

[Shadow ÒÓ]

I've heard a number of times that fans (larger ones) generally use around 7 watts. I'd either get the better one on line or have the shack order you a better one.

 

[Timmæy]

before you go buying radio shack stuff take a look at this place
www.allelectroincs.com

www.allelectroincs.com
just went out there yesterday and picked up a peltier for 26.00 120mm .56amp fan for 6.75 not too bad huh
they have great prices on all kinds of **** and they ship within 24hours
Tim

 

[Hoot]

To answer your question, the 5W Radio Shack rheostat will work. The fan draws enough current to develop 8W at 12V. You are lowering the voltage to obtain a lower speed/noise. At the lower voltage, the fan will draw less current, thus consuming less wattage. The current rolls off quickly, as does the speed/noise, as you lower the voltage. Use the 10 ohm unit. This would be different if you were, say, using an 18V P.S. and using the rheostat to drop the voltage down to 12V, in order to run the fan.

Hoot

 

[lightning]

thanks guy....thank for all ur input....