Ok, so yesterday I was out and thought about replacing the thermistors on my fans with variable switches (pots?). So I walked into ratshack to have a looksee and I found several different kinds. Although they all appeared the same, there was a 5 Ohm, 10 Ohm, 15 Ohm, and 25 Ohm (I think that was all). What's my best bet between these? I want to have the maximum cooling power for when I'm gaming, but I don't want to burn the LEDs by having too small a resistor. BTW the fans are These.
Check out Macro's article on baybuses here . Look on the Rheostat Fanbus section. He says he used a 50 ohm rheostat. When I built my baybus the first time, I used one of the 25 ohm pots from radioshack. It worked...I guess. The fan spun. When I turned the pot all the way down, the fan spun just a speck slower. My LED didn't dim at all. Radioshack doesn't stock many pots. Even online. I ended up having to order my pots from Jameco . I ended up getting Jameco part no. 140513. They are 5 watt 100 ohm. And they worked great.
But those rheobuses hook up from the power. I'm thinking it would be more convenient to attach it in place of the thermistor that I have now. I'm just not sure if I could get away with having no resistance, or as little as 5 Ohm, in place of it. Putting the pot on the line from the psu doesn't make sense, to me, in this application because the thermistor would still slow it down.
That's true. I'm afraid I don't know enuff about electronic type stuff (especially thermistors) to be able to help much with that. Maybe Macro or someone more knowledgeable will chime in for ya.
The Papst Variofans use a 100k thermistor, Coolermaster DAF-B81 thermal fans a 12k one, and the link doesn't say what value yours is. But you need a potentiometer about the same value, a little 1/4W is fine if you're wiring it in place of the thermistor. Wiring into the 12v line (like the rheobus) you need something like a 3W 50R. Sometimes the thermistor value is printed on it, so 104 is 1-0-0000 ohms, or 100k (measured at 25degC).
Does that mean the thermistor is basically at "full-throtle" at 25ºC? Or that just happens to be how much the thermistor is resisting at 25ºC? The thermistor on mine is almost completely covered with the wire insulator. About 2-3mm cube is visible.
