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rheostat question

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xbassman

Golden Member
My son is enjoying his new case (Thermaltake SViking)
But...The fans are the most annoying loud thing I have ever heard!
Heck, I thought my case was loud when I had 6 Enermax 80mm adjustables! 😱

My question though is......

His case has built-in fan controllers.
They hook up to the fans kinda like how a Smart Fan II rheostat is.
It has a 4-pin power cable and a 2-pin cable that leads to the knob that controls the speed.

What I am wondering is if I can buy some quieter fans and splice the control knob into the +12v wire.
 
You are gonna have to splice into the control wire lead in order to controll the fan RPM. All a rheostat does is change the reistance and therefor changes the amps flowing to the fan. As long as the controller is rated for the larger input voltage, if one exists, it should be fine.

Does this answer?
 
Thanks for the response Smithy.
I am not an electronics engineer, so you'll have to excuse my ignorance here. I do know what a rheostat does though. I was hoping maybe sombody could confirm my notion that the fan controller was tied into the +12v to vary its amperage. As to the control wire.....I don't know what to look for. I know +12v, ground and rpm sensor. (standard fan wires)

The only TT 120mm fans I have here are the 2 that came with my son's case. Although, I have a couple of 80mm TT smart fan II's sitting in a box. They look to be setup similarly. (3-wire power, 2-wire speed control, 2-wire thermal sensor) The 120mm's are the same with the exception of the thermal sensor.

I could disect 1 of the 80mm's I have to help figure it out.
 
Yes the rheostat does vary the amps but it also changes the voltage drop across the fan (by the formula V=IxR). Some fan controllers use active circuits (voltage regulator) because you never know what type of fan is to be controlled - that type of control will have an exact voltage output range (usu between 7 and 12V) and a maximum current rating and the variable resistor used does not have to be as hefty as a rheostat needs to be. The size of a rheostat-only control should be matched to the fan for best operation (about the same resistance as the fan at about half the power rating of the fan).
.bh.

Here, have a :beer: !
 
umm...Zepper I appreciate you input but....
I am not an electronics engineer, so you'll have to excuse my ignorance here.
Click to expand...
OK maybe I should try this another way...

Could something catastrophic happen if I tied in the control knob as I described above?
I mean those fans are ridiculous. I am starting to wonder why guys keep saying that 120's are the way to go.
 
I'd say yes, if you are absolutely sure that the pins on the controller connect directly to opposite ends of a rheostat. However, if the wires coming off the pins are one blac and one red, then it needs to be across the fan red-red, black-black. Won't a regular two or three pin fan connector (like the mobo fan connectors) fit directly to the controller pins? Then that's the way to go - just buy fans with two or three pin mobo connectors and splice extra wire in if needed (or buy two pin extension cables - available at most places that sell large numbers of fans).
.bh.
 
Actually the connectors for the controller are 2-pin (small ones) kinda like you see on a video card sometimes. I wish it was standard 2,3 or 4-pin (I have all of those)
The wires to the connector are 1-red and 1-black.

I am looking at SFII (80mm) I pulled apart since is has the same kinda connector that you hook up a speed control to and it has 2 yellow wires leading to it, but in parallel it also has 2 red wires that lead to a jumper (for thermostat control). I am thinking maybe that they aren't sticking to a wiring standard.
All the wires on this one are soldered to a little round circuit board that was in the fan.

Heck I may just take apart one of the 120mm fans that the case is using cause they IMHO are unusable
 
Well....anyway if the stock controller doesn't work I am gonna have to do something different figure something else out.
this sucks cause I am sitting here looking at an extra Sunbeam controller, but it won't fit behind the door.

Is the general consensus that the Globe and Evercool 120x25 fans are the quietest?
The only other 120mm I have is a Panaflo L1A but it won't fit.
 
I found a pic of the controller.
TScroll down a bit to see a 2ch bay mount controller link. It looks identical to the controller built into this case.

I thought it was kinda funny, Thermaltake's site list these 120mm fans as 21dBA! 😱
Although I haven't tried decoupling them yet.
 
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