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Adding 3-pin connectors to a fractal fan controller.

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Salmon91

Member
Joined
Jun 28, 2007
I hope this is the right section.

I received a fan controller with my Fractal Design XL case. I was considering to add 2-3 more 3-pin fan connectors to it. My main concern is that will the fan controller be able to hold 5-6 fans, or will it cause too much strain on the fan controllers components?

help/suggestions/explanations are highly appreciated.
 

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As long as you don't exceed the rated wattage, you will be fine. You will need to find that value and figure out how many watts the fans the fans will take.
 
As long as you don't exceed the rated wattage, you will be fine. You will need to find that value and figure out how many watts the fans the fans will take.

My thoughts exactly.
If you read the numbers off the black upright thing I may be able to help figure out the rating if Fractal doesn't list one.
 
My thoughts exactly.
If you read the numbers off the black upright thing I may be able to help figure out the rating if Fractal doesn't list one.

I tried looking at fractals site, but couldn't find any information on it. I had to slightly bend it to be able to read the numbers, it had numbers and letters on two separate rows:

D882
014
 
Bobnova will have to confirm this, but it looks like it is 0.6A, which is 7.2 watts.
 
No components on the other side.
 

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Ok that explains everything!
Fair warning, large block of test. Feel free to skip it till the bold line.
We're starting with theory.

The transistor is acting as a voltage regulator and the knob sets how much current is being fed to the base pin, which in turn sets how much current is allowed to flow through the transistor as a whole.
This makes calculating how many fans can be used an interesting and somewhat difficult exercise.
In theory the transistor is rated at 3 amps, assuming I'm looking at the correct unit (datasheet). However it is also rated at 12.5W assuming a junction temp of 25c.
The transistor is acting to drop the voltage, at full on I expect a voltage drop of around 0.7v to 2v.
If you have fans that magically draw one amp at all voltage levels (lower voltage they'll draw fewer amps, that's part of what makes this awkward) and the transistor is dropping 1V at the full speed setting you calculate the power disapated by the transistor thusly:
Voltage drop (1) x amps (1) = watts (1).
A typical temp gain for that package is 100c per watt. If your case is running at 35c or so (the hot end of cases) and the transistor is getting little to no airflow that means that in the above example it'll be running at a toasty 135c. It's rated for 150c though, so that's OK. In reality the hotter it gets the better it conducts and the lower the voltage drop.
Now if you turn the fans down a bit, say from 11v (max) to 9v, now you have a 3v drop. If you still had 1 amp of current (like I said, you won't) you'd have three watts and the poor transistor is looking at temps of 335c. Poof! Dead.
In reality that theoretical 1a @ 11v fan would be drawing more like 0.8a at 9v, but that still puts the transistor way too hot.
More airflow helps keep it cool, as does a heatsink.
The part itself is rated for a maximum of 12.5w in any situation.

The above is all the theory, give that theory I would say 0.33a of fans at most, 0.25 amps max would be safer.
If you added a heatsink and airflow you could use probably twice as much fan.


How about some Real World? This is what I recommend you actually do.
Plug a fan in, any fan you know the draw of (it's on the sticker). Run it at full blast for a while.
Measure the temp of the transistor.
Turn the fan down, run it a couple minutes, check the temp again.
Keep doing that.
If the temps are reasonable, try a beefier fan or two of the first fan and re-test.
Keep in mind that 150c (max safe for the transistor) is plenty to burn flesh instantly. A fingertip isn't the worlds greatest thermometer for this.

Worst case situation the transistor dies. You can get a new one for $0.73 at digikey.
If it dies it may smell pretty bad and make some deliciously nasty smoke while it does it.
 
Ok that explains everything!
Fair warning, large block of test. Feel free to skip it till the bold line.
We're starting with theory.

The transistor is acting as a voltage regulator and the knob sets how much current is being fed to the base pin, which in turn sets how much current is allowed to flow through the transistor as a whole.
This makes calculating how many fans can be used an interesting and somewhat difficult exercise.
In theory the transistor is rated at 3 amps, assuming I'm looking at the correct unit (datasheet). However it is also rated at 12.5W assuming a junction temp of 25c.
The transistor is acting to drop the voltage, at full on I expect a voltage drop of around 0.7v to 2v.
If you have fans that magically draw one amp at all voltage levels (lower voltage they'll draw fewer amps, that's part of what makes this awkward) and the transistor is dropping 1V at the full speed setting you calculate the power disapated by the transistor thusly:
Voltage drop (1) x amps (1) = watts (1).
A typical temp gain for that package is 100c per watt. If your case is running at 35c or so (the hot end of cases) and the transistor is getting little to no airflow that means that in the above example it'll be running at a toasty 135c. It's rated for 150c though, so that's OK. In reality the hotter it gets the better it conducts and the lower the voltage drop.
Now if you turn the fans down a bit, say from 11v (max) to 9v, now you have a 3v drop. If you still had 1 amp of current (like I said, you won't) you'd have three watts and the poor transistor is looking at temps of 335c. Poof! Dead.
In reality that theoretical 1a @ 11v fan would be drawing more like 0.8a at 9v, but that still puts the transistor way too hot.
More airflow helps keep it cool, as does a heatsink.
The part itself is rated for a maximum of 12.5w in any situation.

The above is all the theory, give that theory I would say 0.33a of fans at most, 0.25 amps max would be safer.
If you added a heatsink and airflow you could use probably twice as much fan.


How about some Real World? This is what I recommend you actually do.
Plug a fan in, any fan you know the draw of (it's on the sticker). Run it at full blast for a while.
Measure the temp of the transistor.
Turn the fan down, run it a couple minutes, check the temp again.
Keep doing that.
If the temps are reasonable, try a beefier fan or two of the first fan and re-test.
Keep in mind that 150c (max safe for the transistor) is plenty to burn flesh instantly. A fingertip isn't the worlds greatest thermometer for this.

Worst case situation the transistor dies. You can get a new one for $0.73 at digikey.
If it dies it may smell pretty bad and make some deliciously nasty smoke while it does it.

Thanks a lot for the explanation, appreciate it!

If the transistor would break, could I replace it with something else that could withstand more? Furthermore, do I need to worry about the other components, or is it just down to this one transistor?

Plug a fan in, any fan you know the draw of (it's on the sticker). Run it at full blast for a while.
I could use a multimeter to measure this too, right?
 
Yes. If you're feeling especially creative you can put an ampmeter on the fan power lines while it's plugged into the fan controller. Then you can tell exactly how much current is being drawn at any time.

The active components on that board are the transistor and the diode. The diode simply serves to protect the transistor from negative voltage spikes.
The transistor is the part most likely to die.
If it does you can most likely replace it with something similar but rated higher. The knob and resistor resistance may not be perfect for it, but it'll probably work.
Alternatively you can buy some PWM fans and build your own controller.

EDIT:
Here's a thread with more PWM info than you can shake a stick at: http://www.overclockers.com/forums/showthread.php?t=641111


2.EDIT:
I'd probably replace it with this if it fails:
http://www.digikey.com/product-detail/en/2SD2012/497-5900-5-ND/1578304
Twice the wattage rating, similar electrical characteristics and the TO220 package has a ton of heatsinks available for it to help keep it cool. Even radioshack still carries TO220 heatsinks.

Probably the first thing to do if the stock one gets hot is bolt a heatsink on. a TO220 heatsink will probably fit, or you could drill holes in a ram heatsink and bolt it on (with TIM). That'd look awesome and do a great job cooling it. Both sides even, if you're feeling creative.
 
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