PWM 3-Pin Mod!

Biowarejak

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PWM 3-Pin Adapter:






I wasn't sure it was possible until I did it. I have an adequate understanding of electronics in theory, but I don't often get to make myself real circuits. I knew though, that transistors act as switches when used properly. I used that and developed the idea in my head, and then I made use of my rudimentary google-fu and came across this post.

"Perfect," I thought, "I wasn't the only one to have the idea!"

And so I pushed forward after a couple days debating between building what the original poster's question suggested and the more robust solution provided in an answer given. I used what components I had on hand, an intermediate resistor and a 2222A transistor, and assembled as above - also as a schematic here (image found on the post):


After a couple false starts, mostly due to me inserting both ends upside down, I actually got it to work! The Alphacool DC-LT pump inside my Kelvin T12 is no longer hideously noisy! Unfortunately, the circuit itself is hideous. I'll have to use solder and the appropriate connectors next time, and then get it sleeved. :)

I don't have much in the way of RPM data at different PWM levels (probably need to re-crimp that wire), but I did manage to go from ~2311 RPM at 100% PWM, to ~760 RPM at 80%, according to the ASRock Tuning software. I was using a low noise adapter also.

 

Elerek

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Jul 17, 2017
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I'm surprised no one sells an inline 4 pin pwm to 3 pin voltage controlled fan adapter anywhere.
Doesn't seem like it'd be hard to do. You could probably get it to work in a similar form factor to noctua's low noise adapters.
 

Biowarejak

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I'm surprised no one sells an inline 4 pin pwm to 3 pin voltage controlled fan adapter anywhere.
Doesn't seem like it'd be hard to do. You could probably get it to work in a similar form factor to noctua's low noise adapters.
I'm a bit surprised too :) I'll see how compact I can get it and everything, I'm sure I can make it look nicer.
 

royalba94

Airflow Optimizer
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I'm surprised no one sells an inline 4 pin pwm to 3 pin voltage controlled fan adapter anywhere.
Doesn't seem like it'd be hard to do. You could probably get it to work in a similar form factor to noctua's low noise adapters.

Yeah, I thought Noctua's N-FC1 controller did that but after looking at the product page again apparently that's not the case...
 
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1461748123

Master of Cramming
Nov 5, 2016
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This is really cool :D All the 40mmx10mm fans don't have PWM control and this might be the solution!
I'm no electrical engineer, but I do have some knowledge of PCB design. Can you confirm that this circuit will work? (I only have knowledge in designing PCB with someone else's schematics haha)
 
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Biowarejak

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That's a bit more complicated than what I did! :) It looks more robust but I can't be certain that it will do exactly what you want.

Do you have a board fab in mind?