Custom USB powered case fan

[Ross Siggers]

Hi all,

 

I'm building an eGPU enclosure, and due to it's very tight dimensions I've decided to put a slim fan in one end to prevent heatsoak. Now I'm using an power brick with none of your usual power connectors, but the PCB itself has USB-A output. So I'm looking for something like the image below, if anyone has any suggestions...because that one is butt ugly. 

But then, if it's not asking too much it'd be great to have it adjustable, because I'll set the fan curve on the GPU down when not gaming. How hard would it be to add a rotary controller in-line, so I could dial back the power and slow it down? As I've got fans with this feature in my old PC case, but those are unsuitable. I'm a bit of an electronics n00b. 

 

 

[Zagna]

Maybe something like DC USB 5V to 6-15V Step-Up Boost Converter and USB A Male to 3 Pin Case Fan Adapter?

[Ross Siggers]

@Zagna Do you think the step up is required? I was hoping I could simply wire a switch into the power wire if possible, but I'm assuming if I want it truly adjustable it's slightly more complex? Definitely keeping that link to the adapter though just incase, ta!

[Zagna]

Without the step up, the voltages you can control from a USB port are 0-5V. So if the fan even supports starting at 5V, it'll run at 40% speed max. And for example Arctic F12 starts at 2.7V. So you would have very limited control and the fan would always run slow.

With a adjustable step up, you can use the up to the full 12V that PC fans run at.

[Ross Siggers]

Sweet, gotcha. So I could run without the step-up, but you're saying that would pretty much negate the need for adjustable speed because they'd already be running slowly. I went away and did some digging inside my old pc + my spare parts box, and came up with.... Three different style adjustable fans I already have!! Whoops...

 

So I have one which actually has a control board, another that's three step, and the final one has a cool rotary encoder, which is the one I was thinking of when I decided to add a fan to my build. I even found a slim fan which would be great, if I could adapt it from molex...and add speed... 

 

Third photo taken at distance because it's disgusting 

[Ross Siggers]

Well... I took the black fan with the rotary switch... And the clear slim fan... And frankensteined them together

 

The black fan had a waaaay bigger motor, so a dremel was involved. But it went together great. Should fit my needs, and I saved a few quid! Thanks for the response @Zagna