Controlling/powering PC fan?

I know there's a million of these threads already, but I am dumber than all of those folks and I sort of need specific advice and help, sorry. :drooling_face:

Anyway I have an Uno, as well as a variable volt AC/DC adapter (3v-15v), and eventually some kind of fan. I was hoping for a small one, so 40-60mm ideally (like this one perhaps).

One point I need to make, I want this fan to go slow. I will NOT need a lot of air flow, it isn't for cooling anything, and I need it to be as quiet as possible.

I also will not need to adjust the speed once it's set at a desirable setting.

So, what do I do? :blush:

I read that using less volts means the fan goes slower, does that mean I can use the Arduino's power supply only, and kill two birds with one stone?

Or will I need to use my adapter/external power supply? Or some weird MOUSEFAT thing I keep seeing mentioned.

I only know the basics of Arduino (eg: I've powered up some LEDs with it and made them flicker!)

Sorry again if this makes folks facepalm in disgust and anger. Please back out if it does, don't worry about it! :smiley:

If it isn't for cooling anything, what is it for? Blowing away soldering fumes?

Switch it with an NPN transistor, emitter to ground,and base to the UNO pin via a 2k resistor (or similar). Put a resistor in series with the fan powered from whatever supply voltage you feed to the UNO (other than USB; in other words 8 or 9 volts). Adjust the resistor to a suitable speed on the fan. You may find a 8 volts you do not even need the resistor.

Beware that unless the adaptor is regulated, its voltage may vary wildly depending on whether the fan is running or not.

Daveyploo:
I want this fan to go slow. I will NOT need a lot of air flow, it isn't for cooling anything, and I need it to be as quiet as possible.

I also will not need to adjust the speed once it's set at a desirable setting.

So, what do I do?

Find a voltage which makes your chosen fan go at the speed you want. Choose a power supply capable of delivering as much current as the fan needs with a safety margin (I suggest at least 50%) at that voltage.

Connect the fan to the power supply.