Making a variable speed exhaust fan.

I know this has nothing to do with PLCs. I just was wondering if anyone could steer me in the right direction. I got a soldering exhaust fan out of the dumpster. Well 3 to be exact. They all work. Score! Yet I wanted to make it so I could turn them up or down. How do I figure out what type of (pot) I need? The fan is a Fulltech model # uf-12a12.

The specs are:
Fan rated voltage-120v/230v
Frequency-50hz/60hz
Input power-17W/15W
Rated Current-.21,.19,.10,.09
Locked Current-.22,.20,.11,.10
Speed-2700,3100rmp

Just was wondering how I can figure out with an equation what type of pot to use to adjust it.

Thank you for your time and help.

Joshua

You may want to use maximum current of 0.22A for the POT minimum rating.
As for the resistor ohms are concerned, use the value which closely match your desired speed-change.
(A resistor of this rating may cost you as much as the price of a small VFD)

A cheap 500 Watt light dimmer should do the job for you. You could also use a ceiling fan speed controller. I believe these are essentially a light dimmer which does not go to zero output.

This is a good bit out of my specialty but, wouldn't a variac be a better choice here?

And, being single phase, am I correct that only a little speed reduction is possible before the motors just go limp?

From the locked rotor currents, they seem to be a shaded pole type motors there. From the speeds, you don't have a lot of poles.

You might be able to achieve some basic speed control, but not a lot.

Frankly, you'd probably get better results with oh, say, 12 or 24vdc muffin fans and a small variable dc supply.