1
\$\begingroup\$

If not, what else component do I need to control the fan?

I ordered the parts and is still yet to arrive and am a newbie in electronics. I want to know if this is doable.

Components I ordered: 5k, 10k, 20k potentiometer, different types resistor (220, 1k, 10k, 100k).

Thanks!

\$\endgroup\$
7
  • \$\begingroup\$ What parts did you order? \$\endgroup\$
    – Chu
    Jul 18, 2021 at 14:09
  • \$\begingroup\$ A 5k, 10k, 20k potentiometer, different types resistor (220, 1k, 10k, 100k). I have the fan now, tested it and it works. I googled this but nothing of this particular scenario shows up. I only see a 3-pin fan with thermometer, 4 pin fan using arduino and a thermometer, etc. \$\endgroup\$
    – Cyan
    Jul 18, 2021 at 14:23
  • 1
    \$\begingroup\$ You should add info to your question. And without some op-amps and a capacitor, you don't have enough. \$\endgroup\$ Jul 18, 2021 at 14:39
  • \$\begingroup\$ Link the fan data sheet please. \$\endgroup\$
    – Andy aka
    Jul 18, 2021 at 14:45
  • \$\begingroup\$ If You just to increase and decrease the speed of the the fan, and depending on the fan you have, and what you want to do with it, you could get away with making a voltage divided with the resistors and potentiometer. It wouldn't be PWM, but "AM", but should still work somewhat \$\endgroup\$ Jul 18, 2021 at 16:23

1 Answer 1

1
\$\begingroup\$

Well, a PWM fan is controlled by PWM - i.e. a rectangular signal that varies in the time it's "high".

You can't make a rectangular signal (or any time-varying signal, really) from a DC voltage with just resistors/potentiometers.

So, no. This is not giving you what you need.

You can, however, use the potentiometer to control a circuit that includes some active element that generates such a rectangular signal.

Now happens something very rare: I recommend a 555 IC:

You can use one of the CMOS 555 variants¹ to generate a rectangular wave with variable duty cycle.

The LMC555 datasheet shows such a circuit:

PWM generator

You'd replace RA+RB with your potentiometer (attach the Disch pin to the potentiometer's wiper).

The Datasheet on page 10 explains the duty cycle you'll get from adjusting your potentiometer.


¹ not an NE555 but a TLC555 or LMC555. If the datasheet doesn't say "CMOS" on the first page, wrong component. It's not that you can't build this with a NE555, it's just more annoying, because of higher voltage rail headroom needs and leakage currents, and stupidly high current draw.

\$\endgroup\$
1
  • \$\begingroup\$ Thank you! I will definitely try that. \$\endgroup\$
    – Cyan
    Jul 18, 2021 at 15:20

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.