PWM Signal Generator for Fan Control?

[Zarathustra[H]]

Hey,

I am working on a project in which I need to be able to manually control pwm signals for fan control.

There used to be a device for PC's that did this, the Zalman PWM Mate, but they must have discontinued it, as I can't find it on Amazon, Newegg or eBay...

Does anyone know of a current device that can do this? There are a lot of cheap PWM signal generator boards on eBay, but I have gathered that now all PWM is the same, and I need one with the frequency range that the PC fan specification uses. Does anyone know how to select one that might work?

Thanks,
Matt

 

[unrlmth]

http://www.formfactors.org/developer\specs\4_Wire_PWM_Spec.pdf

It looks like you are looking for something that outputs a 25 kHz 5V square wave. It should be pretty easy to do with a microcontroller if you want to DIY.

 

[Zarathustra[H]]

http://www.formfactors.org/developer\specs\4_Wire_PWM_Spec.pdf

It looks like you are looking for something that outputs a 25 kHz 5V square wave. It should be pretty easy to do with a microcontroller if you want to DIY.

That is a very good suggestion.

I found a writeup over at the OCF about this very thing.

Still struggling to understand the qualitative difference between their 555 and 556 (dual 555 design) though.

I'm not a stranger to soldering irons, but I usually only use them to splice wires. I've never tackled circuits.

 

[InvisiBill]

Still struggling to understand the qualitative difference between their 555 and 556 (dual 555 design) though.

From Building PWM Controller for 4 wires PWM fan | Overclockers Forums

Above circuit actually still the same as the one from Nidec, its just I added additional amplifer (aka Inverted Schmitt Buffer) to beef up the PWM signal so it will be clean and powerful enough to drive multiple PWM fans.

 

[Zarathustra[H]]

From Building PWM Controller for 4 wires PWM fan | Overclockers Forums

Ahh, thanks for that. I read through most of the thread, but must have missed that one.

 

[Eldata]

Ahh, thanks for that. I read through most of the thread, but must have missed that one.

I know of a device, around the size of the PWM Mate, that will allow you to reduce the specified idle RPM (and noise) of high speed PWM fans without affecting the maximum RPM.