120mm Fan Testing on an MCR120 Radiator Round 6

[Martinm210]

Good discussion.

I guess I did miss the lower RPM advantage of PWM. This PWM controller does give me a slight advantage in have a lower RPM floor (Maybe .5 to .7 "Volts" worth). I don't quite understand why yet, the PWM signal is almost converted to lower voltage using the large capacitor but it does seem to have a better ability at going a little lower in speed..

So far I haven't noticed any benefit to "Less motor Tick" with this particular PWM controller, but it also appears there are several types and ways of doing PWM control.

When I play around with my Crystalfontz PWM controller, it actually has an obnoxious "Kick" if I dial it down really low. The fan will actually torque on off at a very slow cycle rate (maybe 4times per second) and you can even feel and watch a strong fan move at each kick. The designer of the PWM circuit I used to build the video test actually notes he had this same problem until adding the large cap to smooth out the PWM pulses. The only good thing about my Crystalfontz controller is that it maintains RPM readout, so it must be reading during each pulse and calculating or something along those lines.

Regardless, so far I haven't found "3 PIN" PWM to be superior to voltage as I had hoped.

Either you get the "PWM KICK" noise without the cap, or "Voltage TICK".

Seems like 4pin PWM is the only real good PWM setup, but even that is a bit "Fan Specific". Some of my 4 pin PWM fans have a large range of control, nearly 0-100%, while most seem to only turn down a little bit...and some make some noise, while others seems to be pretty good.

I plan to do some 4pin PWM testing after I get my last order in using my 4 pin PWM controller Bing designed.