Controllable Fans - PWM or Rheobus or ?

[dsumanik]

Ok made an interesting discovery tonight...

I finally unpacked my TMS-200 and started testing some different fan configs out using 3 controllers heres the results summary:

These 140mm yate loons mounted on my MONSTA rad are silent up to 30% (870 rpm) and "quiet" until about ~40% (1050 rpm) after that definately noticeable, but not overly intrusive until about 70%(1260 rpm) Max speed on these fans is 1440 rpm.

So mounted in a case the best combo of performance/sound ratio will be between 30 and 40% on the tms-200

Controller results

Sunbeam Rheobus - no howl, fans start to spin at about 7.2 V
Noise Isolator PWM - Very audible howl of varying pitch at any voltage below 80%, fans will spin from minimum setting.
TMS-200 - no howl, fans will spin from dead stop at 20% voltage.

I am SHOCKED, the PWM on the koolance is identical sound wise to the analog controller...zero howl, none zip, nada....I had honestly planned to use one of the the pump outputs for fan control...in fact i think its possible the post you linked above might be accidentally incorrect? It almost seems like the fan control on the TMS200 is analog man, there is seriously NO howl. I tested every single rpm setting in the software and I am very sensitive to noise..a minor buzz drives me nuts. I have avoided PWm like the plague for years cuz of this.

I just cant believe it is PWM. That said...

The TMS-200 also seems to behave like PWM from startup, beacuse if i completely stop the fan channel on the controller, and let fans spin to a dead stanstill and select 20%...they fire right up spinning at 750 rpm.

Using the analog controller i have to give it about 7.2 volts before the fans spin, then can turn it back down.

So how can this be??? This little controller has completely changed my view of PWM.. ALL the silence minus the heat dump and minimum voltage spin that analog requires?

If koolance can interface with board temps this will be the best controller on the market hands down, no competition.

can we get Dean in here to verify it is in fact PWM control? I still can't believe it, using my other PWM controller these fans HOWL liek crazy at anything less than 80% voltage, its an unnacceptable and extremely annoying buzz...it sounds like the wake up strips they cut in the highway to remind people not cross the centerline/curb..or if you have ever ridden in a big 4x4 truck with mud tires on the highway..very similar sound...drive you nuts man.