Need someone good with math involving watts and amps

[Martinm210]

Thanks!

I'm going to play around with my custom 4pin PWM controller vs Kaze Master vs direct variable PSU. So far I can't tell any difference between the Kaze Master and PSU with my subjective listening tests, but I haven't done anything really controlled yet either.

Maybe it would even be worth adding a separate capacitor after the fan controller to help stabilize the voltage?

[terramir]

Interesting, thanks for sharing

So, in essence, the fan will see voltage control, but the controller is converting 12V to a lower voltage through PWM + Capacitor?

The advantage of this is simply not generating heat in the controller?

Sorry for the dumb questions, just trying to get at least a little pinky around the topic. I've had a few people indicate on my 38mm fan tests that the problem is lower voltage, and PWM is the better way to go....yet it sounds like this controller is converting PWM to lower voltage. Why not leave it PWM if PWM is better?

Yes less heat, but not no heat, there are always some losses.
see below on the PWM question

Because some non pwm fans might get extra noise under analogue regulation. IIRC In normal 4pin pwm fan there is separate wire for pwm synchronisation, that solves that issue, but with analogue fan with normal 3pin these voltage spikes might differ at different rpm at which point coils should actually charge and push to turn rotor and at one position have more voltage, at different less, so possibly resulting in that extra noise.
Otherwise pwm of course is better then analogue regulation in several ways - it's circuitry is cheaper, as doesn't require monstrous heatsinks to dissipate redundant power, with pwm minimum rpm-s can be lower (as less of a problem minimum startup voltage to start turn motor, because it's always full 12V or 0V). But probably because that pwm rpm regulation is newer, and many analogue fans/pumps exist, some choose analogue regulation as safe bet for everything. (eg. Aquaero).

This noise thing can be solved by properly choosing the capacitors for the output, however the problem is that different kinds of fans will create different kinds of induction noise (electrical noise) hence choosing the right filter capacitor, unless you over-design (which is more expensive) is difficult, when designing a generic fan controller. To really do a fan controller well you would either need to do two things, A. limit the voltage to about 11.1V max usually it's about 11.3V-11.6V why the lower voltage, because you would need to add a shottky diode and another filter capacitor in order to prevent induction noise from messing with the controller and eliminate voltage spikes.
Or B. Design a controller that works well with a specified tested limited range of fans
My $.02
terramir

[bing]

Thanks!

I'm going to play around with my custom 4pin PWM controller vs Kaze Master vs direct variable PSU. So far I can't tell any difference between the Kaze Master and PSU with my subjective listening tests, but I haven't done anything really controlled yet either.

Maybe it would even be worth adding a separate capacitor after the fan controller to help stabilize the voltage?

Martin, don't be confused with the term of PWM, in your case, DO NOT put any capacitor on that custom PWM "SIGNAL" controller of yours, cause the signal generated intended to be sharp and going to be fed into the fan's PWM signal IN wire, adding capacitor will ruined the signal. And this has nothing to do with the "powered" pwm that is used like that Kaze Master or other 3 wires fan controller.

While for Kaze Master, I assumed its using PWM switching power design, this is different animal, although it has the word "PWM" , its the internal working circuit mechanism to to lower the voltage for supplying the fan efficiently compared to other low efficiency circuits like using linear method such as using transistors, linear IC or the classic using rheostat (high power pot)

For these type of controllers, adding capacitor might smooth out the ripple, although I doubt it will make any huge different since the switching frequency inside the power switching circuit might be very2 high beyond human range, prolly above 50Khz, depends on designs.

When undervolted, under certain conditions and certain fans, they don't react well since the internal circuit was reaching the minimum threshold of their normal working voltage, that condition sometimes will create the oscillation that making those ticking noise when undervolted.

An old but still good reference on controlling DC fan -> Why and How to Control Fan Speed for Cooling Electronic Equipment , just skip and scroll to the bottom if you don't understand the tech jargons, and jump at the summary section.

[fgw]

as said before, when i played around with PWM control i ran into the problem of sizing this output capacitor (cap). as someone posted before, by using such a cap (and probably an inductor) you can convert the PWM signal to an analog voltage. if the cap is too small the cap's charge wont be able to hold the voltage for the supplied load and will have almost no effect. if the cap is too large, the cap will be loaded during the PWM pulse but wont be discharged completely by the load during the PWM pause. this results in a limited control on the lower PWM range (e.g. PWM 0%-20% results in 9V-12V, everything above 20% = 12V) and that's the issue i ran into. the cap needs to be sized correctly for the individual load to get full range rpm control!

the internal circuitry of some fans prevents them from working well on PWM.

i have some nzxt fans reacting well to PWM but i also have some sflex which have very limited control when used on PWM.

almost ever you will get erratic rpm readings at lower rpm as power to the rwm reading circuitry is switched off and on periodically at the PWM frequency which overlays to the rpm signal itself.

PWM frequency also plays a role here, this is the frequency at which the PWM signal is switched on an off.

as mentioned before, this ticking sound comes from the fan periodically switched on and off. if PWM frequency is in a range above the frequency we can hear, above 20kHz (which is also intels spec) the ticking sound problem goes away, but unfortunately lower PWM frequency works better in controlling the fan speed than higher frequency does at least with the fans i tested here.

to me using a more costly and inefficient analoge (or linear) voltage control circuitry is the way to go. i don't really care about this additional one or two watts per fan when the whole system burns hundreds of watts already. i like the idea of PWM and

• yes it will be more efficient, thus produce less heat

but if it

• does not allow me to control all of my various fans
• prevents rpm reading at lower speeds
• makes this ticking noise

its of no use to me.

this all holds true for 3-wire (non PWM) fans only as 4-wire (PWM) fans already have their own PWM controller with their own switching transistor built in and use the PWM signal supplied on the fourth pin just for controlling the built in switching transistor.

martinm, as posted by bing: your controller is just generating the control signal of 4-wire (PWM) fans for their built in circuitry with its own switching transistor. the cap we were talking before is the output cap behind the switching transistor where you have no access to.

[terramir]

as said before, when i played around with PWM control i ran into the problem of sizing this output capacitor (cap). as someone posted before, by using such a cap (and probably an inductor) you can convert the PWM signal to an analog voltage. if the cap is too small the cap's charge wont be able to hold the voltage for the supplied load and will have almost no effect. if the cap is too large, the cap will be loaded during the PWM pulse but wont be discharged completely by the load during the PWM pause. this results in a limited control on the lower PWM range (e.g. PWM 0%-20% results in 9V-12V, everything above 20% = 12V) and that's the issue i ran into. the cap needs to be sized correctly for the individual load to get full range rpm control! some sflex which have very limited control when used on PWM.

There is another way to do that not quite pwm but close it's called a linear switching regulation, While I was writing the post I thought of a simple regulator, and posted it to my electronics lists. With this it's not about frequency the current is switched on and off depending on capacitor charge level, with this you should be able to get 5 volts or less and the switching should not effect the fan at all as long as you dun mind the fans running for a few seconds longer after your computer is turned off. this is doable just waiting to hear back from a few and get a few more inputs to figure out which parts I will use. should work and with a PTC I might be able to even temperature control the fans. calculations are necessary but it could be doable. , Heck I might even use a comparator or an op-amp to make this a reality, but I want to keep it fairly simple.
I really dun like those 4 pin fans cause they tend to cost more, and do their own thing. A few two or three pin fans should do nicely though.
terramir