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FEATURED Building PWM Controller for 4 wires PWM fan

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Feb 22, 2009
Ok Project PWM for SANYO DENKI - 9SG1212P1G01

This may apply to Delta as well depending on project results.

Goal, ~1000 RPM (tolerable noise level) up to 6000 RPM (Full Load) Pulse Width Modulation from Motherboard with Voltage draw from Power Supply.

List of parts needed.

Will a lower PWM of 1000 RPMs result in no performance on these fans?

All input is welcome. These questions are primarily directed at bing/mudd
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Well which one would be a better choice? It would appear that Mudds Baby Beast beats the Delta in CFM and in Static Pressure.
Yup, imo that baby beast is the most powerful 120x38mm 12 volt dc fan in the world ! :D
I don't think I will be able to achieve this with my PSU. Currently I am at about 500-550W TDP (and that is stock values) from my current system. If what Mudd says is true and it pulls 100W on startup and 60W during 100% usage, then I won't be able to run even one of these. I am already pushing my 650 as it is.
That 9SG1212P1G01 from the datasheet is rated 4 Amp at 12 Volt, so the power is 4V x 12A = 48 Watts, so both will draw 96 watt, close to 100 watt. This at their full speed.
Yeah, but what about on start up? will they pull more?

And Would 260 CFM in push be much greater than two Panaflos 114 CFM in Push/Pull.

I guess I could just get one first and see, I tend to think the Extra Fan might just be Overkill and would not really net any real benefit.
PWM does not work well in low rpm situations due to a low duty cycle, but is more efficient than resistive/rheostat control. youll find that there is a minimum you can throw at it.
Hi and :welcome: to OCF!

By "does not work well in low rpm" do you mean, will not go down very far, or are you saying its not efficient, or are you saying it won't work at all? Since I currently use rheostat controlled Panaflo X1BX Fans, there is also a minimum I can turn it down before it shuts off, but only in voltage. I can turn them from about 400 RPMs (which is the point at which they shut off) up to 2500 RPMs.

If "does not work well" means once I turn it below 1000 RPMs, then this is not so much an issue, because its about 1000 RPMs where a fan is "tolerable" to my ear. Obviously this varies from fan to fan, but in general I can live with 1000 RPMs.

If, however, the fan has 0% efficiency at 1000 RPMs, then that is something different. If I can get the same kinds of efficiency out of this fan as I can with any other fan at 1000 RPMs, then that is sufficient. The reason I want to be able to go up to 6000 RPMs is for Benching only.
It wont have enough of a pulse width to move the motor, you may need 1200 rpm's of pwm just to make the motor move. PWM itself is more betterer since you are not sinking that power without use..wasted power. I tried to find a post for ya but couldnt locate it...stated that when switching from voltage control to pwm on a motherboard, couldnt run fan motor below 1500 rps...meaning the motor wouldnt start at a level below 1500 rpm's. But would in voltage mode.
The intention is to build a PWM controller IF the fan speed can not be lowered enough using the Motherboard Header.

bing from a previous post has already recommended this PWM controller.


Nidec America
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Brutal, suggesting you to PM mod to change this thread's title to "Building PWM Controller for PWM fan (aka 4 cables fan)", this will reduce misunderstanding like above.

One more thing, don't buy those components yet, I'm currently tweaking that circuit to make it more powerful and will provide better & stronger PWM signal, and prolly with this single circuit alone, this fan controller can drives 50 PWM fans. Miah should be interested in this too. :D

Give me a day or two, I will post the new circuit here and give the complete shopping list for that circuit.
ahh i see...Determining the frequency for your 6000 rpm motor....that will be used at 1000 most of the time....different ends of the spectrum. I believe that a bit o trial and error is going to be your guide for the most part.
Yeah, exactly. Ideally, I will probably end up with two of the San Ace fans in Push/pull however if this should work, I may end up with more than that. Kind of a Super Overclocking Case. It seems the majority of cooling problems are actually related to case ventilation.

If for example your Case Fans cannot pump enough cool air to the CPU cooler, then no matter how fast/efficient your fans are they will choke.

Initially this is a test to see if it is at all possible. If so, then have the controller where under specific load circumstances, the fans will work at anywhere from a "silent" cpu idle speed, to a Max Speed under full load like when P95 is run. Using a Fan controller "gets the job done" however I noticed that the fan will not reach its Maximum Speed while plugging into a fan controller.

@bing, I will pm a mod when they wake up. :D
About controlling PWM fan, without any circuit, when you connect the PWM pin to the ground (negative), that is equal to 0% PWM duty cycle, the fan will slow down to it's rated minimum speed, and if you leave that PWM pin disconnected, it will automatically equal to 100% aka max speed, easy & nice isn't it ? ;)

Actually without any connection, that PWM pin is internally pulled high (electronic speak) equal to connecting to 5 Volt line (not the 12 volt), and remember, NEVER CONNECT THAT PWM PIN TO POSITIVE 12 VOLT, it will toast the fan's internal circuit instantly. :(

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Oh, I understand that much. :) I am a mechanic (auto tech). I deal with PWM on car blower fans. I also understand the basics of PWM being controlled with a 5V circuit. The 12V is the Fan supply voltage while the PWM 5V signal is the control circuit.

Basically, I am trying to accumulate some data for trial and error tests, because you can't exactly read a data sheet and infer noise levels and performance as a general value. The only other way would be off experience, but most people don't go through such ends for a cooling solution.

I surmise that I will find that I get no better performance using this fan over my Panaflos, but if I were to use this outside of the case, I am sure it would do a great job.

I have considered bringing a blower (from a bus) home to try it out. I wish I could find a data sheet on it. I bet it produces over 500 CFM, the problem is, it won't be quiet. It is also not PWM, so it can only be controlled with voltages, and lets face it. Lots of voltage and amperage = lots of heat.

I am doing this more or less as a project with no real expectations. If its viable, then I will use it in my computer and will be able to give tips like Muddocktor does.
Great, with your skill & experience, that PWM generator circuit should be piece of cake for you to build.

About the VX, if I'm not mistaken read it somewhere, it scales really well with high speed fan.