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Discussion Starter #1
Hi all,

I have a motherboard that has 4 pin fan headers, but found out that only CPU fan header was PWM controlled. I realized after buying some PWM fans, and I could not use full range of the fan speed. My motherboard can only control the voltage level on the fan header, so I started a little project. I made a board that reads DC voltage and create PWM signal so that I can control PWM fans with DC regulated fan header. I need to do more testing on this. I would like to know what people think about this. I also built 3 boards, so I can sell 2 boards if anybody is interested.
The board takes 12V and 5V from SATA power header, two fan inputs, and four fan outputs. Each input controls 2 outputs or one input can control all four outputs depending on the switch setting.
 

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Senioritis Member
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Please keep us posted on this. There is a possibility I may be interested in something like this later this year.
 

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Interesting idea, but why not use a PWM splitter hub attached to CPU's PWM fan header to control all of the PWM fans? Only drawback may be that all fans' speed would be controlled by CPU temperature, but I've done this for many years with few problems. Only issue I've had is if fans are being used to cool GPU.

Also, Noctua's NA-FC1 is a PWM fan controller that can use PWM signal from motheboard to set it's PWM controller or be manually controlled.
https://noctua.at/en/na-fc1/service

Faster_is_better is controlling 12x Delta fans wiht NA-FC1.
http://www.overclock.net/forum/26912601-post28.html
 

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The CPU PWM signal will support only so many fans unless some kind of PWM amplifier is used which can be bulky, expensive, and complicated to use. paulbee's little controller appears to solve those complications with the added bonus of being able to have more than one fan profile by using more than one controller on multiple DC headers (assuming the MOBO will permit that).

The Noctua fan controller will not work from a DC controlled MOBO header except, maybe, as a manual controller.
 

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The CPU PWM signal will support only so many fans unless some kind of PWM amplifier is used which can be bulky, expensive, and complicated to use. paulbee's little controller appears to solve those complications with the added bonus of being able to have more than one fan profile by using more than one controller on multiple DC headers (assuming the MOBO will permit that).

The Noctua fan controller will not work from a DC controlled MOBO header except, maybe, as a manual controller.
Actually the PWM signal power is from fan, not controller, but controller can only work with a finite number of PWM fans before the signals become too strong and stop the controller from opening the PWM signal from controller in fan to stop it from sending power to motor and we have no PWM control Number of fans PWM can control is dependent on compatibility of fan's PWM circuitry and control circuitry .. and can be a s few as 2 or 3 fans and as many as 16+ fans.

If you read information Noctua supplies it clearly says it can function as an in-line controller using motherboard PWM control to trigger it's interal PWM controller or a a manual PWM controller by using it's control knob.
[quote]PWM based control
While most fan controllers are voltage based, the NA-FC1 uses the more sophisticated Pulse Width Modulation (PWM) technique that allows for more efficient control and lower minimum speeds, regardless of the fan’s starting voltage.

Manual control mode
If the NA-FC1 doesn’t receive an input PWM signal from the motherboard, it works as a simple and efficient manual controller that allows the duty cycle to be set from 0 to 100%. This makes it ideal for manually slowing down high-speed PWM fans such as Noctua’s industrialPPC series in order to achieve consistently quiet operation.
[/quote]
Source of above and more here: https://noctua.at/en/na-fc1
 

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Actually the PWM signal power is from fan, not controller, but controller can only work with a finite number of PWM fans before the signals become too strong and stop the controller from opening the PWM signal from controller in fan to stop it from sending power to motor and we have no PWM control Number of fans PWM can control is dependent on compatibility of fan's PWM circuitry and control circuitry .. and can be a s few as 2 or 3 fans and as many as 16+ fans...
Hunh? Seriously? Then what the heck do you call the PWM signal coming from a MOBO PWM fan port? And as far as I know, the only signal being sent from a fan is the RPM signal and only one fan's RPM signal lead should be connected to the MOBO when using a PWM splitter.

...If you read information Noctua supplies it clearly says it can function as an in-line controller using motherboard PWM control to trigger it's interal PWM controller or a a manual PWM controller by using it's control knob.
[quote]PWM based control
While most fan controllers are voltage based, the NA-FC1 uses the more sophisticated Pulse Width Modulation (PWM) technique that allows for more efficient control and lower minimum speeds, regardless of the fan’s starting voltage.

Manual control mode
If the NA-FC1 doesn’t receive an input PWM signal from the motherboard, it works as a simple and efficient manual controller that allows the duty cycle to be set from 0 to 100%. This makes it ideal for manually slowing down high-speed PWM fans such as Noctua’s industrialPPC series in order to achieve consistently quiet operation.
Source of above and more here: https://noctua.at/en/na-fc1[/QUOTE]

You are pretty much just paraphrasing what I said. What's your point?

Second thought, this little "discussion" of ours has gone way off topic so let's cool it. I feel paulbee's controller may be of interest to me. You feel it is unnecessary. Let's just leave it at that.
 

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Hunh? Seriously? Then what the heck do you call the PWM signal coming from a MOBO PWM fan port? And as far as I know, the only signal being sent from a fan is the RPM signal and only one fan's RPM signal lead should be connected to the MOBO when using a PWM splitter.


Source of above and more here: https://noctua.at/en/na-fc1
You are pretty much just paraphrasing what I said. What's your point?

Second thought, this little "discussion" of ours has gone way off topic so let's cool it. I feel paulbee's controller may be of interest to me. You feel it is unnecessary. Let's just leave it at that.
I know it's confusing.

I was simply trying to clarify the common misconseption that PWM controller is the source of PWM control circuit power. It is powered from fan, not controller, so an 'amplifier'. to the PWM signal cannot be added in the controller.

Please stop misinterpreting what I post and claiming I said something I did not. I did not say anything about paulbee's bit of kit being good or bad. I simply asked why not just use a conventional PWM fan hub.
 

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Discussion Starter #8
The reason I started this project was I wanted to have different fan speed profile than CPU fan. My motherboard got 4 fan headers and allows them to be controlled. I'm using SpeedFan control automatically. This will also give the ability to read RPM from other fans.

Noctua fan controller would not work since it needs PWM signal as well and I need automatic fan control.

Interesting idea, but why not use a PWM splitter hub attached to CPU's PWM fan header to control all of the PWM fans? Only drawback may be that all fans' speed would be controlled by CPU temperature, but I've done this for many years with few problems. Only issue I've had is if fans are being used to cool GPU.

Also, Noctua's NA-FC1 is a PWM fan controller that can use PWM signal from motheboard to set it's PWM controller or be manually controlled.
https://noctua.at/en/na-fc1/service

Faster_is_better is controlling 12x Delta fans wiht NA-FC1.
http://www.overclock.net/forum/26912601-post28.html
 

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Discussion Starter #9
As I worked this project, I learned about the PWM fan control. I think you both are right. The PWM control is really coming from the motherboard, but the PWM line power is coming from the fan. I have not looked at the PWM Fan hub circuit, so I don't know how they did it, but I don't think the PWM lines can be just spitted to support multiple fans. The motherboard controls the PWM signal, but it can only bring the line to ground or 0V. If the motherboard does not bring down the voltage to ground, the fan powers the line to be high voltage up to 5V, so the motherboard cannot really control the line without fan connected. This is why I had to have more component on the board to support multiple fans.
 

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The reason I started this project was I wanted to have different fan speed profile than CPU fan. My motherboard got 4 fan headers and allows them to be controlled. I'm using SpeedFan control automatically. This will also give the ability to read RPM from other fans.

Noctua fan controller would not work since it needs PWM signal as well and I need automatic fan control.
Good reasons. :thumb:
Thanks for explaining that.
 
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