PC motherboard: PWM 4 pins to 3 Pins digital converter.

[Mechatrommer]

The speed of a 3 pin fan header can be adjusted. The mobo bios must be set to manual fan speed and an app like Speedfan used to control the speed of the fans. The third pin is used for tach only. The speed on the 3 pin fans is controlled with voltage rather than pwm.

simple but nice explanation! i was just confused when Kiri said, its 12V constant only and cannot be controlled. now its become clearer that a "voltage averager" can do the job. and oppps! i dont have any schematics... sorry

[scrat]

simple but nice explanation! i was just confused when Kiri said, its 12V constant only and cannot be controlled. now its become clearer that a "voltage averager" can do the job. and oppps! i dont have any schematics... sorry

He was only saying an obvious thing: if you directly connect a 3-wire fan to a 4-wire output the fan will be at 12V supply all the time, since the PWM control isn't connected. They've certainly made the 4-wire connection like that for compatibility reasons.

[PeterG]

CPU fans generally use a 4 pin header, case fans use a 3 pin header. The believe the 4 pin header is used for the cpu because it is easier for the bios to control the fan speed accurately and also detect failure.  Case fans do not require such control. Most 3rd party cpu cooling fans come with adapters when required to connect to either the 3 or 4 pin header. Better quality cpu fans come with a 4pin connector, some with there own fan speed controller.

Regards

[Mechatrommer]

@scrat: maybe its just my ignorance

[scrat]

@scrat: maybe its just my ignorance

Or you're just too angry with Kiriakos
"     "   "    "     "   inattentive, like me.

[Mechatrommer]

Or you're just too angry with Kiriakos
"     "   "    "     "   inattentive, like me.

no dont get me wrong, i like him! he is one of the cool guy with alot to talk ... or complaint
ps: and he can transfer a thread from low energy level, to "high" energy one, didnt you noticed?
ps: if i angry at him, i will simply ignore him and let him blow his MB the sh*t out!

[Kiriakos-GR]

CPU fans generally use a 4 pin header, case fans use a 3 pin header. The believe the 4 pin header is used for the cpu because it is easier for the bios to control the fan speed accurately and also detect failure.

That's True , and I had emailed Gigabyte , asking about the actual RPM scaling against temperature raise.
As it looks that the PWM controller , it will offer an base voltage (min rpm to 700-800 INTEL fan) ,
and the controller it will increase the speed of the fan if the temperature raise above an specific limit.

The reply that I got from Gigabyte was , that if the CPU temp gets more than 40C , the fan will work at full rpm ( 1700) , and if it temp  drops down, the fan rpm will fall back to the base minimum (700-800 ) .

I bet that this was an quick answer ...  If I believe this .. it translates to, that the PWM its an stupid non scalable way about handling speed of motors .  

I know that shafri hates me , because I am an Olympus digital fun boy, all the Canon fun boys are the same..    

 
  

        

[Mechatrommer]

I bet that this was an quick answer ...  If I believe this .. it translates to, that the PWM its an stupid non scalable way about handling speed of motors .  
I know that shafri hates me , because I am an Olympus digital fun boy, all the Canon fun boys are the same..    

no you are utterly wrong about the PWM. makes me thinking, the actual circuitry that you are looking for might resides in the 4pin fan, and most likely the fan is the DC, its just the PWM->DC converter already embedded in side it.

and why you still understand me wrongfully?! i'm a practical man, i dont care what brand it is! i only care what comes out of it, for the sake of humanity (technologically and psychologically)! i'm not a "fun boy"! and i dont care if you are!

ps: I choose Canon because it serves my purpose! I wish i could convert to Nikon, but there is no turning back anymore at least not... for now.
fyi: I'm building TTL remote flash trigger compatible to most popular camera brand (TTL capabled), and i would loved to include the Olympus, its just i dont have the neccesary gear to R&D.
here! if you dont believe me! need to register i think to see the pictures.

[sonicj]

canon is cool for chdk.

[Mechatrommer]

ooo! i didnt notice there is "Canon Hacker's Development Kit"! o well, i will not bother! since my machine is more than twice the price of rigol, if it broke, i'm not sure someone will be able to fix that other than Canon Service Centre. as i said... it serves my purpose already

[scrat]

I'm pretty sure things on that famous fan controller work like this:

- The mother-board decides (in its maternal wisdom) at what speed her son /the fan /has to run (a little bit of verse).
- The speed controller on the motherboard measures fan's speed from the tacho signal: frequency of tacho signal = rotations/sec.
Worst issue here is the motherboard speaks English, while tachos are Mexican, and so they only speak Spanish.
- As in all feedback regulators, if the frequency of tacho signal is lower than the desired spinning rate, PWM duty-cycle will be increased, while it will be decreased in the opposite case.
- The 4-wire fan controller takes the PWM signal and 12V supply. With the 12V supply it feeds the control electronics (minimal, but there is one, with 1 to 3 Hall sensors to detect rotor position). A PWM switcher just executes chopping (slicing) of the 12V supply, just applying the PWM to it, ending to have a 12V square wave with the same shape (duty-cycle at least) as the input PWM coming from the motherboard fan controller. The control electronics on the fan then gives this PWM signal (power) to the motor, connecting in the proper direction 2 of the 3 phases at a time, depending on the rotor position (sensed by Hall sensors, since the rotor has a magnet). The fan is in fact a BLDC synchronous motor.
Hall sensors could be avoided (sensorless BLDC), but I doubt they do it into a computer fan, since it will require using a more complex controller (this is usually done with an MCU).

As I said I'm not sure at 100% of this, as I never opened one of those, but this is the explanation I give myself, and it seems quite straightforward.

[Kiriakos-GR]

Interesting explanation that targets about wide understanding for the masses .

But the true hierarchical pyramid goes differently.

Intel builds the CPU  and the primary motherboard design,
with all the extras that would help the specific CPU design, to be functional and safe .
    
Intel selects the CPU fan specs : rpm / duty cycle / electrical requirements.

Intel sends white papers of the original design to all the motherboard manufacturers,
so to follow the original design unchanged !!  ( For compatibility reasons mostly about the supplied Intel stock cooler and motor )

On this document http://www.formfactors.org/developer/specs/4_Wire_PWM_Spec.pdf
page 14 , its all clear about the base theory.


Result : the PWM circuitry of any motherboard that supports an specific INTEL CPU family are all alike.
a) Motherboards that supports both CPU generations 65nm & 45nm  , are capable probably from Bios,
to supply an different duty cycle info, so the motherboard to correspond correctly , with the two versions  of the INTEL stock coolers. ( different motor specs )

So far I was aware, the fan speed detection wire (3 pin), was there to just trigger an Bios alarm ,
about damaged CPU fan , and nothing more.

( And so dear shafri , its not the motherboards brand that makes any difference about PWM )

About the 3 pin  CPU headers and motors (INTEL CPU coolers) :  
a) Its another INTEL design , that was followed some years back by the motherboard manufacturers,
and had as main target to support again the INTEL CPU coolers.
( this design it was had his own logic (automated control circuitry)  able to be bypassed and controlled also by software , the famous speedfan software reviled that it was an scalability  " min to max rpm " of five steps.

The marriage of  PWM 4 Pin  with the automated control circuit of  3 pin fans :    
There is no such thing , the motherboard manufacturers in order to do that, they need to build both speed control circuits , plus an setting about manually activation from Bios.
By having the PWM one, active by default .
This dual solution gets the cost up , and it starts to not be widely in use any more.

Today : Every computer owner , who cares to add an third party cooler  ( heat-sink fan compo)
needs this  PWM--> DC board , so to be able to use and choose an fan , with out to be limited,
from the current few PWM, aftermarket choices.

There is few high quality 3 pin fans , that they do worth having them.
And there is no equivalent in the PWM marketed ones.  


Additional info about the PWM signal.
It can used to trigger more than one fan , but its one fan, it must be connected on different header.
My motherboard has two PWM headers , and another two 3 Pin type ( case fans)    

( bad news from the German that I ordered my controller, he will had to delay shipping,
because he had no stock of something in the list ... but promised that I will receive an extra gift)
Estimated arrival about 12 of November.    
          

    
  


  

 

[sonicj]

ooo! i didnt notice there is "Canon Hacker's Development Kit"! o well, i will not bother! since my machine is more than twice the price of rigol, if it broke, i'm not sure someone will be able to fix that other than Canon Service Centre. as i said... it serves my purpose already

its only for their P&S cameras afaik. the "firmware" is non-invasive. it runs on top of the stock firmware so chances of killing your camera are nil. if you are into creative photography, i highly suggest giving it try. you can pick up a compatible model for less than $100 on ebay. the motion, intervalometer, and RAW scripts allow for some pretty amazing shots with a consumer P&S.



sorry for the threadjack! at least its about cameras!  carry on!
-sj

[Mechatrommer]

nice workout Kiri! kudos!
@sonicj: thanx 4 d info.
ps: looking at the vidz reminds me of Karl von Moller's, when will his SoE be out? hmmm.

[PeterG]

I am happy with my EOS 500D for now.

Yeah ok , i am a canon fan.

Regards

[Kiriakos-GR]

Yeah ok , i am a canon fan.

How many rpm ?      

[TheDirty]

But the true hierarchical pyramid goes differently.

Intel builds the CPU  and the primary motherboard design,
with all the extras that would help the specific CPU design, to be functional and safe .
    
Intel selects the CPU fan specs : rpm / duty cycle / electrical requirements.

Motherboard manufacturers only uses the basics of the Intel original reference design now, it's not a straight copy.  They definitely do not use the reference design for fan control.  Speedfan constantly has to update itself to handle all the different fan control methods used by different manufacturers.

Many newer motherboards allow both PWM control for 4 pin fans or VDC control for 3 pin fans using the same 4 pin connector.  The Gigabyte can select Auto Mode, PWM mode (4pin), or VDC mode (3pin) from within the BIOS.

[Mechatrommer]

The Gigabyte can select Auto Mode, PWM mode (4pin), or VDC mode (3pin) from within the BIOS.

ahhh! software mod!

[Kiriakos-GR]

The VDC control for 3 pin fans , by just software control, from windows, its not something that great.

Yes I agree that some motherboard manufacturers, does not use the reference design for fan control,
but they do that,  so to use alternative chips = cutting corners & cost.  


Mark , how much it cost ?  just the part list of your above design ?

[TheDirty]

Using alternate fan control methods isn't cutting costs or methods at all.  Some of the fan control on non-Intel motherboards far surpasses that of Intel reference designs.

The design I used uses an Analog ADT7460, looks like they sold this line to ON Semi.  In theory you can connect these directly to the SMBus on your motherboard and talk to it with a driver and you wouldn't need any other interface hardware.
http://www.onsemi.com/PowerSolutions/parametrics.do?id=2126

In my design I have the ADT7460, with a cheap microcontroller talking to it over I2C and I have a FT232RL to allow the PC to talk to it to reprogram the temp/fan speed maps and to get the current fan speed data.  Looks like the ADT7462 is $8 and the FT232RL is $4.50...  with the uC and MOSFETs, I would say it's about $20.  If I was doing it now, I'd use a uC with integrated USB, maybe I'd get rid of the ADT chip all together. 

[Kiriakos-GR]

By just looking the PCB that you had made ,
I had the feeling that this was what I am looking for.
But, by looking in use SMT parts , I lost my interest about replicating this design.

Even so, I feel the need to congrats you, because you got that far.  

[Mechatrommer]

But, by looking in use SMT parts , I lost my interest about replicating this design.

there is always DIP replacement?

[alm]

there is always DIP replacement?

As long as they're old parts, few new parts are brought out in DIP anymore. If you want to use modern parts, it's hard to ignore SMT.

[Mechatrommer]

As long as they're old parts, few new parts are brought out in DIP anymore. If you want to use modern parts, it's hard to ignore SMT.

then you should award Reply #1 as a winner Kiri!

[Kiriakos-GR]

My brain had stuck to this NANOXIA PWMX ..

How its possible, no one to have even open one, and take some pictures !!

 
( I just finished the build of my new quad core computer,
I had to format and all , but now its just perfect " super fast and silent " ,
but I like the idea of having an ace under my sleeve for the Summer time.    )