fan PWM frequency

venkel

Hi,

I have these fans for print cooling: XYJ24B3010H from XINYUJIE electronics, but they refuse to turn on any other setting than 100% (M106 S255).

Other type of fans on the same connection can be modulated. The board output voltage is OK, for example M106 S128 gives 13V and M106 S255 gives 24V.

In the configuration.h file setting PDM instead of PWM reduces fan power, but still only works at 100%.

The fan supplier does not react to my request for info.

Changing to another type of fan is not preferred, so I'm looking for a way to control the PWM speed in Repetier. Maybe changing the frequency could help.

Repetier

Frequency is only 16hz. You need to use simple cheap fans with only power to have them work. 3 pin fans want a high pwm frequency on 3rd pin i think. Also many fans only woek over x% and stand still on less power.

venkel

Well, that's a nice problem if I want to keep using 24V and decent quality fans.

Is there any other way, with a extension board maybe?

By the way, my fans are of the 2-pin type.

RAyWB

simplest way is to add capacitor parallel to fan. around 2 to 10 microFarads should be ok.
take care on polarity!
had same problem with some small fans.

venkel

Ah! We were thinking the same way, but had not calculated a value yet. Thanks.

RAyWB

btw, the fans i have dont even start at 50% pulse width and 900 Hz PWM frequency. so adding the cap is nothing else than
building a kind of step down converter.

venkel

My fans are 24V 0,08W, and yours? How to calculate the desired capacity?

venkel

Excuse me, 0,08A that should be.

venkel

Repetier said:

Frequency is only 16hz. You need to use simple cheap fans with only power to have them work. 3 pin fans want a high pwm frequency on 3rd pin i think. Also many fans only woek over x% and stand still on less power.

But seriously, I'm doing a €30.000 project. Is it actually impossible to change to higher frequencies, or is it just not implemented?

RAyWB

i just tried ;-) and as far as i know higher pwm is not possible. which hardware do you use?
from my experience problem appears mostly on brushless fans, depending on their internal electronics.
they cannot handle pwm on small pulsewidth.
And as repetier already mentioned, cheap fans work best

venkel

It would be a shame to use cheap fans. How can I explain customers to bare with noise?

But I'll be experimenting tomorrow with higher PWM and some capacitors.

Other option is to use a resistor and 12V fans. Freaks me out but I need a solution.

venkel

With Sunon fans 12V in series same effect.

How do I get out of this mess?

RAyWB

are you shure you use pwm capable pin? what hardware do you use?

venkel

I have the RADDS 1.5 board with Arduino Due.

venkel

<font face="Arial, Verdana">A colleague wrote me some alternative lines in the commands.cpp file:</font>

From ine 1777:

#if FAN_PIN > -1 && FEATURE_FAN_CONTROL

case 106: // M106 Fan On

if(!(Printer::flag2 & PRINTER_FLAG2_IGNORE_M106_COMMAND)) {

if(com->hasP() && com->P == 1)

// setFan2Speed(com->hasS() ? com->S : 255);

analogWrite(9, com->hasS() ? com->S : 255);

else

// setFanSpeed(com->hasS() ? com->S : 255);

analogWrite(8, com->hasS() ? com->S : 255);

}

break;

case 107: // M107 Fan Off

if(com->hasP() && com->P == 1)

setFan2Speed(0);

else

setFanSpeed(0);

break;

RAyWB

did that solve the problem?

Repetier

Thatonly works on very few boards and pins, You should better put that in setFanSpeed and setFan2Speed since these are also called from other functions!

venkel

No, did not solve anything. And yes it's crappy code, will remove it.

venkel

But still, the fan problem is there. I might need to design an extra analog output board. Quite annoyed to be honest.

ecj

Use Marlin!