Pwm fans...pulsing noise.Solution?

Hi at all.
I've change the stock fan with 2 fans.
The problem it's the noise generate by fans at low speed.
For explain it, it's like the fan receive a pulsating voltage at low frequency,and this cause a spin that induce the fan a vibration and cause the noise.

Maybe I can post a video to explain what i mean?

There's an option in the Configuration.h file ..

//#define FAST_PWM_FAN

Try uncommenting it and recompiling, see if it helps.

Ok I try to do it.
If I uncomment fast_pwm_fan, I have to comment fan_soft_pwm? (Now it's active)

no no, keep that if that's what you're using.

Ok.I've try.But it's the same....The fans pulsing

oh, hmmmm

Yes, try commenting out FAN_SOFT_PWM

Edited 1 time(s). Last edit at 05/22/2019 12:52AM by Pippy.

Well....I try to eliminate fan_soft_pwm
There is less noise,but now I think I've work on pwm_scale and or dither,cause till 50% fans don't move

Edited 1 time(s). Last edit at 05/22/2019 07:11AM by zonalimitatore.

Solved.
I use only #define:

Fan_soft_pwm
Soft_pwm_scale 3
Fan_min_pwm 26 (cause at 0 fans don't spin)

Finally I've fans work well and without "pulsating noise" at every speed

Hello, i using extruder auto fan too.
And print cooling fan very noise with pwm. I uncomment fast_pwm and the noise less but my fan start %30
and i have 2nd fan for extruder auto fan but the noise very loudly on this fan, and dont less whatevet i do.

#define E0_AUTO_FAN_PIN 4
#define EXTRUDER_AUTO_FAN_TEMPERATURE 55
#define EXTRUDER_AUTO_FAN_SPEED 128 // 255 == full speed

#define FAST_PWM_FAN
#define FAN_SOFT_PWM
#define SOFT_PWM_SCALE 0

and orange lines;

MARLİN\Marlin-bugfix-2.0.x\Marlin\src\module\temperature.cpp: In member function 'void Temperature::init()':
MARLİN\Marlin-bugfix-2.0.x\Marlin\src\inc\Conditionals_post.h:1686:43: warning: overflow in implicit constant conversion [-Woverflow]
MARLİN\Marlin-bugfix-2.0.x\Marlin\src\module\temperature.cpp:1632:50: note: in definition of macro 'SET_FAST_PWM_FREQ'
MARLİN\Marlin-bugfix-2.0.x\Marlin\src\module\temperature.cpp:1638:106: note: in expansion of macro 'FAST_PWM_FAN_FREQUENCY'
MARLİN\Marlin-bugfix-2.0.x\Marlin\src\module\temperature.cpp:1822:5: note: in expansion of macro 'INIT_E_AUTO_FAN_PIN'

what should I do? :/

Edited 1 time(s). Last edit at 11/30/2022 03:18AM by yucelll.

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[elektromanyetix.com]

Ignore the orange lines - those are just warnings.

You may have to buy low noise fans. I'm glad I did.

#define E0_AUTO_FAN_PIN 4
#define EXTRUDER_AUTO_FAN_TEMPERATURE 55
#define EXTRUDER_AUTO_FAN_SPEED 128 // 255 == full speed

#define FAST_PWM_FAN
//#define FAN_SOFT_PWM
#define SOFT_PWM_SCALE 0

this way there was a real silence in the printing fan. there is only the sound of the air.
But the extruder automatic fan is making a lot of pulsing noise.
I tried with many mosfets but the problem is not solved. Probably something software related.
Is there anything else I can do for extruder_auto_fan? Or do I need to put something like a voltage reducer in between?

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[elektromanyetix.com]