I am having a problem with my part cooling Sunon maglev fans, they will not rotate when the PWM is lower than 80% in default conditions and 60% when using the FAN_SOFT_PWM and SOFT_PWM_SCALE 0 directives. Is there any way to make them work with a lower value? Maybe lowering the frequency even more, as to get an occasional blip? https://reprap.org/forum/read.php?415,863013,863013#msg-863013 Tue, 15 Sep 2026 23:14:54 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?415,863013,863033#msg-863033 https://reprap.org/forum/read.php?415,863013,863033#msg-863033
You could use a flyback diode and a series inductor as a low pass filter, but in order to keep the inductor reasonably small you need to increase the PWM frequency to several 10s of kHz.

Some people use a parallel capacitor to partly smooth the PWM, but this risks blowing the mosfet because of the high peak current when the mosfet turns on and the capacitor charges.]]> dc42 Firmware - Marlin Sun, 24 Nov 2019 04:19:03 -0500 https://reprap.org/forum/read.php?415,863013,863032#msg-863032 https://reprap.org/forum/read.php?415,863013,863032#msg-863032 Ohmarinus Firmware - Marlin Sun, 24 Nov 2019 03:23:44 -0500 https://reprap.org/forum/read.php?415,863013,863018#msg-863018 https://reprap.org/forum/read.php?415,863013,863018#msg-863018
So a low-pass (or averaging etc.) filter solves it? Wow, that is the exact opposite of what I would expect, in fact, by experience, usually these fans will stop working below a given (usually high) DC voltage. But I will try you suggestion anyway.]]> bowzee Firmware - Marlin Sat, 23 Nov 2019 20:29:24 -0500 https://reprap.org/forum/read.php?415,863013,863017#msg-863017 https://reprap.org/forum/read.php?415,863013,863017#msg-863017
Google putting a capacitor over the power wires]]> Dust Firmware - Marlin Sat, 23 Nov 2019 19:48:52 -0500 https://reprap.org/forum/read.php?415,863013,863013#msg-863013 https://reprap.org/forum/read.php?415,863013,863013#msg-863013 bowzee Firmware - Marlin Sat, 23 Nov 2019 18:06:57 -0500