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UNDER CONSTRUCTION

Remove Fan PWM Noise

Author: AETEK

The changes shown here require knowledge in the field of electrical engineering and can overwhelm normal users. Also, I would like to point out possible dangers that exist in certain interventions. All adjustments have been checked for function.

Difficulty: Advanced

What is this about?
https://en.wikipedia.org/wiki/Pulse-width_modulation
PWM (Pulse-width-modulation) is a technique to control the performance of e.g. a fan (as in the A5). As a side effect, noises can be emitted through the fan due to the pulsating current. This refers to noises that cause the propeller to vibrate due to the electric coils. Noise can also have other causes. Worn bearings are often the cause. The PWM filter does not help against this kind of interference noise. If the fan is mechanically good and there is still noise, then it is the PWM frequency emitted by the fan. The Marlin firmware offers several options to reduce noise by software. I have checked all these options. Unfortunately, hardly anything has changed in the result. That's why I developed this hardware solution. It is specially tailored to the fans of the A5. If you're already there, then you can build the circuit twice. One for the Cold End fan (A5 upper) and one for the component cooling fan (A5 lower).

Note:
Just as the A5 is delivered from the factory, only the component cooler is PWM controlled. The Cold End Fan is directly connected to 24V. Here the filter can not filter PWM noise. In another post, I show how to regulate the cold end fan via PWM and thus gets quieter. Then the filter helps to prevent PWM noise for the Cold End fan.

Required Electrical Parts (for one fan)