Author: AETEK

The changes shown here require knowledge in the field of Arduino IDE, Marlin and 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). Just as the A5 is delivered from the factory, only the component cooler (A5 lower fan) is PWM controlled. The Cold End Fan (A5 upper fan) is directly connected to 24V and constantly makes annoying sounds. I will show how to automatic control the Cold End Fan (A5 upper fan) via PWM and thus gets quieter. Thanks to the PWM control, the Cold End fan runs slower and also temperature-controlled. The Marlin firmware only turns on the fan when needed. When the hot end has cooled to 50°C, the cold end fan will shut down. As a result, the upper A5-fan gets noticable quieter. Unfortunately, there is a side effect. Due to the fan control with PWM, the fan generates additional PWM noise. To achieve the maximum noise reduction, it is necessary to add my PWM filter. The mentioned hardware-optimizations can be combined in one adapter cable.

Required Electrical Parts (for one fan)

• 1 x Diode 1N 4007
• 1 x Resistor 100 Ohms 3 Watts
• 1 x Electrolytic Capacitor 220uF 35V
• 1 x 2-Pin male plug for building a plug-in-adapter.
• Some cable and heat shrink

The hobbyist will most likely have the parts in the tinker box.

Please note the polarity

Status 6. July 2018: Working…