Splitting PWM signal from fan for dual fan upgrade
Hi there!
I recently stumbled upon this dual fan upgrade:
https://www.prusaprinters.org/prints/14312-mk3-dual-fan-mount
https://www.thingiverse.com/thing:2978427
The author in thingiverse suggests just to connect the red (+12V or 5V, idk) and black (ground) cable of the second fan to the previous one, resulting in it beeing always on. While this might be an option for PLA is not really good for PETG. If I connect the yellow (PWM signal) I get some fan issues while printing. I can just continue if I'm fast enough by pressing "continue" in Octoprint but thats not really a long-term option.
I'd really like to use this mode permanently without having troubles when printing PETG from time to time.
Does anyone have a smart solution for this?
Cheers
RE: Splitting PWM signal from fan for dual fan upgrade
the three wires on the fan are
Red + volts
Yellow Tachometer output
Black -volts
at rest,
Red is 5 volts
Tacho has no output and
Black is floating...
During operation
Red is 5volts,
Tacho returns a square wave signal, relative to the fan's actual speed of rotation,
Black is Pulsed LOW (Towards Ground) by the controller.
If you connect a second three wire fan
Using ONLY the RED and Black wires of the second fan, your printer will monitor the remaining yellow wire and it will pulse the black wires to raise or lower the fan speed as normal.
IF you connect both yellow wires as well, the tacho output from both fans will try to signal the controller, but the signals will interfere with each other, and you will get an error message (which I believe is what is happening now.
there are other fans with 4 wires (Which to the best of my knowledge PRUSA DONT USE , usually used on computers where the
Red is + volts
Black is -volts
White or Yellow is the fan tacho output, and
Blue is the incoming PWM instruction signal from the PC Motherboard
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK