Fan with multiple voltages
fbunel last edited by fbunel
First of all, thanks a lot to everyone in Duet for the wonderful work ! I love this board.
I'm just facing a simple problem about connecting fans. Here is a description.
I run my duet with a 24V PSU.
I also have a 12V/5V dual PSU for other things.
The two V- of the PSUs are connected.
Then I have multiple fans :
- An always on fan to cool the duet (12V)
- A temperature controlled fan for the hotend (12V)
- A part cooling fan for printing PLA (24V)
Since I have one fan which is 24V and the two others that are 12V, I decided I will wire the V_fan pins for the fans to the 12V from my PSU.
So I attached the 12V to the V_fan and I connected my two fans to two available slots (FAN1- and AlwaysOn). They are working fine (the always on is always on and the other one starts when I heat the hotend).
Now I have the 24V part cooling fan left to connect and I want to control it.
So what I did is I connected the black cable of the fan to the FAN0- pin and the red cable directly to the V_in pin that is nearby.
The problem in the end is :
When I set the part cooling fan (24V) to 100%, it works. But when I set it to 0%, the fan still spins a bit and my PSU does a wierd noise that I don't like.
What I have tried :
- Connect my 24V fans to the 12V like the others : it works and is controled, but I only have half the power on this fan
- Connect the red cable of the 24V fan directly to the PSU : same problem as above : wierd noise and it runs even at 0%.
I read this post : https://duet3d.dozuki.com/Wiki/Connecting_and_configuring_fans#Section_Using_12V_fans_when_VIN_is_24V
and realised you suggest doing the opposite (option 3 : connect the 24V to the V_fan using a jumper between V_IN and V_Fan and connect the two other fans to the 12V PSU)
I don't understand what this would work better than what I did.
Thanks a lot.
fbunel last edited by
On this old post I found :
@dc42 which is the god of this forum apparently says :
"One thing I should mention for the benefit of future users. When the new Duet WiFi 1.02 boards arrive, they will have flyback diodes to V_FAN included. Then you will need to ensure that V_FAN is the highest voltage that any fan will be connected to. So your scheme of setting the V_FAN jumper to VIN connecting a fan between +5V and a PWM FAN- output would still work. But the reverse scheme of setting V_FAN to 5V and connecting a fan between +12V or +24V and a PWM FAN- output would not."
So I guess this is the reason for my problem. Can anyone confirm ?
Do you think I did some damages to my board or my PSU running this wrongly ?