Always On Fan Voltage Selection?



  • Morning All!

    I was wondering if someone could point me in the right direction. I have an always on 24v fan to cool the electronics. It is currently connected to the always on fan connection on the duet wifi however it's very loud (obviously). I know you can select voltages but can it be done for the always on fans only? I wanted to run it at 12v or possibly 5v? Maybe even switch it out for a larger 120mm 12v and run that at 5v to get it nice and quiet but maximise the air flow?

    Thanks.


  • administrators

    Some possible solutions:

    1. Do you really need to cool the electronics? You may not need to, especially if it is a Duet WiFi with the motor current set at 1.5A or lower.

    2. Do you have a spare controlled fan output? If so, you can connect the electronics fan to that, then you can set the PWM.

    3. Connect a resistor in series with the fan to slow it down. Try 100 ohms 2W.



  • Thanks dc42.

    OK so:

    1. All motors are set below 1.5A, in fact they are all below 1A, maybe cooling is not required then. Whats a decent temp for the CPU?

    2. Nope no spare controlled inputs. Dual heat sink fans and the print cooling fan take up the connections.

    3. Definitely an option.

    Are there any more sources for 12v/5v on the board that are safe to use? I have the exp 5v running the BLTouch so that is not available.



  • Hi,

    I use a noctua 60mm 5V FAN to cool the board, it's very quiet, I've connected it to a 5V output on the duet wifi board. (I started with the panel due connector now I get it from the expansion one) (see https://duet3d.com/wiki/Duet_WiFi_wiring_diagrams )

    i also tried noctua 40mm 5V fan to cool down the hotend, they're not powerful enough.



  • How about a 5v fan running off a 3.3v and GND from the EXP is that a possibility?


  • administrators

    @Syko_Symatic:

    Thanks dc42.

    OK so:

    1. All motors are set below 1.5A, in fact they are all below 1A, maybe cooling is not required then. Whats a decent temp for the CPU?

    2. Nope no spare controlled inputs. Dual heat sink fans and the print cooling fan take up the connections.

    3. Definitely an option.

    Are there any more sources for 12v/5v on the board that are safe to use? I have the exp 5v running the BLTouch so that is not available.

    Can you connect the dual heatsink cooling fans in parallel?

    The other source of 5V is the PanelDue connector.



  • I have a panel due connected (which is amazing by the way). In fact, while I am on the subject, the whole package is fantastic and I can not praise you guys enough I have been recommending it to anyone and everyone who will listen.

    I suppose I could but then they would both be running when using a single head. Not a problem really but I maybe trying to solve an issue that doesn't exist. What is the recommended temp for running the Duet Wifi? It currently rests around 28deg (CPU).


  • administrators

    I didn't realise you were using two print heads - I assumed that you only had one because you only mentioned one print cooling fan.

    First of all, you need to calibrate the CPU temperature to get a reasonably accurate reading. I've just written a wiki page on this, see https://duet3d.com/wiki/Calibrating_the_CPU_temperature.

    Preferably, during printing the calibrated CPU temperature should remain below about 50C and lower if possible, although this isn't a critical figure.



  • @dc42:

    I didn't realise you were using two print heads - I assumed that you only had one because you only mentioned one print cooling fan.

    First of all, you need to calibrate the CPU temperature to get a reasonably accurate reading. I've just written a wiki page on this, see https://duet3d.com/wiki/Calibrating_the_CPU_temperature.

    Preferably, during printing the calibrated CPU temperature should remain below about 50C and lower if possible, although this isn't a critical figure.

    Funny, printing in my garage in the summertime I'll be seeing 50C ambient temps. When I replaced the chip I only went with the 85C rated model, she'll be just fine.



  • Thanks all. Will follow the guide dc42 and then monitor it.



  • BTW, you can buy a cheap buck converter off of amazon or something and run it at 5v or whatever voltage you need. The cheap ones can run a few fans. This would also allow you to slightly overvolt the noctua if necessary (be careful).


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