Additional Fan Inputs - Duet 3 Mini 5+
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I have exhausted my two 24V and two 12V PWM fan inputs using a chamber fan, board fan, liquid cooling fan, and layer fan. i have a need for one more 12V fan input. is there any way i can repurpose another part of the Duet 3 Mini 5+ to achieve a 12v PWM input? not critical, but just curious if there are any options.
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Can any of your fans be converted to always on fans?
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@RogerPodacter are you using the second hotend connection?
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@jay_s_uk yes i'm actually using my spare heater for another PWM fan already. here is a pic of my board setup. I guess the only option i was curious are the 5V IO (but using the negative only for PWM) or the temp daughter board or one of those similar connections.
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@RogerPodacter you may be able to use one of the output pins to activate a relay to power a fan.
or maybe consider to moving to a CAN-FD toolboard for your hotend, freeing up someone of the mainboard pins -
@jay_s_uk basically i have a 3 pin 12V liquid cooling pump, 0.8 amp. i wired positive directly to the power supply, but can i use the negative and RPM pin to the 24V fan pins? basically i am thinking since the 12V is lower than the 24V fan connectors it would be ok. But i dont know electrical that well. is the negative pin where the current returning would overload the board, or is that the positive?
i am likely using about 500-600 mA of the 800 mA already available for the 12V side. does the 24V fan pins have a similar current limit?
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@RogerPodacter the overall 12v limit comes from the onboard regulator (assuming you're using a 24v PSU).
The 24v fan outputs will be limited by how much the MOSFETs can switch, which I think is around the 1A mark but I can't remember the exact part number of the ones fitted.
As you say, all the PWM outputs switch on the negative side (which is where the regulator is) so the limit is the MOSFET fitted. -
@RogerPodacter the simplest options are to use a mosfet driven by the output pin on one of the IO connectors, or add a tool board to your system. You can see which IO connectors support PWM at https://docs.duet3d.com/Duet3D_hardware/Duet_3_family/Duet_3_Mini_5+_Hardware_Overview#io-headers.
