pylon:
If you simply use analogWrite() the PWM frequency is set to 1kHz which is not sufficient for operating the PC fan. But you definitely can achieve the needed 25kHz signal with the hardware of an Arduino UNO.
How would I go about achieving the 25kHz signal without using analogWrite()? I will have 5 separate fans, each will need to be controlled separately depending on a switch status and readings from one of two temperature sensors. Would it be possible to control all 5 fans from the same arduino? How would I control them? Thanks
pylon:
I would expect your 3D printer to already contain some sort of 12V power supply. If ever possible I would use that one.
Unfortunately I need to keep these separate from the printers. The printers will be powered on and off at times when the fans need to remain active. Equally, there will be times that the printers need to be easily removed from the enclosures.
Thanks for your help by the way.