24 _and_ 12V fans on the same system



  • So, I am converting my Delta from 12V to 24V because [reasons].

    Previously: 12V PSU, 12V fans (Two chassi fans, one fan for heatbreak, and 12V Berd AIr pump on external MOSFET).

    Planned upgrade: 24VPSU, 24V Berd Air, 24V Heater cartride and then I thought i would just use a 12V stepdown for the fans.

    Then I read that BerdAir wants a high PWM frequency to run cool. But my MOSFET does not appear to like anything over a few kHz. It become "on or off" as i go over about 5kHz.
    I read that it is safe to use a 24V Berd Air directly on a fan output (1.03 version of Duet2 WiFi). But then I will not be able to use my 12V existing fans. And since they are Noctuas I would like to keep them.

    So, what would the recommendation be in this case? Could I be creative with my as of yet unused extruder heater output? I will assume that it has no built in flyback diode?

    I have searched the forum, and seen many split voltage setups, but nothing that appears to fit my scenario.

    Any help appreciated.


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