Wiring separated PSU for Duet and Heated Bed

  • Hello eveyone,

    I know the question has been asked several times.
    To begin, thoses posts have been a great help and I would like to thanks all the contributors :

    Powering a printer with 24V has many benefits especialy for 0.9 stepper motors but it come also with downside for running 12V heated bed and fans.
    One a the solutions is to use two separate power supplies, a 12V and a 24V.

    About my printer
    Cartesian printer
    24V Power supply

    Printer Parts

    Can you give me a feedback on the schem bellow espesialy about :

    • the wiring of the 12V powering fan based on this comment :
      If all your fans are 12V, you should connect VOUT+ (the 12V from the regulator) to the middle pin (pin 2) of J3 (Fan Voltage Select) - DO NOT CONNECT ANYTHING to the other two pins (pins 1 and 3). Then connect your fans normally to the fan headers - they will all be 12V, whether switched or unswitched.
    • the wiring of the emergency button (do I need a pull-up/down resistor?)


    (download at full size here)

    I hope this sketch will be a clear help to people in the same case of me

    Thanks by advance for your help!

  • administrators

    The emergency stop button should be connected to the two outer pins of the endstop connector.

    You could omit the 12V step down converter if you common the negative outputs of the two power supplies and feed +12V from the bed heater power supply to the centre pin of the fan voltage selector block.

    The Mosfet board isn't needed if you connect both PSU negative outputs to the negative VIN terminal of the Duet, and connect the bed heater between the positive output of the bed heater PSU and the BED- terminal of the Duet. If you do that then the bed heater LED will always be lit (brighter when the bed heater is turned on), but that won't do any harm.

Log in to reply