12V devices on a 24V powered Duet Ethernet



  • Hi to all

    I am new on the forum as I just received my brand new Duet Ethernet yesterday.

    I am 3D Printing for more than a year on a custom Mankati Full-scale XT Plus. As of this morning, the printer wasn't stock anymore for months except the motherboard, but it nearly died from overheating due to a low quality PSU chinese (ADC is faulty).

    The previous board was delivering 5V, 12V internally from a 24V PSU so :

    • fans, LED lightning and capacitive sensor are 12V - I have a board to decouple the NPN NO sensor signal from power, so no problem to use an endstop on +3,3V
    • logic in under 5V for all the switches.
    • steppers and bed are 24V
    • I haven't measured for the temp sensors, but I don't care as I'm upgrading to PT100 with the convenient board.

    I have already exchanged my PSU, just before realizing the board was faulty by a 24V 500W TDK-Lambda.

    I have bought a small 24V to 12V dc converter to power the 3 pwm (fans) and 2 always on (led and probe) from digikey : https://www.digikey.fr/product-detail/fr/cui-inc/PYB30-Q24-S12-U/102-3263-ND/4477521

    Based on the other topics I should connect the +12V of the converter to the V_FAN or the + of each fan and the - of the fans to the ground of each board's pwm and always on connectors.

    But where should I connect the ground of the dc convertor ? Directly to my 24V PSU ground ?

    Again sorry for the newbie's question.

    Your support will be much appreciated !

    David



  • I did this very thing yesterday to get 12V fans on a 24V-powered Duet Ethernet. You can source 24V and GND from your PSU (or anywhere else that is convenient) to power the regulator, and connect the +12V output of the regulator to the middle pin of V_FAN (removing the jumper that is present of course). There is no need to connect the GND output of the regulator anywhere.

    Cheers,
    Ben.


  • administrators

    @V3DPrinting:

    Hi to all
    Based on the other topics I should connect the +12V of the converter to the V_FAN or the + of each fan and the - of the fans to the ground of each board's pwm and always on connectors.

    Correct.

    @V3DPrinting:

    Hi to all
    But where should I connect the ground of the dc convertor ? Directly to my 24V PSU ground ?

    Yes, that is also correct.

    A note on the post above by fulg: if your DC-DC converter has ground connections on both the input and output sides, they will be connected together within the converter, so you need only connect the input ground terminal to anything.



  • Thanks a lot for these valuable inputs.
    Indeed my DC - DC converter has ground connection on both input and output. Connecting the input was obvious, the output ground not.



  • I finished wiring and testing this morning.
    I had an issue yesterday with the DC DC converter as it is an isolated one. No V+12V on V_FAN.
    Finally solved it by making a common ground between input and output of the converter.
    It is not anymore isolated, but it making is job as a voltage step down device.
    Thanks to David for the clue on the common ground.

    Now I'm in the configuration process of the Duet. I hope my printer will be live again this evening.


Locked
 

Looks like your connection to Duet3D was lost, please wait while we try to reconnect.