Wiring Issues 5 V, 12 V, Waterpump, 24 V PSU

  • Hi Guys,
    I'm stucked with my wiring. I red some posts but I am not sure how to do it right. Maybe you can help out. I draw a wiring sketc of my set up.
    1 Extruder: 5V Hotend Cooling Fan from Noctua and a 5V Part cooling Fan from Noctua two
    2. Extruder: 12 V Waterpump and 12V Radiator Fan cooler

    I am using a 24 V PSU and my jumper is set to 5V.
    I have 2 step up converter and 1 step down converter.!

  • 0_1523637216974_Wiring Duet.png

  • I have a Duet Wifi.
    I read that's it's not smart to directly wire a volt converter to the fan outputs. I also read that's possible to get 12 V on the fans by wiring a 12 V step down modul between PSU and the fan jumper. But than I don't know how to control the 5 V fans.

    The water cooling is ment to work with a 500 °C dyze hot end. So water cooling pump and the Fan for the radiator should only run when the hotend is in use.
    The water pump I am going to install is: https://www.amazon.de/gp/product/B073JRKZBX/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1

  • There are ways to run the converters for each individual fan, I don't believe you can pwm through them but (if I remember correctly) the switching is done through the ground, your setup is much more complicated as you have multiple different voltages. That said there should be a way to get it to work.

    My printer is using a 24v PSU and 12v fans, if possible I would be inclined to switch your 5v fans to 12v just for the sake of only dealing with two voltages and having all the fans on a standard voltage.

    I am running a single 24v -> 12v step down converter from my PSU with the + lead of the converter connected to the middle pin on the fan selector, this feeds 12v into the fan circuits and they all behave as if I was running them off a 12v PSU.

    However I am unsure of how to deal with the water pumps and other peripherals, it may be beneficial to instead of using a step down use a second 12v PSU to drive those devices

  • administrators

    As you have your current diagram you have 24V going out of the E1 heater output to what you say is 12V.

    As @Dino has already said the Duet switches the ground so its possible to connect a 12V supply to the +'ve of that fan and water pump and just switch the ground side.

  • Thank's for your quick response, maybe I have to switch the 5 V fans. @ T3P3Tony the arrows are only indicating that the pump and the 12 V Fan belong to the hotend and not that I connect them to E1.
    So the the easiest way is to swap the 5 V fans and connect like shown in the new pic. I am just wondering if there is an other option to keep the 5 V fans.

    0_1523650132164_Wiring Duet2.png

  • You can PWM converted voltage. The buck converters tie the grounds between the 24v input side and the 12/5v output side. So connect the input side to the PSU (+ and -), run the positive output side to your fan/pump then return its negative to the fan header negative pin of your choice. As the grounds are tied the output ground can remain unconnected.

    Although as you have shown feeding 12v into the fan voltage header central pin will set all of your fans to 12v, as long as the ground is tied in the 12v step down module to the 24v ground.

    As for still using 5v fans also, you can by using a series resistor to get the 12v down to 5v, but its value will be different for each fan depending on their current draw.

  • HI DjDemonD, I made a nother sketch just for clearance. Will that work without crashing the mosfets on the always on fans? The 12 V fans don't need much ampere! The ground from the waterpump is connected to ground Fan3 to crontrol it? Is it a idea to put step up converter direct on fan outputs?

    0_1523650935306_Wiring Duet3.png

  • administrators

    Do not connect the input of step up or step down converters to fan outputs. Instead, set V_FAN on the jumper block to be the highest fan voltage you want to use, which is 12V in your case. So you will need to remove the V_FAN jumper completely, and connect the output of your 12V step down module to the centre pin of the VFAN jumper block. Then you can connect your 12V fans directly to fan outputs. Connect the 5V fans between the +5V pin on the expansion connector and the FAN- pin of your chosen fan output.

  • Thank you for this great idea.
    I have a bltouch on pin1 and 2, so which pins should I use for the two 5 V fans? Can I hook them all three on one?

  • administrators

    Yes you can hook all 3 to the +5V pin.

  • I have a similar setup with water cooling and the main system running at 24V. With that, I'd recommend you to follow DC42's advice and feed the 12V power into the fan voltage selector pin. That and maybe just get all of the fans in 12V.

    On my system I also went for a separate 12V PSU since with the pump, LEDs, all of the fans and a webcam I'm drawing above 3A total and it made little sense to get a boost converter at this point. As I've mentioned the currents - a word of warning. I don't know how much your water cooling pump is drawing, but if it's as hungry as mine, I would consider hooking it up directly to the 12V converter. In my case I was afraid of overloading the fan selector connector - I think those simple pin connectors aren't rated for more than 1.5-2 amps of continuous power.

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