12v and 24v…Sorry for asking, I just don't want to do anything wrong



  • Hello, I received a first round Duet wifi board last year and am finally at the point on my (own version) Delta build to start hooking up the wires. I have an Meanwell 750 watt ps that I would like to use for my Onyx7 heatbed and .9 degree steppers and a 12v Meanwell 250 Watt ps that I want to use for the rest. I also purchased an Auber 100A #MGR-1DD80D100 ssr thanks to Michael Hackneys recommendations to use for the heatbed off the 24v ps. Of course I know how to hook up all the easy stuff…steppers fans endstops and all, however can anyone jot out a wiring diagram of the connections for me using the duet wifi and both ps's to achieve the above? Also designate where they would use the lower gauge wiring for to handle the high amperage? I do not want to burn the house down. I am new to Deltas and find them fascinating and will be using the DC42 variant of software to run my new one....thanks to David.
    Thank you for reading and considering my questions. God bless



  • Read this, there are drawings that use a motor just wire your heated bed the same way as the motor. You are going to use DC to DC SSR. the output from Duet wifi will be whatever voltage you are powering the board with so make sure your SSR is 3-32V, some are less.

    http://www.phidgets.com/docs/Solid_State_Relay_Primer



  • Thank you for the response. I really appreciate it.
    I understand the hookup of the dc to dc ssr to the 24 v supply, as the link shows. Is it correct that I hook up the heat bed output from the Duet (proper polarity) to the input of the DCtoDC ssr. Output of one side of SSR is going series through 24v outputs pos to neg to pos and neg of Onyx heater bed back to other side of the SSR output. Correct?
    My issue is not knowing how to hook the 24v and the 12V power supplies up to be able to use both with the Duet? I use an inline 30 amp fuse off the 24v power supply? How do I feed 24volts to the Stepper Motors with this configuration? How does the 12volt hookup to everything else but the steppers and the heatbed? That is the hard part for me to understand and where should I use lower gauge wires …...I would guess between the ssr output sides all the way through the 24v PS and on both terminals of the heatbed...Correct as well?



  • My understanding is that you are only using the 24v for the heated bed. If this is the case this PS is not connected to the Duet Wifi at all and is only wired to the SSR and heated bed on the load side , also called the output of the SSR . The 12V PS will be wired to the Duet Wifi as described in the wiki. this will power everything including the heated bed output which is wired to the input side of the SSR with the correct polarity.

    The Duet Wifi only has one power connection that feeds everything, the motors and bed/hotend so it is 12v or 24v for the duet. (5v has options)

    I would recommend running 24V hotend and fans and just use the 24V PS for everything.

    Read through all the documentation for the Duet Wifi.



  • If you want to use 24V for heated bed and motors, why not just add 24V hotend cartridges? This way you can just run the whole board on 24V and wire in the 12V supply just for the fans, which is a lot easier.



  • Mike, i like the idea of using 24 volts on the board, but can you still use the ssr with the bed heater due to the higher amps? And then how would I drive the fans with 12v supply to turn on and off at the correct speeds for different layer needs? I would not be able to control that….right? wouldn't they be always on? Maybe I can't use both supplies but I thought a lot of people have. Any more thoughts on how to accomplish this?
    In the end, if possible, I would like only the heat bed and the steppers to be at 24v and all else to be 12v. If needed though, I will purchase the 24v hot end cartridge and 24 volt fans along with end stops but I want to make sure the ssr is still being used as I don't want the higher amperage going through the Duet Wifi

    Is this possible?



  • btw thank you all for even reading and replying. I really need the help 😉


  • administrators

    You can use a SSR to control the bed if you wish regardless of whether the SSR is using the same PSU as the Duet or a different one. If they are both using the same 24V supply, then connect one pair of wires from + and - output terminals of the power supply to the Duet. Put a 5A fuse in series with the positive lead if you wish. These wires do not need to be heavy gauge. Then make a separate bed heater circuit using heavy gauge wires connected to a different pair of output terminals on the power supply.



  • Thank you so much David. I understand what you are saying. First of all, thank you soooo much for your contributions to the 3d world!!!!!!! Can you see anyway to drive the DuetWifi with the 24v Meanwell supply and yet use the 12v Meanwell for the fans with the fans still being controlled by your Duet so that they are not just always on? Or am I just going to have to switch everything to 24v? Thank you once again Sir.


  • administrators

    To use a separate 12V supply for the fans, connect the negative output of that PSU to the negative output of the main 24V PSU. Remove the fan voltage select jumper from the 3-pin header strip and connect the positive output of the 12V power supply to the centre pin of that header strip. Do this carefully, because you will damage something if you short it to either of the other pins.



  • I thank you once again for your help. It saves me alot of trouble.



  • So I still plug the positive wire of each fan to their respective connector and I connect all the black wires of the fans to the negative on the 12v power supply?


  • administrators

    No, just connect the fans to the fan connectors on the Duet WiFi as usual.



  • So I am new to using the DuetWiFi and I have a 300mmx300mm dimension system. I will be using a 120v heated bed. I have a lot of 12v Corsair RM650 12v power supplies. Would you recommend hooking those up to the Duet or should I get a 24v system to start out and make sure I get a 24v hotend etc. or do you recommend something else. I just want to do the best to begin with so I don't have to do it again. Thanks!


  • administrators

    If you plan to use 0.9deg motors, or high inductance motors, go with 24V. Otherwise you may as well use 12V IMO. I don't know that particular PSU but the Corsair CX400M that I was using for a while worked well.



  • If I connect 2-12v DC terminals from the same power supply I should have only 12v DC correct? If I put them in parallel then I would have 24v DC and that should work for 24v correct?


  • administrators

    No, you can't get 24V out of a 12V PSU other than by using a boost converter.


 

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