Need help with wiring 12v fan and LED on 24v system.



  • Hello, I'm nearing completion of my DBot build and have just started on the wiring. I thought I had things figured out but now I'm not so sure.

    I tried to source as many 24v components as possible but I have a 12v LED strip, and 12v Noctua hot end cooling fan. For these 2 components I obtained two LM2596 buck converters.

    The LED strip is plain white, not RGB, and I intend to have it be always on. Therefore I was going to connect it to the Duet Wifi Always on fan connector through the buck converter. positive and negative from the Duet to the positive and negative input on the buck converter, and then the same out to the LEDs. This should be no problem, correct?

    Where I am less sure, is with the hot end fan, as I would like to have it be thermostatically controlled. The fan itself is the 4-wire PWM version, but I am using the provided 4 to 2 pin converter with it, and planned to use the Duet for PWM control. So how do I wire this fan to the Duet through the buck converter and still preserve the ability to do PWM control? Bare in mind that I'm an absolute novice with electrical stuff. I can follow a diagram though. I was originally thinking it would be wired the same as the LED strip, but after doing some more searching and reading on this forum I'm not so sure.

    I'd like to use the Noctua on the Titan Aero for some silence, but maybe just easier to get another quality 24v fan.



  • Correct me if I am wrong as I am also considering going this path, but there is a fan jumper for 5v or V_in, depending on the position of the jumper it'll either run the fans off the 5v line on the duet or whatever the V_in is, there's also a 3rd option if you connect the + of the buck converter onto the middle pin of the jumper it'll feed 12v into the duet to use for fans. There's more information in this thread from a couple months ago.

    https://www.duet3d.com/forum/thread.php?id=2959


  • administrators

    @Dino:

    Correct me if I am wrong as I am also considering going this path, but there is a fan jumper for 5v or V_in, depending on the position of the jumper it'll either run the fans off the 5v line on the duet or whatever the V_in is, there's also a 3rd option if you connect the + of the buck converter onto the middle pin of the jumper it'll feed 12v into the duet to use for fans. There's more information in this thread from a couple months ago.

    https://www.duet3d.com/forum/thread.php?id=2959

    That's correct. If you want everything connected to the fan outputs to run from 12V instead of 24V, that's the simplest option. Connect the input of the buck converter directly to the VIN terminal block.



  • @dc42:

    @Dino:

    Correct me if I am wrong as I am also considering going this path, but there is a fan jumper for 5v or V_in, depending on the position of the jumper it'll either run the fans off the 5v line on the duet or whatever the V_in is, there's also a 3rd option if you connect the + of the buck converter onto the middle pin of the jumper it'll feed 12v into the duet to use for fans. There's more information in this thread from a couple months ago.

    https://www.duet3d.com/forum/thread.php?id=2959

    That's correct. If you want everything connected to the fan outputs to run from 12V instead of 24V, that's the simplest option. Connect the input of the buck converter directly to the VIN terminal block.

    That could be an option. I would have to swap out the 24v fans I was going to use for the Duet enclosure and the 24v radial blower I was going to use for the part cooling fan. This may end up working better anyway since those 24v fans weren't of great quality. I have some 40mm quiet Sunon fans, but would need another 12v blower.

    So just so I'm clear, is this how it would be wired?

    PSU to buck converter and then positive output from the buck converter to the V_Fan jumper pin? Negative to ground?

    This would mean I would only need one buck converter, since all fan outputs on the Duet would now be using 12v, and PWM would function properly?

    Thanks for the help.


  • administrators

    You don't need to connect the -ve output of the buck converter to anything if it's the usual non-isolated type. Otherwise, that's correct.



  • Good to know. Thank you.

    I've ordered a new 12v sunon blower from Digikey for the part cooling fan. By the time it arrives I should have the rest of the wiring in place and should be ready to commision the printer. Very excited to finally be able to start using the Duet.


Locked
 

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