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BeTrue3D Printer build part 9 – LEDs – 12v from 24v Duex5

Finishing our LED installation

We previously installed front LEDs, including an on/off rocker.


Back then, I only had 12v LED strips and as I use 24v on this system, I needed to get 12v from somewhere.

In order to test it worked, I used a small fixed 24v to 12v step-down buck-converter and used some double-sided tape to stick it in place below the Duex5 as shown here:


Use Duex5 to get 12v

As far as I know the Duex5 (also in Duex2) is the only Controller or Expansions -board for 3D Printers with build-in 12v switching regulator, which means you can easily get 12v even if you use a higher voltage to power your machine (VIN Power – opens Duet3d Glossary)

In order to activate this 12v switching we need to:

  1. Put a jumper on the pins marked with nr. 1
  2. Check the FAN jumper nr. 2 is placed on the 12v position
  3. I’m going to use the FAN3 Connector marked with nr. 3 for my LEDs

In case you have difficulty seeing the colors, the + wire is to the right side of the 2-pin connector, and – wire on the left side.

Image is part of the original conenctions diagram on Duet3D wiki.

You can also see the full diagram here:

Configure LED in firmware

We really just need to open the Config.g file and insert a small line under the other fans in our FAN section, like this:

M106 P3 S1; Set fan 3 value for our LED to on.

It really just put FAN connector 3 on full power. We can put it on half power by setting S to 0.5 instead of 1, or use the 0-255 range if that’s more to your liking.

It also means you can control it using Gcodes to do different things like turning LED on when a print starts and turn it off when a print job ends or what ever you like.

All done

Here you can see the new jumper on nr 1, set jumper on nr 2 and our LED connector on nr. 3

2 thoughts on “BeTrue3D Printer build part 9 – LEDs – 12v from 24v Duex5

  1. As of revision 0.9 on the Duex5, the “12V Enable” jumper (nr 1 in the picture above) has been moved to the far left of the board, next to an extra “always on” fan header.

    1. Thanks. Also saw your comment on my Instructables post about this 🙂

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