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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