Model Trains | Märklin BR 128 21MTC & LED Conversion

During winter time I like to fool around with model trains. Because of the Covid-19 evening curfew, the winter season is extended and I took the time at home to really get into converting some of my locomotives to LED lights and ESU Lokpilot decoders.

The Märklin BR 128 was the first patient and received a new 21MTC adapter PCB. Stock from Märklin it already has LED lights but I wanted to add High Beam and Shunting lights so it also received new LED PCBs.

The PCBs were designed in Eagle CAD and made by JLCPCB in China. They use all SMD components so I opted for using solder paste and a hot air solder station to do the soldering. The design also incorporates two parallel capacitors that function as a power buffer. They can be switched on or off using an SMD switch on the adapter PCB.

To prevent light scatter I used Fusion 360 and my Prusa MK3s to make a plastic spacer that goes in front of the LED PCBs.

I’m very happy with the end result and clean install. The design files are available on my GitHub.

Check out my video on the conversion in YouTube.

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