Did I do it right? Following the instructions on the Tony's Train site, The blue wire is the common wire (or +) while the yellow or white is the return wire ( or - ). According the schematic in the article the resistor is soldered to the common wire and then to the + lead on the LED. I also used a small metal clamp inbetween the LED and the areas to be soldered as a heat sink. Plus it also acted as a little holder for the LED. The wires are not insulated yet. I wanted to show you guys and see if I'd done it right or messed up. I'd try it on a test track, except that my DCC system hasn't arrived in the mail yet. :grin: The LED's are 3mm that came with resistors for working 12v. They came together as a set labelled "AMBER MEGA BRIGHT".