FRED for my MMR

The requirements for the Model Railroader Engineer - Electrical certificate can be found here. In addition to wiring my layout, I had to build a couple of electrical projects. The NMRA gives some ideas and there are others online, and I purchased a couple of old Electrical Project books on Ebay and flipped through for something interesting. Most were either too advanced for me, or required circuits that were severely outdated, but an article in the February 1990 Model Railroader magazine seemed simple enough and fun. It was to build an end-of-train device (also referred to as "FREDs") for Flashing Rear End Device. Essentially, it is a blinking LED circuit.

I built one of these as a kid from a different article in MR, and it ran off of a 9 volt battery. A friend helped me build it, and I remember it had a potentiometer which allowed you to adjust the rate of the blinking. I wanted to do it again but couldn't find the article, and a call for help on the MR online forum didn't produce the article. If you know what article it was, please let me know. So, I went with a different design using a LM 3909 circuit chip. They are not manufactured anymore in the USA, but I found a couple on Ebay for $3 each and bought them from China. Very cheap, but shipping took a month and a half.

While reviewing the circuit diagram I found an error in the MR article. The diagram showing the LED has the polarity (+ and -) notations correct but the length of the anode and cathode reversed. Trust the polarity as indicated and not the length of the LED prongs as drawn. I used a small project board to make everything cleaner and mounted it all in a boxcar that I had lying around. I cut a notch in the bottom of the boxcar shell for the LED to stick out from, as I didn't want to have it permanently mounted to the boxcar's body should I need to get inside. It isn't a perfect scale model of a EOD, but it does demonstrate my electrical abilities.

I love cabooses but I may actually purchase a D&H decorated boxcar shell to use for times when I want to ... shudder... model a period train when cabooses weren't used anymore.