Most here are familiar with the DIY constant current boards, for which gunrunnerjohn graciously developed and made available the Gerber files on the forum, about 3 months ago. So far I have been able to convert two sets of Railking 60' ABS cars using these kits, and I am very pleased with the results. These boards are easy to build using all thru-hole components, and all components are readily available online. Being only 0.75" wide, they easily fit into most any small cavity in the car interior, such as bathroom, hallway, or end door vestibule. They are very easy to hide. I will be doing several more sets of cars in the hopefully near future as time permits.
I find that batch building the boards in lots of about 6-12 works quite well, and it seems to take about 15 minutes per board doing it this way, including testing. Here is a pic of some ready to go, tested, and set to a common current output:
I have also taken to pre-building the LED strips with pigtail soldered on before I start a new car project, like this, since I know that 60' cars will mostly accept 14" long LED strips:
This system seems to work quite well. I have mostly been using the boards with R1=12 ohms, R2=100 ohms, which gives an adjustment range of about 10 to 105 ma output. (Next I am going to build a batch with grj's original values of R1=27 ohms, and R2=200 ohms; giving an adjustment range of 5-45 ma; for those applications needing lower outputs) One concern was how hot the LM317T IC would get at higher loadings, so I did some "semi-scientific" testing just to find out. Here are the results:
At 105 ma; temp= 54 C
At 60 ma; temp= 48 C
At 40 ma; temp= 40 C
At 20 ma; temp= 31 C
It should be noted that these temps were read using a laser gun, at the hottest spot on the bare tab of the IC, and there was no heat sink attached. Moreover these readings were taken with room ambient of 18 C in free air; so temps in the confines of an enclosed passenger car would of course be higher. Supply power to the board was 18 VAC in all cases.
I ordered a small batch of boards first from OSH Park, just to test the waters so to speak. Then after finding that all was good, I wound up ordering a batch of bulk boards from AllPCB in Asia, and I was pleased to discover when they arrived that they are quite high quality. And unlike OSH Park boards, the pads are all pre-tinned, so soldering is a snap, very easy to assemble. I finish each board with a mini JST 2 pin 1.25 pitch output pigtail, for easy connection to the mating LED strip pigtail during final car re-assembly. I leave the AC input board connections bare during pre-assembly, since this wiring varies from car to car. Mostly I have been able to re-use a pair of existing car lighting wires, after clipping all extra wires and removing all original interior lights. I just solder the wires into the input holes in the board. I usually don't bother converting baggage cars, since it seems odd to me to see a baggage car lit when moving, but that's just personal taste. I usually just disconnect the existing baggage car lighting right at the roller connections.
So to anyone who ordered these boards and who might be a little sweaty about launching into the project, hey I was too. But guess what, it's all good, and I think you will be very pleased with the results!