GRJ, would that be because of heat from the LM317, or just not a good application for it?
And is the buck/boost switcher you mention the small inexpensive Asian one with the bridge rectifier already added and LM2596?
I am going to try your light boards in a couple of caboose (cabooses, cabeese?). (Still don't have any passenger cars, Lionel got my entire train budget this time around for those new command control accessories...)