Is green on top and red on the bottom in train-world?
Just curious.
a7
there are actually many different types of signals from semaphores that have arms, to lit position signals that have a pair of lights oriented vertically, at an angle or horizontally and multi-headed shown below for a relatively modern day railroad
but even the chart below doesn't answer your question
i believe early signals use white and blue lamps as well. but the color was a colored piece of glass that could be broken, so a plain white light is no longer used (in general). and of course, modern day traffic signals are based on the experience from RR signals
THX @gcjr, I followed some clues and I have been reading, well skimming, through 197 pages of RR arcana. I can't imagine studying to pass my whatever you get when you master all that stuff test.
Gives me a reminder to be empathetic when noobs come wondering about stuff I kinda do know. 
a7
I'm sorry, you are totally correct. I did start out worrying about the max current the board could provide, then after seeing I was drawing so low a current, I got distracted by conversation. If you are talking about taking my DMM and putting it in series with the load and ground to take the current reading, then yes, I do know how to take the current readings and I have an extremely good Fluke DMM with a built in shunt to use for that. Also, my variable DC power supply can provide me with the volts, current and watt readings for the load it is supplying as a backup. That was where I was amazed to see how little the mA load of the 8 LEDs in the signal devices actually was. At 5v the power supply was only providing 2 to 3 mA for a single LED and only 23 to 25 mA for all 8 LEDs (each LED will be on a separate pin). If that is the case, the power limit I was concerned with is no longer an issue, at least in this application of the board. Plan to take the DMM readings as well to confirm my power supplies readings just to be safe.
Here are actually many different types of signals from semaphores that have arms, to lit position signals that have a pair of lights oriented vertically, at an angle or horizontally and multi-headed shown below for a relatively modern day railroad
And in most all cases, not like shipping where there are only 3 sets of rules in the US (International Rules of the Road, Inland Rules of the Road and the Western Rivers Rules of the Road) each railroad line (CSX, PRR, N&S, CN, B&O, UP, AMTRAK, BNSF, etc) has their own signal system and the lights may mean different conditions. Engineers have a big job learning the lights for the rail system they are driving on.
interesting list considering that the B&O is now part of CSX along with parts of the PRR which became Penn Central then Conrail. not sure AMTRAK owns its own track much less signals.
in the early days of RRing, it took a while for RRs to start using signals to minimize accidents. many developed their own types (e.g. Hall)
i believe locomotive operators not only need to follow the rulebook describing the signals on the RR, they also need training for specific routes to know where speed restrictions exist
mergers (e.g. Conrail) made things more difficult when a train traversed trackage from different RRs having different signals.
i'm not sure there is a standard signal system for north america. there is NORAC, Northeast Operating Rules Advisory Committee, but i believe both CSX and NS extend beyond it
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