LED circuits for TMCC rolling stock

Here's what I use, you can also substitute an LM317T for higher current.  The value of R1 can be adjusted to yield any desired current, depending on the intensity desired and the number of LED's.  For TMCC with 18V track power, the LED strips work great for passenger cars, they nominally use 12V at 20ma for each segment.  I normally run them with a lot less voltage as 20MA to them makes them far to bright for my tastes.

You can also add a large capacitor across the .1uF cap to provide some flicker prevention for momentary power interruptions.

There are lots of threads here on using LED lighting and various circuits.

THANKS... this confirms my thinking and will get me started with a proven circuit... J

One last thing.  If you run DCS, you'll want to add a choke at the roller pickup to avoid killing the DCS signal.

Again, THANKS for the tip... even though DCS is not considered right now, would you go ahead and share the "choke" specs / part number so I won't have to readdress this should I make a future upgrade... also, I am new to this forum... how do I search for the LED topics previously posted??? THANKS AGAIN, J

Here's a 15uh choke from AllElectronics.

GOT IT... THANKS, J

Could you please quantify "large"? Perhaps a uF range for a capacitor. Thanks.

I'd use at least a 220 uf 35Vdc capacitor. It's about 1/4" dia. and .75 inch long. A 470uf 35V cap is .375" dia. and.75" long. This should be large enough to prevent momentary flickering.

I'm thinking more along the lines of at least 1000uf, and perhaps more.  The value will really depend on how much current the lights end up drawing, obviously if they're all powered on 20ma, it'll take a smaller cap than if they're drawing 60ma.

For 20ma, you can probably use a 470uf, for 60ma, I'd be thinking at least 1000uf.

Fec fan and gunrunnerjohn, thanks for the info.