Led number board conversion

I use warm white and a fairly large resistor.  I don't think the number boards should compete with the headlights to be the brightest thing on the front of the locomotive.  For the F40PH that runs them on track power, I settled on a 4.7k resistor for the number boards, that was a nice compromise.

gunrunnerjohn posted:

I use warm white and a fairly large resistor.  I don't think the number boards should compete with the headlights to be the brightest thing on the front of the locomotive.  For the F40PH that runs them on track power, I settled on a 4.7k resistor for the number boards, that was a nice compromise.

So, parallel 2 diodes for lighting of the two number boards in reverse polarity to each other. Using a 4.7k resistor for limiting. I don’t need a protection diode in the case. So, simplifies things. 

Also, have a bunch of leds from a Lionel factory tmcc repair kit. I assume those are warm white

Actually, a 1/4w resistor will be more than sufficient.  15V dropped across a 4.7k resistor is .04 watts.  If you go to 3.3k for a little more intensity, that's still only .07 watts.  Even going to a 2.2k is quite safe, .1 watt in the resistor.  As far as the resistor value, once you get the LED's mounted, just "fine tune" the value to your liking as to brightness.

shawn posted:

Also, have a bunch of leds from a Lionel,factory tmcc repair kit. I assume those are warm white

 Probably not, Lionel seems to use bright white for most everything.  I've changed the LED's in a host of Lionel Legacy for people to more suitable color ranges.

Lol, I’ll have to pull my old resistor kit out. It’s been 30 years .... Lol, amazing how one forgets things. Switched fields a long time ago. But, did have fun in the Engineering labs....But, appreciate a real world value for the leds and resistor range —. The last time I saw a led was building a frequency counter in college.

The good news is, Ohm's Law is still a constant.

gunrunnerjohn posted:

The good news is, Ohm's Law is still a constant.

Lol, In the old days ...I blew up more mosfet doing switching power supply’s, forward converters ,buck converters. Got out of it early. Tired of getting laid off losing mil contracts.

Anyway, Good choice of led’s and resistor - it really looks great. But, need to get some smaller led’s. Miss the supply house on Long Island Kip electronics in Freeport. The guy has a ton of stuff and semi’s. The nice part I can mount right to the pub and put the resistor inline with the harness feed. Lol, we use to call the ferrite beads we put on the to3 package mosfets Rosary Beads

Yep, those 5mm LED's looks a tad large.   3mm ones are better.  I'd use the flat-top ones and sand the front to defuse the light better, that would do a good job for the number boards.

gunrunnerjohn posted:

Yep, those 5mm LED's looks a tad large.   3mm ones are better.  I'd use the flat-top ones and sand the front to defuse the light better, that would do a good job for the number boards.

Exactly, what I ordered...flat tops. The picture - they are  3 mm ones in there - for some reasons look like 5mm. Must be make everything giant iPhone day

They do look big, how do they work in the number boards?  I'd still sand the tops to break up the beam.

gunrunnerjohn posted:

They do look big, how do they work in the number boards?  I'd still sand the tops to break up the beam.

Agree, ordered the flat top leds. It looks great  with the warm white the cool LEDS and the value of limiting resistor you suggested.