I've finished wiring and installing my headlights and ditch lights on my 3 athearn C44-9w's. The headlight has been replaced with a bright white 5mm 3V LED and the ditch lights are details west 3V 26ma gow bulbs ditch light kit. Even when wired in parallel(draws more amps but should light earlier) with the recomended resistor they light up way to late. If I cut the resistor value in 1/2, they light quickly but I'm afraid will burn out at full throttle. The led on the other hand, is fine. It lights up early and has no problems. I've read some constant voltage circuit posts and diagrams that look easy enough, how about one for about 2.5-3v though?
I'd have to think a bit more to say for sure, but I think the LEDs are starving the bulbs for current. I'd try wiring the LEDs though one resistor, and the bulbs through another, and see if things work better. You could use a voltage regulator, but it is going to take a bit more voltage before things light up, I expect. And it's that much more work. A DC lighting expert may wander by and be more useful!
