BigCityFreightI wanted to quickly swap out the dim 1.5 bulbs with some LEDs that I have wired up with resistors to take the full 12v.
Ya, if the bulbs were 1.5 volt bulbs, then each output would be producing about 1.5 volts, not 12 volts. If you're hooking up an LED that runs at 1.5 volts, you wouldn't need resistors to reduce the amount of power going to the LED...especially by 88%.
Note too that some decoders use CVs to set how much power is going to the headlight outputs, so it could be that would need to be turned up.
The circuit board is set up to drive the original lamps, which are about 3V, not 12V, so configuring LEDs for 12V operation, they will not work connected in place of the original bulbs with nothign else changed. Connect your LEDs with resistors directly to the track pickups (or on the board where the track pickups come in). LEDs are polarity sensitive, so if you hook them up opposite one another, one will light when going forward, and one will light when going reverse. If they are backwards, just flip the connections to the LEDs around.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
This is a flyer, I think you may have to hook up the front and back LEDs to where the yellow and white + blue common would connect on your decoder board. I think this would supply enough voltage that the old lighting outputs do not provide.
I hope others can give an idea if this is good.
I have a P2K SD9 that I bought used and already had the decoder installed via the plug. I wanted to quickly swap out the dim 1.5 bulbs with some LEDs that I have wired up with resistors to take the full 12v. However, I took out the headlights, but the LEDs will not light when attached to the board on the same spots (swapping wire positions doesn't do anything). I'm guessing there isn't enough voltage to light my beefier LEDs?
On the circuit board are two fat resistors and some little black components (capacitors?) I have a vague recollection on P1K boards of cutting off the resistors (and maybe the capacitors or whatever they are). Should I do the same here to get my LEDs to light?
I know hard wiring would be better, but was looking to not spend a lot of time on this older loco that runs fine as-is. Thanks for any help.
Todd