Need help with LED headlight

Unfortunately I can’t offer any real advice.  I can however say that I tried replacing the incandescent headlight in my Polar Express Berkshire with a LED using a very simple circuit board designed by @gunrunnerjohn.  It worked great when tested with a 7 volt AC wall wart but once the engine  was placed on the track (CW80 set at approximately 14 volts) the first LED lasted about a day, the second LED lasted a few seconds.  I could not figure out what I messed up so I put the incandescent light back in.

Edited to add:  Correction, it was a circuit design from GRJ, I should not have typed “board” in the sentence above.  See my additional post below.

Looks like the LC+ 2.0 drives the LED headlight directly, so I'm not sure what happened there.

Greg, have no idea what you tried, but I've put a ton of LED's in many locomotives, they don't go up in smoke for me.  I don't remember any circuit board design, what are you referring to?

Here's the Lionchief Plus 2.0 Docsider 0-6-0T connection map, the LED's are wired directly.

<click on graphic to expand>

Thanks, that's a good start.  So then, is there a way I can determine if something went wrong with the board, so I know if I should get another LED or not?  Or, is there any way to wire an 18v bulb to the board?  Worst case I guess I could just wire it to the screw coming up from the pickup rollers.  The cosmetic stuff is my wheelhouse - this stuff, not so much - so I appreciate your help!

The board will not support an incandescent bulb.  Truthfully, I don't see how you cooked an LED with the two headlight wires unless something went wrong with the board.

@gunrunnerjohn

Whoops, it was just your circuit design, I designed the PCB.  The one with three components.  IIRC 1) diode  2) capacitor 3) current limiting thingamabob.

I will edit my earlier post.

@GregM posted:

Whoops, it was just your circuit design, I designed the PCB.  The one with three components.  IIRC 1) diode  2) capacitor 3) current limiting thingamabob.

I was just curious what circuit design I might have posted that would yield that result.  If you wired the circuit correctly, short of defective components, it's pretty hard to believe the CL2 circuit was killing LED's, they've been used for decades!  I'm thinking of this circuit...

One thought comes to mind.  If you connect the LED backwards, the CL2 will increase the voltage trying to get to 20ma of current through the LED.  That could kill the LED with excessive reverse voltage.  However, the LED would never light in that scenario, so it doesn't sound like that is what happened.

@gunrunnerjohn

Yep, that was the circuit.  It was late when I posted last night and I couldn’t remember that CL2N3 was the name of the third component.  The LED would light up so I am confident I didn’t have it wired in backwards.  Upgrading the PE Berkshire headlight is on the try again someday list.

Well, for TMCC locomotives, I just use a diode, 470 ohm resistor, and the LED off the lighting outputs.  For MTH PS/2 locomotives, I use a 220 ohm resistor and the LED.  I've done tons of them over the years, never had an issue killing LED's after I included the diode for TMCC models.

Before I just rig up an 18v bulb, I'd like to try another LED.  I suspect I may have damaged it when I soldered on the new wires.  What kind would work here, and would anybody like to sell me a few? 

I'm sure it's a bog standard white LED.  I don't recall the exact look as I haven't had the shell off one of these since I first got them.  My guess it's a 3mm LED.

Thanks - contacting you by email.