Lionel Headlight LED Question

3mm LEDs are standard for headlights. Something like this would work: https://www.digikey.com/produc...F/350-1561-ND/808959

There are warm white versions as well.

Dave, they'd work if Digikey didn't have zero stock.  

Warm white LED's are available everywhere, it shouldn't be an issue to find a 3mm warm white LED, that's probably the most common size.

Another headlight question, sort of.  I recently robbed a DC-LCRU more exactly an R2LCO2 from a Lionel NYC Alco 18953 with a Signal Sounds board along with the DCDR to install in an early Williams FM Trainmaster, the good one with Pittman motors and Magnatraction. The three boards were working flawless till I converted to LED lamps at each end of the loco. Just one LED at each end. I used a 1.2K ohm resistor on each end as well, to load the triac. Now after twenty minutes or so of operation the sound will cut off all the other functions work including the electro couplers which I also installed and the lights change with the direction of operation. Once the Signal Sounds cut out there is a slight hum coming from the speaker but no horn or bell. If I power down and unplug the light connector the sounds come back after I power back up. Any ideas ? Attached is a photo of the LED and the board it is mounted on before I added the 1.2K resistor across it's leads to load the triac. I think the triacs could also be loaded with a small capacitor but have not tried that yet as the leds are in a light box I built on each end of the loco and it's some trouble to open up.  Anyone have any ideas ?        John Acton

First off, I've found that anything larger than a 470 1/2W ohm resistor doesn't always insure the triac fires.  However, a .01uf 50V capacitor works perfectly and doesn't put any additional load or power dissipation.

I'm assuming the resistor you mention is somewhere else as what is pictured is a 1k resistor and the LED.  Adding those certainly wouldn't affect the sound in any way, so you're chasing ghosts, at least IMO.  I'm not sure why you're fooling around with that old an R2LC, I don't recall even seeing an 02 version in years!  The serial data goes from the R2LC to the SS board, it has nothing to do with lighting.

John, thanks for the reply.  I'm using the R2LCO2 because I'm retired and have another expensive hobby, sailing. The boards were functioning fine before I added the led lamps. The 1.2k resistor is soldered across the leads of the board on the same pads the leads are soldered on.  I took the photo of this led board after the ones in the loco were already installed in the loco and too hard to get at. I am aware that the lights are on a different circuit on the board but for some reason when I plug in the lights the loco runs fine for about twenty minutes. Then the sounds quit. Unplug the lights and the sounds come back. Went through the problem about twenty times before I yelled UNCLE.  The lights work fine with the 1.2k resistor, always on depending on the direction of travel. I think I will try substituting capacitors for the resistors and see if the problem goes away. Defies common sense why this would affect the sounds but after 20 go-rounds I am convinced it does. Just hate to pull the light boxes apart, their glued with hot glue, I will bend them up, and I'm out of pie pans. (Been avoiding "Mrs Smith", till I can get my suits on.)            I bought the Led boards on ebay for nearly nothing and use them in dozens of places this seems to be the first time they have caused problems. If indeed they are somehow the cause of the problem. Let me add they are great, and cheap, come on about 3v  near full brightness by 6v and good to a claimed 18V. Seller is out and I have been unable to find anyone else selling them. Wish I had bought two hundred of them.  BTW, I have a cheap solution for the micro connector problem, gonna make some pix and let everyone see.  Regards, John Acton

Well, I certainly can't explain why the lights would affect the operation, it's certainly something that I've never seen.  A 1K resistor in series with a standard 20ma LED would indeed compute out to more than 18 volt capability.  I would caution you about actually trying to reach that figure as the power dissipation of the resistor would be about 1/4W,  Given the 2:1 guideline for power dissipation, you'd want a 1/2W resistor, that would be a 1212 size chip, 2.00mm x 1.25mm, and about 0.70mm high.

Since you're only running on half-wave track power in command mode, you don't have nearly that much voltage, probably no problem here.