Lionel M1a led headlight?

You can put one in pretty easily.  If it's the standard headlight feed from the R2LC, you will need two 470 ohm resistors, one 1N4003 diode, and one white LED.

You will require a load resistor directly across the headlight feed from the electronics, I use a 470 ohm 1/2W resistor.  The diode, a 470 ohm 1/4w resistor, and the LED are connected in series fed from the load resistor connections.

For the doubting Thomas's in the peanut gallery, the load resistor is required for the triac on the R2LC to fire properly.  They are intermittent or won't fire at all with just the LED, they require a resistive load.

For those of you younger guys,not familiar with the "peanut gallery",it is described here

http://www.youtube.com/watch?v=FQEqLUtp9Bg

Here is an instructional video if you are hungry

http://www.youtube.com/watch?v=VK5xsXa9LMw

Dale H

Will this also light up the number boards on the sides of the headlight?

You'll have to verify the operation, LED's are pretty directional, so you may have an issue if these are lit by the same bulb.  One way to do it is to position it farther back in the light assembly.

I'd probably slide the bulb out and try the LED from a bench power supply to see the effect before making the mods.  There are some other tricks you might try as well, I'd have to see the specific light assembly.  There are ways to diffuse the light from the LED, depending on the specific situation.

Yes, a single incandescent bulb inside the headlight assembly lights up the number boards. There is not much room in that assembly.

Hard to say if it'll work.  You might try pulling the LED back a little and also sanding the sides to diffuse some of the light and see if that scatters it a bit more. 

Funny, the atlas LED work fine with the Code 8 R2LC, but they use a higher resistance in series and no diode.  G

The diode is just there to prevent reverse voltage spikes from affecting the LED.  I was occasionally losing a headlight LED until I started putting the diodes in, so they're a standard feature now.

I am an idiot when it comes to circuits, I can fry a circuit board just by looking at it.

I like evans lighting when it comes to upgrading to LEDs... they are plug and play.

http://www.evanslighting.com/support.htm

I picked up a couple of the Evans LEDs at York to upgrade the lighting in my scale Williams GG1 that I upgraded to TMCC. They are not plug and play and need the installation of the resister because the LEDs do not draw enough power from the circuit that powers the lighting. I still have the bulbs but never go around to installing the resister.

Really? I bought a bunch with the resistor already in place, dont have to worry about the polarity issue either.

The load resistor is required for any stock Lionel R2LC, otherwise the triacs don't have the resistive load sufficient to allow reliable operation.  The ERR stuff includes the load so you don't need it for the upgrades.

Not that resistor.  The incandescent bulb offers resistance low enough to trigger the triac on the R2LC, an LED with a resistor and diode (or just the resistor) won't reliably trigger the R2LC triac.  You'll end up with either a flickering headlight, one that sometimes works, or one that doesn't work at all.

The cure is a parallel resistor directly across the R2LC lamp outputs.  I use a 470 1/2W resistor.  I found a 1K resistor didn't always do the job, so I went lower.

thanks john, I used mine for tender marker lights, thanks for clarifying.