Williams Bud Car upgrade to TMCC

Bi Color LEDs come in either common anode or common cathode configuration.  I believe only one configuration will work with the radio board but I can't tell you which one at the moment. You should be able to determine which type you have with an ohmmeter though.

Pete

You need a common anode 3-pin LED for the TMCC board as the lighting outputs are negative in respect to frame ground.  One of the many reasons I always "roll my own" LED assemblies, I can use the correct parts for the application.

GRJ- thanks. These were my first install for the club engines. Wanted to play it safe, but I agree on the whole roll your own. They will agree with me now about letting me make my own LEDS for the upgrades. 

What type of bi-polar red/green led should I use? Common anode or cathode? 2 leads or 3 leads?  And resistor value? 

Thanks for the help all. 

Chris. 

Chris, Like John said, common anode. You will want 3 leads assuming you will wire these into the headlight/taillight circuits. Figure 600 ohms minimum as they are typically rated for 20 ma and the radio board outputs are ~12V. The resistor will need to be higher if the LEds have a lower current rating.

I did the same thing on my Williams Budd cars but quite a few years ago. I thought I had some LEDs around to check but couldn't find them. The RPO is a Lionel dummy repainted.

I suggest 1K resistors for the bi-color 3-lead common anode LED.  Put the 1K resistor in each leg from the two TMCC light outputs, don't try to save a resistor in the anode lead, there are sneak current paths if you happen to drop into conventional and get AC on the light outputs that will kill the LED.  Don't ask me how I now this.

GRJ - thanks again. Common anode bipolar LEDs are Center lead is "positive" and the outside leads are negative correct?

Norton - thanks, those look sharp, I'm doing a set of LV and have them just about ready to run fully lighted. Glad I added the extra lights, make them look more realistic.

Correct, the anode is the positive side, so a common anode has the anodes of the two LED chips common on the center lead.