Adding LED tail lights...here's how (pics)

[lionelsoni]

That's right. If you have a specific combination of lights that you would like advice on, ask away; and we can find the best way to hook them up.

[FJ and G]

I suppose that if 2 LEDs allow AC then 3, 4, 5, or 6 would not be a problem either (thinking of lit number boards and stuff for locomotives.

[darsenau]

Great article. Got the parts at Radio Shack and converted some cars. They look great, am now looking for more applications.

[FJ and G]

Yes, I forgot to mention that the schematic is one of the few I've ever seen that virtually anyone can understand.

[TurboOne]

Great Job Jim, and the pictures are great. Great photography.

Tim

[FJ and G]

Thanks Bob, I feel more enlightened now. I'll stick to a 1 W resistor

[lionelsoni]

The LED lights when current flows in the "forward" direction (anode to cathode). In the other direction, it acts like an open circuit, except that it can stand only a few volts that way. That is why, in an ac application, it needs a diode (in series) to disconnect it or (in parallel) to keep the reverse voltage at a safe level. When you use two of them, as Jim did, each one acts as the parallel protection diode for the other.

Jim's 1/2-watt 1000-ohm resistor is amply safe for the 14 volts that he is using. One might want to use a 1-watt resistor at 18 or 20 volts.

[FJ and G]

Thanks Bob for that illuminating explanation.

My understanding is that the LEDs can use either AC or DC, as they filter the current in one direction?

Also, when Jim D is running high voltage, the resister doesn't heat up too much?

Such a simple project it's a wonder we haven't done this minor surgery earlier!

[lionelsoni]

Congratulations, Jim! Here are a few comments:

I would cut the LED leads much shorter, to prevent them from touching each other. What to do if you then lose track of which lead was long (anode) and which was short (cathode)? You will find that there is a flat spot on the LED's base next to the shorter lead.

A picture caption says "Wire LEDs in series..." Actually they are in parallel. But just follow the diagram.

The diagram shows "AC hot" and "AC neutral". It doesn't matter which wire connects to the center-rail pickup and which to the wheels.

The car lamp is not the ballast, the resistor is. In principle, a small lamp would make an excellent ballast; but as a practical matter, the typical lamp's current is about a factor of ten too high for most LEDs.

The light output does vary with track voltage, but much less than with an incandescent lamp, to the point that it is not really noticeable. White LEDs also have the advantage that the color does not shift toward yellow and red as they dim. This helps the illusion.

Normal white LEDs are much too blue to be convincing as headlights. However, you can get LEDs that mimic incandescent lamps in color from Richmond Controls: http://www.richmondcontrols.com

For numbers of LEDs other than two, you can of course simply build several circuits of this kind. Or you can wire pairs of LEDs like this in series with a single ballast resistor. This will increase the variation of light output with track voltage change, however. For a single LED, you can put a diode (1N914, 1N4148, for example) in series with it and the ballast resistor. Or put the diode in parallel. This reduces the sensitivity to track voltage a little but doubles the power dissipated in the resistor. In either case, connect the striped end of the diode (the cathode) to the long lead of the LED.

I would not count on the LED's diameter's being any particular exact value. Drill the hole a little undersized at first and work up to a snug fit.

[FJ and G]

Thanks, more info to download!

I notice when my VRE train stops, side lights come on on all the passenger cars. That would be a challenge, modeling lights so they come on when the train stops

[ChiefEagles]

Good idea Buckeye. Maybe the "Boss" Bob Keller will make one. Don't know how hard it would be. I'll email him and ask.

[Jim Duda]

Jon - perhaps Professor Nelson or Roy will weigh in...or someone that has actually converted their cars using WHITE LEDs. In their natural state, they might be a little too BLUE, but Bob knows a source for "incandescent appearing" LEDs.

Since I wired my two in series, it negated the need for a diode - I know for just ONE LED, you would need a diode...I'm not sure what happens if you would need 3, 4, etc. Anyone?

[AntonioFP45]

Jim,

Beautiful job! Amazing how details like this really makes a train stand out.

Thanks!

[jonadel]

Thanks Jim, very informative and easy to follow. I run two long passenger trains and those cars really suck up the power. I've thought about going to LED's but I'm afraid to jump in and make the switch, any thoughts?

Jon

[Anonymous]

Love it Jim, This is a keeper.......Tim

[Jim Duda]

Mr. Pearson...before I actually installed them in the car I connected the LEDs and resistor directly to the track - no lamps in the circuit - and they worked fine. I think the resistor is the ballast. Of course, a lamp in the caboose AND the LED markers would look even better...

[dougdagrump]

[8D][8D][8D][8D][8D]

[Buckeye Riveter]

Great job Jimmy! I wish we had a special folder to keep these ideas stored on the web.

[Anonymous]

I have a small prewar tinplate collection. Recently I got a rough looking Lionel #2657 caboose. I also have a spare set of trucks that have a pickup roller on them. my caboose doesn't have a light in it though. Can I do this mod to my caboose and put the red LEDs on as marker lamps on the rear sides? It looks like a fun thing to do and I want to learn to do a little detailing to my stuff. I think I can solder all the stuff up like you showed in your pictures. Do I need to also install a light inside my caboose? Is this neede for the circuit to work maybe like a ballast?

[Jim Duda]

I use an old LW and the lowest voltage I can get out of it is around 5.7 volts...the passenger car lamps come on, but are very dim. Interestingly, those LEDS are the same brightness all the way from 5.7 up to 18 volts! Since I usually operate in the 10 - 14 volt range for DCS and TMCC and 6 - 12 volt for conventional, I'm happy.

[ChiefEagles]

Good job Jimbo

[Anonymous]

Jim;
Thanks so much for the amazingly simple diagram/
pictorial! It makes doing the modification a whole lot
easier when you can see how one was actually done!

I've been wanting to do this to the observation on an
old Lionel Post War set!

BTW could you please post the operating range (volts)?

Thanks again!

[Jim Duda]

I like to run the trains with the room lights off and those Williams Baby Madisons really needed some red lights at the rear end. You might recall Bob Nelson gave us the Radio Shack part numbers and the value of the resistor to make this modification several pages earlier. Since the K-Line scale Hudson's tender already has 2 LEDs, the additional red lights at the end of the train look even better.

Total cost of each car conversion was under $4.00 and is easily accomplished. Here's how I did it...

(click each one)

[image]http://img.villagephotos.com/p/2004-11/888231/MadisonLEDschematic.JPG[/image]

[image]http://img.villagephotos.com/p/2004-11/888231/Wiring-EndComposite1.JPG[/image]

[image]http://img.villagephotos.com/p/2004-11/888231/Wiring-EndComposite2.JPG[/image]

[image]http://img.villagephotos.com/p/2004-11/888231/EndComposite3.JPG[/image]