Coach Car Lighting on DCC

[PadreCraig]

I recently upgraded to DCC on my small layout.  My problem is that now my Bachmann coach cars light up too bright.  It there anything I can do to dim the lights to more of a glow like they were when I was using just a DC transformer?  TIA - PadreCraig

[Jim Banner]

Solution 1:  buy a bunch of 22 ohm, quarter watt resistors and start adding them, one at a time, in series with the lights in one of the cars.  When you get down to the correct brightness, add the same number of resistors in series with the lights in the other cars.

Solution 2:  Install a locomotive decoder in each car, using the motor output of the decoder to control the car's lights.  Program all the car decoders to the same address which must be different than the locomotive address.  Now when you dial up the car address, you can brighten or dim all the cars' lights at once.  This is a particularly good solution on a portable layout where you do not have control of the ambient lighting.  Ask around and you may find some cheap used decoders that have been replaced with better decoders.  Fortunately, it does not take much of a decoder to run the lights in a car.

Jim

[CalgaryOn30guy]

I dimmed mine by a little blue craft paint  paint on the bulb.

[JohnR]

A 100 ohm 1/4 watt resistor will dim the light.  Inserting a function-only decoder will give you the ability to turn off the light.  The resistor would go on the output side of a decoder.

I've use this resistor value to dim headlights on Moguls and Porters.

-John

[Jim Banner]

I dimmed mine by a little blue craft paint  paint on the bulb.

This will dim the light alright but it will not reduce its heat output and it will not prevent early bulb failure.  The higher track voltage with DCC, compared to normal speed track voltage with dc, increases the power consumption of the bulbs which in turn causes them to heat up more.  The higher temperature may cause plastic cars to distort or to harden and crack in the areas near the bulbs.  The extra heat also causes the bulbs to burn out sooner.  For example, it you used to run your trains with 8 volts dc on the tracks (i.e. at about half speed) but now you have 14 volts of DCC on the tracks, you can expect your passenger car lights to last less than 1/1000 as long.  Put another way, if the bulbs used to last 1000 hours on 8 volts dc, their estimated life on 14 volts DCC is about 40 minutes.  This is because the life of small lamps is inversely proportional to the 12th power of the voltage ratio.

Jim 

[lvrr325]

Given full throttle operation with any transformer is 14-16 VDC, model train bulbs have to be rated to take this voltage in the first place. 

That said, I've disconnected most of the bulbs in my passenger cars, as they don't look that realistic; and unless you paint the trains they tend to show through the plastic. 

[Jim Banner]

The incandescent bulbs in passenger cars and locomotives are often rated at less than the maximum output of the power pack on the assumption that model railroaders will be running their dc trains at realistic  scale speed, not full speed.  This also helps the lamps come on a bit sooner in terms of throttle setting than they would otherwise.  With DCC, the voltage on the rails is maximum no matter what the train speed is.  With H0 DCC, the track voltage can vary between 15 and 18 volts rms which is the voltage fed to the  bulbs in normal passenger cars.

Going back in history to the days when model trains were run by transformers, the bulbs in those old 0-gauge hi rail cars were often just 12 volt automotive bulbs which did not last very long at 16 volts.

[Royce Wilson]

I removed my lights and installed a Grandt Line interior. New windows that are not 1/2 scale thick along with window shades. these really are beautiful passenger cars and with a little work they are outstanding!

I also removed the locomotive light because in the old days lights were only used after dark.

Royce

[Royce Wilson]

Correction, the headlights were not totally removed from the locomotives, I just up graded them to PSC with MV lens and the results was outstanding.

Royce

[lvrr325]

Several of my passenger cars and at least one caboose date back to the first runs, the cars are from one of the sets, I'm running an early MRC Prodigy DCC and while the lights are bright, none of those that are still hooked up, have burned out.  Most have a lot of hours on them. 

[Jim Banner]

lvr325, I am glad to hear that.  It means they were fitted at the factory with lamps that could take the gaff.  Many H0 passenger cars were sold with 9 or 10 volt lamps so that they would be bright enough at normal running speeds.  At 15 volts, which some power packs could deliver, their life was down to about 1/2 of 1 %.  So the people who ran their trains like slot cars had lights for a day or two.  The rest of us had them for years.  Then came DCC with its higher voltages.

I suppose higher voltage lamps make sense in another way too - they give a gentle, slightly brownish glow like the kerosene lamps used way back.  Bright lights in passenger cars might pass as gas lights (acetylene or carbide lights) particularly if the bulb were given a light wash of green.  But that would date your layout to post 1900, which might or might not work for you.

I have been slowly replacing passenger cars lights with warm white surface mount LEDs operated by an adjustable current regulator which allows me to dim them or brighten them to match the ambient lighting wherever the layout is being shown.  It is a neat system but should not be necessary for a stationary layout.

Jim