Take one apart to find out.   I put in LED's and a capacitor to keep things from flickering, but I think they still use bulbs in those.

Thanks John,

Well since I'm going to be populating the cars with passengers I'll accept the challenge and take a look. I had seen some other threads on light flicker that talked about adding a capacitor but nothing definitive. I'm sure it's not magic but the difference is impressive. Brightness changes with throttle setting but absolutely NO variation around the track.

Our Polar Express cars never flicker due to the inclusion of collector assemblies on both trucks and Lionel having wired them in parallel.  If one does flicker, it means a wire has broken to one of the collector rollers.

Rob,

By collector do you mean pickup roller? If so, wiring in parallel would be pretty darn simple and would suggest that my MTH rolling stock has assigned one bulb per roller rather than parallel wiring.

S

Rollers and ground/axle wiper straps - on both trucks.   The wires are all combined with the two bulb leads using wire nuts. 

The collector assembly part number is 9050-150 if you want to retrofit Lionel rolling stock that only has 1 pickup:

Originally Posted by Scott T Johnson:

That's how it has been on some cars in the past - Williams was notorious for this early on with the early aluminum runs.  I doubt MTH would resort to to it. 

Lionel starting in 1973 on the Milwaukee cars only used one collector/wiper assembly for the whole car and they blink like crazy.  Same for all of the caboose issues. 

The exact same caboose made by Lionel in China today(as well as the O-27 passenger cars) now comes with a 9050-150 collector/wiper assembly for each truck.  It's quite an improvement - it seems the extra expense based on Chinese parts and labor was so little they adopted the practice for the whole line.

That really has me curious. I have some MTH Madison cars with fore and aft lights and it's definitely one light per roller. As each roller crosses the non-powered rail thru the switch, that light goes out and then comes back on. I have last years Polar Express passenger cars on the shelf and will give the pick-ups a look.

Thanks Rob

If you use LEDs with a capacitor and bridge rectifier,it really makes up for bad rollers.

There are several ways I do it shown here

www.jcstudiosinc.com/BlogCategoryMain?catId=426

Also search the forum,there are numerous posts on other methods.

Dale H

Dale it right, since I'm halfway through converting all my passenger cars to LED's, I don't get any flicker.  I do indeed wire the rollers in parallel, but I include a 3A PTC between them to protect the wiring in the event of a derailment shorting one roller to the outside tracks.

That's actually a safer scheme as it eliminates the possibility of fault currents passing through the wiring inside the car.

A simple solution to the flickering while protecting from fault currents would be to power the bulbs in each car, however many there are, with two small bridge rectifiers - each one getting it's AC from one of the truck's collector rollers, and chassis/axle wiper ground.  Connect the DC sides of the rectifiers in parallel and to the bulbs.

The avoids the possibility of a polarity imbalance(as opposed to using single diodes and alternating them from car to car) and maintains bulb brightness with full wave DC to the bulbs instead of half wave.

Dale,

The link you give is fantastic and really appreciated. Thanks.

In the instruction sheet that RMT provides with the car it shows 12 bulbs on an overhead strip so I'm guessing they must be LED. When I open the cars to populate I will look further.

Reading John and Rob's posts leads me to ask if there's a reference that's a little more advanced than the book I have on track wiring. I have an extensive knowledge of heat transfer and thermodynamics but my model trains don't run on steam power -- unfortunately. So to understand and do the really neat stuff you guys are referring to I need a better reference. In the meantime I have a bunch of EEs right around the corner at work.

Thanks!

I can't comment on the "better reference", 40 years of electrical engineering has given me the background that I need for most of my train electrical projects.   However, if I ever get into live steam, you're my man!

Scott

I am not familiar with the RMT lighting. If you look at the strip and there is not a diode or a bridge rectifier,most likely they are using bulbs. If they plug or screw in,they are most likely bulbs. No real need to plug in LEDs,they rarely need replacement.

John has some good circuits using 12V lighting strips for command,he is a pretty sharp EE. I use the strips in buildings sometimes, I run conventional and use individual ones mounted on fish paper with a constant voltage circuit. I sometimes add super capacitors which leaves the lighting on for a couple minutes after power is removed.They fade slowly after shutdown. CV circuits are not really needed for command operators. I am a toy train guy and light cars very bright. But you can also make them subdued. Once you understand the circuitry you can customize your cars according to your preferences. Really worth doing your own if you like to do it. After you do a few it is easy. Hardest part is getting the cars apart for me.

Dale H

John and Dale,

Thanks to both of you for the feedback. Makes me realize that a some basic circuit know how would add an extra dimension to my hobby. I like Dale's stuff on lighting -- brighter is better for me too -- so I'll start with one of the schematics and have the power supply guy around the corner at work walk me thru it. I keep his power supplies from overheating so I figure he owes me.

S

wouldn't it be nice though if Lionel or Mth offered a version already with the capacitor.  Sort of like the vision line of cabooses or passenger cars?

I'm not sure why one of them haven't at least gone to LED lighting, it's more even and eliminates the power issues with passenger trains. 

Here's the sheet that came with cars and the circuit diagram from the patent.

http://www.google.com/patents/US6231421

So the diodes look like a rectifier arrangement (?). But I don't see a capacitor. I had an MTH caboose apart the other day and found that one roller powers both lights. But it still flickers on occasion. By comparison the RMT cars are steady and brilliant. Huge difference in light quality.

The Streamlighting is a K-Line thing, and they were indeed incandescent bulbs.  It's impressive that they don't flicker, maybe there's some magic we don't know about!

BTW, the diode strings are to supply a low voltage to the rear light bulbs, they must be 1.5V bulbs.

Guess so. I have a bunch of MTH passenger cars with dual bulbs and the lighting is ok but otherwise unimpressive while the RMT lighting has this Wow factor. Even my wife and daughter are impressed. Nice to hear her say "that's cool" instead of the usual eye roll when she comes by the train room.

The StreamLighting was some of the best back in the K-Line days as well, it always looked much better than the wimpy bulbs in the other brands.

K-LINE stream lighting were really power hogs. Run in command settings they generated a lot of heat and burned out fast. The diodes in the diagram are voltage droppers. They clamp about 1.5 volts for the rear lights which are most likely low voltage,low wattage bulbs..If you have stream lighting I suggest you convert it to LEDs.

Dale H

Can't argue with Dale, I converted all my K-Line passenger cars to LED's already.

Scott

  Problem is, the car is still enclosed,even with heat sinks the heat has to go somewhere.  The lighting really was designed for conventional. A lot of command operators learned this the hard way. At 18 volts they will pull even more than the wattage you mention. More than 12 watts per car I imagine. If a bulb is burned out I think there is a shunt designed in to keep the rest lighted but it still strains the rest of them and they burn out even faster.

Dale H

How does RMT keep the car lights on?

They partnered with Motel 6

They will get pretty warm with those lights operating in command, I can tell you that!

At 18 volts track power, I have a 15" K-Line Interurban dummy unit that draws 1/4 amp.  That's 4.5 watts, a ways from 12 watts, but still quite a bit.  It has streamlighting with a bunch of bulbs just like the RMT car, I'll bet it's the same scheme.  So, four of those cars would be knocking on the door to an amp of current from the track, ten times or more what LEDs would draw.