Question on CTT's 2 trains on 1 track article

[FJ and G]

First, nice diagrams and explanation. Scenario 3 obviously is the best, with the relay.

I run both DCS and conventional (usually not at same time). Would this wiring scheme be OK to use? Or would it present problems for the TIU?

The article is supposedly written for conventional operators but Plummer fails to realize that there are a couple of us who run both conventional as well as command control. Odd but true.

[Big_Boy_4005]

Dave, the relay method in system 3 could get messy with command if loss of power causes an engine to reset. If not you should be OK.

System 3 is the first step in a full blown block signaling and operating system. One thing to keep in mind is that, automatic stop applications kind of go against the concept of command control, as they form an override situation. They are much more interesting for conventional running.

[FJ and G]

Elliot,

Thanks. The other option I have would be an override toggle switch or switches, to separately run the setup as conventional and then to separately run it with command control. However, that would turn off the signals in command control.

Wi***here were some type of comprehensive book on these things.

Also, Elliot, you probably get MR magazine, in it is a nice article on white LED replacements for locomotive headlights. Again, an entire encyclopaedia could be written about these electronics projects that seem to terrify 75% of everyone, much like calculus or chemistry scares some right-brained students.

[Big_Boy_4005]

I was thinking of an override switch Dave. all you would need to do to override is supply power to the sections of insulated center rail. Let the signal continue to do its thing.

Yes, I do get MR. My new one came in yesterday's mail, and I haven't had a chance to look at it yet. I'm guessing that the article about white LED's is in there. I'm going to run out and vote quick, I'll look at it when I get back.[swg]

[Big_Boy_4005]

Seems like a fairly simple and interesting project. The one thing that the author is giving up is lights on his number boards.

I'm not sure if I like the bright white LED's for this. A golden white LED could be easily substituted. They give a more incandescent as opposed to a halogen look.

For use with AC, I'm not sure what would happen. We may lose half of the intensity. You shouldn't damage the LED with AC, you just won't get the full effect. If installed in a modern engine, they would work correctly when wired in after the track power was rectified. For post war, a small bridge rectifier may be necessary. This is a perfect question for Bob Nelson.

The text of the article makes no mention of command control, but that may be a good part of the motivation behind this concept. With full track power on the old style bulbs at all times, they were burning out. Actually, looking at the photos in steps 6 and 7, you can see a DigiTrax decoder (that light blue thing). Upon closer look, the caption for step 6 does mention DCC.

There was an article this past summer, I think in OGR, about replacing bulbs in Lionel switches with LED's. Same principle here, but this time there is a fiber optic involved.

[lionelsoni]

I haven't seen the OGR article; but replacing headlights by LEDs is not hard. I have done several, both modern and postwar. The golden-white LEDs are much better. It also helps a lot to put a capacitor across the LED. They turn on and off instantly otherwise and look unrealistic compared to incandescents. The value is not critical--a few hundred microfarads. You probably can't find a capacitor with too low a voltage rating. Then drive that parallel combination through a resistor, with a diode in series (e.g., 1N4148) if you're using AC. (AC will damage LEDs. They can't stand much reverse voltage at all.) The white LEDs are so bright that you don't need much current, just a few milliamperes. You can actually turn down an 8-millimeter LED to fit into a Lionel headlight hole. And you can flatten the tip and polish it with toothpaste. Just don't cut into the chip inside.

I had an article a while back in CTT about adding directional lighting to postwar locomotives. Instead of connecting the lamp between the frame and the pickup, as lionel did, you reconnect it between the frame and one of the motor brushes. The incandescent lamp does come on, but very dimly, in reverse, since incandescents are very sensitive to voltage. This will also work with LEDs, but you will probably have to put extra diodes in series to soak up the voltage that is still present in reverse.

Using LEDs, I feel no need for regulating the brightness of headlights, as I would with incandescents. The brightness does vary with voltage, but not nearly as much. But, beyond that, the color remains exactly the same at different voltages, so that clue to voltage changes is absent: They look fully lit over a wide range of voltage.

[daan]

A LED is a small rectifier, but the reverse blocking is minimal. You should wire a diode in series, as said before. Making numberboards lighted is the same easy trick. Besides that, it keeps forever, as long as you have the resistors chosen right. (a resistor is needed in series, otherwise the LED, which uses a voltage of 2.4 volts, gives a different color for a short time. Green will be yellow, yellow will be orange and red gets very red[:D])
The multiple trains on one track article has a few big drawbacks. First, 2 trains consume more power then one. So if one train shuts of on the dead track, the other starts to speed. The second drawback is that the stops are emergency brakes. From driving nice and fast to an abrupt standstill in length of inches. If you use the block signal feature, wire from the power input on the trackpower a resistor (wireresistor of 1,5 ohms will be sufficient enough about 20 watts) towards a section of isolated track in front of the stop section. Use a 3 pole relais (one for the lights, one for the stop section and one for the resistor section) to switch the thing.
The result is a more gentle halt because the wire resistor lowers the voltage on the track section in front of the stopsection.

.........Red----[...]...]----green
track stop....[...]...]----- track powered
resistor---\....[...]...]----- track powered
...............\-{R}-/

Note that the "R" is the resistor and that it comes of the middle pin, which is the input of the track power. The stripes are wires, the dots are needed to give space in the drawing.
Red and green is obvious, track stop is the halt section, not wired, the resistor is wired to the middle pin. If the relais is unpowered (middle and most right pins joined), the lights are green, both tracks are powered and the resistor will be overruled by the relais. If the relais is powered (middle and most left pins joined), the lights are red, the stop section has no power and the resistor section gets power via the resistor since the overrulement of the relais falls off.

[Big_Boy_4005]

QUOTE: Originally posted by lionelsoni

I haven't seen the OGR article; but replacing headlights by LEDs is not hard. I have done several, both modern and postwar. The golden-white LEDs are much better. It also helps a lot to put a capacitor across the LED. They turn on and off instantly otherwise and look unrealistic compared to incandescents. The value is not critical--a few hundred microfarads. You probably can't find a capacitor with too low a voltage rating. Then drive that parallel combination through a resistor, with a diode in series (e.g., 1N4148) if you're using AC. (AC will damage LEDs. They can't stand much reverse voltage at all.) The white LEDs are so bright that you don't need much current, just a few milliamperes. You can actually turn down an 8-millimeter LED to fit into a Lionel headlight hole. And you can flatten the tip and polish it with toothpaste. Just don't cut into the chip inside.

I had an article a while back in CTT about adding directional lighting to postwar locomotives. Instead of connecting the lamp between the frame and the pickup, as lionel did, you reconnect it between the frame and one of the motor brushes. The incandescent lamp does come on, but very dimly, in reverse, since incandescents are very sensitive to voltage. This will also work with LEDs, but you will probably have to put extra diodes in series to soak up the voltage that is still present in reverse.

Using LEDs, I feel no need for regulating the brightness of headlights, as I would with incandescents. The brightness does vary with voltage, but not nearly as much. But, beyond that, the color remains exactly the same at different voltages, so that clue to voltage changes is absent: They look fully lit over a wide range of voltage.

Thanks Bob, I didn't realize that about the reverse voltage damaging them. The article Dave was talking about is in the December issue of Model Railroader, if you get a chance to check it out. The concept is fine, but the application requires special consideration in an AC environment.

[lionelsoni]

Sure enough, I must have fixated on Elliot's mention of OGR. I'll look for that article when I next see MR.

[FJ and G]

Interesting comments.

I was wondering if there are LEDs that could throw light the way incandescents do to lite up my passenger cars. The high voltages used on DCS tend to make short life of those bulbs.

As far as AC current goes, it can always be rectified before going to the LEDs.

[daan]

You could also wire the indescendants is series, voltage on the lamps will be half the voltage on the trackand the life will be longer of course.
The thing with LED's is that they only shine forward. They are perfect for headlights, but the diffus lightning on illuminated passenger cars can't be immitaded with it.
LGB has one of the restaurant cars fitted with miniature lamps on the tables fitted with LED's, that is a possibility too.

[FJ and G]

daan,

To create an LED diffuse light, mount them in an array. Individually, they are not particularly bright, but en masse they produce a lot of light. These could be used, I theorize, in passenger cars. For reference, see: http://www.reed-electronics.com/tmworld/article/CA187559.html

scroll to "use LEDs as an Array

another nice site to visit that's easy to understand is:

http://www.kpsec.freeuk.com/components/led.htm

[lionelsoni]

Putting lamps in series can be a problem if the sockets are grounded to the frame or if, as in the 2400-type small streamliners, the two lamps are already in series. It also reduces the voltage by half, which may be more dimming than you really want. You can put a resistor in series; but that exaggerates the sensitivity of the lamp's brightness to voltage changes. However, a diode rectifier in series (with AC track voltage) reduces the effective voltage by 30 percent (and doesn't get as hot as a resistor would). Thus 18 volts becomes about 13.

If you do this with a number of cars, it is best to put half the diodes one way, half the other way, to cancel the DC currents that the lamps will draw.

[FJ and G]

Bob or others,

Has anyone ever experimented with mini flourescent bulbs to fit inside passenger cars?

Perhaps the insides of the cars could be coated with anti-UV paint. Would voltage fluctuations mess up mini flourescents?

Flourescents would provide a fairly cool, bright, and longer lasting light.

-------------------------------------------

Reg. lighting locomotive lights, would be interesting to see what could be done with fiberoptics. Perhaps on the control panel inside a diesel or for lighting firebox glow in steam engines.

And here's the real wild idea. Have near-invisible fiberoptics protroding from the smokestack, fixed to hidden blinking red and orange lights to simulate embers coming from the stack. These would turn on when the smoke is coming out. Perhaps insulate them from the heat with thin metal conduit.

[lionelsoni]

Fluorescent lamps generally need large surface areas and high voltages. Notice that the "compact fluorescents" are actually long tubes coiled up into a smaller space, so that there is enough phosphor to get out the required light. It would be problematical whether the small amount of tubing that you could get into a model would give enough light to do any good.

They also want fairly high voltages to make the arc inside that generates the ultraviolet light. The usual 4-foot long 40-watt T-12 tubes, for example, cannot be run directly on American 120-volt circuits. What is labeled a ballast for those in this country is actually a combination transformer-ballast. In Europe, they can run them directly on 230 volts and, in American industrial and commercial applications, on 277 volts. A train fluorescent, being shorter, would not need as much voltage but probably quite a bit more than the 6-to-16 volts typically available. It would therefore need some sort of voltage conversion and probably also frequency conversion to keep the ballast size reasonable.

I think that LEDs are much more practical and really not that hard to diffuse. By the way, the white ones, like fluorescents, also produce short-wavelength light that is down-converted with phospher to white. Their light is so bluish because the makers skimp on the phospher, not taking into account folks like us who want to imitate incandescents' yellowish color. The golden-whites are just normal whites encased in orange plastic.

[FJ and G]

One final question, related to the last line of Bob's reply. If the LED is too white or too something else, can't one simply put a bit of paint or colored plastic (a homemade filter) over the LED? Realize, however, that you'd lose a bit of light.

[daan]

A LED doesn't get hot, so any type of filter can be used..

[lionelsoni]

Yes, you can in principle filter it yourself. I tried that when I first experimented with white-LED headlights, but never found a decent filter material. I think the problem is that the phosphor has a "spiky" spectrum, which interacts unpredictably with the spectrum of filter materials to produce undesirable colors, unlike the inherently smooth spectrum of an incandescent lamp. Everything I tried seemed to result in a sickly greenish yellow. The Richmond Controls guy seems to have found a more suitable filter pigment.

[lionelsoni]

I finally got a December CTT and read Plummer's article. It's the same scheme that I proposed in this old topic: http://www.trains.com/community/forum/topic.asp?page=-1&TOPIC_ID=8453&REPLY_ID=54416#54416

I have added a red-green signal to the circuit, still without using relays. Just connect the red lamp to the outside rails, the green lamp to the center rails, and the common between them to the isolated rails. If the two sections with isolated rails are not adjacent, shunt the green lamp with a few other, hidden lamps so that the signal is red when the incoming train is between those two sections.

If you use this scheme with modern cars that do not conduct from axle to axle, as I do, you don't need the stop section to be any longer than the locomotive plus coasting distance.