well some red LEDs have a forward voltage of 1.7 some are 2.2. When you set the voltage of the regulator to 2.2 you don't need a resistor for the 2.2 volt LEDs and only a small one for the 1.7 volt LEDs.

That doesn't sound like the right way to drive an LED from what I understand. LEDs are current mode devices and the "voltage" on an LED is only approximate. My understanding is that you either need to set up the LM317 as a current source (such as shown here: http://www.reuk.co.uk/LM317-Current-Calculator.htm) or have a series current limiting resistor. This circuit can be use to drive 1 LED or several in series with the same current spec assuming the voltage can be supported by the LM317 and source voltage.

If you drive an approximately 2.2V LED with 2.2V "exactly" the LED will either poorly light or could draw too much current and possibly burn it out quickly. I guess you could measure the current and see if the voltage was too high or too low.

I'm not an expert with LEDs but I am an EE and every LED circuit I have seen has a current limiting resistor or has a current (not voltage) source. Plus I did a little studying before putting LEDs into my Schuco signal lights.

This link is one (of many) references on the need for a current limiting resistor: http://led.linear1.org/why-do-i-need-a-resistor-with-an-led/.

Karl:

When I use LED’s I try and keep the circuits and the math simple, because the audience does not have a degree in EE. For the average person an LED is a light bulb for DC current and they just want it to work for a long time.

In a simple series circuit with a variable power supply (track power) you can limit the LED current to the device maximum at maximum voltage but at lower voltages the LED will still produce light. As an example:

V max = 20 , LED V = 3.2 (white), Diode V = .7 The resistor for max current of 20 mA is (V max – V led – V diode) / .020 = 820 ohms.
The current in the circuit at different voltages will be: (V source – V led – V diode) / 820
@20V = 20.0 mA
@15V = 13.5 mA
@10V = 7.4 mA
@5V = 1.3 mA
The LED will be "ON" for all but the last voltage, and it may be dimly lit.

The calculations used the LED and DIODE as constant voltage and they are not. Per the article you sited the LED voltage/current is not linear like a resistor but for the tiny piece of the curve from 7 ma to 15 ma it can be treated as linear, just don’t exceed the maximum current.

In the case of the Schuco chassis I had all LEDS on 39 ohm resistors but had to go to 0 ohms on the center light to get it visible and since I want to keep the “on” voltage as low as possible I don’t want to kick the voltage up if I don’t need it.

All, I have added a rotary beacon to my LED equipped blue schuco monorail:

so here are two video clips at low resolution of the LED monorail on my tiny test oval:

http://s99.photobucket.com/albums/l295/jazzfan4/?action=view&current=DSCF2439.mp4][/url]http://i99.photobucket.com/albums/l295/jazzfan4/th_DSCF2437.jpg
This is the little circuit in the front unit:



And this is the circuit in the rear unit:

A little off topic....did anyone see Pawn Stars last week, replay last night, of the guy who brought in a mint Schuco set and extra train??? They offered the guy $200 and the guy said no. He wanted $400

Yes, I saw the Pawn Stars episode.

First, the trains were definitely not in "mint" condition. Second, Corey started at $100 and ended at $300 for the Blue 3 car "G" set and the red 3 car train. The red train had rust showing and the blue train, which they didn't show as much of, had visible scratches.

The guy selling the monorails was inflating their "Ebay value" based on what I could see. He sad the Blue G set was worth $600 and the red train by itself was worth $300. I would say they would go for about $500 for the blue set with box and about $200 for the red train (perhaps less because of the condition).

Then you have to understand how the pawn dealer works. They consider the "Ebay price" to be full blown retail (the most they could get for it) and they typically seem to want to pay 50% of what an item is worth (unless it is gold or silver where they will pay at least the "melt value" plus maybe up to 50% of the additional "collector value" -- also if there is a clear market value of the item they may pay a bit over 50%). The dealer has to figure in the labor and overhead of selling the item. People going to a pawn dealer to sell and item are usually wanting the "quick cash price" and this is going to be less than 50% of what an item will sell for.

When you net it all out they probably figured the items were worth maybe $600 to $700 on Ebay so they ended up with 1/2 of $600 or $300 as their final offer.

I think they look great!!!

Karl,

Can you post static pics of each of your monorails.

It looks like you have a few custom monorails and I am curious as to their look. I know Schuco made red and blue 3 car trains. What other colors were there? And did they make the Mrk II's or did you just add cars to your sets? I am thinking of spending the money on an ebay auction, but I really have to justify it, so any tips, tricks, or pros and cons you have learned would be appreciated. I also see you have what looks like graduated pylons for over and under operation. As those original Shuco or after market?

I'm very busy today, but I will try and take some pics soon.

Colors Schuco Made (I think I have all variations):

1. Red (frosted) with Silver Windows - I think there were more of these than any. These are the reds you see.
2. Red (cherry) with silver windows - A darker red and is very smooth finish. I have one and it is the only one I have seen. This might have only been an early production model as it did not have "weights" (and there are not holes to hold the weights) but it did have tail cones .
3. Blue (dark) -- Basically a darker/duller blue.
4. Blue (sky) -- Lighter blue -- the one I have had no "tail cones" which places it as an early model (not sure if this is indicative of only being an early model). I think Doug Burwell has some evidence that Schuco may have switched over and mixed up some of the blue colors and/or some of the colors shifted over time. (see his site).
5. Silver with red windows and silver bolsters
6. Silver with red windows and red bolster sections -- This one is fairly rare and apparently was made near the end of production. There are no red middle bolsters for a 4 car train so it is kind of strange that they did this toward the end of production. I have one in near mint condition by the way (it is not in any of the videos).

KarlG

Schuco did make four car sets, in both red and blue. However, they did not change the pilot domes.