3rd Rail Pass LED strips

sorry for the blurry picture!

My next problem is figuring out why these Atlas Amtrak cars flicker so bad?

A capacitor would boost 18 volts track to about 24. The resistor should be at least 1K or better 1200 ohm,half watt. If you want it dimmer you can go higher.  Last pic I saw I could not figure out the resistor bands to get the value. Try putting a meter across one of the resistors. Or post the colors of the resistor bands.

 

You could unsolder and remove the resistor and replace it with a CL2-n3 chip. This assumes a cap across the bridge + and -,   220 uf  up to 1000 uf.

 

Dale H

Here is a color band chart,I can not make out the colors in your photo.

 

LINK

Don't ask me to help with colors! If you click on the picture, it gets clearer to see.

Anyways, they measure 470 ohms with my meter. I should have thought to post that above.

That (470) is not enough IMO even without the cap. blue,blue brown I think is 660 ohms.

 

Dale H

Hmmm, I checked again and they all measured 470?

I have some 910 or 920 ohm 1/4 watt in stock. That's the biggest I have.

Why is the 1/2 watt needed?

I'll either have to order 1200 ohm 1/2 watt, or supply the board from those buck assemblies I'm making for the other cars? If I used them, I could adjust the voltage and leave the resistors?

Will this operate on DCS (command voltage)?

 

If you're planning to use a 99 cent DC-to-DC module and are willing to do some board surgery (as it appears you are), seems you can use the bridge-rectifier on the board.  You still need the choke/inductor (for DCS compatibility).  A capacitor is included with the DC-DC module or you can add more for improved flicker tolerance.

 

The polyfuse between the rollers has nothing to do with LED lighting per se.  It's so you don't melt the internal wiring during a derailment-short.  The idea being if you're opening up the car anyway for modification why not included this simple protective feature.

 

 

Note that the board is specified for 3-30V operation which is one feature that sets it apart from the popular 12V LED strip methods.  That said, since you're planning to modify the electronics and mention the DCS choke (i.e., it appears you're using command voltage levels), I'm curious why you're using these boards vs. 12V LED strips.

Stan, maybe Joe has lots of money and he really likes Scott at 3rd Rail.

 

Well, I bought a set of 3rd rail passenger cars. They are beautiful. I thought I would use their lighting board inside too. If you can afford their cars, you can afford their lighting board!

 I planned to unsolder the bridge or cut it off. Build my LED circuit, and connect it to these strips. I was adding caps to the circuit. Maybe that's not needed with the boards? Might be why I blew one up?

 The 12 volt LED strips that I have are probably brighter. I do like these LEDs on the 3rd rail board and will use them if they fit and light the car properly.

 I've got to go look at the buck board again!

If you have the cars open, and are adding lights.... I would put LED strips in them. I have a bunch of GGD cars and want to replace those GGD strips.... I just don't wanna open all those cars up Just My Opinion...The only CON I have with my GGD cars is the lighting. The LEDs stand out, and there are dark spots within the cars. Use some strip and have some adjustability.

I was given a list of components to buy for converting passenger cars to LEDs. It specified these buck boards, along with cap, choke, bridge rectifier, and polyfuse. I was just following the post. The smaller buck board also listed had a lower input voltage. That one blew up on me. So I switched to just using the larger board listed with a higher input.

 

Ooops, and it's a yes to command voltage with DCS on two rails. I use AC power on my O scale and DC power on the G. I like to be able to run either.

 I have not tested these Buck boards alone, without the extra cap.

If you use strictly command voltages, you don't need a boost power supply, you have plenty of voltage. FWIW, that power supply you picture is not a buck/boost model, it's strictly a buck power supply.

 

How high a voltage to you run on the G layout?

 

 

 

I had it set up around 27 volts on the pack. I lost the lights in the LGB Amtrak cars. I lowered it to read 25. With it there, the voltage at the track outside is around 21 or higher.

 It's tough because of voltage losses, and all the equipment requires different voltages. I need to try my Z4000 outside with AC to the rails. I had so many problems this year, I lost my ambition to test things! I don't need extra grief!

I'm doing every other car I own first. If I open these up, I don't want any mistakes. They look like museum pieces to me. I've actually shied away from doing this!

I'd consider using a home-rolled regulator that has high voltage capability.

 

Here's the LM317T that should be good to 40V. LM317TG

 

This is the basic circuit, I'd use a capacitor with a 50V rating to give a little extra margin for the higher voltages.  This circuit should be good to at least 28 volts RMS AC or 35 volts DC on the rails.  Unless you go crazy, this should not die due to over-voltage.

 

 

 

Resistor size is voltage drop divided by the amperage. 25-3.2/.02 equals a bit over 1000 ohms. 1200 ohms is the next standard value. 22 volts times .02 amps equals .44 watts used by the resistor. I would replace the resistor with a CL2-n3 chip,then there is no worry. Add a cap to the board. Or go the buck converter route John suggests. You can leave the bridge in. 

 

Dale H

I wouldn't say "no worry".  The CL2 TO-92 package gets pretty warm with close to half a watt, remember it's dropping the same amount of power as the resistor.  One reason I use the LM317T is the package is larger and handles the heat a lot better.

Given the amount of surgery you're apparently willing to do to the 3rd Rail LED strip I can't imagine why you wouldn't convert to 12V LED strips.  As Laidoffsick points out of first-hand knowledge, with only 4 LEDs on that strip you don't get the even/smooth lighting as you could with 12V LED strip where LEDs are only 2/3" apart.

 

Since you confirmed you're using command voltages, another issue with the 3rd Rail strip is its configured to operate down to 3V.  This comes at a price.  With a 470 ohm resistor for each LED, a lot of power is wasted when the LEDs operate at the nominal current (brightness) of 20 mA which requires about 12V DC on their strip.  That is, a white LED runs at about 3V.  So 9V is dropped by the 470 ohm resistor which means about 75% of the power goes up as wasted heat.  You can do so much better efficiency-wise with the 12V LED strip and either the roll-your-own regulator as GRJ shows, the off-the-shelf Hennings LED circuit board, or the DC-DC buck module plus a bridge rectifier, DCS choke, and if needed an additional capacitor for better flicker reduction.

 

 Thank you all. I think I will just go with replacing everything then. There's no sense modifying this board and not getting good results. I don't wish to go back inside these beautiful cars again!

 

Joe I personally think that is a wise choice, and I think you will be much happier with the results of the LED strips. I guarantee you... I would be.

Actually if you modify the boards,they could work well in conventional. I run conventional and use a 7805 circuit and individual LEDs like the GGD strip you have.

In command,I think you are better off with John's kit and the lighting strips if you want plug and play. There are many methods of using the lighting strips and individual LEDs.  Here is yet another method to consider if you want to do a bit of soldering.

 

LINK

 

Dale H