# Wiring dual LEDs on one side of Tsunami board:need help



## SRV1 (Nov 14, 2010)

This is the wiring diagram I'm supposed to use for wiring LEDs to this board. But it only shows one LED being wired up for each end. And then it shows the use of the FX side which I'm assuming would be for interior lighting or ditch lights?? It doesn't explain that very will.










My question is, what do I do with dual LEDs in the front and duals in the back? Do I need to send anything to the FX side? And how should the wiring go based on this diagram? They're just front lights and backup lights. The wiring at the rear of the board is a carbon copy of what they show on the front.


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## gunrunnerjohn (Nov 10, 2010)

Try connecting them in series first, if that doesn't work, I'd connect them in parallel with a 10 ohm resistor in series with each LED. The resistors are to provide a balancing, since LED's typically don't have exactly the same voltage characteristics.

Since I can't see the rest of the schematic, it's hard to advise further.


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## gc53dfgc (Apr 13, 2010)

be careful, if you exceed the 50 ma rating of the outputs you will fry the decoder. If you don't plan on wiring in ditch light or cab lighting just move them their.


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## gunrunnerjohn (Nov 10, 2010)

Two LED's in parallel won't exceed 50ma, unless you do something very wrong.  Or are you saying you only get 50ma total from all the lighting outputs?


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## SRV1 (Nov 14, 2010)

gunrunnerjohn said:


> Try connecting them in series first, if that doesn't work, I'd connect them in parallel with a 10 ohm resistor in series with each LED. The resistors are to provide a balancing, since LED's typically don't have exactly the same voltage characteristics.
> 
> Since I can't see the rest of the schematic, it's hard to advise further.



Like I stated above, the schematic is a mirror image of the front. Just with higher numbers on the tabs. I get the sense that the fx tabs don't need to be used for anything on this model. I have no interest in doing interior lighting. There will be some residual light left over from the cab LEDs anyway. 

A lot of this discussion has been pretty vague to me. Do you think you could explain in further detail? 

This is how I'm perceiving this now. Feel free to correct whatever I say wrong here.

In the diagram shown, I will have one LED as pictured, with the wire on the bottom coming off (pos?), with a supplied 460 ohm resistor in line going to tab #3. Then a wire coming off the other (negative?) lead with a 10 ohm resistor??going to the negative? lead of the other LED? Then a wire coming off the other LEDs positive with a 460 resistor in line going to tab #2? I know this probably is not right. I just wanted to show an example of what I was looking for. I don't think the front ones have any connection to the back ones.


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## gc53dfgc (Apr 13, 2010)

one resistor off of the common which is your positive. tabs 3 is the negative. so just a resistor on the positive for each led so if you are doing four leds then you need 4 resistors on the positive or if you use just one of the proper size when one led goes out you are likely to blow the others at once to. That might only be for standard bulbs.


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## gunrunnerjohn (Nov 10, 2010)

If you have parallel LED's, you should always have at least a small balancing resistor for each, they don't all operate at the exact same voltage, so one can draw more current than the others without it. I also simply prefer a resistor for each LED or set of series LED's.


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## SRV1 (Nov 14, 2010)

gunrunnerjohn said:


> If you have parallel LED's, you should always have at least a small balancing resistor for each, they don't all operate at the exact same voltage, so one can draw more current than the others without it. I also simply prefer a resistor for each LED or set of series LED's.



Well, I talked with Soundtraxx yesterday and ended up wiring up some LEDs on one end. They advised me to step up to a 1000 ohm resistor since I'd have to be dropping the power down from 12v. They were installed as follows:
Took one LED and soldered the resistor to the negative leg. Ran a wire off the end of that to tab 3. Then ran a wire off the positive leg to tab 2. Then I just got two short pieces of wire and ran one from the positive on the first LED to the 2nd LEDs positive. And the other from the first LEDs neg. to the other LEDs neg. (Edit: It just hit me that maybe I should have put the resistor on the positive side!)

I finally wired up some track and tested out the switcher last night. Also tested out my NCE power cab for the first time. Everything worked as it was supposed to. The sound is awesome. But the LEDs were blinding. Extremely bright. 
Even with the 1000 ohm resistor it's not near enough to drop them down. Should I add another resistor inline somewhere? And if so where? Or should I just get a stronger resistor and how much? Or should I just live with super bright headlights?


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## gc53dfgc (Apr 13, 2010)

get a 1500 ohm resistor and also pick up a 500 if it is still to bright with the 1500 add in the 500 in line to lower it even more.


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## gunrunnerjohn (Nov 10, 2010)

You can simply up the resistor value until you're happy with the results. I'd start with 2200 ohms, and maybe up it to 2700 or 3300 ohms if they're still too bright. There's no reason for multiple resistors, one will do the job.


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## gc53dfgc (Apr 13, 2010)

Some of those higher up resistors are hard to find though. At least from Radio Shack they are.


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## gunrunnerjohn (Nov 10, 2010)

gc53dfgc said:


> Some of those higher up resistors are hard to find though. At least from Radio Shack they are.


You have to be kidding, right? You can buy any value resistor you want from either Mouser or Digikey, and last time I was at a brick and mortar Radio Shack, they had everything up to 10megs.


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## gc53dfgc (Apr 13, 2010)

well you must have a better radio shack then I do because the most they had was a 2000 ohm of the proper size.


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## gunrunnerjohn (Nov 10, 2010)

Well, you can use the other two on-line sites I mentioned, both have excellent prices and USPS shipping is typically only a couple of dollars. They also ship very fast, they're both fully automated parts warehouses and obviously have greased the process to a fine art. I usually place one or two orders from one or the other a month, rarely does it take more than two days to get my order.


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## SRV1 (Nov 14, 2010)

Yeah, I think I'll have to try a higher resister. My local radio shack seemed to have a pretty extensive collection of them.


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## gunrunnerjohn (Nov 10, 2010)

You can buy assortments, how would you like to have 50 each of most common values, 2500 resistors in all?

2500X 1/4W 5% Assortment Carbon Film Resistor 1R -1M for $16 with free shipping.

There really isn't a good reason not to have the correct sized resistors for a project.


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## SRV1 (Nov 14, 2010)

Ok guys. I just got back from Radio Shack. I ended up getting a few different strengths. I ended up going with the highest one. I tested with a 9v battery to get a rough idea what the different resistors could do and decided to go with the 1/4w 4.7k ohm. 

I just tested it on the track and they light up real nice now. Still plenty of light but a lot more prototypical.


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## gunrunnerjohn (Nov 10, 2010)

Great, I figured the higher values were going to fit your situation better.


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## gc53dfgc (Apr 13, 2010)

You must be using a really really low voltage LED. I got some 3mm or 5mm and jsut a simple 500 is enough with a Tsunami decoder though a little to blue colored. It must be the same type my Bachmann Spectrum 4-6-0 had before I broke the Tsunami factory decoder trying to get a new brighter one in it. I am planning on doing an install of replacing the standard Bachmann board with a replacement Tsunami with upgraded lights when I get the money for another 100 dolalr decoder, I will also be going over how to add a cam mechanism in so it has acurate chuff chuff sounds.


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## gunrunnerjohn (Nov 10, 2010)

Or maybe he just doesn't want to blind the mice along the tracks.


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## SRV1 (Nov 14, 2010)

They're 2mm LEDs. They're cylindrical to the front with a square portion in the back where the leads come out. They were still a little big. I had to drill just a hair more out of the holes in the shell and I had to trim off quite a bit of the squares in the back so they would fit in and sit side by side. But they work well. They're yeloglos and have a real pleasing look to them. 

Like I said, I'll do an install thread once I get it done. Have several pics of progress in case anybody else wants to modify one of these. It's a decent amount of work but a fun project.

All I have left to do right now is modify a couple LEDs for the front, wire them up, install them, and put it back together. Hope to get it done tomorrow.


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## gunrunnerjohn (Nov 10, 2010)

I've installed LED lighting, ditch lights, and marker lights in a number of locomotives. Being O-scale, the 3mm ones are perfect for headlights and ditch lights, and I use the 2mm ones for markers.


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## gc53dfgc (Apr 13, 2010)

John has everything easy when it comes to space issues.


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## gunrunnerjohn (Nov 10, 2010)

gc53dfgc said:


> John has everything easy when it comes to space issues.


Yep, and it was very carefully planned that way.  Actually, there have been a couple of TMCC installs where space actually got a bit tight, remember the components are a lot bigger as well, 8 amp driver boards take more space that the HO stuff.


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## gc53dfgc (Apr 13, 2010)

gunrunnerjohn said:


> Yep, and it was very carefully planned that way.  Actually, there have been a couple of TMCC installs where space actually got a bit tight, remember the components are a lot bigger as well, 8 amp driver boards take more space that the HO stuff.


Your trains are such energy hogs. Are HO doesn't even use 1 Amp of power.


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## gunrunnerjohn (Nov 10, 2010)

Well, 8A is the maximum capacity of the driver board, I've measured 4.5A for a dual motored locomotive going up a 3.5% grade with a 20 car train. I would hope that they don't get to 8A in any normal scenario!


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