# LED's in Streamliners



## Ladder72 (Jan 5, 2011)

Hello everyone-
I am in a little lost with the install of LED's in my Aristo streamliners. I run battery power so I removed the track pickups from the cars and the large incandescents from inside the cars. I have read most every article I could find on LED installs and still I find myself scratching my head.
I installed 3 Ultrabright 15deg led's, in parallel across the ceiling with clear diffusers to spread the beam. These are #LED-127 from AllElectronics.com. I wanted to run them from a 9 volt battery in the "fuel tank" underneath for easy battery change outs (like the bachmann passenger cars I have). 
I ran the "hot" wire to each anode, tapping the hot as it went by, and the ground to each cathrode. This parallel "ladder", was then going to get get a resistor at the on/off switch. I realized then that I basically combined the series and parallel wiring types. Frustrated I plugged in the 9 volt (hoping to see a neat "poof") but was surprised to get a beautiful light in the car. I have had the car lit now for over 5 hours on a cheap 9volt. 
I tried to find the current, voltage specs to rewire this correctly but the spec sheet on AllElectronics page is written for MIT graduates. I want to run them in series (I think?) so I will get the most life out of the battery, but I cant figure out what specs to use to choose the correct resistor.
Did I just get lucky and the draw from the 3 LED's just happened to be correct for the 9V battery? Should I leave well enough alone? How much more life could be expected if I were to wire it in series with the correct resistor in place?
Sorry so long winded but I wanted to put out all of the info I could to help you help me (that sounded like something a politician would say, didnt it?)
THANKS, Trent


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## DennisB (Jan 2, 2008)

http://swogscale.com/index/ARCHIVES.html There is a pdf article on using LEDs here. It may be of some help. If not, my email is on the site and I can answer any questions. Regards, Dennis.


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## Greg Elmassian (Jan 3, 2008)

Take the easy way: here is a calculator for you.

All you need is the source voltage, and the current specs for your LEDs.... 

*http://led.linear1.org/led.wiz* 


The spec sheet says continuous forward current max is 30 ma, but you can run 20 most likely.

Forward voltage is typically 3.2 volts.

Notice that three in series will require APPROXIMATELY 9.6 volts. 


LEDs do not "run" on voltage, they run on current. You picked a situation such that the battery is basically incapable of delivering full power to the LEDs, but enough to have them light.

You can run 3 in series, and if the light is bright enough, you can leave it... if not, you need a different circuit, with no more than 2 in series.

Run the program above, it will show you options. 


Greg


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## Ladder72 (Jan 5, 2011)

Greg - SUPER GENIUS...The program is great. It even drew out schematics and resistor colors. 

SO...Did I just get lucky that this has lit for 13hrs (and still going, just not as bright)? I wired them in parallel w/o any resistors while the calculator shows that I should have used 3-220 ohm resistors. Would the bulbs stay lit even longer if I had installed the resistors per the schematic? Would the life of the LED's be shorter if I leave them w/o the resistors.....I know - so many questions young Padawan (Star Wars quote!)


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## Greg Elmassian (Jan 3, 2008)

Yes you are lucky, normally they should have burned out. Not a good plan. I suspect there is more to the story somewhere. 

Take one led, and put it across the terminals of a 9v battery, I'm pretty darn sure it will burn out. I think there is a resistor somewhere. 

Greg


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## Ladder72 (Jan 5, 2011)

Greg - There in lies my questioning. I ran the wires myself, no resistors. I took the hot from the battery to the first LED anode, then to the next LED anode and finally to the last LED's anode. I then ran the ground from the last LED's cathode to the middle cathode then to the 1st catode, terminating at the 9volt battery. Could it be that these LED's you looked at on AllElectronics site are that current hungry that it kept it in the "Green". I will put this baby to rest soon I promise...I just wonder how it has be going for over 14.5 hours and is still decently bright (although fading). Thanks again Greg for helping me out. Much appreciated. Trent


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## Greg Elmassian (Jan 3, 2008)

That's all I can surmise, but I'm sure that a 9v battery can put out more than 300 ma... that should be the limit of 3 in parallel... 

Where's George? He will figure out what I am missing. 

Greg


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## Dan Pierce (Jan 2, 2008)

For battery operation, I would use 3 in series to reduce current load om a 9 volt battery, plus a 100 ohm resistor, assuming 3 volt leds.


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## thumper (Jan 31, 2009)

Take a look at the LED ribbon advertised at the link below. At a local meet this past weekend, a vendor had a strip of the LED ribbon with LEDs spaced at about 2 inches. Using nothing more scientific than various battery clusters [including a single 9v], we were able to get various levels of brightness from the entire ribbon. I think resistors are built into the ribbon.

What I like about the ribbon is that it can be cut with scissors between every 3rd and 4th LED, and power leads can be soldered to the printed circuit type terminals which are adjacent to each 3rd LED. The ribbons come in 5 meter lengths [16 feet] and cost upwards of $4.00 per foot. The ribbons have a peel and stick backing, so nothing special has to be done to mount them on the roof of a coach, caboose or even loco cab.

The only drawback of the ones I found is that they must be ordered directly from China. Otherwise, you will pay upwards of $150 for a 5 meter strip from a domestic supplier.

http://www.dhgate.com/smd3528-30l-m-non-waterproof-strip-light/r-ff8080812d36cf93012d55b18a804a6e.html

If you don't like the color of the light, Tamaya offers a paint to tint the individual LEDs.

Regards,

Will


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## Greg Elmassian (Jan 3, 2008)

Yep, been posted several times, I have them on my site, under Rolling Stock.... Aristo .... Heavyweights .... I show pictures with them and with the stock lighting. If you look around a bit more, you can find vendors with warm white also that needs no tinting.

Back to the LEDs 

Dan, as stated, the forward voltage drop is about 9.6 volts, so no current limiting resistor is needed (remember he is using a 9 volt battery), in fact the ones he got seem to be beyond the specs published. Something is not right, a diode directly across the battery should have burned up. 

Greg


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## Dan Pierce (Jan 2, 2008)

Greg, I never run leds with a current limiting resistor. 

If one decides to go bad with a short, the others will have excess current flow, short, and then plastic will burn. just not worth the chance of a 10 cent resistor protecting a 100 dollar plastic car or engine!!!! 

Even cheap toys have a 10 ohm resistor in series with the batteries. They would not do this of it was not a problem. 

I know you can get away with out the resistor, but I just will not do it.


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## Greg Elmassian (Jan 3, 2008)

You mean without, right? 

Me neither... but something is wrong here, especially where leds with 9 volts applied did not burn out. 

On your other statement, if you had 3 leds in series, and calculated the resistor right, I completely agree that you could make a setup that would give 20 ma to the leds and if one shorted, limit the current "sort" of in a reasonable safe zone... maybe 100ma.... note well though, normally this philosophy would quickly kill the remaining leds, so in my opinion, this is of limited use, especially since not all led failures are shorts, many are opens. 

Regards, Greg


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