# lighting power source



## ScottBly257 (Nov 20, 2011)

I have been into Ho trains but I want to go further and start lighting buildings and passenger cars now where do I begin and what steps are needed to light up my town and passenger cars???
Thanks Scott


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## Artieiii (Apr 25, 2011)

The town is the easiest to wire. You will need some LED's and some resistors and a soldering iron. I wired my truss bridges this way and for power I used an old 6v cell phone wall charger. I had a bunch of these in my "junk drawer".
-Art


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## ScottBly257 (Nov 20, 2011)

Where would I get the resistors at? I'm guessing I would cut the end off the phone charger and use the two wires for power and ground


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## Artieiii (Apr 25, 2011)

ScottBly257 said:


> Where would I get the resistors at? I'm guessing I would cut the end off the phone charger and use the two wires for power and ground



Correct ScottBly, + goes to the longer side of the LED (can be purchased at Radio Shack). the resistor can be on either lead of the LED then - lead from the cell phone charger goes to the short end of the LED. If you hook it up backwards, no harm done but the LED will not light. Resistors can be purchased at Radio shack as well. Use this web page to calculate the size resistor needed depending on the source voltage from the cell phone charger and the recommended miliamps for the LED (its printed on the package back).
http://ledcalc.com/

DO NOT hook up LED without a resistor or it will make a loud pop and scare the crap out of you and you will have wasted an LED. More lights are hooked up in parallel. LED's can be run in series but like christmas lights if 1 bulb goes out the whole string will not light. Running in parallel avoids this.
Hope this helps.
-Art


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## ScottBly257 (Nov 20, 2011)

Yes that helps alot thank you very much


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## NIMT (Jan 6, 2011)

You can get resistors at Radio shack or online.
Cheap way to get LED's is to buy a Christmas light string and cut it apart and use the individual LED's for lighting!
To light cars you will need Pickups for the wheels, If DC Power you'll want a constant voltage unit, If DCC you can use a cheap Decoder to run the lights.


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## Artieiii (Apr 25, 2011)

ScottBly257 said:


> Yes that helps alot thank you very much


No problem at all. I was in your shoes about 6 months ago with the same questions. Now both my truss bridges have lights and a flashing red beacon on the top!!!. Looks great on my shelf layout with the room lights off.
-Art


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## gunrunnerjohn (Nov 10, 2010)

One thing to consider with LED's in parallel. 

First off, the current adds up for each LED, so if you get enough of them, the resistor power will have to be scaled up, depending on how much voltage you're dropping. For instance, if you power white LED's from 12 volts, having five of them running at 20MA will give you current of 100ma through the resistor, and you're dropping 9V across the resistor. That's .9W, so a 2 watt resistor would probably be called for. 

Second, they likely won't all light at the same brightness, since the junction voltage of individual LED's can vary. It's best to use individual resistors, one for each LED, you'll get more uniform lighting. The issues of uneven lighting do not exist for series connections, since the individual LED characteristics don't affect the current in the string. You'll also be able to run several in series to minimize the power required and the size resistor required. I use LED strips that have three white LED's in series with a 130 ohm 1/8W resistor, they are designed to run at 12 volts and light nice and bright at that voltage.

Finally, as far as an LED failing, remember that the MTBF of modern LED's starts at 100,000 hours and works up, so I don't think this is a real concern unless you abuse them.


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