# Help with LED



## chrisb (Jan 3, 2008)

I am making a new head light for a Davenport. I think the one on it is an incandesent bulb. To use a LED in the new fixture. what would be the voltage for the LED.
I believe that a capacitor needs to be used with an LED. What size and how does it get wired/soldered to the lead wires? Thanks in advance for any advice..


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## jimtyp (Jan 2, 2008)

I would use a resistor, not a capacitor. The resistor size depends on how much voltage is getting to the bulb now. Do you know what the voltage is? 

You would solder the leads to the wires that you are using now for the bulb, but unlike a bulb an LED has to have the positive connected to the positive wire. Don't worry, if you connect the wrong wire it will not blow, the LED just won't light. The longer stem of the LED is usually the positive.


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## peninsok (Feb 9, 2009)

I use a 1k (1000 Ohm) ½ watt resistor for all my LED installations. The long lead is generally the + lead. The resistor may be soldered to either lead.

Cheers
Ian


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## lownote (Jan 3, 2008)

You use a resistor--you can use and electrolytic capacitor to deter flickering, but you almost always need a resistor to lower the current draw. What resistor? It depends on the voltage going to the track and on the specs of the LED.

I use this very excellent online calculator to figure resistor values, but you need to have some idea of the maximum voltage the led can take, and the maximum "forward current," measured in milliamps (ma). Do you have that info?


I run my track at 21.5 volts all the time, because i'm using DCC. So I often use "warm white" 5mm leds, and figure they can take 3.2 volts and a forward current of 25-30 milliamps, which leads me to a 1k ohm resistor.


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## chrisb (Jan 3, 2008)

Thanks, I have a bunch of LED's that are not in any kind of packaging. Is there a way that I can figure out what thses are rated for? I have a multi meter.


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## Greg Elmassian (Jan 3, 2008)

nope... 

All you can do is set the resistor up to allow 20 milliamps and you will be safe, but you could have LEDs that are rated at a higher current. 

The only way you can really tell what they are rated for, is slowly increase the current until they wink out... then you can probably figure on half of the current that took them out. 

If you are careful, if you slowly increase the current, the point at which the led stops getting brighter can be seen, but that is often past the proper current rating. 

Remember that LEDs are rated in current. There will be a nominal voltage spec, but near the rated current, small variations in voltage can blow them out. 

LEDs do NOT act the same as incandescent lamps, which are rated in volts, and have a nominal current spec. (reverse of each other) 

Regards, Greg


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## Torby (Jan 2, 2008)

You can figure out a lot about them...

1. With your multi meter set to Ohms, measure the resistance of the LED. One way will be very high, likely "Over." The other will be very low. Now you know which lead is +.

2. Take a resistor, like 1000 ohms (brown, black, red) and put it in series with an LED. Hook it across your track or whatever and run the throttle up to about 12v. Be sure of the polarity. The LED will likely glow fairly dimly. Take you meter and measure the voltage across the LED. Now you know your LED's "forward" voltage. You'll usually find something between 1 1/2 or 3 v, depending on how the LED was made.

How much current can your LED take? Again, pretty easy to get a workable figure. 20mA is almost always appropriate. Take a resistor about 500 ohms, and connect your meter, resistor and led in series with your throttle and set your meter to measure milliamps. Now ramp up the throttle till the meter says 20mA, and your led should shine nicely. Increase the throttle to get like 25mA and the led should shine brighter. Increase to 30mA and it will be brighter yet. How to tell if it's too much? Feel the LED. It's ok if it feels warm, but you don't want it running so hot it hurts. If it's too hot to hold, back down a little. Running an LED at a higher current than it's made for will shorten its life. At 20mA, it'll likely work when your great grandkids inherit it, and something else will probably happen to it first. At 30mA, it will likely work longer than you'll care about it. At 150mA, it's life will be very short indeed, you might not even see the blink. (Some applications actually pulse an LED at like 150mA). Yes, even a pulse throttle will work.

So with your measured voltage and the current you've figured out, you can figure the resistor for any voltage you like with a calculator. Say you have a 20mA LED at 1.7v and you want it to work in a 24v circuit: 24 - 1.7 is 22.3, and 22.3 / 0.02 is 1115, so 1.2k resistor should do nicely. 22.3 * 0.02 is .446, so in this high voltage system, you'll want a 1/2 watt resistor. A 5v system? 5-1.7 is 3.3, and 3.3/0.02 is 16.5, and you can likely find an 18 ohm resistor.


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## Greg Elmassian (Jan 3, 2008)

I'd agree with tom's elaboration, although I would stop short of anything more than warm, normally you can get almost max brightness with no feeling of warmth. 

Regards, Greg


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## George Schreyer (Jan 16, 2009)

see 

http://www.girr.org/girr/tips/tips7/white_led_tips.html


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## Madman (Jan 5, 2008)

What of these LED Christmas string lights that seem to be popular this year? How can they be cannibalized for our use, if at all?


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## Stan Cedarleaf (Jan 2, 2008)

Posted By Madman on 30 Nov 2009 07:33 PM 
What of these LED Christmas string lights that seem to be popular this year? How can they be cannibalized for our use, if at all?


Absolutely. The individual bulbs will light with 3 volts. 2 AA or AAA batteries. Check the Warm White LED from Walgreens post in the Public Forum....


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## Havoc (Jan 2, 2008)

Don't worry, if you connect the wrong wire it will not blow, 

LED can and do blow due to too high reverse voltage. Most are speced for an abloslute reverse voltage of 5V.


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## lincoln pin (Feb 24, 2009)

OK so I'll ask a neophyte electronics question. I some LED lights at Walgreens (thanks for the tip Stan) I am lighting them up two at a time with two AA batteries. I don't need a resistor because I am only giving them 3v input correct? But if I were to put them in a headlight and run them off of track power, I would then need to get a resistor to control the voltage right? 
Thanks Mike


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## on30gn15 (May 23, 2009)

Yep. 

Don't know the math to figure the resistor, but do know that. 

I just use resistors valued at what Miniatronics says on the back of their LED packages to use.


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## lownote (Jan 3, 2008)

Yes--3 volts is fine. 

LEDs are easy if you have constant voltage, as with battery and DCC. But if you want to run them on variable track voltage then it's a little harder--you need a bridge rectifier and maybe a voltage regulator, so that they light at 3 volts and stay lit the same way at higher voltages. Dave Bodnar has some good info on his site--link below 


See the "LED related Articles."


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## Stan Cedarleaf (Jan 2, 2008)

Posted By lincoln pin on 01 Dec 2009 07:34 AM 
OK so I'll ask a neophyte electronics question. I some LED lights at Walgreens (thanks for the tip Stan) I am lighting them up two at a time with two AA batteries. I don't need a resistor because I am only giving them 3v input correct? But if I were to put them in a headlight and run them off of track power, I would then need to get a resistor to control the voltage right? 
Thanks Mike 


Mike........ I've been running regular and red blinking LED's, both 3mm and 5mm without resistors for about 10 years with 2 AA or AAA batteries. Never had one fail. 

It's just that simple.









Yes, if you're going to run them off track power, you will need resistors. For more times than not, without fancy formulas, a 1k resistor will do the job for 18-24 volts. 560 for 12-14.


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## Totalwrecker (Feb 26, 2009)

Stan, 
Track power now has two meanings; variable and constant. 
If using variable, to control loco speed, will a 1k resistor be too much at lower speeds? Thus dimming the light output to none? 

Thanks, 
John


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## Stan Cedarleaf (Jan 2, 2008)

Hi John.... Constant track power should have no effect on the lighting as the voltage to the lamps and motors are controlled by a voltage controlling device such as a decoder or receiver.

However, if the lights are wired directly to the receiver/decoder that will apply full voltage to the lights with the motor output to be variable, then you would have full 18-24 volts coming to the LED's and a 1k resistor would be ok. I generally use 560's for my 14.8 volt sources (batteries) and they work right nicely. I've used 1k's as well without a real noticable low voltage drop out. 

HOWEVER, again. I ain't no e-lek-trickal tek-in-i-shun. They work that way just fine.


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## Dan Pierce (Jan 2, 2008)

For analog track power I used the 7805 regulator and then resistors to my led's. 
Lights come on bright at 7 volts and remain the same up to full throttle. 
A yellow highlighter can be used on the lens to lessen the blue light effect.


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## Stan Cedarleaf (Jan 2, 2008)

Dan... Do you use a bridge rectifier before the 7805?


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## Bill Swindell (Jan 2, 2008)

LED's can be very simple. Forget the regulators & resistors. By a Supertex CL2 current regulator. It limits current to 20ma with inputs up to 90VDC. On a DCC system, a single diode and one of these regulators will control your your LED current. With most DCC systems, you could put 1 to3 LED's in series with one regulator. No more resistor calculations!


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## George Schreyer (Jan 16, 2009)

or use an LM317 as a current regulator. It takes a single 62 ohm resistor to set 20 mA


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## Bill Swindell (Jan 2, 2008)

That's my point George. This thiing is smaller, cheaper & simpler than an LM317. I think I paid $0.43 each.


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## Torby (Jan 2, 2008)

"Supertex CL2 current regulator"

Cool part.

Stan, you put the bridge between the regulator and the track so it sees the same polarity whichever way the train is going.

Try making your bridge out of mosfets. You don't get the 2 diode drops.


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## Dan Pierce (Jan 2, 2008)

Stan, since I am track power a bridge rectifier is a must, diodes with a .3 volt drop, not .7volts. 

For battery power, no rectifier is needed. 

The Superflex soujds good, but I use the 5 volt regulator for lights and smoke. Have to use the Super flex for directional lights.


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## Stan Cedarleaf (Jan 2, 2008)

Posted By Dan Pierce on 02 Dec 2009 06:38 AM 
Stan, since I am track power a bridge rectifier is a must, diodes with a .3 volt drop, not .7volts. Thanks, Dan. Thought you might have it there, but just had to ask.









Even with batteries, I use a bridge rectifier if I want constant lighting. Although, I run much of my lighting right through the OEM boards and they control directional lighting. There are so many ways to do things and discussion like this covers most situations.

Thanks.


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## Torby (Jan 2, 2008)

Supertex CL2

44 cents each at mouser.com.


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## lownote (Jan 3, 2008)

That's very interesting. And cheap! You can get twenty of them for under 12 bucks. I'm not clear though--do you need rectified voltage going into the CL2? Does it rectify the voltage itself? It looks like it needs a single diode across the + and - outputs? It's not gong to have any capacitance, so I'm assuming with DCC the leds would flicker, but you could put a capacitor upstream.... 

How many leds can you drive in series with one of these things? The data sheet shows three. To run six you'd need two CL2s, to run 9 you'd need 3?


I'm not sure it's an advantage under DCC. Under variable track voltage, looks very good


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## Torby (Jan 2, 2008)

1. You need to provide rectified voltage of 5 to 90 v.

2. Yes, you might need a capacitor. Like any electronic thing, it likes DC.

3. Any number of LEDs in series, depending on your voltage and your LEDs. If you have 1.7v LED's and 15 v, 8 Leds. If you have 90 v, 50 Leds.

(I no almost nothing about DCC)


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## Stan Cedarleaf (Jan 2, 2008)

Just checked the Mouser site for specs on the CL2 and I have a question. The CL2 is listed as an LED Driver. Does that mean that it has an output of 3 volts with input of 5-90? 

Thanks in advance.


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## Bill Swindell (Jan 2, 2008)

LED's are current devices. The CL2 limits output to 20ma. That way, if you have 2 white LED's in series, the output will be about 7v @ 20ma.


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## Stan Cedarleaf (Jan 2, 2008)

Thanks, Bill.. If I'm using one 3 volt LED, will it light it just fine?


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## George Schreyer (Jan 16, 2009)

An LED wants to run at about 20 mA for maximum efficiency and brightness. It will get brighter at higher current, but by not as much as the current increase which means that it's efficiency is dropping and it is getting hotter. They won't last long that way. 

A white LED has about 3 volts drop at 20 mA which is why it works raw from a 3 volt battery. However, the voltage drop is pretty much independent of current. 

If you want to light one or more LEDs, even of different types, wire them in series. The same 20 mA flows through all of them. The CL2 (or any other current regulator) will set the 20 mA as long as the input voltage to the regulator is greater than the sum of all of the individual LED voltages plus about 2 volts (to run the regulator). If the input voltage is higher, the regulator will adjust it's own voltage drop to maintain an output current of 20 mA. 

It MUST run from DC so you need a rectifier in front of it if you are going to run from DCC or any source of changing or unknown polarity. The 100 nF capacitor shown in the CL2 schematics is to provide a low AC impedance at high frequency at the regulator input to keep it stable. It may do funny things without that capacitor.


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## lownote (Jan 3, 2008)

Now let the dumb questions begin.

If I were to use one of those to light a string of, say, 8 warm white Xmas bulbs, how would I wire it? I know this is really basic, but I'm puzzled about the input/output. 


Track power leads to rectifier, rectifier +/- to capacitor, capacitor +/- to ???? There are three leads coming out of the CL2 (the cheapest one anyway). I've got two leads coming off the capacitor. Sorry for the dumbness, but what would connect to what?


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## Ray Dunakin (Jan 6, 2008)

Does anyone know what the specs are for the LEDs used in Bachmann 4-6-0 headlights?


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## George Schreyer (Jan 16, 2009)

If you want to use 8 LEDs in series, the total stack voltage would exceed 25 volts. You'd need at least 27 VDC to light the things up. 

You'd want to separate them into two stacks of 4 and use 2 regulators 

Each LED has a + and a - lead. The + one is usually longer and goes the smaller electrode inside the package, you can see the electrodes from the side. They wire like batteries, + to - so that you end up with a + lead on one end of the stack and a - lead on the other. 

The data sheet for the CL2 shows the connections 

http://www.supertex.com/pdf/datasheets/CL2.pdf


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## lownote (Jan 3, 2008)

Goerge I had already downloaded that data sheet and just found it confusing--the CL2 has three leads on it, but the data sheet seems to only show two being used., I apologize for asking freshman level questions, but I really don't know


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## Greg Elmassian (Jan 3, 2008)

N/C and NC means "not connected" or "no connection"... ignore it. 

Normally they use the extra lead for physical stability when soldered. 

Could be heat sinking too, but I doubt it. 

Regards, Greg


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## George Schreyer (Jan 16, 2009)

The TO92 package comes with 3 leads. It would cost them more to get one with 2 leads because that is a special part. 

NC means DO NOT CONNECT. It MAY be connected to something inside. 

Further, all the CAD outlines for TO92 packages have 3 leads so that the PWB layout tools expect to have 3 holes drilled to accommodate it. Don't mess with standard designs, just go with the flow.


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## George Schreyer (Jan 16, 2009)

Ray, Bachmann has apparently used several kinds of LEDs, mostly yellow ones. IMHO, they are all wimpy. Yellow LEDs can be seen in daylight, but do not cast any sort of beam at night. They've run them anywhere from a couple of mA to nearly 20 but even then, they don't get very bright. 

I change them out and usually have to adjust the current.


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## lownote (Jan 3, 2008)

Thanks George and Greg--that makes sense, kind of--why include a long lead just like the other two leads to which you are not supposed to connect anything? heat sinking, maybe. My question was not quite as dumb as I thought!


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## Bill Swindell (Jan 2, 2008)

When I used the CL2 in a battery conversion of a 3 truck Shay, I just cut the center wire off. I also didn't use the capacitor and it works fine (your results may vary).


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## Totalwrecker (Feb 26, 2009)

Thanks to all for this info, it's most helpful. 

John


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## Greg Elmassian (Jan 3, 2008)

Mike, if you read the datasheet the different packages have different wattage capacitiies, the flat pack one and the surface mount are both rated higher, but need to be soldered to a circuit board to help dissipate heat. 

The one in the "traditional transistor package" only handles 0.6 watt, although that's enough for a 30v input and 20 milliiamps, so it should be fine. 

Regards, Greg


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## on30gn15 (May 23, 2009)

Found at Radio Shack - 

*10*mm bright white LED :shock: 

Model RR suppliers list only 3mm and 5mm as far as I've seen. 

_This_ will make a headlight which lights the way! 










Okay, so what is this obsession with huge bright headlights :?: 

Umm, the imaginary setting fro my freelance RR is a semi-tropical island with a portion of its route through jungle. 
There are things living in there which would see you as a midnight snack. 

And it would look really cool lighting up Mike's garden railway.


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## Torby (Jan 2, 2008)

Keep an eye on that. Some brat might swipe it.


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## Pete Chimney (Jan 12, 2008)

LEDs for Christmas lights are extremely popular this year. Tonight I went to my local Home Depot for a few things and thought I'd stop in the Christmas secton and see if they had any set of LEDs to add to what I previously purchased. Before Thanksgiving they had shelves and shelves of LED sets. Tonight there were none. They did have stacks and stacks of minilights however, a old technology that I believe will soon be eclipsed by LEDs.


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## Torby (Jan 2, 2008)

Yea, I decided vacuum tube Christmas lights are for the birds, and only buy LED's now.


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## chrisb (Jan 3, 2008)

Thanks
My LED works. 25 mA 3.6V max with a 1K Ohm, 1/2 watt resistor. 
If I use a 500 ohm resistor instead will the light be brighter on lower throttle settings? This is where I see this engine operating at any how.


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## Greg Elmassian (Jan 3, 2008)

Yes, it will be brighter, in fact it might get like a flash bulb just before it burns out! 

Don't do it, you could easily burn out the LED. 

Greg


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## George Schreyer (Jan 16, 2009)

LED's do get brighter at higher current, but they start getting hotter much faster at currents past 20 mA. A 1K resistor is probably limiting your current to less than 15 mA at 18 volts or so, 500 ohms would be about right for 13 volts.


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## Greg Elmassian (Jan 3, 2008)

500 ohms gives about 26 ma at 13 volts... at 18v you would have 36 ma... probably not burn out the LED immediately, but after a while, and probably build up heat. 

You need to understand that the brightness of an LED does not vary greatly like an incandescent bulb. 

If your LED is not bright enough, you probably need to get a brighter LED, not pump more current through it. 

Regards, Greg


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## Madman (Jan 5, 2008)

Here's a question for you Graig or George. I am entertaining the idea of lighting my buildings with LEDs. Based on the three volt experiment I did with two AA 1 1/2 volt cells. I saw this regulated power supply;

http://www.allelectronics.com/make-...T/-/1.html 
In my experiment, I had 4 LEDs hooked up to the two AA cells. I left it connected for a few days without any diminishing, in brightness, of the LEDs. My thought is to take some of the power supplies from All Electronics, and power the lights in my buildings. At 1 Amp, how many LEDs can be powered. These power packs are inexpensive enough that using more the one would not be a problem.


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## Torby (Jan 2, 2008)

At 1 Amp, how many LEDs can be powered. These power packs are inexpensive enough that using more the one would not be a problem.


Depends on how much current each led draws. The sure way is to take your handy multimeter and put it in series with one of your leds and your battery. Usually around 20 to 30 mA. 20 mA is 1/50 of an amp. 30 mA is 1/33 of an amp.

Now, if each LED runs at 3v, and you have a 9v power supply, you can stack 3 of them in series:

+ --- LED --- LED --- LED --- -

And they'll be quite happy. If your 9v power supply is good for 1 amp, you could put at least 33 of these 3 led strings:

+ --- LED --- LED --- LED --- -
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|
|-- LED --- LED --- LED --|


Hmm. I've never tried to type a schematic before.


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## Madman (Jan 5, 2008)

So, LEDs can be wired in series I take it? + to - leads?


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## Torby (Jan 2, 2008)

Of course. Why not?


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## George Schreyer (Jan 16, 2009)

wiring in series is a great way to save current load at the expense of higher operating voltage. 

see these paged for more info 

Heavyweight Tips 
Streamliner Tips 
White LED Tips


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## Dennis Cherry (Feb 16, 2008)

Posted By George Schreyer on 09 Dec 2009 07:06 PM 
wiring in series is a great way to save current load at the expense of higher operating voltage. 

see these paged for more info 

Heavyweight Tips 
Streamliner Tips 
White LED Tips George: Excellent write ups on LED's.

I have one comment, that is the voltages of the different LED colors. My experiences have shown that the actual voltages of the White, Green & Blue are higher. Using 20,000 LED lights in my Christmas display teaches you much when you modify the light strings.


See this link:

http://www.oksolar.com/led/led_color_chart.htm


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## Madman (Jan 5, 2008)

Based on all of this knowledge, I went ahead and converted three of my passenger cars from track powered incandescent to battery powered LED lighting. Here are some photographs.


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## Madman (Jan 5, 2008)

OK, Whats going on here. I resized my pictures and they are comming out gigantic?


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## Greg Elmassian (Jan 3, 2008)

Yes you resized your pictures... BIGGER.... 

right click on the picture and select properties: 282px Ã- 212px (scaled to 2560px Ã- 1920px) 

Yep, a slip of the finger... looks like the original picture was pretty small.. 

You should be able to do it over... 

Regards, Greg


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## Madman (Jan 5, 2008)

Greg, I resized the pictures the same as I have always done before loading then onto my web space here on my Large Scale. Let's try it again.










The above is lit with LEDs










ON/OFF switch 




















I still cannot get the picture that I posted in my last post to resize smaller. I have removed the same photo from my web space here, and replaced it with a downsized picture. And still the picture inserter thing pulls up the larger photo. HMMMMMMMMMMM


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## SteveC (Jan 2, 2008)

Dan

I fixed the picture sizing on page two, the reason it wasn't changing size when you changed the image file is because the settings in the HTML were remaining the same, and so long as it could find a file by that name it was going to display it as the size specified in the HTML no matter what size the image file had.


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## Greg Elmassian (Jan 3, 2008)

Ask and ye shall receive. 

Do you have larger versions, like 640 or 800 across, would love to see them larger... the effect looks nice... 

Regards, Greg


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## Madman (Jan 5, 2008)

Greg, I will do that later today. Thanks for your comments.


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## Madman (Jan 5, 2008)

Posted By SteveC on 13 Dec 2009 09:57 PM 
Dan

I fixed the picture sizing on page two, the reason it wasn't changing size when you changed the image file is because the settings in the HTML were remaining the same, and so long as it could find a file by that name it was going to display it as the size specified in the HTML no matter what size the image file had.











Ah ha! My lack of computer knowledge hits me like a ton of bricks once again!!


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## Greg Elmassian (Jan 3, 2008)

I think that one has caught many people, I think you cannot edit it to change the size, you have to delete the pictures from the post and insert again. 

I have gotten "caught" by this exact same thing myself, even on my personal web site, so do not feel bad Dan! 

Regards, Greg


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## SteveC (Jan 2, 2008)

So long as you get back to it before the edit window expires you can change it.
[*] Open your posted reply in the edit mode.
[*] Point to the desired image and double left-click it.
[*] After the image properties dialog displays.
[*] Select the value displayed in the 'Width' field, and type in the new value.
[*] Click the 'OK' button at the bottom of the dialog.
[*] Click the 'Submit' button.
[/list]


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## Madman (Jan 5, 2008)

I have my pictures stored in Photosmart on my computer. I tried to enlarge them from blog size to email size, which is larger, but the program would not let me do that. 
But wait!! I can upload them again from my camera. Let me try that and we'll see what happens.


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## Madman (Jan 5, 2008)

I hope these are larger than the last batch. 
(Dan, I changed the display size, SteveC mod.)[/i]


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## on30gn15 (May 23, 2009)

Photos are coming out same size again on my machine. No problem though, they do show how it goes together.


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## Madman (Jan 5, 2008)

Greg, I'm sorry but I cannot get the photos to be posted any larger than the original posted ones. I deleted them from MLS web space, and reloaded them. Then posted the reloaded, enlarged to 1500 x 1125 pixels, photos.


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## Totalwrecker (Feb 26, 2009)

The smoke jack could be a rotary switch to keep it all on the roof... or a vent over the lavatory...
I noticed these aren't 3 in series, will they burn up faster parallel?

John


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## Madman (Jan 5, 2008)

Posted By Totalwrecker on 14 Dec 2009 08:39 PM 
The smoke jack could be a rotary switch to keep it all on the roof... or a vent over the lavatory...
I noticed these aren't 3 in series, will they burn up faster parallel?

John



Wow! Thanks for enlarging them. Would you mind explaining, in dummy terms, how you were able to accomplish what, to me, seemed to be the impossible?

By the way, the rotary switch on the roof is an excellent idea.


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## Semper Vaporo (Jan 2, 2008)

Posted By Totalwrecker on 14 Dec 2009 08:39 PM 
The smoke jack could be a rotary switch to keep it all on the roof... or a vent over the lavatory...
I noticed these aren't 3 in series, will they burn up faster parallel?

John


If they are 3-Volt LEDs and they are attached to two 1.5-Volt batteries in series (totals 3-Volts) then they will not burn up. If the power applied were 9-Volts, then yes, they should be 3 in a series to have each drop just 3-Volts of the power applied.


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## Totalwrecker (Feb 26, 2009)

All the pixels were there after they were compressed. I right clicked and Save picture to my MLS folder on my hard drive and ran them through the Fast Stone Image Viewer program and edited to 'standard' pic size, then saved those adding an l (large) behind the name. Then I used the reply editor to upload them. 

I wired the smoke jack in my engine house to kill a rail inside, thus allowing me to run the other loco on track power. Rotary switches are nice because the movement can be hidden. 

You're welcome, 

John


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## SteveC (Jan 2, 2008)

Posted By Madman on 14 Dec 2009 06:32 PM 
Greg, I'm sorry but I cannot get the photos to be posted any larger than the original posted ones. I deleted them from MLS web space, and reloaded them. Then posted the reloaded, enlarged to 1500 x 1125 pixels, photos.
Dan

The only problem with the new image files is the fact that each one is close to 1MB is size, which will cause some long download times.

Question, which of the MLS HTML Editor image options are you using...
[*] The 'Insert Image'







or...
[*] The 'Image Gallery'








[/list] Because I downloaded a copy of the 100_4421.jpg file, which is 1.03MB in file size and the image size is 1500 x 1125, and regardless of how I selected and posted the picture in a test reply. It automatically went to the 1500 x 1125 dimension.

At this point the only thing I can point to is something on your computer has changed. Have you changed the browser you're using lately? Like from MS/IE to say FireFox.


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## Totalwrecker (Feb 26, 2009)

Another thought; if instead of running your buss rods down the center, you had run them in a u shape down one side, around one end and back down the other side you could solder your led leads to them and eliminate the wires... 
I'd also experiment with painting the bases of the LEDs black to reduce the light on the ceiling... 

OK 2 thoughts... 

John


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## Totalwrecker (Feb 26, 2009)

Steve C... did ya then delete my contribution? Resized pics...


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## SteveC (Jan 2, 2008)

John, yes sir I did, no insult intended just didn't see any reason for the same images being re-posted multiple times. That was before seeing that you had downloaded and re-sized & compressed'em, otherwise I would've kept yours.


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## dieseldude (Apr 21, 2009)

So, while we're on the subject........ Could you use the transformer from a 'Malibu' type DC incandescent garden light set to power some Christmas type LED's for buildings and street lights and such? How would you wire them? What would the 'math' be- resistors,etc.....


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## Madman (Jan 5, 2008)

Posted By SteveC on 14 Dec 2009 09:34 PM 
Posted By Madman on 14 Dec 2009 06:32 PM 
Greg, I'm sorry but I cannot get the photos to be posted any larger than the original posted ones. I deleted them from MLS web space, and reloaded them. Then posted the reloaded, enlarged to 1500 x 1125 pixels, photos.
Dan

The only problem with the new image files is the fact that each one is close to 1MB is size, which will cause some long download times.

Question, which of the MLS HTML Editor image options are you using...
[*] The 'Insert Image'







or...
[*] The 'Image Gallery'








[/list] Because I downloaded a copy of the 100_4421.jpg file, which is 1.03MB in file size and the image size is 1500 x 1125, and regardless of how I selected and posted the picture in a test reply. It automatically went to the 1500 x 1125 dimension.

At this point the only thing I can point to is something on your computer has changed. Have you changed the browser you're using lately? Like from MS/IE to say FireFox.



John,
I am using the insert image prompt. I haven't changed my browser. It's still MS. After Greg asked for larger pictures, I went through the process of deleting the photos from my web space here on MLS, and reloaded the larger, 1500 x 1100 pixel photos. Originally, the ones Greg was looking at, they were email size.


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## Madman (Jan 5, 2008)

Posted By Totalwrecker on 14 Dec 2009 09:47 PM 
Another thought; if instead of running your buss rods down the center, you had run them in a u shape down one side, around one end and back down the other side you could solder your led leads to them and eliminate the wires... 
I'd also experiment with painting the bases of the LEDs black to reduce the light on the ceiling... 

OK 2 thoughts... 

John

That's a great idea! I have seven more cars to convert. It would be alot simpler to make up the lighting stips on the bench, then just install them in the roof.


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## Madman (Jan 5, 2008)

What do you think of these?

http://cgi.ebay.com/20-x-Red-LED-Lamp-Light-Set-20cm-Pre-Wired-5mm-12V-DC_W0QQitemZ160386854127QQcmdZViewItemQQptZModel_RR_Trains?hash=item2557cd2cef


http://cgi.ebay.com/LED3W-100-pcs-3mm-White-LED-15000mcd-Free-Resistors_W0QQitemZ160386905593QQcmdZViewItemQQptZUK_Trains_Railway_Models?hash=item2557cdf5f9


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## Greg Elmassian (Jan 3, 2008)

For what usage? You have one red and one white. 

For example, if you were running track power then 12v would be too low, you would need additional resistors. 

If you were using these to light a passenger train, then the 30 degree angle would be too narrow in my opinion, would want the light to spread more.. 

Really depends on where and how. 

Regards, Greg


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## Madman (Jan 5, 2008)

Thanks Greg. I was considering car lighting and similar uses. I always prefer a second opinion when something looks too good to be true.


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## Greg Elmassian (Jan 3, 2008)

It's hard to find leds with a greater dispersion of light, but it will make a difference in how even the light is inside. 

They make low profile leds where they are almost flat, will tuck up in the passenger roof very well and have high dispersion. 

I have been looking at the led strip lighting, http://www.theledlight.com/flexible-ledstrips.html

While not cheap, notice the dispersion angle of light is 120 degrees as opposed to 30 in a normal led.

This would allow fewer leds to be used and more even lighting.

Stock lighting with bulbs: notice the hot spots:









Now notice it with LEDs (This are the led strips)









I did not run a full length strip on that bottom car, this was first experiment.

Regards, Greg


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## Totalwrecker (Feb 26, 2009)

Posted By SteveC on 14 Dec 2009 10:03 PM 
John, yes sir I did, no insult intended just didn't see any reason for the same images being re-posted multiple times. That was before seeing that you had downloaded and re-sized & compressed'em, otherwise I would've kept yours.








Wasn't insulted Sir, was curious when after posting an answer, they were gone! lol thought at first the New and Improved MLS-OS was acting up again...

But it did kinda leave some posts hanging without their foundation....








A nice feature of the Fast Stone Image Viewer is it's one click to make a standard upload image, size and pixel count are automatic. Best of all it's free!

John


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## SteveC (Jan 2, 2008)

Hey John

Yes you're right, that's what I get for jumping too quickly.









Took a look at the Faststone programs, pretty nice stuff, but I'm so used to using IrfanView, GIMP, & Screenshot Captor (also all free) old habits are hard to break.


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## Greg Elmassian (Jan 3, 2008)

Irfanview is pretty hard to beat... It's what I recommend the most. 

Seems to do a very good job resampling and sharpening when resizing, other programs seem to muddy up the picture. 

When I'm serious, then I use the Adobe products. 

Regards, Greg


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## Totalwrecker (Feb 26, 2009)

I just mentioned it in case somebody needed a program, not trying to sway anyone one way or the other.. my computer skills aren't anything to brag about... 

Had that on the other tower, but used a program that came with my camera more, this one came from cnet's download.com ...... 

Back to lighting strips; I like the softer yellow look better, that's personal, but many clerstory windows were dark green and muted the lights from the outside... it wasn't like airplanes and individual lights... 

John


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## Greg Elmassian (Jan 3, 2008)

Did not take your post as anything other than information, as my recommendation was also meant John... no sweat. 

Yes, those lights are the white, the next will be the warm white, those in my picture are definitely too blue. 

I think I want to research some HW coaches, but I'll bet it hard to find pictures of lighted ones at night. 

Regards, Greg


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## Madman (Jan 5, 2008)

I am now on my way to converting my building lights, etc to LEDs. In the process, I have considered using an automatic light sensitive switch to turn all the lights on at dusk/off at dawn, with an override switch so that I can turn them off when I so desire. I have found a switch at Home Depot that is an add on for outdoor lights. I think it was about twelve dollars. I would like to have one of these switches for each structure, but I don't want to spend that kind of money. I'm sure there must be miniature light sensitive switches available, but I'm not sure were to look. Any suggestions?


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## Greg Elmassian (Jan 3, 2008)

You might be able to use a photodiode, or a photoresistor, but you might need some extra circuitry to make them work, and that means more time and money. 

Aren't you using a single power supply? Not quite sure why you want an individual switch for each structure. 

Regards, Greg


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## Madman (Jan 5, 2008)

Greg,
I am considering a separate power supply, in the form of batteries, for each structure.


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## Greg Elmassian (Jan 3, 2008)

Wow, are you going rechargeable or just total loss system? 

You will probably need a phototransistor circuit to turn power off when it's light. 

Regards, Greg


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## Madman (Jan 5, 2008)

Not sure yet Greg. I may decide to use a central 12 volt power supply, and either buy 12 volt LEDs, or wire the 3 volt LEDs in series. The latter method would require only one light senitive switch. Or perhaps a few, so that all of the lights don't come on at the exact same moment.


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## Madman (Jan 5, 2008)

Now that the holidays are gone, it's alittle difficult to find strings of LED Christmas tree lights. I am looking for 5 mm white, preferably warm white, 3 volt LEDs. I checked through All-Electronics online catalog. I would prefer to find some left over strings of lights. I may have found some on Ebay. Does anyone know of any other sources?


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## Torby (Jan 2, 2008)

Pretty easy to find:

http://lmgtfy.com/?q=5mm+warm+white+LEDs


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## Greg Elmassian (Jan 3, 2008)

No, that is too tough Tom... 

Greg


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## Torby (Jan 2, 2008)

Just maintaining my reputation as "brat."


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## Totalwrecker (Feb 26, 2009)

Got any Dollar stores in your town? Or Big lots or other clearing houses? 
The local Harbor Freight has a sale coming up, they're good for solar patio lights this time of year. 



John


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## Madman (Jan 5, 2008)

In my investigation, and learning more about LEDs, I found this power source, or "Driver". With one of these, I would imagine a resistor is required. How would I determine the number of 5mm LEDs I would be able to power with one of these drivers. 
http://ledsupply.com/docs/L03U-350.pdf


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## Torby (Jan 2, 2008)

Oddly, I can't open your PDF.

Yes, there are integrated circuits specifically for driving LEDs.


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## Greg Elmassian (Jan 3, 2008)

Works fine here. Brat must be catching up to you. 

Dan you can assume 20 milliamps (0.02 amp) per led so divide that into the max current. Why do you want to do it this way? Like building a light for a traffic signal. 

Regards, Greg


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## Michael Glavin (Jan 2, 2009)

Link works for me. 

A typical 5mm LED consumes 20mA. Specification on power source states 4 Watts / 350mA output @ 4-12VDC. I'd suggest you could easily power 60, 5mm LED's. 

I'm assuming 4W/3.3V=1.21A 1.21A x 1000=1221mA 1221mA/20mA=61.05LED's 

Michael


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## Torby (Jan 2, 2008)

Works fine here. Brat must be catching up to you. 



You reap what you sow!


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## Greg Elmassian (Jan 3, 2008)

Since the voltage across a led is "nominal", best calculate with current. Each of the units had output current specified except last one. 

So there is .35 amp, .7 amp, and 1.05 amp.... divide each by .02 amps for rough numbers. So, for sets of led and dropping resistor, you could have 17, 35, or 53 LEDs...

But these say 4.5v output (I'll get to the 4-12 volt one). 


So if you were running LEDs that use about 1.7 volts, (usually colored ones) so you could probably use 2 leds in series with a dropping resistor.


Without a resistor, the voltage would be high enough to short out any single led across the output. 

My guess is that this is a specialty driver for a single high output led... not the ordinary leds that work at lower voltages. 

I do not believe this is what you want to use, you will spend too much money and time on resistors.

A better way to do this is use a higher voltage, string more LEDs in series with an appropriate dropping resistor, or a device like the CL2

*http://www.supertex.com/pdf/datasheets/CL2.pdf* 



Regards, Greg


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## Madman (Jan 5, 2008)

Posted By Greg Elmassian on 19 Jan 2010 08:27 AM 
Works fine here. Brat must be catching up to you. 

Dan you can assume 20 milliamps (0.02 amp) per led so divide that into the max current. Why do you want to do it this way? Like building a light for a traffic signal. 

Regards, Greg Thanks Greg,

Basically, I'm not sure, yet, what I am doing. My desire is to light up my garden railway, this year, with more ambient light. I am looking at solar powered LED landscape lighting that will augment my LGB lamp posts. I am toying with the idea of converting the lamp posts to LED lamps. In reality, I could probably power them with my Aristocraft 10 AMP ultima that now powers my streetlights. I experimented with some LEDs and a solar panel, making a scratch built landscape light, but the brightness wasn't so bright.


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## Madman (Jan 5, 2008)

*In my effort to keep things as simple as possible, I have found this on Ebay. Based on what information you guys have posted, I would suggest that this power supply could run quite a few 12 Volt 5mm LEDs.

* Waterproof LED Driver Transformer 18 Watt 120 Volt 12V 
Click to Enlarge
Light emitting diodes (LEDs) are low-voltage light sources that require a constant DC voltage or current to operate optimally. Because they operate on a low-voltage DC power supply, they easily adapt to different power supplies, have longer standby power, and are safer. LEDs require a device that can convert incoming AC power to the proper DC voltage and regulate the current that flows through the LED during operation. This Switching Power Supply LED driver converts 120V 60 Hz AC power to the 12 Volt DC power required by the LEDs and protects them from line-voltage fluctuations. You will be getting 1 Brand New LED Driver Switching Power Supply Transformer from 110 Volt 50-60 hz to 12 Volt DC 
*Specifications* 
*Input Voltage* *110 -130 Volt* *Output Voltage* *12V DC* *Power* *18Watt* *Width* *35 mm or 1-3/8"* *Length* *200 mm or 8"* *Height* 

*26 mm or 1"*


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## DennisB (Jan 2, 2008)

http://www.modeltrainsoftware.com/ledlights1.htm This company sells leds of all sizes. Even have flashers for welding and misc. applications. Worth a look. Regards, Dennis.


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