# Light Emitting Diodes



## T-Man

LED's are here to stay. I adapted the idea from u tube. This can be a small portable light source. The neat thing is that the battery can run the light for weeks ( To be Tested).I used some cheep 1.5 volt batteries from a dollar store. The small led 3mm came from a radio shack package. The blue is 5mm from ebay throws 7000 mcd's of light in a beam. The red is about 4000 mcd .












In the video he's using 3 volt battey and a jumbo LED 10mm


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## Boston&Maine

I like how your LEGO guy is standing there, I hope he has sunglasses on! 

Anyways, I have never done anything with LEDs... They do not get hot, right? What are you planning on using them for, lights for accessories on your layout?


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## train4myboys

Thanks for posting, I've been looking at those for street lights lately.


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## T-Man

Lego guy is for scale. They do run cool. Last winter I bought Kambach books on RR electronics. I alway wanted to make a diesel horn generator.I spent 3 months getting parts together.Next winter if time permits. Now I'm studying LED's and flashing circuits. I have installed two front lights into Lionel Diesels(AC motor). I have one track side that lights when I have power just to see how long it will last.I'm working on a bi directional lighting in an HO engine. It's kicking me badly. One led keeps blowing out. I'll give more details later, but I wanted to start a thread now. They run on DC so general lighting would be a good use.On board engines it gets tricky, a lot of flashing units use a 9 volt supply.


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## T-Man

*The Test*

Both LED's are till running after 4 and half days.Barely. 
After 4 hour they lost their brilliance.
After 48 hrs they went down even more. 
Now they are just hanging on. :thumbsdown:
That's what I get for cheep batteries. 
I'll have to find the source for the year long light . I saw it somewhere????
Stay Tuned
5th day red is down for the count
Blue is still on
8Th day ,blue has been barely on for two days. Light is not visible from the side with only a dim light from the beam. I learned that red LEDs use a little more power.


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## T-Man

*general lighting*

I found this easy to follow instruction about LEDs. A 12 volt DC output is about right for most transformers. The toy transformers go to 16 to 18.
Anyway it can be used for general lighting wiring 3 LEDs in series with a resistor. LEDS vary in color, intensity, and angle dissipation. Use, is up to your imagination.

Jeepers "unclean" No it's not a porno site

http://unclean.org/howto/led_circuit.html

For you die hards who want to use ac voltage.
My MRC has `14.7 volts ac

three LEDs in series each with a *1N4001* Radio Shack 276-1101
3 LEDS have a 9.3 voltage drop
3 diodes have a combined 2.1 voltage drop

so using the math in the article

14.7-9.3-2.1/.02 =165 ohms use a standard 220 ohm resistor
Theoretically you could use a single diode with a 235 resistor or 330 ohms from radio shack
Read up on diodes at this site

diodes are soldered to the neg side of the LED ,use an aligator clip as a heat sink and keep the bar on the diode away from the LED

http://www.kpsec.freeuk.com/components/diode.htm

If you want to wait I don't blame you. I think I can easily do this and snap a pic.

The Kelly school site is very basic and great for the beginner. Explore

01/04/09 update. The wattage is less than 1/2 watt. Because of the AC calculations the resistance can be lowered to 150 ohms. This above set up is stable for 14.7 watts and will handle 16 volts ac.


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## sptrains.com

T-man,

Thanks for the write up, I am working away at getting much more versed in electronics so that I can help customers install dcc decoders etc without frying anything.


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## T-Man

*Thanks*

Finding information and understanding was a winter challenge. 
I haven't got into DCC. I'm still twenty five years behind. That why it's nice to have B&M around he's current.
The little IC chips are sensitive to static electricity, always ground out before touching one. Try not to wear clothes that carry a charge.


Ok I set up an example three Leds with a 330 ohm resistor and one *1N4001* diode it's running now and I intend to leave it on . Pictures to follow.










Also I started a test with a 3 volt lithium battery CR2032 and a LED. Will it go a week????
Going strong after 3.5 days


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## Boston&Maine

T-Man said:


> I haven't got into DCC. I'm still twenty five years behind. That why it's nice to have B&M around he's current.


LOL, what do you mean by "current"? 

I know barely nothing about DCC, both of my Protosound 2.0 MTH locomotives get run on conventional mode


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## T-Man

*Just shocking*

OK at least you have Proto Sound.
All I have is a train sound wall clock.:laugh:

Day 6 for the Dim light with two 1.5 volt batteries
Day 13 Still on, but light has not been visible from the sides for a few days.
It doesn't cast a beam and you can look directly into a faint beam.

Day One for the cr20023 3 volt battery.
Day 6 Still on Getting faint, looks more like the LED on the right.

The 3 volt battery is handy as a tester for the LEDS. Especially, when I'm trying new circuits in a breadboard. I have burned up a few.


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## Boston&Maine

That is a big difference, lets hope that the new CR20023 battery lasts much longer than six days


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## Stan kolak

*LED"s*

I bought a bunch of amber led's from a surplass electr. shop. 3 to 8 led's in parallel with a 500 ohm series resistor to the group of led's, works well.
However, when you back up, (rev. pol.) there will be no lights. I spread out about 4 in a passenger car. You have to get the conductive, one side, wheels and make a wire contact to bring in. a 2nd type of this wheel is needed, and is reversed for contact to the other track.


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## T-Man

*Bridge rectifier*

If it works stick to it Stan. Another option is a bridge rectifier. Using two rails with a DC power supply, you reverse polarity to change direction.Leds are diodes that work in one direction. So when you reverse your lights go out.The back feed to the LEDS is not good for them you should protect it with a *1N4001 diode*. Radio Shack 276-1101

Here is where the rectifier comes in. Imagine a four sided Kite. Top is positive feed to LEDS and bottom is negative feed. The sides are the feed from the rails. These four corners are connected by the *1N4001 *diode with all of them with the POS side facing the top. So when a positive feed comes in it will go up and the negative feed will go down.

Radio Shack Bridge Rectifier 276-1146 will work
use the two inner leads for track power and the outer marked +- for the LEDS
*Caution* use an aligator clip as a heat sink when soldering the diodes to prevent any damage to them.
With this installed you will light in the forward and reverse direction.
Any Questions?


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## T-Man

*LED definition and description*

I found this site, that is worth reading for the beginner.

I'm working on a description with pictures on the bridge rectifier and 1N4001 diode. 
For the beginner the hardest thing is figuring out is the goZ in and goz out when talking about current flow from pos to neg. The positive end of the LED is the long conector but the cathode end is on the other side(short end ) were the pos current comes out. A lot of times I mock up a circuit on a bread board to make sure it works before soldering.



http://acept.asu.edu/courses/phs110/expmts/exp13a.html


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## T-Man

*Bridge Rectifier*

These two circuits will light LEDS in both directions using DC power. I used a MRC 2800 transformer for my HO work. The diode shows the circuit flow and blocks the reverse. 500 ohm resistor is fine. I drew in one rectifier since they come in different arrangements and I found it after I took the picture. Also the long lead to the LED gets soldered to the positive end of the recifier. With Resistors ends don't matter. For now you have directions for scenic lighting off an AC acc feed and car lighting from the track. 












For the diode, the arrow shows current flow. So the Positive side is connected to the short negative side of the LED. This gives the LED back current protection from AC or reverse direction DC.


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## ntrainlover

you could stick one of those to a screw under the layout where u are working and have a nice light. I ought to try it thanks man 8)


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## T-Man

*LED Use*

Nice Idea Ntrainlover!

MCD (luminous intensity in Milli CanDle power)) is important when buying LEDS. Off course with a Model RR you don't want to overpower the layout. Low mcd LCDs are getting more difficult to find since LEDs performance is improving constantly.Angle dispersion is important too, do you need a beam or something just for general lighting.


Why stop at just one!! Just buy a set of LED Xmas lights and string them under the table Rig up a switch and Light up the underside.( you probably couldn't get the kids out from under the table) LOL:laugh:


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## T-Man

*LED in series*

The tower projest is a success. It has been running for a week. I perioically switched it off and on and has proven reliable.

You can wire four LEDS in series to 14.7 volts Ac using one *1N4001* diode and a 100 ohm resistor.

Rado Shack sells an inexpensive package of LEDS. You get Red Yellow and Green, in 5mm and 3mm. The ones that look white are actually yellow and narrow angled. I used one on the 600 MKT Switcher for a forward beam. I prefer, the 7000mcd LCD like the ones in the tower, were brighter by 3000 mcd.


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## ntrainlover

I typically use 3mm for ho because of the size.


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## T-Man

*Battery Hint*

Today, you can find scale modelling lighting accessories in craft stores around Halloween and Christmas. Lemax is popular. They run on 3 or 4.5 volts. Running string lights even have an adjustable speed. Of course they sell a RR crossing lights, usually the first item to sell out.

My kids burn AA batteries with gameboys and DS game pad. I use these batteries to power the Lemax accessories. The LEDS run on low amperage, so the batteries can't run a gamepad, but they operate the lights. Might as well get every last milli amp of power from them:smokin:


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## ntrainlover

great idea


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## T-Man

*Crazy test*

It's been just under a month, both are still illuminated. I had to take the pic directly into the LED. They are not visible from the side, but they haven't died.


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## T-Man

*T-man Travels*

A couple of interesting things I'd like to share. 

LED's now are sold in a warm white color. Great news for someone looking for an old incadescent lighting.

Good news is that this is a buyers market. If you go for lots of twenty or fifty or more you can shop around amd save.

I'm not endorsing any buyer but you should find them under 50 cents apiece.

The latest is the surface mount LED's. They are flat, square, and can be extremely small. They have a 120 degree viewing angle. Normal working size is under 1.5mm square. It is recommended you buy them with leads. About $3.00 apiece.


Surface Mount can be found by using SMD or SMT with LED on searches.

Here is a link using a surface mount LED
http://www.picturetrail.com/sfx/album/view/16755888/268633342?&offset=850


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## T-Man

*Update for AC use*

In the September issue of Classic Toy Train Mag. An Article was written by Bob Nelson on LED Lighting. What he proposed was to install LED's as pairs in parallel to protect each other from back voltage. They actually blink but are so fast you cannot see it.This eliminates the need for the diode. So if you pair them up only use the voltage drop for one not two to calculate the size of the resistor.


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## B.C.RAIL

That is a good piece of info...I tried to put LED's in my locos and they would just burn out...when turning the power up higher...


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