# LED or Miniature Strip Lighting Question



## MattyPark (Dec 22, 2011)

Hello,

I was wondering if any model railroaders out there can assist me.

I build HO Scale miniature amusement rides and my next project is a merry-go-round / carousel. I would like to add miniature lights to it, but confess am not too experienced.

I was wondering if anybody has any experience with SMD LEDs (such as this eBay link here ) or (this German website link here )?

If so, any tips as to how you install them? Can I can solder SMDs together onto a copper wire? 

I have tried grain-of-wheat bulbs in the past, but they are slightly too big for this model, and they don't create a realistic effect. 

Essentially, I am looking for miniature .mm size lightbulbs which can be soldered onto copper and powered by my transformer - if such a feat is possible? 

Thanks in advance for any information!


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## T-Man (May 16, 2008)

John has worked with them here. He lit up some passenger cars.

You want to buy them mounted, they are very small and will test you solder technique.

Anton had purchased some but I have not seen any of his results. They were tiny, very tiny, separate pieces and not for me. The strip is the way to go if you can make it work.

I have worked with 1.8 mm LED, This is how I did it.


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## NIMT (Jan 6, 2011)

I have worked with SMD LEDs and SMD resistors for lighting projects. Not any easy task to do, but it is doable! You could do copper trace tape (sticky on one side) and solder the LED's to the tape! It will just require you to have a one heck of a strong magnifying visor and a very steady hand!


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## gunrunnerjohn (Nov 10, 2010)

I like the LED strips, and I recently bought some that came higher density as well. Here are the higher density ones, they're made to cut on any three light section and run on 12V DC. I bought a spool of them with 300 LED's for $15.


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## waltr (Aug 15, 2011)

SMD's are tiny but thin wire can be soldered on. Here is an article showing how to do SMD LEDs in marker lamps (click "tutorials" then marker lights):
http://schutzer.net/index.htm


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## gunrunnerjohn (Nov 10, 2010)

Unless the strips don't do the trick, there's no need to deal with individual chip LED's.


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## MattyPark (Dec 22, 2011)

Thank you everyone for the help, advice, and links! 

The strips would be great, but unfortunately the LEDs are spread apart too far. I need to keep the lights close together like this photo:










Sorry for the basic questions, but to confirm:

- I will need a resistor for each bulb? Does it matter where the resistor is soldered? 

For example, say I have:

100 bulbs @ 1.8-2.2 forward Voltage (eBay link). 

*What do I solder where? For example:*
*Power source -> copper wire (possibly copper tape) -> LED 1? -> resistor 1? -> LED 2 -> resistor 2 ...etc?*

Thank you again for any help you can provide! I truly appreciate it.


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## T-Man (May 16, 2008)

DO you know the difference between parrallel and series?

It's a matter for Ohm's Law, DA, DA, DUM.

What is the power source.

John had three LEDs with one resistor for 12 volt DC operation. If they operate at 3 volts and .o2 amps then they have about a 200 ohm resistor. (12-9)/.02


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## gunrunnerjohn (Nov 10, 2010)

Actually, I believe it's a 130 ohm resistor, but then I suspect they're probably running at 3.2-3.3 volts. They do draw just about exactly 20MA at 12V.

Clearly, for a bunch of bulbs, I'd be doing some series wiring, unless you want to see a LOT of wire and resistors!


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## MattyPark (Dec 22, 2011)

T-Man said:


> DO you know the difference between parrallel and series?
> 
> It's a matter for Ohm's Law, DA, DA, DUM.
> 
> ...


Thanks T-man. I do not know the difference between parallel and series. 

The power source is just a transformer - it says on it 
*Input:* 120 V. A. C. 50/60 Hz
*Output:* 0-16 V.D.C. Variable
18 V.A.C. fixed 7 V.A. Total

Thanks John - so it appears I will have to investigate how to wire in a series. Naturally, the less wire and "resistors" that are seen, the better. Right now I am just uncertain the order which they have to be soldered, or if I could get just one resistor to handle everything...and if that is the case, where does it go logistically...

It feels good to be learning!


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## T-Man (May 16, 2008)

In that case I suggest you work on the cotton candy stand before doing the carousel.

You have to make some decisions, like using a constant DC power supply and I have a few LED threads search those out in the Technical forum. 

For entertinment I tried some 1.8mm tower LEDs on a bread board, Here.


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## MattyPark (Dec 22, 2011)

:laugh: yes, I always have been one to bite more than I can chew. Maybe I will learn someday? 

I will do some more research and give something a try.

Thank you for the link as well.


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## gunrunnerjohn (Nov 10, 2010)

Since you have a transformer and you'd like to wire as many in series as is practical, let me make a suggestion.

Take the DC output of that transformer and use that at maximum voltage. You can probably wire four white LED's in series with one resistor for a 16 VDC output. I'd be using a 330 ohm resistor 1/4 watt is fine. Each set of four LED's will require another resistor.

If you're using colored LED's, they typically run at around half what the white ones do, and you can probably string 8 of them together with the same value resistor.

One point with LED's. NEVER wire them to a power supply without some sort of current limiting!

I'd also get a handful of LED's and do some tinkering so you know what to expect.


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## oldSmokey (Jul 31, 2011)

Here is a link to a sight that should be helpful and give you a better understanding of Leds and power requirements.

LED series/parallel array wizard
http://led.linear1.org/led.wiz

LED calculator
http://led.linear1.org/1led.wiz


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