LED light strings

Does anyone know how to make an led light string? I have heard a few methods but I didnt want to spend a fortune. I wanted to make my own set so that I could control the length between lights and be able to replace them as they are shot out.

I looked at buying them but they are very expensive for that many lights.

Thanks

 

Why don't you just buy a bunch of LEDs and do it yourself? LEDs and wire are dirt cheap. They are simple to wire up, basic circuity stuff, most problems will come if you don't watch the polarity.

 

For supplies of Ultra BRIGHT LED's otherwise unavailable in N America at any price - check out Best Hong Kong. http://besthongkong.com/ That's where I get all my LED's from, and I can get them in bulk for less than a a few somewhat bright LEDs locally. Shipping is quick.

HTH's
Jeff

 

I would LOVE to buy a bunch of LEDs and do it myself... I dont know how and I dont know about the polarity, the basic circuitry stuff. Is there something I can read that will tell me how?

 

Thanks a lot. I will study it and see what I can do.

 

Does anyone have a decent LED searchlight design that looks somewhat scale?

 

Mike, BC has resin searchlights i believe, why dont you look into that?

 

Someone mentioned to me that they got some scale search lites from Harbor Models and put the led within them. It was expensive but it looks great. I bought some chrome domes to use that I will embed in the SS. The SS is crappy anyway so I dont care how scale the lights look.

 

Boomer-

I want some LED ones that I can use to light up during night battle!

 

oh ok, i understand now. I can imagine how wild one of those must be.

 

Has anyone checked out the local model train shop? "N" scale is almost the same scale as ours (1/148- 1/160) and there is ALLOT of stuff for trains. There are several different types of light posts available, including an overhead street type light. Check out the "Woodland Scenics" or "Preiser" websites.
J

 

Also, look into "grain of wheat" tiny incandescent lamps. For some applications, they might work better than LEDs. Scale ship modeler & model train forums/sites should be able to tell you where to find them, as should a Google search.

You can build a circuit of LEDs almost as simply as a string of Xmas lights (some of which ARE LED's, nowadays). You'll need to add resistance, to reduce the current (which will blow the LED if it's too high). How much resistance? It's probably not critical & a big range is possible, although you could do the math if you want to be precise. 100 Ohms or so ought to be plenty for a 6V system; a 12V may need more. Here's an interesting calculator that I just found; when I put in 6V supply, 2V drop, & 25 mA current (all typical values) it tells me 160 Ohms for a single LED, 80 Ohms for 2 in parallel), which isn't far off my initial guess:

http://www.quickar.com/noqbestledcalc.htm

Being a diode (basically, a 1-way "check valve" for electrons), a LED will only only allow current to flow in 1 direction. That means that there's a "backwards" way to connect one, where it won't work. Most LEDs have leads of different lengths. The longer lead is the "+" lead, & should be connected to the "+" side of your power source. I'd connect them in parallel instead of series.

Here's a very basic circuit that you can try:



There's probably more info. than you'll ever need at:

http://en.wikipedia.org/wiki/Light-emitting_diode

JM

 

For a quick, simple, cheap way of doing what the OP wanted, I wouldn't worry too much unless a lot of very different LEDs are used. Here's an update, though, that shows what Greg means:



JM

 

when i went looking for resisters there were so many different 100 ohm resistors, some said 100% or 70% and different voltages. How do I know which one to choose?

 

Resistors are rated wattage, not voltage. For a low VOLTAGE application like this, 1/4-watt resistors are fine besides being smaller, cheaper, & probably easier to find in a variety of resistance values than other sizes. However, if all you can find in the Ohm value that you want is 1/2 watt or 1 watt, that's not going to hurt anything. A larger wattage rating is just overkill, is all.

Percentages refer to the tolerance, i.e. how close to the stated Ohm rating the resistor is guaranteed to be. Usually you see values like 1%, 2%, 5%, etc. - I don't think I've ever seen 100% or 70%. Are you sure you got that right? The lower the percentage, the tighter the tolerance, & the more it costs. Example: A 1K Ohm, 5% resistor may have actual resistance anywhere between 950-1050 Ohms, while a 1K, 1% will be between 990-1010 Ohms. Some applications are critical that the values be precise; this isn't one of those, so feel free to go with what's cheap.

All you need to know about any resistor, you can tell by the colored stripes around it. 2 are the base value, then a multiplier, then the tolerance. If you can remember, "*Bad boys rape our young girls but violet gives willingly" you're set for life!

Here's a page that lays it all out:

http://www.elexp.com/t_resist.htm

Or, to see a more visual "calculator" version:

http://www.dannyg.com/examples/res2/resistor.htm

JM

* "Bad" used to be something else, but it's non-PC so you can't say it that way anymore.

 

Thanks John! that explains a great deal. I made a test string of three 3v led in series and plugged to a battery with no resistors and it worked fine. I guess you need the resistors when you are in parallel? I was curious as if I had 10 3v lights then I wasnt sure how to determine whether to use serial or parrallel and what resistor to use. I wasnt sure how to drop from 6v to 3v for the led I have no idea if the ohm output of the battery is different than the voltage.