led wiring help

[casemodzod]

Works coming along slowly but surely on the superman case mod but i need some help from you wiring experts.....let me preface this by saying i totally suck at math...ive viewed a couple of led wiring tutorials and seen a few resistance calculators but its all greek to me....what to know is whats the best way to wire
8 to 12 green leds (radio shack variety) in a cluster?? if someone could take a moment or two to figure the wiring out along with what leds to use and the resitor i would be forever grateful....thanks.....rob

[xmastree]

Somebody call my name?

What's the spec. on the LEDs? Forward voltage and current is all you need.

http://www.thebestcasescenario.com/forum/showthread.php?t=2669
http://www.thebestcasescenario.com/forum/showthread.php?t=642
http://www.thebestcasescenario.com/forum/showthread.php?t=2653

And when you've read that lot...

Let's assume a volt drop of 2V per LED, at 10mA

I'd string four in series, giving 8V, and use a resistor to control the current based on the remaining voltage, i.e. 4V.

So, R=V/I, or 4/.01 = 400 Ohms. The nearest you'll get is probably 390, that'll be fine.

So, one 390 Ohm resistor and four LEDs in series, across the 12V supply. But you want 8 - 12, so do it two or three times.

Keep the three strings separate, don't be tempted to connect LEDs directly in parallel. It won't work correctly.

Something like this: (but use four LEDs in each string, not three)

http://i50.photobucket.com/albums/f341/chrispollard/LEDs.png

[isunktheship]

What program do you use to make those images x-mas tree?

Also, maybe you can help here:
http://www.thebestcasescenario.com/forum/showthread.php?t=6639

[xmastree]

I drew that with Inkscape (http://www.inkscape.org/). It's a SVG graphics editor.