when looking for resistor values, it is a simple manipulation of Ohm's Law. V=IR or voltage = current X resistance. measure the voltage, look at the package your LED comes in to find the current and then you get V/I=R or voltage divided by current = resistance. so in a 12 volt system, where the (forward current) of the led is 30 milliamps it would look like this:
12V/.03A=400ohms
so you could get away with pretty much anything between 380 and 420 ohms. the 4th (or 5th) band on a resistor is a tolerance. a silver band is plus or minus 10% so a 400 ohm resistor could be anywhere from 360 to 440 ohms and be in spec. a gold band (plus or minus 5%) is 380 to 420 ohms. if you want to use an online led calculator, try this one:
LED calculator for single LEDs
hope this helps...
BTW, good thread, and great job!
There are also these available so you don't need to worry about soldering or finding resistors:
http://www.superbrightleds.com/cgi-b...nstrument.html
