What resistor or driver to use to power UV led from 11.1v Li ion?

Hi all!

I am trying to find out what resistor I need to drop the voltage enough to run a UV led I got from DX using a 11.1v Li-ion pack (Peak voltage 12.6v)

This is the led
http://www.dealextreme.com/details.dx/sku.2398

Or would it be ok if i run 8 leds parallel using the circuit that came with a DX dropin that can handle 3.7v to 18v? I have the board now but are not using it.

This one
http://www.dealextreme.com/details.dx/sku.11836

According to the DX forums this board supplies 940 ma at 3.42v. when voltage input is over 9v

What do you suggest?

AlexGT

When in doubt, calculate: http://ledcalc.com/ :thumbsup:

Here's another that could help. Try using this calculator from the LED Center. LED Wizard

Others better versed in circuit design than I am could tell you if it'll work for you.

You need to know the forward voltage and forward current for the LED. Enter that information, the supply voltage, and the number of LED's and it will design the circuit for you as either a wiring diagram, a schematic, or even an ASCII diagram. It will also provide the resistor(s) color coding and tell you what the wattage ratings the resistor should be. The resistor value is not rounded up or down to what might be available - it tends to give you the exact value and you'll have to ballpark it to see what you can find for parts.

If this doesn't make sense to you, you probably need to get a bit more practical circuit building experience before you go ahead.

Thanks! Cool links! Will keep them handy for future reference.

If anyone else was wondering, both calculators resolved 270 ohms for 40ma for each led and 330ohms for 30ma for each led.

AlexGT