Which Resistor should I use for this LED?

Question

Here is the LED
http://www.lsdiodes.com/shop/index.php?main_page=product_info&products_id=28

and here is the list of available resistors
http://www.lsdiodes.com/shop/index.php?main_page=product_info&cPath=10&products_id=68

I guess while we're talking about circuits, does anyone have an affordable soldering iron that they could recommend.

Thanks!

Answer 1

The LED's forward voltage is ~3.3 and the forward current ~ 0.02 A. You shouldn't exceed the rated fwd current or the LED may blow. The resistor you choose depends on your power supply voltage. The resistor should allow current = 0.02 A when the voltage drop across it is the supply voltage minus the forward voltage.
Example, a 10-v power supply. You want to drop 10-3.3 = 6.7 v with 0.02 A current. Use Ohm's law and away you go.
Soldering irons seem overpriced these days, but see the ref. For small electronics go for 15-40 watts or a soldering pencil. And the tip should be replaceable.