resistors and LED's

[blake]

hi, Blake here , i was wondering if someone could tell me what resistor to use if i was running a 1.2 volt LED from a 9v battery ?

[SmAsH]

this should be in the electronics forum
the formula for determining a resistor is (supply voltage)-(voltage drop)/(current in amps)
so it would be 9-1.2/.02=390 so a 390 ohm resistor will do
if you're lazy you can also use this site http://led.linear1.org/led.wiz

[Soeren]

Hi,

[...] a 1.2 volt LED [...]

What kind of LED would that be?

[GearMotion]

Here is something helpful on LEDs. It is an "LED 101" from The LED Light: http://www.theledlight.com/LED101.html

Hope that helps you learn a little about LEDs and supplying them with voltage and current.

[Admin]

http://www.societyofrobots.com/electronics_led_tutorial.shtml