Originally Posted by ercapoccia
Hi guys, i need some advice about what resistor i need for adding a 3mm white led (3.0v~3.4v 20mA 100mV) into the canopy of my v911 for night flying. Is it 100ohm right?
I'm not sure what/where the 100mV comes from.
You could go up to (down to) 50 Ohm for 20mA.
V = I * R
R = V / I
In this case V = the maximum voltage seen by the resistor
That is 4.2 (maximum of fully charged battery) minus 3.2V (minimum seen across LED) = 1V.
R = 1 / 0.020 = 50 Ohm.
See my blog for some cool (I like to think so) lighting ideas.