A standard EE does it so:1. Vcc is 3V32. my LED lits fine at I=1.0mA 3. My LED is red, red LEDs have Vf=1.5V (for example)4. R = (Vcc - Vf) / I = (3.3 - 1.5) / 0.001 = 1800 ohm = 1k8I do not understand who recommends to use 20mA current through an LED today (when used for indication purpose).. We used 20mA currents 40y ago. Today's LEDs lit fine at 300uA.. Unless you going to cut the steel with your LED gun
as the LEDs are the main feature of it.
Quoteas the LEDs are the main feature of it.yea, by DUE controlled 2Watts LED lightsaber