terryking228:
IWorking voltage: 4.5V; Working current: 20mA;And if Arduino puts out about 5.0V for a HIGH (close), the resistor needs to drop 0.5V. So:
5.0 - 4.5 = 0.5 R=E/I R= 0.5 / .02 = 25 ohms.
The calculation process is the same. The resistor has to drop (Supply voltage - Diode Voltage) The resistor value is
(Supply Voltage - Diode Voltage) / Diode current you want.
Right. My head wasn't working was it? I quoted you showing what I said you didn't. D'OH!
I have no defense except for stupidity! I was just through watching History Channel video, I should know that my brain stops after 30 minutes of that.
We need a bowing down emoticon here.....