If I have an LED with 3V forward voltage. A 12V power supply, and 4 LEDS that I want to put in series.
What size resistor do I use? If you do the normal calculations you wouldn't need any resistors, but is that right? How would you get the 20mA current needed?
What size resistor do I use? If you do the normal calculations you wouldn't need any resistors, but is that right? How would you get the 20mA current needed?