Question 1The resistor that I will need for this:V = 5v - 3.2v = 1.8vI = 150mA (I want to run it at ~50%)
Question 2I want to switch this LED on/off with Arduino Uno and TIP120 transistor. I read that TIP120 will introduce a voltage drop (of 1.2v?). Is the following correct?V = 5v - 3.2v - 1.2v = 0.6vI = 150mA
Question 3What will happen if I will just give this LED ~3.2 volts with a voltage regulator? How much current will the LED consume at this point? And the same questions for 3.5 volts.