M
Masonchen
Newly Enlightened
- Joined
- Apr 8, 2021
- Messages
- 10
I'm going to add an IR LED to my Arduino Uno and I'm attempting to understand the math involved in determining the exact resistor values required to drive the LED using a PN2222A transistor.
I'm aware that my LED has a voltage drop of 1.35V, that I intend to run it at 100mA, and that I'll be powering it with 5V from the Arduino. What I don't understand is how to calculate the exact voltage drop of a transistor between its collector and emitter. I'm also trying to figure out the arithmetic used to compute the milliamps that must travel through the transistor's base in order to fully turn it on (but not waste extra electricity).
I'm aware that there is a lot of leeways in which resistors may be used and the circuit will still work, but I'm hoping to figure out the math so that I can go as near to utilizing the exact correct resistor values as feasible.
I'm aware that my LED has a voltage drop of 1.35V, that I intend to run it at 100mA, and that I'll be powering it with 5V from the Arduino. What I don't understand is how to calculate the exact voltage drop of a transistor between its collector and emitter. I'm also trying to figure out the arithmetic used to compute the milliamps that must travel through the transistor's base in order to fully turn it on (but not waste extra electricity).
I'm aware that there is a lot of leeways in which resistors may be used and the circuit will still work, but I'm hoping to figure out the math so that I can go as near to utilizing the exact correct resistor values as feasible.