I made this circuit for a 5v logic. I plan to use it as a remote control. So pulses. i hope that with this circuit i achieve more range as with the default remote. I already made it but now i have some doubts.
IR LED Datasheet
NPN Transistor (2N3904) Datasheet
As there is a voltage drop of 0.7v because of thee transistor i simply used 4.3v to do the math
For the signal/base resistor i used 330ohm 1/4Watt just to be sure that it saturates the transistor properly.(should be around 13mA, arduino handles 20mA)
The max forvard voltage of the ir led is 1.6v it and should work with 100mA.
As the ir led resistor needs to be 1/2 Watt i used 2 resistors 68ohm+56ohm in paralell which i measured and give me 31ohm (math suggests 27ohm 1/2).
1. Would you change something?
2. Can i use this circuit with a 3.3v logic as signal but feed the led with 5v?
I'm new to electronics and the more i learn the more doubts i have.