I am using Arduino Nano (5v), and I want to transmit an IR Signal using an IR LED.
I am using this IR LED: Vishay - TSAL7400
Since Arduino Output Legs can give a max of 40mA,
I am currently connecting the IR LED directly to an output leg, with a 100ohm resistor,
meaning around 37mA now.
My IR LED can accept a max of 100mA,
so I want to use a 2N3904 NPN BJT transistor, to drive the IR LED.
This is the transistor that I have: Fairchild - 2N3904
What I know now, is that the IR LED should be connected to the transistor like this:
What is the correct value for the Resistor in series with the IR LED?
At 100mA, the Voltage Drop on the IR LED is 1.4v
5v-1.4v-Vce = Vresistor
Now the question what is my Vce here?
On which graph should I look at the transistor's Datasheet?