How to Calculate Resistance Values for a Phototransistor Circuit?

[yaasir]

I need help to calculate the resistance values for the attached circuit diagram. I have also attached the data sheets. Can you help me.

 

[davenn]

hi there yaasir
welcome to PF :)

for the IR LED (or any LED for that matter), choose a resistor that will limit the current (I) to a chosen value at an assumed Vf. And we have both of these.

R = (V - Vf) / I

R = the resistor
V = The supply voltage
Vf = the LED voltage drop
I = the LED current

Vf and I can be obtained from the datasheet you posted

see how you go :)

Dave