the project is taken from this website for my college project
I think I have figured out function of few components but still need confirmation on below points.
I think that the C2 is used to block DC current due to Vcc is it correct. also I made a assumption that the audio input creates the signal which can be allowed through this C2.
The diode will allow forward current but no backward current but what is the need and what will happen if i remove it?
Also they said if I will be using electrect microphone as input then R6 is required but in case I use mono audio cable with pc as input then it is not required, but why ?
why is both the output wires from the audio amplifier block is connected across the R3, I hope the transistor circuit in LED modulator block is used as potential divider mode.
what's the use of R4 and what will happen if I remove it?
What's the use of R5, and C4?
In the website they have used a simple receiver to receive the modulated light with solar panel with speaker but can i use the same circuit below as a receiver but instead of audio input put a photo diode and instead of LED put a small speaker or earphone? specially i was thinking of using earphone