Fall $2024$

Transferring Audio Information via Light

This project involves conversion of an audio signal to light, transfer of this audio$-$signalcontaining light over a distance, and finally converting the optical signal back to audio signal. The system that you will design will be composed of four subsystems each of which shall be fully analog: i$.$ Audio$-$receiving subsystem, ii$.$ Light$-$emitting subsystem, ii$.$ Light$-$sensitive subsystem, iv$.$ Audio$-$generating subsystem.

In the audio$-$receiving subsystem, the audio input should be converted to an electrical signal. Your audio circuits should employ transistors and it should be fully analog $($i$.$e$.,$ you are not allowed to use Arduino etc.$).($BONUS: In case the audio signal is converted to an electrical signal using optical means, a bonus point of $\backslash (15\backslash \%\backslash )$ will be added to the overall score$).$

In the light$-$emitting subsystem, you are asked to design a circuit to turn a light source on and off $($or make the emitted light dimmer and brighter$)$ in response to the audio signal that you received. You are expected to use a monochromatic light source.

In the light$-$sensitive subsystem, you are asked to utilize a photodetector. The photodetector should produce photocurrent due to the radiation from one of the light sources. Your system should work when the light$-$emitting and light sensitive subsystems are at least $50$ cm apart from each other.

In the audio$-$generating subsystem, the signal obtained from the photodetector should be converted to an audio signal. Your purpose here is to recover the original audio signal. Note that your audio$-$generating circuits should employ transistors and again it should be fully analog $($i$.$e$.,$ you are not allowed to use Arduino etc.$).$