@Ian0 it is just for a home project, the exact same thunder sounds will be played each time, we just need to show a dim light when no sound, and a bright light when sound (current schematics will be provided as soon as I receive them).Plenty of simpler circuits which don't have an auto-level. i.e. if you don't mind having to adjust something every time the level of the music changes
So in your opinion there is no way to have a simpler circuit (based on the one I provided, for example), that would not need a manual intervention?
@Tonyr1084 thank you for the explanation and example! Still, the way I understand transistors (please correct me) is that if the base is not powered, then the current does not flow (which means zero light); whereas if the base receives enough power, the current can flow (which means full light). In other terms: it seems to be a simple on/off switch, right? If so, how could this provide a small current when the microphone does not detect (enough) sound, if no current flows through?Instead of a pot (digital or otherwise) you'll need an amplifier. I'm showing a simple transistor, which will take small currents and apply the higher source voltage to increase current. So you'll need to specify a starting voltage and then determine the final output of the microphone to see IF it provides enough current to turn the transistor on. The transistor will drop the voltage by (typically but not specifically) 0.7 volts. If the microphone does not exceed that then you'll need to build an amplifier stage to get the transistor to switch. MY schooling was back in the 70's. MOSFET's might be a better choice but then they get connected in a different way.
You can safely consider that everything is [insert difficult language here] to me I did some reading earlier today and saw "mosfet" but they said it was mainly used for storing data (which would not help me much).If "MOSFET" is "Chinese" to you, it's an acronym for Metal Oxide Silicon Field Effect Transistor. It's not a transistor per se'. Yet, it does the same job. However, it depends on voltages and not currents. Little different approach.