My circuit does not work as I thought it should and I'm really confused now.
What I want? Two LEDs which will pulse to audio LEFT and RIGHT channel separately. And same for display BACKLIGHT, but there is going to be SPDT switch, which will switch between direct voltage or voltage from transistor - in order to react to sound.
So far I have this:
1.) It works when I don't use power supply of GameBoy but external for the circuit.
This is what it looks like
2.) LEDs with no transistor will light UP when I use GameBoy power supply.
3.) Somebody told me before to put ground from audio to actual ground, not to emitter, but it works like that. When I tried to connect it to ground it stopped working. But still don't know why it works with audio ground on emitter.
4.) It is really weird, but when I switch the switch, it works as expected, BUT it switch LEDs not BACKLIGHT.
I really can't find any logical explanation in my head. I started with electronics few days ago, so there must be things I cannot see.
Thanks in advance!