I made a "laser aux cable" a few years back. I used a laser pointer (an actual laser one too, I think) and I can't remember exactly what I used as the receiver,

I made a "laser aux cable" a few years back. I used a laser pointer (an actual laser one too, I think) and I can't remember exactly what I used as the receiver, I think I may have used an LDR with a transistor, I don't think I would've had any photodiodes floating around. Interesting to see it can be done with an LED as the receiver.