When I was a young lad (maybe 12 years old), I had a 100-in-1 electronic project kit and got a bright idea.
They had a project in the accompanying book that was a simple audio amplifier. I used that amplifier to drive the LED in the kit and used the small speaker in the kit as the microphone input to the amplifier. It worked well enough and it was fun to watch the LED brightness go up and down with my voice. Later I hooked up the solar cell (or maybe the photodiode? I forget) as a detector to a second amplifier and a second speaker and I could sort of hear myself on the other speaker. It probably had the audio quality of Alexander Graham Bell's call to "Watson, come quickly. I need you." but it worked.
Thus I made a transmitter and receiver. I figured out later that this was essentially AM.
I showed it my brother but he didn't care about the details. All he wanted was a bloody QSL card. Bastard.