A couple of days ago I found a single ear plug lying on the street, with wires coming out that had been yanked off its companion piece, in some hit and miss accident of a runner. I couldn’t wait to get home to open it up with pliers and look inside, because I often wondered what it looked like, but would never have cracked a functioning one open to satisfy my curiosity. Here was my chance. Sure enough, there was a tiny perforated plate, and a tiny tiny membrane, and behind the membrane I saw a tiny spool of copper wire – everything astoundingly small.
The reason I was so curious is that there was a time when I made one all by myself, from scratch, as a boy.
This is what I did. I emptied a Nivea sample tin, no bigger in diameter than ¾ of an inch, and gave the cream to my little sister. Then I put a hole in the back part of the tin for the lead to go through, and a number of holes in the front part of the tin for the sounds to come out of. I bought thin insulated copper wire, thin as hair, and wound many feet of it around a piece of iron, which I glued to the inside of the back tin. I made a membrane from Aluminum foil and glued a thin iron washer on it in the middle. I put the membrane at the inside of the front tin, behind the holes for the sound to come out of, making sure it was not making contact with the piece of iron.
When the whole thing was done, and the thin wires were soldered to the lead that was threaded out of the back tin, and actual sounds came out when I plugged it into my home-built soap box radio, I was ecstatic with excitement.