You can still do this today, and it still works as well as it did back in the day. For an even more impressive trick use a razorblade as your rectifier, a toilet roll for the tuning capacitor, another toilet roll for the coil. Haven't found a low-tech way to make a piezo earphone just yet, but this gets the list of ingredients down to a jam-jar, a couple of toilet rolls, some insulated wire, an old razorblade, a bit of aluminum foil, some cardboard, that piezo earphone and a 100K or so resistor. Pure magic that such a list of parts can function as a radio, and without any power source other than the transmitter itself.
It’ll work for as long as there’s AM radio stations at least, they’re a bit of a dying breed in Europe although there’s still a few remaining networks of powerful national transmitters. The BBC just finished shutting down mediumwave local radio citing high costs per listener, though there’s a few hobbyist pirates popping up here and there along with noncommercial broadcasters like former offshore pirates Radio Caroline (if you haven’t read about those guys seriously give it a look, it’s a ridiculously cool story and very much in the hacker spirit if you’re into electronics).
The longwave transmitter for Radio 4 will probably hang on a while yet I imagine though, hell hath no fury like English cricket fans deprived of Test Match Special.
In a way that's great. Can we get something like that for the web please, make a next generation internet so the advertisers will fuck off from this one? We'll tell them it's the hot new thing where everybody went to.
