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Comment by garyrob | Hacker News Reader

I'm 65. When I was a kid I built a crystal radio, which inspired my grandfather to tell me about the early days of radio. He said he and his friends used to compete with each other to build radios that could receive stations from the farthest away. It was a real hacker culture!

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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.

Is AM radio still on the air? or has digital kicked it to death?

Definitely still a thing in the US

It is dying off in Toronto, Canada. Advertisers migrating to FM as well as digital and internet.

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.

> Haven't found a low-tech way to make a piezo earphone just yet

The closer way I've found is this guy making it with a recycled transformer, a hard drive magnet, a jar lid, some wood, and some cables.

https://www.youtube.com/watch?v=cEMXlLqwwTA (First part. 7:07 min.)

https://www.youtube.com/watch?v=MXpprO5h79I (Second part. 9:32 min.)

Those videos are in Spanish but subtitles are available.

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.

This is called DX-ing, it's very well alive, however I'm not sure how much of the equipment users still build themselves, if any.

A lot of experimentation these days is SDRs. But people still build. The founders of Elecraft met at a club focused on building radios and decided to monetize their hobby.

I've just started getting into this using SDR.

Although I cannot design and build such low cost high performance digital receivers, I do have a lot of control over:

- software: I can make my own DSP pipelines for demodulation and filtering

- antenna: building antennas is completely approachable, using bits of wire, terminal blocks and basic tools

- RF input chain: analogue filters and amplifiers to cleanse the signal coming in

I also built a crystal radio as a kid. For something so low-tech and "simple", it was an amazing eye-opener into the nature of radio waves. As a form of energy and how information require energy.

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