Do crystal radios still pick anything up?

Oh yes, there's a few. Radio 4 on long wave and a few on MW as well

I depends where you live. If you're fairly close to an AM transmitter then you stand a good chance. Many AM transmitters have been shut down, but if you live near Droitwich, for example, you're on the pig's back.

Wikipedia has a list of European (which we're still in) AM transmitters.

Cheers

Yes, Medium wave is full of them. It depends where you are of course. The issue with crystal sets is selectivity. In the case of a basic one with a tapped coil and tuning capacitor, its hard to just get one station without bleed through. Here in sw London all you seem to get on medium wave is the God station Premier. Brian

There was even a supercharged version of the crystal set, using a germanium transistor which harvested the power from the aerial to give some amplification. It was not very good but better than a straight crystal set. Then if you had a 1.5 v battery you could get the ZN414, which was a thre pin trf radio. It was often used instead of a diode in superhets in the

Of course my favourite sets were those with regeneration or reaction as it used to be named. Then there was the superregenerative sets. One transistor and it could get fm or aircraft etc, little selectivity, but its mai drawback was the crud it generated on any radio nearby.

Those were such simple days.. sigh. Brian

Of course. The AM band is packed full. That method of transmission is the same as always.

In message , Dan S. MacAbre writes

What a coincidence! I recently dug mine out of the shed, to play with. Build mid sixties and not used since. I have even bought a little ear piece (via eBay) but have not yet rigged up suitable aerial and earth connections.

See here for a list of stations :

Back then, I was in North Herts and could easily pick up the BBC stations and the pirates out on the North Sea, and even Luxembourg in the evenings. Now, I'm in NE Scotland, and should be able to pick up Aberdeen and Hopeman, and possibly further afield.

My school had an old Scientific Encyclopedia which included instructions for making a Morse Code-like Wireless transmitter. It used a spark gap to generate the signal. We didn't build one after all.

Gosh, that brought back memories. A crystal set was the first thing I made, using a soldering iron shoved in the coal fire to heat it up. Probably aged about 8 and (slightly) more than half a century ago :-(

Okay, thanks for the great replies. I had a Ladybird book that showed how to make them. Beautiful illustrations that I still look at fondly. The first version was without batteries, and then it evolved into something amplified with an OC71. It said to drive a long copper tube into the ground for the earth side, but I just used a mains plug. And the aerial was supposed to be something like a washing line, but I used a bit of wire dangled across the room; and once, an old mattress in the loft (which was no better). That may have reduced what I was able to pick up :-)

In my book any external power for a crystal set is cheating. Even from a solar cell!

Only exception, if it's needed at all, are those parasitic circuits which used two tuners. One to draw radio energy from a powerful station used to improve reception of the station you listen to.

I'd never heard of that. I wonder how much power could be obtained from such a thing?

The aerial is key, IIRC, to capture plenty of signal. Mine was strung from the eaves of the house, across the road to a tree in the woodland opposite, about thirty yards, using egg-insulators at each end.

Thing is that one time all radios worked best with a long external aerial. Many would have one running the length of the garden. Ferrite rod aerials made this unnecessary for most.

A crystal set has no RF gain. So needs a very strong signal to work at all.

You can have reasonable lighting run purely off RF. If you are close enough to a powerful transmitter and have a big enough aerial. Until they catch you, of course.

A standard fluorescent tube will light with no other connections close to some TX aerials.

It's actually been made illegal, or something? I'd have thought they would encourage you to do it. I was wondering if you could just slowly charge batteries off it. I never imagined you could run lighting off it.

I never tried it but I saw it described in a booklet showing dozens of crystal set circuits.

I wonder if the power extracted depends on the amplitude of the audio being transmitted at that very moment.

I've just discovered a few articles that discuss what they call RF-based Energy Harvesting. I don't know if that's the only term for it, but it certainly sounds interesting.

This looks interesting

would have done, yes, but only instantaneously. I.e. a over a second loud sound is the same as no sound, but at the moment of the peak of the audio waveform power is more.

SSSC is the modulation where IIRC the actual power varies with audio.

Not bog standard AM.