Tag Archives: Crystal Radio

“Crystals Go To War”: A 1943 film about the production of Signal Corps radio crystals

Many thanks to SWLing Post contributor, Charlie (W4MEC), who shares this fascinating film which documents the production and calibration of crystals in 1943. I had no idea of the amount of labor and attention to detail this process required–an absolutely fascinating process:

Click here to view on YouTube.

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Dave sheds a little light on wireless electric transmission

Many thanks to SWLing Post contributor, Dave (NM0S), who left the following comment on our previous post regarding wireless electric transmission:

This company [Viziv] had been known as Texzon until recently, and must have apparently had a recent change of name.

Their main published paper is found here:

Click here to download PDF.

Basically they claim to be exciting a ‘Zenneck Surface Wave’ by using an electrically small antenna, which by virtue of its very small radiation resistance, requires very large currents to radiate power. Their supposition is that these high RF currents injected into the ground propagate with low loss, and can be harvested at some remote location. Presumably, by exploiting the reciprocal nature of antennas, a similar device would be employed to receive this RF power. It is not clear that they will be able to do something beyond what every crystal radio hobbyist has been doing for the past century.

Thank you, Dave! I love the crystal radio analogy.

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Make your own 3-D printed crystal radio

(Source: Southgate ARC)

Did you know you can build your very own working 3D-printed radio – without any soldering, electronics experience, electric cord, or even batteries?

Digital Trends reports that’s exactly what talented Houston, Texas-based 3D-printing and electronics enthusiast Sage Hansen has created. And he’s willing to show you how to do it, too.

Called a crystal radio receiver, or sometimes a “cat’s whisker receiver,” this is an incredibly simple type of radio receiver that was popular in the earliest days of radio. The only power it requires to work is the received radio signal, which is used to produce sound. It is named after its most important component, the crystal detector or diode.

“AM radio was one of the first ways of transmitting audio to a very broad audience in the early 1900s, but it is still very popular today,” Hansen told Digital Trends. “It starts with the radio station converting their audio sound waves into electromagnetic waves, which can travel great distances.

Each radio station uses a specific frequency that is constant, but the sound waves are mixed so they amplify and modulate the base radio wave. What makes the crystal radio so exciting is how simple the circuit is, and how it can be made out of normal household items.

Watch the video and read the full story at
https://www.digitaltrends.com/cool-tech/3d-printed-working-radio/

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Radio Caroline and a crystal radio: “The making of a rebel”

Radio Caroline circa 1960's.

Radio Caroline circa 1960’s.

Many thanks to SWLing Post reader Mike, who shares a link to this story from the blog
République No.6:

Growing up in Piennes Lorraine, Radio Caroline the making of a rebel

[A]t night with my younger brother we would listen to a “pirate radio station” on a boat that would put real good music on, crusing the international waters between England and France. He burst in laughter and told me: That’s Radio Caroline“. That was it. My brother and I would listen to that station nearly every night on an old “galena radio receiver” with a huge antenna hidden in the attic built with copper wire we stole at the mine. I mean we didn’t really steal it, it was everywhere. It was the wires used by miners to connect detonators to batteries when blowing new tunnels and locals were using it for all sorts of things, like holding parts in chicken coop to tie tomato or green bean plants to stakes and could be found everywhere.

Actually at first we set the antenna in our bedroom but somehow it wasn’t long enough not to mention mom who saw it and tore it down giving her an other excuse to punish us. So we decide it to place it in the attic where no one ever went.

The most difficult part was going to the attic, there wasn’t any stairs. We had to bring a ladder to the trap leading to it. Mom was watching us like a hawk, looking for any excuses to punish us.[…]

Read the full story at République No.6.

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Listener Post: Greg Blair

SP600Dial3Greg Blair’s radio story is the latest in our series called Listener Posts, where I place all of your personal radio histories.

If you would like to add your story to the mix, simply send your story by email!

In the meantime, many thanks to Greg Blair who originally posted the following on the Shortwave Listeners Worldwide Facebook group.  Greg writes:


How I Discovered Shortwave Radio

BoysBookOfRadioI discovered shortwave radio almost by accident.

I had built a simple crystal radio from plans in a library book…(I think it was “The Boy’s Book of Radio” or similar. ) I added a one transistor amplifier later. I had a really great long wire antenna from the garage to the house, up about 30 feet, about 75 feet long, and a good earth ground.

I was playing around with it, and I had an old phonograph amplifier I connected to the output of it. I de-tuned the coil and apparently managed to get it tuned into the 49 meter band. All of a sudden I was hearing broadcasters from Europe. Some were in English, others in foreign languages.CrystalRadio

Up to that point I had thought that all radio was like AM broadcast, only good for a few hundred miles even at night. I was flabbergasted. That marked the beginning of my addiction to radio. I have never gotten over the miracle of HF radio ever since.


Many thanks, Greg, for sharing your memories with us!

I can only imagine the thrill is must have been to tune in stations from across the planet on your simple, home-brew radio set.

I encourage other SWLing Post readers and contributors to submit their own listener post!  Tell us how you became interested in radio! 

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