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Your support makes articles like this one possible. Thank you!
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:
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:
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.
(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
Many thanks to SWLing Post reader Mike, who shares a link to this story from the blog
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.[…]
Greg Blair’s radio story is the latest in our series called Listener Posts, where I place all of your personal radio histories.
In the meantime, many thanks to Greg Blair who originally posted the following on the Shortwave Listeners Worldwide Facebook group. Greg writes:
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.
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!
A few weeks ago, we published a short post about a credit card crystal radio from an eBay seller in the UK.
I purchased a kit–at $17-18 US shipped, it’s quite a modest investment for what might be a fun little project.
The crystal radio arrived while I was traveling during Easter break, but my free time has been so (extremely) limited lately, I was only able to unpack and try out this new arrival yesterday.
The biggest surprise for me was the fact that this isn’t really a kit–the board is fully populated and requires no soldering whatsoever. The board feels of very good quality.
All that is required is connecting the high-impedance earphone, earth/ground and aerial/antenna to the board. Since all of these components can be connected with the supplied alligator clip cables, getting it on the air took all of 20 seconds. I simply hooked up the ground and connected the aerial to my sky loop wire antenna.
I instantly heard a signal and station ID which confirmed it was our closest local broadcaster on 1010 kHz. This station isn’t of the blowtorch variety, but is the strongest one I receive on the MW band simply due to its proximity. Audio was quite faint through the earpiece, but I believe if I tinkered with antenna length and the two variable capacitors, I could improve reception.
SWLing Post reader, Richard Langley, received his crystal radio and had a very similar experience with reception.
With any crystal radio (especially one this small), performance is directly correlated with antenna length, availability of a good ground connection and, of course, strong broadcasters in your vicinity.
I plan to spend an evening tinkering with this little receiver and see if I can pick up some of the night time powerhouse AM stations on the east coast.
I can say this: if you’re looking for a simple, uber-compact emergency receiver for your go-bag, bug out bag or emergency kit, this one will certainly fit the bill. This crystal receiver and all of its components weight no more than a few ounces and could easily fit in compact pouch or sleeve.
Have any other readers have enjoyed tinkering with this little emergency crystal radio?
If you would like to purchase one, try searching eBay with one of the links below. The product will only appear in the search results if currently available.