[Eric] Talks Crystal Radios

The AM broadcast band doesn’t have a lot of mainstream programming on it across much of the United States today. That’s a shame because a lot of kids got their first taste of radio and electronics by building simple crystal radios. [Eric Wrobbel] has a well-done page discussing some of the crystal radio kits and toys that have been around.

[Eric] should know, as he’s written two books on toy crystal radios. The pictures range from a 1945-era “Easy Built Radio Kit” which looks like a piece of masonite with a coil, some Fahnestock clips, and a cat whisker, to a very slick looking Tinymite from 1949. Honestly, though, the one we really want is the X-50 Space Helmet Radio that comes in a box marked “For Young Moon Travelers.”

Continuing the space theme, there’s a picture of a radio built in a rocket by a Japanese company. Oddly enough, there was also a crystal radio made inside a pincushion that included a thimble and a tape measure. Presumably, you could listen to tunes while you mended a sock.

It makes us a little sad to think of the times we built crystal radios and strained to hear pop music, sports, or news. With all the options today, it hard to imagine a young person listening to a tinny earphone to some weak mono audio. On the other hand, there’s still something magic about building something simple that takes no power and can pull audio out of the air around us from relatively far away.

We wonder what counts as today’s crystal radio? Is a blinking LED on an Arduino? An IC-based FM radio receiver? A simple robot kit? Perhaps if we were making a crystal radio kit today, we’d pair it with a preassembled AM transmitter that could take a feed from a phone or other audio device. If you want to be super modern, why not 3D print the chassis?

42 thoughts on “[Eric] Talks Crystal Radios

  1. “The AM broadcast band doesn’t have a lot of mainstream programming on it across much of the United States today.”

    Well that’s a bit harsh. Hard to define “mainstream” when AM radio still has about 58 million listeners a week. A lot of podcasts (a part of an industry going through huge growth) are basically re-wrapped talk radio.
    The mule is still kicking pretty hard.

    1. As a resident of a city with a long standing and strong AM heritage (at least since 1925), I’ll heartily agree. I point to a certain Country Station here in Nashville Tennessee that still has the universal appeal of live jockeys; Furthermore, it hosts segments attractive to vintage radio enthusiasts, especially on the weeknights when an old fiddle player turned dj and music historian fills the airwaves with vintage tracks and his scholarly commentary. Too far out in the flyover to actually hear it? They now have a streaming online presence, of course; adapt or perish.

      A lot of ‘Good That Once Was’, has gone away from the AM band in my lifetime, but the format will probably be assassinated by digital imperatives imposed, long before it succumbs to natural causes.

      1. I don’t live near Nashville, but I would love to know the name of the show you speak of, and see if they host a stream or downloadable episodes online. Sounds like a treat of a listen!

        1. They stream online at wsmonline.com In fact, they have several streams, one for their regular broadcast, one of Americana music, and at least one or two others. The primo show though is Eddie Stubbs’ weeknight tour through country music history. It runs from 7pm central through midnight. Finally, even if you’re not near Nashville, if you’re in the eastern half of the US you can frequently pick up the station at night. I live right outside of New Orleans, and WSM 650 AM has a decent signal 80% of the time.

      2. I live in a semi-rural area of Maryland and I have a button on my radio dedicated to WSM on 650 AM. I often hear Marcia Campbell signing off in the early hours of the morning, and the Wild Side Radio program on fishing and hunting in Tennessee. Sometimes if I’m driving on Saturday night I catch the Grand Ole’ Oprey show.

        There is a certain romance to hearing an AM station from a significant distance away with music and programming that one wouldn’t hear on the highly formatted and directed trash heap that is FM radio. Yes, I know I can hear it better using streaming audio from my phone. But I guess I’m just old school.

  2. Back then all I could get was the boring pre-NPR stuff from Purdue (the lady storyteller) and Ag reports. The 2 other daytime stations were 30k apart and just bled together. They were junk too, warmed over big band and pre rock and roll. All are duplicated on FM now. I could never get Indy or Chicago. Somewhere I think I still have a Sputnik satellite shaped clear plastic crystal radio. I wonder how far one could roam with the space helmet radio, with a longwire antenna and ground hooked up. Should lightning be in the area, get sent into space!

    There is such a thing as crystal FM radio, using slope detection and a cavity filter as the tuned element.

  3. (Creaking door) Come in, welcome. I’m E. G Marshall……
    Ah the CBS Radio Mystery Theater.
    There’s a website called When Radio Was where you can listen to the old time radio serials.
    Each week, you can hear this wonderful program and listen to many old time radio shows.
    Today’s kids have nooooo clue :)

    1. “I…am the Whistler, and I know many things, like how to hypnotize a chicken…” I’m a fan of OTR as well, truly theatre of the mind. And ChipMaster if you want some Old Time Radio search the Internet Archive, they have as shiteload of mp3s.

    2. KSFO radio back in the late 70s played mystery theater after 9pm, I listened to the octopus and the who did it playhouses. That was the fun years. When I was growing up in CT all am radio stations played oldies, but those days are long gone, I’d love to see a station dedicated to play 50s, 60s and 70s music now that’s when music was music.

  4. I grew up with crystal sets as a kid in the 60’s and that ended up with my getting my amateur radio ( Ham ) ticket in 74. Then started a collection of crystal radios and 1920’s tube radios. I remember well the Rocket Radio, it actually did a good job receiving the local stations. My current crystal radio is designed for the short waves and that opens up to a lot more to hear but long distance on the AM band is still a thrill and I can always tune in WSM wherever I have lived :-)

    1. Dr. Cockroach – we are the 1st generation “geek” in electronic/tube/transistor. I built my own CB by reading “Popular Electronic” magazine from components when I was a teenager lived in Hone Kong in early 70s. My CB can reach Japan during certain months of the year. Crystal Radio has the best bandwidth because it is rectifying the amplitude of the radio frequency to audio directly with no IF in between the RF and AF! Glad that you talked about the technology instead of the contents.

  5. “We wonder what counts as today’s crystal radio?”

    For undergraduate non-engineers, it’s a cheap Arduino (not 555 timers, though we eventually get to that) and being able to *change* the blinking light. From there the leap to programmable plug and play motors/sensors/etc. is ready to be made and then on into “simpler” things.

    In a way, this is kind of backwards, starting with a finished, relatively complex device that’s easily programmed and working backwards into why it all happens, but if you catch their imagination with what might be done with a more fundamental understanding then the rest falls into place with a lot more enthusiasm.

  6. The local drug store sold crystal detectors potted in a hunk of metal. I recall the little bagged item was about 10 cents. With nothing more than a bunch of enamel wire, aluminum foil, cellophane wrap, and a earphone I was able to listen to some AM rock stations.

    Then one day dad came home with a broken office intercom system. The “master” console still worked and it was essentially an amplified speaker. So with little effort I was able to ditch the earphone and hear my radio in glorious high volume mono sound.

    Nowadays I blink LEDs and click relays with microcontrollers. But I’ll never forget how my hacking love affair all began.

    1. I was thrill to see “Vacuum Tube” tester at drug stores and grocery stores in the 70s. Those were the days!

      Nowadays, I build digital clock with ESP-xxxx sync with Time Server using NTP!

      1. I use a 1N34A Diode it my Kit from United Nuclear and it works just fine.
        Probably not the best choice for a germanium diode in a crystal radio but it does work OK.

    1. I have one of these kits from United Nuclear. The coil is uses a large gauge magnet wire and calculates and measures 89 micro henries. I am wondering how a coil with such low inductance can achieve a wide frequency range in a resonant circuit ?

  7. I have a box full of stuff that is going to become a dandy crystal set one of these days. I am envisioning this being truly mixed media. Old meets new. For the old I have a beautiful old coil wound with cotton over rubber insulated wire, I have a nice big old variable cap, I have a real nice piece of galena, and a very cool old planetary gear dial. I also have some nice old oak for the base and panel. The new meets old come from the cap needing a perch to sit on to be near the right height for the dial, and the shaft on the cap and the shaft on the dial are different sizes. I can see those pieces being 3D printed. I don’t want to use a diode, I want to use a cat’s whisker, sadly they are not stocked in electronics shops anymore. One pup has them on line for $80 on up. Urg. I think that will be a bearing and some brass rod and some beryllium copper wire I have been saving for just such a use. I think I can cut the stand out of acrylic on my laser cutter and line the sides that trap the ball with copper tape. I think that would look really sharp. And for antenna coupling I have a nice antique variometer. That too may take some 3D printing to mount and get a knob on. Over the last year or so the box of stuff has percolated up to the top of the pile and I do ponder getting to it when the weather improves. Even more so if I get the parts I need to make in the indoor shops made while it is cold out. Many of us in the north are faced with this. You wanna play indoors in the winter and outdoors in the summer. My big shops are not exactly outdoors but they are not really heated either.

  8. It doesn’t completely take the place of the old radio experience but my wife and I have been forced to change. Radio in my neck of the woods seems hard to get decent reception. So my wife turned to picking up her stations via websites/apps. Well… I wanted to make things simpler and eliminate the “are you there?” prompt. The end solution was a “Myntz” tin (same style as Altoids) with an OrangePi Zero, and an EC11 rotary encoder + button plugged into our entertainment system amplifier. Push to turn on/off. Turn knob to select stations (play lists). I used XMMS2 to play iNet radio and local MP3s. A custom FPC program watches the EC11 and tells XMMS2 what to do. I do the setup and playlist maintenance via SSH. But that will be replaced with an fpGUI app displayed on the TV.

    It does use WiFi so its still a _radio_ of sorts. And it was made by me like a radio kit you might have bought…

  9. Hey, I have that same crystal set! In his collections under Toy Guns, Space Guns, the Hiller Atom Ray Gun was made by the same company who later went on to be Hiller Aircraft Company who, in addition to helicopters, developed the Hiller Flying Platform. Stanley Hiller starting making helicopters for the U.S. Army at age seventeen.

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