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                                                             on Gopher (inofficial)
   URI Visit Hacker News on the Web
   URI   Crystal Detector
   DIR   text version
        Ccecil wrote 15 hours 11 min ago:
        If you are interested in this type of tech...this is the book to read.
        [1] There is a second book as well which teaches you to create
        electronic parts from scratch.
   URI  [1]: https://www.amazon.com/Voice-Crystal-H-Peter-Friedrichs/dp/096...
        JoeDaDude wrote 2 days ago:
        As for so many things in radio, or in the world generally, there are
        dedicated hobbyists.  I am not a member, I just knew of their
   URI  [1]: https://www.midnightscience.com/
        riversflow wrote 2 days ago:
        So somewhat related, I cant find a half decent crystal radio kit on
        Amazon. Makes me really sad considering how dominant Amazon is.
        I got one as a gift when I was maybe 7 years old. Making that radio
        with my mom, from essentially wires and the crystal and then hearing
        music through that little piezo ear piece might have been the most
        wondrous experiences of my life. Like, my family isn’t religious at
        all and as an adult I’ve come to identify as a materialist, but
        that… that was the closest thing I can think of to a religious 
        experience. I assembled wires such that they produced sound sent
        invisibly through the air by other people, and because of the way it is
        sent it’s completely passive and requires no batteries. Absolutely
        mind-blowing experience for me as kid.
          jareklupinski wrote 2 days ago:
          to be fair there's not much on the air these days to pick up using a
          crystal anymore (around me at least)
          but an SDR would let you teach much much more about whats going on in
          the invisible :) [1]
   URI    [1]: https://www.hanselman.com/blog/software-defined-radio-is-a-g...
   URI    [2]: https://smile.amazon.com/NooElec-NESDR-Mini-Compatible-Packa...
          buescher wrote 2 days ago:
          Funny.    I was fascinated in the same way by the crystal (germanium
          diode) radio kit I built as a kid but I wish now I'd built one of the
          "oatmeal box" more-or-less-from-scratch radios. It's probably easier
          than ever to do that - you can get galena off ebay.
          MisterTea wrote 2 days ago:
          > Like, my family isn’t religious at all and as an adult I’ve
          come to identify as a materialist, but that… that was the closest
          thing I can think of to a religious experience.
          I like to think of electromagnetism as a form of magic (in the
          supernatural/religious sense). In the days before radio, the idea of
          moving energy and information over pieces of metal or thin air would
          be considered sorcery or witchcraft. Today its so much more advanced
          with pocket computers literally putting the world at our fingertips.
          I can casually talk to people on the other side of the planet in near
          real time.
          derbOac wrote 2 days ago:
          Yeah the part about not requiring batteries was fascinating to me
          when I was little. My dad had located an old one from somewhere; I
          remember him showing it to me and having grown up with what were more
          modern radios at that point, the fact it could work without batteries
          was somehow at the same time mystifying but also made the world of
          electronics seem more approachable.
          Reading about this leads me to wonder if there are certain benefits
          to many of these very old designs that have been lost due to
          overlooked priorities. As in, I'm not saying we should all be using
          crystal radios again but having a functional radio that doesn't
          require power seems like a plus at some level.
          0xfaded wrote 2 days ago:
          When I was a kid my crystal radio kit was beer powered! [1] Dad
          bought me Dick Smith's electronic kits when I was 8 (it was an
          Australian thing). I didn't wind up going the EE route, but I will
          credit it with giving me the basics early in life so that whenever
          talk of capacitors and resistors came up I knew how to properly parse
          the information.
   URI    [1]: https://archive.org/details/dicksmithsfunwayintoelectronicsv...
            mnw21cam wrote 2 days ago:
            I remember that one. IIRC the instructions finished by telling you
            not to drink the beer afterwards.
        dr_dshiv wrote 2 days ago:
        Could one have invented radio in Ancient Greece or Rome?
        I’m now deep into the early history of spark gap radio…
          buescher wrote 2 days ago:
          Radio was invented after we had Maxwell's equations - a theory that
          predicts electromagnetic waves.  They probably could have built a
          radio, but they wouldn't have had the idea that one was possible
          without a couple hundred years of advancing math and physics.
            dr_dshiv wrote 2 days ago:
            But stoic philosophy was so focused on resonance (sympathy) in the
            universe. Somehow it doesn’t seem far from their worldview. It is
            kind of surprising that there wasn’t more tinkering and
            scientific development back then.
          pjc50 wrote 2 days ago:
          Well, only with the technology of electricity as a prerequisite.
          Which was invented not far from Rome and recorded in Latin: [1] ...
          in MDCCLXIX, or 1769 as we now represent it.
          Neither the Roman nor Greek empires seem to have had many of the
          "practical tinkerer / gentleman scientist" social positions which
          were very important in the European age of discovery.
   URI    [1]: https://play.google.com/books/reader?id=Ha9gAAAAcAAJ&pg=GBS....
          kwhitefoot wrote 2 days ago:
          Yes.  They were able to draw wire for jewellery.  The could smelt
          iron so they could have made electromagnets, generators, electric
          motors, transformers, and loudspeakers.  That's enough for spark gap
          transmitters and wired telegraph.
          Hero of Alexandria made, or at least described, a simple steam
          turbine.  But it was just seen as a toy or philosophical talking
          point and it wasn't until over a thousand years later that steam
          power became useful.
          Half the challenge is knowing that something can be done and having
          some idea of what might be achieved.  The rest is just work. :-)
   URI    [1]: https://en.wikipedia.org/wiki/Aeolipile
            Cthulhu_ wrote 2 days ago:
            They also appeared to be able to make batteries: [1] But as the
            article states, they're not convinced anymore that they were. Never
   URI      [1]: https://en.wikipedia.org/wiki/Baghdad_Battery
            KineticLensman wrote 2 days ago:
            > Hero of Alexandria made, or at least described, a simple steam
            turbine. But it was just seen as a toy
            It was in fact a toy [0]. It was basically a kettle mounted on a
            spindle with two spouts on opposite sides. When heated the steam
            escaped via the spouts and the whole thing rotated around the
            spindle. For many reasons it could not have done useful work:
            * Very low pressure - with no valves to maintain a working pressure
            or pistons to drive a machine
            * Not engineered to withstand useful pressure (simple copper welds)
            * No way to reload water when in use
   URI      [1]: https://en.wikipedia.org/wiki/Aeolipile
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