4 ms·

Crystal Detector

28 points by ofou 5y ago

dr_dshiv 5y ago
Could one have invented radio in Ancient Greece or Rome? I’m now deep into the early history of spark gap radio…
- kwhitefoot 5y 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. :-) See https://en.wikipedia.org/wiki/Aeolipile https://en.wikipedia.org/wiki/Aeolipile
  - KineticLensman 5y 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 [0] https://en.wikipedia.org/wiki/Aeolipile https://en.wikipedia.org/wiki/Aeolipile
  - Cthulhu_ 5y ago
    They also appeared to be able to make batteries: https://en.wikipedia.org/wiki/Baghdad_Battery https://en.wikipedia.org/wiki/Baghdad_Battery But as the article states, they're not convinced anymore that they were. Never mind?
- pjc50 5y ago
  Well, only with the technology of electricity as a prerequisite. Which was invented not far from Rome and recorded in Latin: https://play.google.com/books/reader?id=Ha9gAAAAcAAJ&pg=GBS.PP10 https://play.google.com/books/reader?id=Ha9gAAAAcAAJ&pg=GBS.... ... 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.
- buescher 5y 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 5y 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.
riversflow 5y 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.
- buescher 5y 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.
- 0xfaded 5y ago
  When I was a kid my crystal radio kit was beer powered! https://archive.org/details/dicksmithsfunwayintoelectronicsvolume2 https://archive.org/details/dicksmithsfunwayintoelectronicsv... 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.
  - mnw21cam 5y ago
    I remember that one. IIRC the instructions finished by telling you not to drink the beer afterwards.
- derbOac 5y 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.
JoeDaDude 5y 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 existence. https://www.midnightscience.com/ https://www.midnightscience.com/
Ccecil 5y ago
If you are interested in this type of tech...this is the book to read. https://www.amazon.com/Voice-Crystal-H-Peter-Friedrichs/dp/0967190509 https://www.amazon.com/Voice-Crystal-H-Peter-Friedrichs/dp/0... There is a second book as well which teaches you to create electronic parts from scratch.

Crystal Detector

28 points by ofou 5y ago

dr_dshiv 5y ago

Could one have invented radio in Ancient Greece or Rome? I’m now deep into the early history of spark gap radio…

kwhitefoot 5y 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. :-) See https://en.wikipedia.org/wiki/Aeolipile https://en.wikipedia.org/wiki/Aeolipile
- KineticLensman 5y 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 [0] https://en.wikipedia.org/wiki/Aeolipile https://en.wikipedia.org/wiki/Aeolipile
- Cthulhu_ 5y ago
  They also appeared to be able to make batteries: https://en.wikipedia.org/wiki/Baghdad_Battery https://en.wikipedia.org/wiki/Baghdad_Battery But as the article states, they're not convinced anymore that they were. Never mind?
pjc50 5y ago
Well, only with the technology of electricity as a prerequisite. Which was invented not far from Rome and recorded in Latin: https://play.google.com/books/reader?id=Ha9gAAAAcAAJ&pg=GBS.PP10 https://play.google.com/books/reader?id=Ha9gAAAAcAAJ&pg=GBS.... ... 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.
buescher 5y 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 5y 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.

riversflow 5y 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.

buescher 5y 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.
0xfaded 5y ago
When I was a kid my crystal radio kit was beer powered! https://archive.org/details/dicksmithsfunwayintoelectronicsvolume2 https://archive.org/details/dicksmithsfunwayintoelectronicsv... 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.
- mnw21cam 5y ago
  I remember that one. IIRC the instructions finished by telling you not to drink the beer afterwards.
derbOac 5y 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.

JoeDaDude 5y 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 existence. https://www.midnightscience.com/ https://www.midnightscience.com/

Ccecil 5y ago

If you are interested in this type of tech...this is the book to read. https://www.amazon.com/Voice-Crystal-H-Peter-Friedrichs/dp/0967190509 https://www.amazon.com/Voice-Crystal-H-Peter-Friedrichs/dp/0... There is a second book as well which teaches you to create electronic parts from scratch.