7 ms·

1901: Semiconductor rectifiers patented as “cat's whisker” detectors

62 points by indus 3y ago

archo 3y ago
Hence the Crystal Set was born.
- indus 3y ago
  It's remarkable to see how crystal rectifiers played a crucial role in early radio sets--without external power.
  - msla 3y ago
    > without external power. The radio transmitter is the external power. The crystal set is a way to grab a tiny amount of the electrical power being paid for by whatever entity is running the transmitter. You can play around with the inverse square law and figure out how little power the set is grabbing, but it's working on the basis of what it does grab.
    - interroboink 3y ago
      Reminds me a little of "The Thing"[1] — remarkable WWII-era passive listening device. [1] https://en.wikipedia.org/wiki/The_Thing_(listening_device) https://en.wikipedia.org/wiki/The_Thing_(listening_device)
      - somat 3y ago
        There is an excellent youtube series where "the thing" is recreated. There is a lot of subtle design involved. https://www.youtube.com/watch?v=NLDpWrwijE8 https://www.youtube.com/watch?v=NLDpWrwijE8
        archo 3y ago
        A Crystal Radio Receiver, also called a Crystal Set : https://en.wikipedia.org/wiki/Crystal_radio https://en.wikipedia.org/wiki/Crystal_radio
  - quickthrower2 3y ago
    I made one in one of those electronic kits in the 80s that had springs you poked wires into. Pretty cool to pick up “the station” on am (there was no tuning I think loudest won)
    - progre 3y ago
      I had one as well, but I recall a variable capacitor used for tuning.
      - philiplu 3y ago
        Yep, the old Radio Shack 100-in-1 kits. Great fun (early to mid 70s for me).
        progre 3y ago
        I think mine was called "MyKit 100", no Radio shack branding. There was a small booklet with circuits and connection lists, like 1-12-14 meaning that you where supposed to put wires between those connections. Absolutely no explenation about how the circuits worked.
    - londons_explore 3y ago
      I'm not sure you can really do that now. There are far more non-voice things transmitted on AM frequencies, so there is a good chance that your not-very-selective home-made radio is picking up someones garage door opener as the strongest signal.
      - msla 3y ago
        The FCC is rather prickly about electrical noise in the licensed bands, to the point companies have had to modify designs to not become impromptu transmitters on those frequencies. This is one reason power cords grow those little black cylinders called ferrite beads: https://en.wikipedia.org/wiki/Ferrite_bead https://en.wikipedia.org/wiki/Ferrite_bead So, in theory, a crystal set should still be a good way to pick up conservative talk radio and sports talk and you kinda get the idea it wouldn't be a popular project for kids these days given the current media landscape.
  - Aloha 3y ago
    Crystal sets are remarkably sensitive, though early radios were not very selective, which describes most of the issues with the first 20 years of radio.
Pxtl 3y ago
I wonder if he had any relation to Amar Bose of the Bose corporation? Googles Nope.
kpgraham 3y ago
It used to be possible to make a radio receiver out of a diaper pin and a blue razor blade. The coating on the blade acted like a crystal. You needed a cheap pair of headphones or a tiny transistor radio speaker. I made one when I was a kid, and I could clearly pick up 77 ABC in New York City from 50 miles away. Razor blades aren't blue anymore, but there must be other things that work.
- Kirby64 3y ago
  Fun fact, the blueing that creates that effect is literally just steel blue. You can accomplish the same thing by torching a razor blade until it glows then letting it cool.
- userbinator 3y ago
  It still is, and I hope it remains that way for future generations too. The first-time experience of hearing "voices from thin air" is unforgettable.
  - pfannkuchen 3y ago
    Did you do this before you ever used a full on radio? That seems hard to believe, so I guess you are implying that it is an experience that feels different. I wonder how so?
    - AnthonyMouse 3y ago
      Consumer radios operate by witchcraft. Presumably a fairy from another dimension rides into town on horseback with a satchel full of vinyl and then camps out outside your window so when she sees you switch on the radio she can play the vinyl for you. It feels different when you put it together yourself out of basic components and see that there is no magic in there, and yet... there is.
      - Maken 3y ago
        On a serious note, it concerns me a little how easy new generations accept that everything is a magical black box and not even question how their smartphones work.
29athrowaway 3y ago
The other day I learned that the National Ignition Facility uses actual cat whiskers. https://www.cbsnews.com/news/nuclear-fusion-60-minutes-2023-01-15/ https://www.cbsnews.com/news/nuclear-fusion-60-minutes-2023-... > Michael Stadermann: All the components are brought together under the microscope itself. And then the assembler uses electromechanical stages to put the parts where they're supposed to go-- move them together, and then we apply glue using a hair. > Scott Pelley: A hair? > Michael Stadermann: Yeah. Usually something like an eyelash or is similar, or a cat whisker. > Scott Pelley: You apply glue with a cat whisker? > Michael Stadermann: That's right.
timthorn 3y ago
> They regained prominence in World War II because of their ability to operate at microwave frequencies I'd always understood the WWII relationship with cats whiskers to be due to PoWs making radios from materials that they had access to. Edit: some evidence to suggest my understanding wasn't wrong, if not complete: https://www.bbc.co.uk/ahistoryoftheworld/objects/C5q84AOFTtq8T20c1X5IzQ https://www.bbc.co.uk/ahistoryoftheworld/objects/C5q84AOFTtq...
- segfaultbuserr 3y ago
  They saw two forms of uses during WW2, both low-tech uses and high-tech uses. Crystal detectors went out of favor soon after vacuum tubes came to prominence, and eventually many researchers almost forgot them entirely due to their outdateness. Later work in microwave electronics made people rediscover their usefulness. Post-war advance in semiconductors made it possible to manufacture small-signal and microwave diodes consistently, finally making them no longer notoriously inconsistent devices. They remain in use for RF/microwave circuit today. Of course, there was also the work by the Indian physicist Jagadish Chandra Bose, an outlier who used crystal detectors to reach millimeter-wave frequency around 60 GHz already in the year 1900 before everyone else. But as far as I can see, his work had limited influence since it was far ahead of his time. In Crystal Fire: The Birth of the Information Age, a definite book on semiconductor history, it described the amazement of this rediscovery: > In the mid-1930s [George] Southworth was trying to detect ultrashort radio waves around a tenth of meter long—what he then dubbed “hyper-frequencies” and are today called microwaves—using specially designed vacuum tubes. But he was having little success. Inherent time lags in the flow of electrons through them were simply too great for the tubes to cope with these extremely short, rapidly oscillating waves. Copper oxide rectifiers didn’t work any better, either. > Frustrated, Southworth decided to try one of the old “cat’s whisker” crystal detectors he had used in radio sets during the Great War, when he served in the Army Signal Corps. These quirky devices had fallen gradually out of favor when vacuum tubes became popular during the 1920s. By the mid-1930s it had become almost impossible to buy one in an ordinary radio store. > So Southworth hopped a train bound for lower Manhattan, where he knew of a secondhand radio market on Cortlandt Alley, near Canal Street. Rummag ing around on the dusty back shelves of one tiny shop, he soon found a few old cat’s-whisker detectors. After bargaining with the shopkeeper, he carried them back to Holmdel, where he dusted them off and carefully inserted one into his receiving apparatus. He began searching around on its surface for a suitable hot spot. Finally, after hunting almost an hour, he found a good one. > And it worked! At last, he could detect his ultrashort-wave, hyper-frequency radiation.
deleted 3y ago
[deleted]
ggandhi 3y ago
They also had memristive properties: https://ieeexplore.ieee.org/document/6518277 https://ieeexplore.ieee.org/document/6518277

62 points by indus 3y ago

archo 3y ago

Hence the Crystal Set was born.

indus 3y ago
It's remarkable to see how crystal rectifiers played a crucial role in early radio sets--without external power.
- msla 3y ago
  > without external power. The radio transmitter is the external power. The crystal set is a way to grab a tiny amount of the electrical power being paid for by whatever entity is running the transmitter. You can play around with the inverse square law and figure out how little power the set is grabbing, but it's working on the basis of what it does grab.
  - interroboink 3y ago
    Reminds me a little of "The Thing"[1] — remarkable WWII-era passive listening device. [1] https://en.wikipedia.org/wiki/The_Thing_(listening_device) https://en.wikipedia.org/wiki/The_Thing_(listening_device)
    - somat 3y ago
      There is an excellent youtube series where "the thing" is recreated. There is a lot of subtle design involved. https://www.youtube.com/watch?v=NLDpWrwijE8 https://www.youtube.com/watch?v=NLDpWrwijE8
      - archo 3y ago
        A Crystal Radio Receiver, also called a Crystal Set : https://en.wikipedia.org/wiki/Crystal_radio https://en.wikipedia.org/wiki/Crystal_radio
- quickthrower2 3y ago
  I made one in one of those electronic kits in the 80s that had springs you poked wires into. Pretty cool to pick up “the station” on am (there was no tuning I think loudest won)
  - progre 3y ago
    I had one as well, but I recall a variable capacitor used for tuning.
    - philiplu 3y ago
      Yep, the old Radio Shack 100-in-1 kits. Great fun (early to mid 70s for me).
      - progre 3y ago
        I think mine was called "MyKit 100", no Radio shack branding. There was a small booklet with circuits and connection lists, like 1-12-14 meaning that you where supposed to put wires between those connections. Absolutely no explenation about how the circuits worked.
  - londons_explore 3y ago
    I'm not sure you can really do that now. There are far more non-voice things transmitted on AM frequencies, so there is a good chance that your not-very-selective home-made radio is picking up someones garage door opener as the strongest signal.
    - msla 3y ago
      The FCC is rather prickly about electrical noise in the licensed bands, to the point companies have had to modify designs to not become impromptu transmitters on those frequencies. This is one reason power cords grow those little black cylinders called ferrite beads: https://en.wikipedia.org/wiki/Ferrite_bead https://en.wikipedia.org/wiki/Ferrite_bead So, in theory, a crystal set should still be a good way to pick up conservative talk radio and sports talk and you kinda get the idea it wouldn't be a popular project for kids these days given the current media landscape.
- Aloha 3y ago
  Crystal sets are remarkably sensitive, though early radios were not very selective, which describes most of the issues with the first 20 years of radio.

Pxtl 3y ago

I wonder if he had any relation to Amar Bose of the Bose corporation? Googles Nope.

kpgraham 3y ago

It used to be possible to make a radio receiver out of a diaper pin and a blue razor blade. The coating on the blade acted like a crystal. You needed a cheap pair of headphones or a tiny transistor radio speaker. I made one when I was a kid, and I could clearly pick up 77 ABC in New York City from 50 miles away. Razor blades aren't blue anymore, but there must be other things that work.

Kirby64 3y ago
Fun fact, the blueing that creates that effect is literally just steel blue. You can accomplish the same thing by torching a razor blade until it glows then letting it cool.
userbinator 3y ago
It still is, and I hope it remains that way for future generations too. The first-time experience of hearing "voices from thin air" is unforgettable.
- pfannkuchen 3y ago
  Did you do this before you ever used a full on radio? That seems hard to believe, so I guess you are implying that it is an experience that feels different. I wonder how so?
  - AnthonyMouse 3y ago
    Consumer radios operate by witchcraft. Presumably a fairy from another dimension rides into town on horseback with a satchel full of vinyl and then camps out outside your window so when she sees you switch on the radio she can play the vinyl for you. It feels different when you put it together yourself out of basic components and see that there is no magic in there, and yet... there is.
    - Maken 3y ago
      On a serious note, it concerns me a little how easy new generations accept that everything is a magical black box and not even question how their smartphones work.

29athrowaway 3y ago

The other day I learned that the National Ignition Facility uses actual cat whiskers. https://www.cbsnews.com/news/nuclear-fusion-60-minutes-2023-01-15/ https://www.cbsnews.com/news/nuclear-fusion-60-minutes-2023-... > Michael Stadermann: All the components are brought together under the microscope itself. And then the assembler uses electromechanical stages to put the parts where they're supposed to go-- move them together, and then we apply glue using a hair. > Scott Pelley: A hair? > Michael Stadermann: Yeah. Usually something like an eyelash or is similar, or a cat whisker. > Scott Pelley: You apply glue with a cat whisker? > Michael Stadermann: That's right.

timthorn 3y ago

> They regained prominence in World War II because of their ability to operate at microwave frequencies I'd always understood the WWII relationship with cats whiskers to be due to PoWs making radios from materials that they had access to. Edit: some evidence to suggest my understanding wasn't wrong, if not complete: https://www.bbc.co.uk/ahistoryoftheworld/objects/C5q84AOFTtq8T20c1X5IzQ https://www.bbc.co.uk/ahistoryoftheworld/objects/C5q84AOFTtq...

segfaultbuserr 3y ago
They saw two forms of uses during WW2, both low-tech uses and high-tech uses. Crystal detectors went out of favor soon after vacuum tubes came to prominence, and eventually many researchers almost forgot them entirely due to their outdateness. Later work in microwave electronics made people rediscover their usefulness. Post-war advance in semiconductors made it possible to manufacture small-signal and microwave diodes consistently, finally making them no longer notoriously inconsistent devices. They remain in use for RF/microwave circuit today. Of course, there was also the work by the Indian physicist Jagadish Chandra Bose, an outlier who used crystal detectors to reach millimeter-wave frequency around 60 GHz already in the year 1900 before everyone else. But as far as I can see, his work had limited influence since it was far ahead of his time. In Crystal Fire: The Birth of the Information Age, a definite book on semiconductor history, it described the amazement of this rediscovery: > In the mid-1930s [George] Southworth was trying to detect ultrashort radio waves around a tenth of meter long—what he then dubbed “hyper-frequencies” and are today called microwaves—using specially designed vacuum tubes. But he was having little success. Inherent time lags in the flow of electrons through them were simply too great for the tubes to cope with these extremely short, rapidly oscillating waves. Copper oxide rectifiers didn’t work any better, either. > Frustrated, Southworth decided to try one of the old “cat’s whisker” crystal detectors he had used in radio sets during the Great War, when he served in the Army Signal Corps. These quirky devices had fallen gradually out of favor when vacuum tubes became popular during the 1920s. By the mid-1930s it had become almost impossible to buy one in an ordinary radio store. > So Southworth hopped a train bound for lower Manhattan, where he knew of a secondhand radio market on Cortlandt Alley, near Canal Street. Rummag ing around on the dusty back shelves of one tiny shop, he soon found a few old cat’s-whisker detectors. After bargaining with the shopkeeper, he carried them back to Holmdel, where he dusted them off and carefully inserted one into his receiving apparatus. He began searching around on its surface for a suitable hot spot. Finally, after hunting almost an hour, he found a good one. > And it worked! At last, he could detect his ultrashort-wave, hyper-frequency radiation.

deleted 3y ago

[deleted]

ggandhi 3y ago

They also had memristive properties: https://ieeexplore.ieee.org/document/6518277 https://ieeexplore.ieee.org/document/6518277