Cat's Whisker, is this where the semiconductor was launched?

Discussion in 'General Electronics Chat' started by VoodooMojo, Feb 10, 2010.

  1. VoodooMojo

    Thread Starter Active Member

    Nov 28, 2009
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    http://en.wikipedia.org/wiki/Cat's-whisker_detector

    Does anyone have any experiences with the Cat's Whiskers that can be shared?

    Was this the true beginning to the semiconductor-age?
    It is certainly not as celebrated as the 1947 development of Bardeen, Brittan, and Shockley.

    I have always taught that "the semiconductor diode was the single most important technological development in the history of mankind."
    and
    "the transistor was the single most revolutionary technological development in the history of mankind."

    just one man's opinions of course.

    I remember my father always scratching around on his to get the farm report. He refused to use the new fangled radio we had...


    http://semiconductormuseum.com/Museum_Index.htm
     
  2. KL7AJ

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    Nov 4, 2008
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    Certainly!

    When I was a youth, eveyone was building crystal radios. The Galena crystal with a steel whisker was the standard method. Alternatives were the Gillette blue blade rasor and a piece of pencil lead.
    (You can still get mounted galena crystals from www.midnightscience.com )

    The cat's whisker was so sensitive because, unbeknownst to its early users, it is a HOT CARRIER DIODE!...basically NO forward voltage drop.

    No question it was the first solid state device!


    Eric
     
  3. beenthere

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    Described to me by my father as a foxhole radio detector.
     
  4. KL7AJ

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    And alas....Blue Blades are no longer made. :(
     
  5. Wendy

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    But Shottky Diodes are, which are pretty much the same thing.

    I read an article a long time ago that stated if you hunted on a natural germanium crystal it was possible to find two points that would be a transistor, though with low gain and really poor performance. I'm not sure I believe it, but it was a nice concept.
     
  6. mik3

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    Why did blue blades make the job and not other blades?
     
  7. beenthere

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    The oxide coating to partially rustproof the blade worked the magic. It was easier for electrons to pass in one direction than the other. The blue coloration of the razor blades might be related to the oxide coating applied to weapons to give them some rust resistance.
     
  8. JDT

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    Semiconductors research was going on long before this.

    You may be interested to know, for example, that the LED was discovered in the mid 1920's by Oleg Vladimirovich Losev who:

    "observed light emission from zinc oxide and silicon carbide crystal rectifier diodes used in radio receivers when a current was passed through them"

    This is from a article in Nature Photonics April 2007 that published a copy of the Losev's original paper.

    OK, that's your interesting fact for today!
     
  9. VoodooMojo

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    Nov 28, 2009
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    That is what prompted me to ask about what might be the beginning of the semiconductor-age.
    The wiki link I posted stated that all this point contact stuff started before the vacuum tube. So, contrary to popular belief, the semiconductor preceded the tube?
    http://en.wikipedia.org/wiki/Cat's-whisker_detector

    My father always preached that Fleming and the like slowed us down technologically by steering the attention away from semiconductor development.
    http://en.wikipedia.org/wiki/Fleming_valve

    It wasn't until the space ship landed in New Mexico and the aliens needed to get back home. They took the sand and mixed it with aluminum from their spaceship and phosphorus they found at Carlsbad Caverns and made semiconductor diodes and transistors so they could repair the electronics onboard their ship. But they got caught and were interrogated and divulged the information to Bell Laboratories.
    The preceding is not my belief, just mumbo-jumbo that makes for good bar-room banter. Although it is an interesting and entertaining concept.

    History

    The "point rectifier effect", as it was then called, was discovered by Ferdinand Braun, a German physicist and radio pioneer, in 1874 at the University of Würzburg. Based on this work G.W. Pickard developed the cat's whisker diode using a silicon crystal, which was patented in 1906. However, Bengali scientist Jagadish Chandra Bose may have been the first to use a semiconductor to rectify radio waves, applying for a patent on a galena detector in 1901.


    Unamplified radio receivers, most of which were crystal radios, were the only way to receive radio signals during most of the wireless telegraphy era, which ended around 1920. Mineral detectors were largely superseded by vacuum tubes, invented in 1906, although the expense of tube receivers meant that full replacement took several decades. By the 1920s crystal radios were relegated to use by hobbyists and youth groups.


    The point-contact Si detector was subsequently resurrected around World War II because of the military requirement for microwave radar. Vacuum tube detectors do not work at microwave frequencies. Even the semiconductor p-n junction detectors may not be fast enough compared to semiconductor point contact detectors because of minority carrier storage problem, and large capacitance if the area is not small enough.
     
    Last edited: Feb 11, 2010
  10. KL7AJ

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    It's prpbably fair to say that tha vacuum tubes advanced faster than solid state devices because their operation was better understood. Electrons drifting through an enpty bottle is pretty straightforward and intuitive, whereas holes and lattices and energy states were still pretty exotic concepts even in the 1950s. People got predictable results with vacuum tubes, and pretty good performance could be had with some pretty crude manufacturing tolerances. Not so with solid state, of course!

    Or to put it succinctly....the squeaky wheel gets the grease. :) Tubes just squeaked louder earlier in the game.

    Eric
     
  11. Wendy

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    For some applications tubes are still king. If you need high power RF that isn't too high in the band tubes just plain work better.

    I suspect when they have a lunar output there will be the mother of all tubes sitting out in the open, doing its thing.
     
  12. VoodooMojo

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    Here's the picture I get of the lunar megatube :)
     
  13. Wendy

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    Remove the glass envelop, it is not needed. Possibly use a solar array using sunlight to heat the cathode, it doesn't have to be electricity. You then have something that puts any FET or MOSFET to shame.
     
    Last edited: Feb 17, 2010
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