Add Crystal Detector to Diode section of e-book

Discussion in 'Feedback and Suggestions' started by otto9K9otto, Jul 7, 2010.

  1. otto9K9otto

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  2. bertus

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    Hello,

    That is a good suggestion.
    I think the Ebook-developers will have a look at it.

    There are still of those "glass" diodes available.
    The AA119 is an example.
    From a dutch supplier:

    Code ( (Unknown Language)):
    1.  
    2. N.B.
    3. Wij hebben diverse Ma/com HF smd (schottky en pin) in kleine aantallen.
    4.  
    5. 1N5711      =HP5082-2800, lange draden, milspecs                            1.75
    6. 1SS97       Medium barrier, verder als 1SS99, echter nog lagere C           4.90
    7. AA119       =1N60 Germaniumdiode                                            0.45
    8. BA182       zie BA482
    9. BA281       50V Schakeldiode zeer lage capaciteit                           0.23
    10. BA282       HF schak.; we hebben ook 482=483                                0.23
    11.  
    12.  
    BA479S =379 PIN regel/schakeldiode axiaal 0.79



    On this linkpage of the EDUCYPEDIA there are some schematics of crystal radio's:
    http://www.educypedia.be/electronics/radiotuning.htm

    Bertus
     
  3. Wendy

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    If one were written it would probably be in the Special Purpose diodes section. As I understand it a Schottky Diode is somewhat similar to a crystal detector.
     
  4. jpanhalt

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    Don't forget the venerable 1N34A

    John
     
  5. Wendy

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    That is a conventional diode that is made from germanium instead of silicon. I'm not sure about diode detectors and shottky diodes, but I think they are the same basic types. If I can find definite confirmation I'll write up a paragraph.
     
  6. jpanhalt

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  7. Wendy

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    Yep, but that doesn't mean it is the same thing. It just means they are drop in replacements.

    From Wikipedia...

    http://en.wikipedia.org/wiki/Schottky_diode

    If you read up on cat's whisker diodes they used iron pyrite, not germanium.

    Another proof.

    https://secure.wikimedia.org/wikipedia/en/wiki/Cat's-whisker_detector

    I'd be interested in how they used Gillette razor blades when our Dad's were kids. It was a common thing for crystal radios of that era.
     
    Last edited: Jul 7, 2010
  8. bertus

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  9. Wendy

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    Interesting. I thing some of the voltages are approximations, because I've seen lower voltages listed for Schottky diodes. For that matter I've seen a large variation on silicon, for low current applications I typically use 0.6V drop, but it goes up fast.

    Another source...

    http://www.teamnovak.com/tech_info/more_info/schottky.htm

     
  10. bertus

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  11. Wendy

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    OK, how about this tacked on to the Schottky Diode section.

    There is an earlier version of the Schottky Diode, it was basically the first solid state RF diode rectifier, and that was the cat's-whisker detector or crystal detector. Basically a thin wire was moved across the surface of a crystal of raw semiconducting material until a location that acted like the diode was found. This was used during the earliest days of radio in crystal radios (hence the name) until more manufacturing friendly techniques and other devices were developed and discovered. Later hobbyist incarnations uses a Gillette razor, which had a silicon coating during the 1930 through 1950's.

    To Dennis Crunkleton, please credit this to otto9K9otto if accepted.
     
    Last edited: Jul 7, 2010
  12. beenthere

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  13. Wendy

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    So do you see anything that is a reach or flat wrong in my writeup?
     
  14. jpanhalt

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    That bizarrelabs is a great link. I had a cousin who was a POW. He didn't talk about it much.

    Anyway, back OT: "Later hobbyist incarnations uses a Gillette razor, which had a silicon coating during the 1930 through 1950's."

    That is apparently true, but I cannot confirm the dates it was used. According to the patent literature, some were coated with silicon, and some apparently had silicone. The link from beenthere suggests that almost any metallic oxide will work, e.g., the old double-edged, blued blades and rusty blades will work. Even copper that has been heated to form a copper oxide coating will work. You might consider adding another sentence to expand on the variations. Here is an unpolished suggestion for such a sentence:

    "Other variations, some were used by POW's (add link), relied on metal oxides such as the surface of blued steel, rusty steel, or the copper oxide formed on a heated copper wire for the diode."

    John
     
  15. Wendy

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    I'm not to sure of those dates either, think I ought to remove them?

    I'm going to google around a bit to see if I can pin them down.

    I like the addition.

    ************************

    OK, lets try it again. When we get it right I'll email Dennis for review.

    There is an earlier version of the Schottky Diode, it was basically the first solid state RF diode rectifier, and that was the cat's-whisker detector or crystal detector. Basically a thin wire was moved across the surface of a crystal of raw semiconducting material until a location that acted like the diode was found. This was used during the earliest days of radio using crystals (hence the name) until more manufacturing friendly techniques and other devices were developed and discovered. Later hobbyist incarnations uses a razor, which is often referred to as a foxhole radio (so named because AM radios were banned in many places during WWII). Powered radios using local oscillators could be detected and traced (and were) during this era, crystal radios did not have this problem. Early razors had a silicon coating, but it is not critical as they are still being made by hobbyists today. Other variations, some were used by POW's from WWII on (http://bizarrelabs.com/foxhole.htm), relied on metal oxides such as the surface of blued steel, rusty steel, or the copper oxide formed on a heated copper wire for the diode. POW's were especially ingenious in creating components from the most unlikely of materials, and the diodes were absolutely critical to receive radio.

    To Dennis Crunkleton, please credit this to otto9K9otto if accepted.
     
    Last edited: Jul 8, 2010
  16. jpanhalt

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    Looks good to me. History never loses its relevance. John
     
  17. bertus

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    Hello,

    You could also make an article in the experiments book to show how radio is working.

    Bertus
     
  18. Wendy

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    I spend a lot of time making experiments (usually several weeks), I spent maybe slightly over a day on this. I've got too many irons in the fire at the moment, and simple crystal radios are a constant and common as far as kits go.

    I think I'll have to pass on this one. :)

    When I was a teen with no training what so ever I made the entire series of oscillators (colpitts, armstrong, crystal,etc.) using coils made from toilet role tubes, single transistors, and other parts, most home made. I also made a huge numbers of receivers of various types. This was the time one of my Dad's favorite expressions to me was "Turn it off". It usually cleared the TV interference, so he wasn't far off.
     
  19. Dcrunkilton

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  20. Wendy

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    Excellent. I think a total rewrite is in order though, basically scrap some of what we've done, add a reference to the Schottky to the crystal detector section, along with a rewrite of the history where appropriate (if appropriate).

    The book still surprises, in a good way. Thanks Dennis.
     
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