what is that diode used for

Discussion in 'General Electronics Chat' started by luciforlove, Oct 19, 2012.

  1. luciforlove

    Thread Starter New Member

    Sep 11, 2012
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    hi,all!
    the diode(D1) between the second BJT'b and e,what it use for,it does influence dc and signal amplification during simulation.
    thank you
     
    Last edited by a moderator: Oct 19, 2012
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    U know u should really learn to tell more abt ur circuit before asking questions.

    Secondly here we have Grand Pa's :D mostly. So I think u should put a clear screen shot. Even I can't make out beside the symbols.
     
    Last edited: Oct 19, 2012
  3. crutschow

    Expert

    Mar 14, 2008
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    That's a real Rube Goldberg of a circuit. :rolleyes: If you tell us what it is supposed to do (and what those squares represent) we might be able to help.
     
  4. Wendy

    Moderator

    Mar 24, 2008
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    I am afraid I have to agree, the schematic is missing too much information to be of much use. I move it to local after waiting almost a minute to upload (I have fiber optic). Did you draw this yourself, or where did you get it?
     
  5. PackratKing

    Well-Known Member

    Jul 13, 2008
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  6. Audioguru

    New Member

    Dec 20, 2007
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    The schematic is fuzzy because it was saved and posted as a fuzzy JPG file type instead of as a very clear PNG file type.
    Its parts are spread out too much which makes them small.
    Also the schematic is covered with chicken pox dots and tiny text all over it.
    The grey background should be white.
     
  7. ramancini8

    Member

    Jul 18, 2012
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    Usually, this diode protects the base-emitter junction from reverse breakdown. If you don't know why the components are on the schematic you shouldn't be on a simulator; that is like letting a chimp drive your car.
     
  8. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Diodes can be used for several purposes:
    You can use them to rectify signals.
    You can use them to isolate signals.
    You can use them to switch signals.
    You can use them to attenuate signals.

    In the circuit given it is not clear how the diodes are used.

    Bertus
     
  9. Audioguru

    New Member

    Dec 20, 2007
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    Hee, hee.
    A chimp does drive my car. ME!
     
  10. BillB3857

    Senior Member

    Feb 28, 2009
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    Possibly to prevent more than .7V Negative voltage from going into the 2nd box, (whatever that is)
     
  11. takao21203

    Distinguished Member

    Apr 28, 2012
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    It is really too much demanded trying to understand what this schematic is about. It is too small, nothing can be read properly. And what is it actually? Confused.

    Diodes are used from many things: dropping voltage, creating a bias, lock out reverse voltage, rectifying...or in a radio perhaps if you fancy.
     
  12. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    If those little squares represent BJTs (which you implied), why do they have 4 terminals?
     
  13. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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  14. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Cool list, what else can we add?

    You can use them to clamp signals.
    You can use them as a constant current source.
    You can use them as a variable capacitor.

    This is fun!
     
  15. MrChips

    Moderator

    Oct 2, 2009
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    You can use them to log signals.
    You can use them to fuzz signals.
    You can use them to or signals.
     
  16. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    RF transitors as I recall have four terminals because of reasons unknown to me, and the values look like this operates at some high frequency, so my gues is some HF amplifier.
    Also I hazard to guess that the left pin is base, bottom and top are emmiter(s) and right pin is collector.
     
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