Transistor symbol "non-pointing" and "pointing" end

Discussion in 'General Electronics Chat' started by jlscott, Sep 7, 2011.

  1. jlscott

    Thread Starter New Member

    Aug 31, 2011
    2
    0
    Re: EBook Vol.III, Semiconductors, Bipolar Junction Transistor, Meter check of a transistor

    First paragraph: "On the symbol, the N-type material corresponds to the “non-pointing” end of the base-emitter junction, the base. The P-type emitter corresponds to “pointing” end of the base-emitter junction the emitter."

    What is this saying exactly? Is it saying that the the P-type emitter is the pointer and the N-type base is the pointee?

    Is this the same thing as saying that the arrow points to the N-type material of the base-emitter junction?
     
  2. Robin Mitchell

    Well-Known Member

    Oct 25, 2009
    732
    199
    Yes i would say, effectively, that it points to the n type material. PNP, arrow points in, which points to the n type base. NPN, points outward to the "sides" of the transistor which indicated where the N type.

    In fact i would say that it points to the mostly doped n type area
     
    jlscott likes this.
  3. tom66

    Senior Member

    May 9, 2009
    2,613
    213
    NPN = Not Pointing iN
    PNP = Pointing iN Proudly
     
  4. Robin Mitchell

    Well-Known Member

    Oct 25, 2009
    732
    199
    Love that :D
     
  5. iONic

    AAC Fanatic!

    Nov 16, 2007
    1,420
    68
    Nice and catchy, like "If the glove don't fit, you must acquit!" (OJ Simpson Trial)
     
  6. jlscott

    Thread Starter New Member

    Aug 31, 2011
    2
    0
    Thanks for your response. However, I do have the same problem with your mnemonic as with "pointer" (subject) and that which is point at (object).

    When first I read "On the symbol, the N-type material corresponds to the “non-pointing” end of the base-emitter junction, the base. The P-type emitter corresponds to “pointing” end of the base-emitter junction the emitter," my interpretation of the meaning was opposite my understanding that the arrow points to N-type material of the emitter-base junction thus avoiding the total insanity of "conventional current."

    It wasn't until I was composing my post that I was able to unravel the unusual grammatical structure of this passage with a possible interpretation consistent with my understanding.

    However, your mnemonic plus the to-me puzzling ebook passage leads me to believe that there is some other way of looking at this pointing process where there is an actor and that which is acted upon. Could you and/or the others who seem to appreciate the mnemonic, please share this perspective?
     
  7. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,669
    804
    I would say it shows the direction of the base current. Not sure however what it means on mosfet transistors.

    OK wiki in the mosfet article says the arrow points from P to N.
     
  8. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    The arrow points to the negative side, this is how I've always thought of it. If the arrow points to the positive side, then the junction is back biased and will not conduct, or as with a zener diode conduct in a specialized way.
     
  9. tom66

    Senior Member

    May 9, 2009
    2,613
    213
    BJTs can conduct in reverse (called reverse active), and that is controllable, but the gain is usually smaller and the breakdown voltage is often lower.
     
  10. Robin Mitchell

    Well-Known Member

    Oct 25, 2009
    732
    199
    i still like my idea ¬_¬

    "points to the most doped n type"
     
Loading...