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Transistor markings

Discussion in 'General Electronics Discussion' started by ALFRED, Dec 2, 2015.

  1. ALFRED

    ALFRED

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    Jul 1, 2010
    hi all. Working on vintage dynavox phono, with stereo amp. The 2n2429 & 2n2431 transistors have red dots...does this indicate base,collector, or emitter? Thanks Al
     
  2. Martaine2005

    Martaine2005

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    May 12, 2015
    [​IMG] Farb = colour. So I would guess 'collector'? I am probably way off though. Sorry.

    Martin
     
  3. ALFRED

    ALFRED

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    Jul 1, 2010
    Here are some pics. I don't have schematic
     

    Attached Files:

  4. ALFRED

    ALFRED

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    Jul 1, 2010
    Thanks Martin. It makes sense!
     
  5. davenn

    davenn Moderator

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    Sep 5, 2009
    I

    I had a feeling it was always the emitter that was the one marked
     
  6. Martaine2005

    Martaine2005

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    May 12, 2015
    I did say I could be wrong Dave!:)
     
  7. davenn

    davenn Moderator

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    Just trying to remember back to my 1970's electronics work and all those old transistors
    till more years ago than I care to remember ;)
    pretty sure its the emitter that's marked :)


    D
     
  8. Martaine2005

    Martaine2005

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    May 12, 2015
    I am reading this now (cheers Dave:eek:) I normally only read on Sundays!!.

    What a great read it is though...
    Seems that they were coloured for hearing aid use first? The whole thing, not dots.
    Ya know Dave, I just thought.... Can you edit out every word 'transistor' from this thread?
    If not, you know what will happen..:D

    Martin
     
  9. Martaine2005

    Martaine2005

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    Just found something else which may be useful..

    "Other than the usual red dot to denote the collector lead". Found 3/4 down page here.
    Getting closer!!

    Martin
     
    davenn likes this.
  10. davenn

    davenn Moderator

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    gosh seeing the old devices on that page brought back many memories
    thanks for the find :)
     
    Martaine2005 likes this.
  11. Martaine2005

    Martaine2005

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    Haha, Dave, It's my first time seeing them! Ouch!!:p

    Martin
     
  12. davenn

    davenn Moderator

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    what age range are u in, Martin ?
     
  13. Martaine2005

    Martaine2005

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    That's a difficult question to answer!
    If you ask my family.....About 12!
    If you look at my birth certificate it says 48! (Nov) just gone..

    I believe my family:D
     
    davenn likes this.
  14. davenn

    davenn Moderator

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    hahahaha

    well ya know the ol saying ... " act your age and not your shoe size !! " hahaha

    but then there's rarely any fun acting my age ;)
    I turned 56 last july


    D
     
    Martaine2005 likes this.
  15. duke37

    duke37

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    The first transistors I used were red spot (audio) and white spot (a bit faster). These were surplus transistors which did not fully comply with the spec. The spot was by the collector and they were emitter/base/collector.
     
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  16. Martaine2005

    Martaine2005

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    So... Trevor.....
    Was the spot defining a leg? or just a spot?

    Martin
     
  17. duke37

    duke37

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    Jan 9, 2011
    I don't have spots on a leg, just on my body.:)
     
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  18. Martaine2005

    Martaine2005

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    @davenn had big rashes on his legs a few months back!
    Is he the Collector or Emitter?:eek:

    Martin
     
  19. davenn

    davenn Moderator

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    :p:p:p:p:p
     
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  20. Martaine2005

    Martaine2005

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    Sorry Dave, as you can see, just acting my age!!:D
     
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