How to tell base and emitter apart on a NPN 2N3055 transistor

Discussion in 'Electronic Basics' started by jc, Mar 31, 2006.

  1. jc

    jc Guest

    I've got an NPN transistor 2N3055. How do I tell the base and the
    emitter pins apart? They both look the same and this transistor is
    symetrical.
    jc, Mar 31, 2006
    #1
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  2. jc

    Phil Allison Guest

    "jc" <>
    >
    > I've got an NPN transistor 2N3055. How do I tell the base and the
    > emitter pins apart? They both look the same and this transistor is
    > symetrical.
    >



    ** A symmetrical 2N3055 is quite a find.

    Care to post a pic on ABSE ?




    ........ Phil
    Phil Allison, Mar 31, 2006
    #2
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  3. jc

    jc Guest

    I can certainly post a pic, what's abse?
    jc, Mar 31, 2006
    #3
  4. jc

    Phil Allison Guest

    "jc" <> wrote in message
    news:...
    >
    >I can certainly post a pic, what's abse?




    ** A real usenet group called: " alt.binaries.schematics.electronic "

    Not accessible to googlegroups users.

    Do yourself a favour an get a REAL newsreader and an ISP that supplies
    access.

    We are all just dying to see that symmetrical 2N3055 you say you have ......





    .......... Phil
    Phil Allison, Mar 31, 2006
    #4
  5. jc

    Jeremy Guest

    Ok, I've posted pics. same subject as this thread.

    "Phil Allison" <> wrote in message
    news:...
    >
    > "jc" <> wrote in message
    > news:...
    > >
    > >I can certainly post a pic, what's abse?

    >
    >
    >
    > ** A real usenet group called: " alt.binaries.schematics.electronic "
    >
    > Not accessible to googlegroups users.
    >
    > Do yourself a favour an get a REAL newsreader and an ISP that supplies
    > access.
    >
    > We are all just dying to see that symmetrical 2N3055 you say you have

    .......
    >
    >
    >
    >
    >
    > ......... Phil
    >
    >
    Jeremy, Mar 31, 2006
    #5
  6. jc

    Phil Allison Guest

    "Jeremy"
    > Ok, I've posted pics. same subject as this thread.



    ** Please DO NOT TO POST !!!


    >>> "jc"
    >> >
    >> >I can certainly post a pic, what's abse?

    >>

    >
    >> ** A real usenet group called: " alt.binaries.schematics.electronic "
    >>
    >> Not accessible to googlegroups users.
    >>
    >> Do yourself a favour an get a REAL newsreader and an ISP that supplies
    >> access.
    >>
    >> We are all just dying to see that symmetrical 2N3055 you say you have

    > ......
    >
    > Ok, I've posted pics. same subject as this thread.




    ** Excellent work.

    Shame the 2N3055 device is NOT symmetrical !!

    In the top pic, the leads are clearly closer to the bottom of the package.

    Same as all TO3 packages ever made.

    The right hand side one is the base pin.




    ........ Phil
    Phil Allison, Mar 31, 2006
    #6
  7. jc

    John Larkin Guest

    On 30 Mar 2006 17:08:53 -0800, "jc" <> wrote:

    >I've got an NPN transistor 2N3055. How do I tell the base and the
    >emitter pins apart? They both look the same and this transistor is
    >symetrical.


    Google a datasheet.

    Or use an ohmmeter; the base acts like the anode of a diode, with
    either the emitter or the collector behaving like its cathode.

    John
    John Larkin, Mar 31, 2006
    #7
  8. jc

    Tim Williams Guest

    It's symmetrical in one plane, but none others. If you take a second look
    you'll notice the pins are off center between the mounting holes. Hold the
    transistor so the pins are facing you, the mounting holes are vertical, and
    the pins are above the middle. The left pin is base and right is emitter.

    See also data sheet.

    Tim

    --
    Deep Fryer: a very philosophical monk.
    Website: http://webpages.charter.net/dawill/tmoranwms

    "jc" <> wrote in message
    news:...
    > I've got an NPN transistor 2N3055. How do I tell the base and the
    > emitter pins apart? They both look the same and this transistor is
    > symetrical.
    >
    Tim Williams, Mar 31, 2006
    #8
  9. "jc" <> wrote in message
    news:...
    > I've got an NPN transistor 2N3055. How do I tell the base and the
    > emitter pins apart? They both look the same and this transistor is
    > symetrical.
    >

    Any to3 transistor - if you hold it with pins facing you and pins closer to
    top, then left side pin is base and right hand is emiter. Usually :)
    James Thompson, Mar 31, 2006
    #9
  10. jc

    Sambo Guest

    James Thompson wrote:

    > "jc" <> wrote in message
    > news:...
    >
    >>I've got an NPN transistor 2N3055. How do I tell the base and the
    >>emitter pins apart? They both look the same and this transistor is
    >>symetrical.
    >>

    >
    > Any to3 transistor - if you hold it with pins facing you and pins closer to
    > top, then left side pin is base and right hand is emiter. Usually :)
    >
    >

    THAT IS REALY WRONG!!! Never keep the pins up , if it slips out you lose your eye, hehe.
    Pins at the bottom reading left to right, smallest to largest terminals you have E B C
    ( base in the middle.)

    Cheers
    Sambo, Mar 31, 2006
    #10
  11. Sambo wrote:

    > Pins at the bottom reading left to right, smallest to largest terminals
    > you have E B C ( base in the middle.)


    Not for TO-3, which this thread was about.


    --
    Sincerely, | http://bos.hack.org/cv/
    Rikard Bosnjakovic | Code chef - will cook for food
    ------------------------------------------------------------------------
    Rikard Bosnjakovic, May 18, 2006
    #11
  12. Re: Re: How to tell base and emitter apart on a NPN 2N3055 transistor

    On Thu, 18 May 2006 05:45:09 GMT, Rikard Bosnjakovic <>
    wrote:

    >Sambo wrote:
    >
    >> Pins at the bottom reading left to right, smallest to largest terminals
    >> you have E B C ( base in the middle.)

    >
    >Not for TO-3, which this thread was about.


    Pinouts for a TO-3 should be readily available but a rule of thumb for 'all
    transistors' is that transistors test as 2 diodes back to back with the base as
    common. You will find the forward voltage drop will be 'slightly' lower on the
    base/emitter junction (in the order of about 0.01v).

    Caviet:- some power transistors, in particular scan transistors will also have
    a diode from collector to emitter typically cathode to collector.

    --

    Australia isn't "down under", it's "off to one side"!


    www.cobracat.com (home of the Australian Cobra Catamaran)
    http://groups.yahoo.com/group/cobra-cat/
    Stan Blazejewski, May 18, 2006
    #12
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