Why is ground connected to pnp transistor?

Discussion in 'General Electronics Chat' started by leoss, Feb 14, 2012.

  1. leoss

    Thread Starter New Member

    Jan 17, 2012
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  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    Please post the schematic you are referring to.
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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    Transistors have a base, a collector, and an emitter.
    You need to refer to the terminals as such, or we won't know what you are talking about.
    Here is a datasheet that contains a PZTA42:
    http://www.fairchildsemi.com/ds/MP/MPSA42.pdf
    The tab and the center pin are the collector.
     
  4. crutschow

    Expert

    Mar 14, 2008
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    In a common-emitter connection the emitter is tied to AC common, the base is the input, and the collector is the output. For a PNP the base and collector voltages must be more negative than the emitter.

    If you only have a plus supply then you can use the PNP as a high-side switch by connecting the emitter to V+ and connecting the base (through a resistor) to ground to turn the transistor on.
     
  5. leoss

    Thread Starter New Member

    Jan 17, 2012
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    I have not the schematic at home, I just remember this picture.
    Mark of this transistor is U1.
     
  6. Ctenom

    Member

    Nov 1, 2010
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    This how it should be connected in circuit
     
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  7. GetDeviceInfo

    Senior Member

    Jun 7, 2009
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    'U1' would not be a typical transistor denominator. Your likely looking at a regulator, but who knows with the zero info provided.
     
  8. leoss

    Thread Starter New Member

    Jan 17, 2012
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    Sorry, I have not any other information, this is all I know.
    And Input is 4,6V and Output is 3,3V.
     
  9. ricoseeds

    New Member

    Feb 16, 2012
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    for replenishment of free electrons
     
  10. Audioguru

    New Member

    Dec 20, 2007
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    You show a BOX, not a transistor.
    A transistor has a base, emitter and collector but your box has none of them.
    You also do not show the circuit the transistor is used in.
     
  11. leoss

    Thread Starter New Member

    Jan 17, 2012
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    This box is in the shematic. And I showed even the picture of this transistor.
     
  12. Audioguru

    New Member

    Dec 20, 2007
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    The transistor is NPN, not PNP.
     
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