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2N3904

Discussion in 'General Electronics' started by pcf, Oct 13, 2003.

  1. pcf

    pcf Guest

    Hi I am a beginner in electronics stuffs (inparticular, transistor)

    I would like to know whats the "threshold" of VCE when the NPN works
    from stauration to linear region.

    The Ic I am using is ~50mA at most. I believe the threshod of VCE is
    ~0.3V

    Am I right?

    pls reply to my email as well

    Thanks !

    PCF
     
  2. Robert Baer

    Robert Baer Guest

    A transistor is still active and fully operational at zero volts
    collector to base, and partly active even with small forward biasing.
    One needs toforward bias the collector-base region sufficently to then
    "flip" the operation to inverted mode where the collector acts as an
    emitter and vice-versa.
    Such operation has been used to achieve lower than "normal" on voltage
    drops, especially in signal choppers.
    Most transistors have a very crummy beta in the inverted mode, and can
    run from 1E-3 to a high of 0.10 .
    However, there are some high forward beta transistors that also have
    inverted betas that exceed one and may get as high as 50 (!!), made by
    Zetex; the ZTX696B is an NPN with beta (min) of 500, and the ZTX718 is a
    PNP with beta (min) of 300. As i remember, their reverse beta is rather
    spetacular when compared with ordinary transistors.
     
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