Transistor

Discussion in 'General Electronics Chat' started by mazzi, Apr 8, 2012.

  1. mazzi

    Thread Starter New Member

    Dec 29, 2011
    3
    0
    Hello
    how can I calculate the drain current for transistor T1 and the base current for transistor T2 in the attached circuit. Given the following data

    R1 = 102
    R2 = 8
    E = 15V
    Vin = 12.3V
    VBE = 0.6V
    hFE = 12
    Vt = 3.5V
    S = 0.05A/v
    Id = ?
    Ib = ?
     
  2. panic mode

    Senior Member

    Oct 10, 2011
    1,320
    304
    using circuit analysis methods you have already learned (KVL, KCL, Ohms law, transistor models and modes of operation...)

    Ve=Ie*R2 // Ohms Law
    Vb=VBE+Ve // KVL
    Id=Is=Ib+ Vb/R1 // KCL
    Ie=(hFE+1)*Ib // BJT
    etc.
     
  3. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    What is the value of R1? 102 ohms or 1k ohms? Sometimes a 1k Oriental resistor is marked 102.

    Why did you list the Vt threshold voltage for the Mosfet which is when its current is only 0.25mA and it is almost turned off? Instead we need to know the gate-source voltage when it is turned on which might be 10V. Then the input needs to be +25V for the output to be at about +14V.
     
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