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  1. LvW

    Transistors / hfe / Active region conflicts

    I cannot resist to reply to this (false) statement again. Didn`t you read my earlier posts - disproving this claim? Did you ever hear about the commonly used method to use a voltage divider for biasing the BJT with a VOLTAGE? And this applies to all three basic configurations - common emitter...
  2. LvW

    Transistors / hfe / Active region conflicts

    This statement was commented already in post#45: https://www.electronicspoint.com/threads/transistors-hfe-active-region-conflicts.275168/page-3#post-1661658
  3. LvW

    Transistors / hfe / Active region conflicts

    Every thing was answered already: https://www.electronicspoint.com/threads/transistors-hfe-active-region-conflicts.275168/page-3#post-1661658 https://www.electronicspoint.com/threads/transistors-hfe-active-region-conflicts.275168/page-3#post-1661733...
  4. LvW

    Transistors / hfe / Active region conflicts

    It remains your secret how you can explain this contradiction to somebody else. (If you make people think they're thinking, they'll love you. But if you really make them think, they'll hate you - Don Marquis)
  5. LvW

    Transistors / hfe / Active region conflicts

    Laplace - I can assure you that I don`t have any "problems" regarding BJT working principles. But do you remember that in one of your former posts you wrote: "Also note that while the BJT operates as a transconductance device (collector current controlled by base voltage),...." And now you...
  6. LvW

    Transistors / hfe / Active region conflicts

    I wrote: I am really surprised how you can come to the conclusion (post#49) that "we never apply a voltage directly to the base of a transistor; we apply a bias current". Your answer: You are correct. That should have said, "we never apply a voltage directly to the base-emitter junction of a...
  7. LvW

    Transistors / hfe / Active region conflicts

    Laplace - with all respect, I hope you know that this is not a "serious" counter argument. We speak about principles of operation - and you are answering with a design strategy that is applied with the aim to cope with non-idealities (tolerances, temp. influence). On the other hand, your answer...
  8. LvW

    Relationship of frequency and capacitance.

    It seems that you are mixing "large frequencies" with "large signals". This must be clarified. Furthermore, if the text speaks about "adjusting the frequency" I think that the subject of discussion is a frequency-dependent network (filter, oscillator,....)
  9. LvW

    Transistors / hfe / Active region conflicts

    Do we really? In contrast, I am sure, most common-emitter stages rely on applying "a voltage directly to the base of a transistor" with the help of a low-resistive voltage divider. I am aware that this is not an "ideal" voltage source because of known other constraints (signal input resistance)...
  10. LvW

    Transistors / hfe / Active region conflicts

    ...and what about the large tolerances of B=IC/IB ? I think, because of this uncertainty, most common-emitter stages are designed with a voltage divider instead of "current injection" using only one large resistor RB. More than that, I think, the linearity is not a problem at all. If we would...
  11. LvW

    Transistors / hfe / Active region conflicts

    Currrent always is "forced" by a voltage (resp. by a corresponding E-field). It is a common misconception that the voltage-current pair would be something like a chicken-egg problem.
  12. LvW

    Transistors / hfe / Active region conflicts

    I think, for a fair and fruitful discussion we shouldn`t mix theoretical/physical aspects with practical and application oriented aspects. Unfortunately, without measuring the device we do not know the exact VBE value - but surely we would appreciate such a knowledge. For this reason, we only...
  13. LvW

    Transistors / hfe / Active region conflicts

    "Many errors, of a truth, consist merely in the application of the wrong names of things." - Spinoza I think, our discussion has reached a point where two terms need some more clarification - otherwise, misunderstandings cannot be avoided. 1.) What means "control"? I think, we have two...
  14. LvW

    Transistors / hfe / Active region conflicts

    Sorry - but that`s not clear to me: Which current are you speaking of (Ib or Ic)? Vbe does not control....? So you think that it is NOT the Vbe value at the bias point that is of interest? Did you forget that the this Vbe value determines the quiescent dc current Ic and - hence - the slope of...
  15. LvW

    Transistors / hfe / Active region conflicts

    Laplace - I see a kind of contradiction between your post'#33 (...nonsense that Vbe controls the base current when the base is driven by a current source) and your post#18 (So there is the full story: base current controls Vbe, and Vbe controls collector current.) Please, can you clarify? In my...
  16. LvW

    Transistors / hfe / Active region conflicts

    Instead of "irrelevant" I would prefer "less important". OK?
  17. LvW

    Transistors / hfe / Active region conflicts

    OK - agreed. It was not clear to me that you comment was restricted to that what we call "current injection". Indeed, in this case - and if the supply voltage Vcc is much larger than VBE (at least 12 V or so) - the choice VBE=0.6V or VBE=0.7V is not too important for calculating the resistor...
  18. LvW

    Transistors / hfe / Active region conflicts

    Even during the design of BJT stages the (assumed) voltage VBE plays an important role. Everybody who ever has designed a common emitter stage (without feedback - just to identify the critical steps) with a biasing voltage divider knows about the influence of VBE during calculation of the...
  19. LvW

    Transistors / hfe / Active region conflicts

    Hi Laplace - with all respect, a simple experiment (hardware or simulation) can show that this assertion is false!
  20. LvW

    Question: DC analysis of a transistor amplifier?

    Yes - it is an interesting circuit - sometimes called "current starving" circuit. The value of Ic1 sounds reasonable. However, it does NOT go entirely through R1. In contrary, the majority of Ic1 is identical to the base current Ib2 of the pnp (Q2). Hence, continue the calculation with...
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