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  1. LvW

    Phase Shift Oscillator Op-Amp Neg Feedback

    Noise would play a certain role only if there would be no other "kick-off" sources. However, each oscillator will be powered (switched-on) at a particular time. And it is this switch-on transient which causes the start of the oscillation process. For simulation purposes you can (a) give a...
  2. LvW

    Phase Shift Oscillator Op-Amp Neg Feedback

    LvW said: ↑ (b) Closed-loop gain Acl This is the feed back gain RC Network I beleve this is 33 = Rf/R = 33/1 Is the phase shift -180deg No - that is not correct. As the name indicates: "Closed-loop gain" is the gain of the amplifier with the closed feedback loop. LvW said: ↑ (c) Loop gain...
  3. LvW

    Phase Shift Oscillator Op-Amp Neg Feedback

    Please notice that your oscillator contains an opamp WITH FEEDBACK. Any negative feedback will drastically change the frequency-dependent behaviour of a "naked" opamp. This is the main purpose of negative feedback: Changing (reducing) the gain, increasing the bandwidth and "flattening" the...
  4. LvW

    Phase Shift Oscillator Op-Amp Neg Feedback

    In this case, I think it is important for you to become familiar with the BODE diagram. In the mentioned alternative forum a corresponding link was given to you.
  5. LvW

    Phase Shift Oscillator Op-Amp Neg Feedback

    Some days ago you´ve got - in another forum - 30 replies to the same question. In one of my last answers I did ask you: Do you know how to handle a BODE plot - in particular, how to derive a phase plot from the magnitude plot? Otherwise, you cannot solve your problem (without circuit...
  6. LvW

    Voltage Drop across NPN BJT C&E?

    You are welcome. Answering such questions (and clarifying contradictory "explanations") is the main purpose of this forum.
  7. LvW

    Voltage Drop across NPN BJT C&E?

    Yes. In your example, you have altered the current gain as well as the collector resistor - and you are surprised that Ic and Vce have changed in spite of constant Vbe and Ib ? There was no change of the input condidtion at all - and you think this "test" could be a counterexample against...
  8. LvW

    Voltage Drop across NPN BJT C&E?

    I must admit that I have problems to understand everything in your response. * For VBE and IB constant I can change Ic (a little bit) by changing VCE only. This is due to the well-known Early effect. However, this effect does not touch at all the question if VBE or IB are (mainly) controlling...
  9. LvW

    Voltage Drop across NPN BJT C&E?

    Yes - the underlined sentence is correct, of course, because you have performed the right sequence: It is the classical procedure - starting with Ic and calculate the resulting current Ib. However, this does not imply any controlling function. In contrary!. Furthermore, may I direct your...
  10. LvW

    Voltage Drop across NPN BJT C&E?

    1.) Quotes Horowitz/Hill (Art of Electronics): * We make the impedance of the DC bias source small compared with the load it drives. This is approximately equivalent to saying that the current flowing in the voltage divider should be large compared with the current drawn by the base. * The base...
  11. LvW

    Voltage Drop across NPN BJT C&E?

    ....as large as possible? Are you aware that (a) this contradicts all the common design strategies and (b) such a design degrades the desired feedback effect caused by RE?
  12. LvW

    Voltage Drop across NPN BJT C&E?

    Forgetting the black box model (that has - for my opinion - no meaning in a technical/physical discussion like this) I have one simple question to you: When a newcomer comes to you asking for the difference between a class-A and a class AB (or class-B) amplifier - what would be your...
  13. LvW

    Voltage Drop across NPN BJT C&E?

    Bob - with all respect, this is another phenomenon to me: Some people believe they would use the current-control view in their calculations - but in reality they don`t! They apply voltage feedback (using Re) for creating a voltage VE (caused by the desired current IE) and they design a...
  14. LvW

    Voltage Drop across NPN BJT C&E?

    Yes - to me this is really a phenomenon: About 60 years after the BJT was invented we still can find in textbook and other knowledge sources two fundamentally different descriptions how the BJT works - in spite of the fact that there are several observable effects and circuit properties which...
  15. LvW

    Voltage Drop across NPN BJT C&E?

    This is just a claim - are you able to give any proof or explanation/justification?
  16. LvW

    Voltage Drop across NPN BJT C&E?

    Colin - of course, it is your legal right not to agree with some contributions. However, don`t you think that it would be helpful if you could list all the points of disagreement and explain (justify !) your own view ?
  17. LvW

    Voltage Drop across NPN BJT C&E?

    For my opinion, your explanation is logical and in accordance with your motto (Einsteins rule). It is the changing thickness of the depeletion layer which matters only - and the thickness depends on the bias and the superimposed signal voltage only.
  18. LvW

    op amp

    I think, a phase shift of -180deg is identical to multiplying the voltage with a factor of "-1". From this, you can derive the answer for a pure dc input voltage.
  19. LvW

    Bipolar Junction Transistor Configurations

    Your question cannot be answered without knowing which circuit you are speaking of.
  20. LvW

    Can someone explain me how a BJT works?

    Colin - some month ago (in April 2016) we had a similar discussion in this forum https://www.electronicspoint.com/posts/1690795/ In the course of this discussion I have asked you several technical questions (in response to your claim of BJT current control). Unfortunately, you did not give any...
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