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  1. LvW

    How a BJT Transistor works (base current version)

    "Show me how voltage drop controls current. Show me." Just to avoid misunderstandings (voltage "drop") - while speaking about "voltage control" I am always referring to an externally applied voltage (in this case Vbe). I do not intend to list my examples again (see post 17, 22, 24, 33 and, in...
  2. LvW

    How a BJT Transistor works (base current version)

    Claude - without going again into details I like to answer as follows: Before presenting new circuits or alternative explanations it is established and legitimate practice to show why present theories are not sufficient (or even not able) for explaining some observed phenomena. I think...
  3. LvW

    How a BJT Transistor works (base current version)

    Claude - save your time. I do not need new simulations from your side. However, to convince yourself you should repeat the simulation I have mentioned (see first part of my recent answer under "EDIT"). It clearly shows what happens when Vbe is changed and when Vce comes into play. I do not know...
  4. LvW

    How a BJT Transistor works (base current version)

    Hi Claude, I will try to respond to your reply as follows (your statements in italics):: "The ie current is the starting point where all begins. An increase in ie can only result in a likewise increase in ic as well as vbe. No way to skirt that. The ie is what absolutely determines ic." How...
  5. LvW

    Different answer using inverting op-amp and KCL?

    The calculation for V_a is correct: V_a=4.5V. This voltage is amplifier by the inverting opamp amplifier having a closed-loop gain of Acl=-96/32=3. Hence: V_0=1.5*(-3)=-4.5V.
  6. LvW

    How a BJT Transistor works (base current version)

    "The CAUSE of ie is the external signal source whose signal is inputted to the bjt amp stage, ................... It is clear that Sue the singer is what "controls ie", and clearly NOT vbe ................... There is no doubt that ic is controlled by ie, and ie is controlled by the signal...
  7. LvW

    How a BJT Transistor works (base current version)

    "The fact that ic/ie/ib settle to final plateau values while vbe continues to rise is proof positive that vbe is NOT the mechanism that "controls" ie/ib/ic." "It is ie that controls ic, not ib." Hi Claude, some time ago we already had a discussion about the same subject - and I do not want to...
  8. LvW

    basic of control system

    The stability of a system with feedback depends on the magnitude and phase response of the LOOP GAIN (gain of the open feedback loop). The stability properties are evaluated using one of the stability criteria (Nyquist). The poles as well as the zeros of the loop gain both contribute to the...
  9. LvW

    basic of control system

    @1) This is a pure theoretical (academic) approach. Background: The transfer function is the Laplace transformed inpulse response. However, in practice we always measure the transfer function in the frequency domain. Measuring the impulse response happens not very often and is problematic...
  10. LvW

    basic of control system

    I think, the test procedure/test signals must follow directly from the requirements - that means: from the main task of the control system. * If the system has to follow (track) a varying input signal (servo systems) it is necessary to know, of course, within which limits and with what "speed"...
  11. LvW

    determinant of transfer function

    N0 - it`s not a highpass; Yes - phi(jw) is the phase function; The name is "allpass" because this filter lets pass all frequencies with the same amplitude, only the phase goes from zero to -Pi (continuously).
  12. LvW

    determinant of transfer function

    |H(jw)|=1 and phi(jw)=-2arctan(w). It is an alppass with a phase between 0 and -Pi.
  13. LvW

    How many volts will be across the capacitor at the second time constant?

    What is the first time constant? How do you define it for this task?
  14. LvW

    ring oscillator with stable frequency

    Do you need such large frequencies? Normally, an oscillator specification starts with the desired frequency.
  15. LvW

    ring oscillator with stable frequency

    For such an oscillator, the frequency is determined by the delay time between the stages. Without any further elements the delay of each stage is set by the output resistance of the CMOS stage and the input capacitance of the next stage. However, I suggest to use - at least - external grounded...
  16. LvW

    Transistor Uses

    I do not intend to go into details for this first answer. Therefore, as a starting point, some general points only: 1.) Usage as a switch: The transistor cannot be used as a signal switch (like a relay) but only as a switch that can provide two FIXED ouput voltages (high/low) depending on a...
  17. LvW

    simple tone generator

    12vdc - in case you are interested in linear (harmonic) oscillators I would not recommend to restrict yourself from the beginning to the WIEN type oscillator only. There are many other oscillator topologies which could meet your requirements. This applies, in particular, to the tuning...
  18. LvW

    Assistance with Transistor Theory

    OK - I will try to answer your questions: Agreed - no "deep understanding" necessary. However, that`s not the point. Did I speak about such a "deep understanding"? However, the question if it is the voltage or the current at the inport port of the transistor which determines its output...
  19. LvW

    Assistance with Transistor Theory

    As another example: The classical opamp (undoubtly voltage driven) very often is used to realize a current-to-voltage converter (current in, voltage out).
  20. LvW

    Assistance with Transistor Theory

    Kris - my answers are in bold within your text. My summary is as follows: In all of your statements you say (more or less directly/indirectly) that you are not happy with the fact that the relation Ic=f(Vbe) is not linear. I think, this applies to all of us. But - is this the question? Of...
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