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  1. LvW

    Common gate amplifier gain

    It`s easy: Output is Vout=Vin*gm*RD. What is the result for RD=0?
  2. LvW

    Good Resource For Learning Bjt Transistors And Amplifier

    Of course, not "everything that is taught in schools is wrong". However, I suppose that we can say that at least 50% of all textbooks (and other knowledge sources) about transistors do not properly explain the basic working principle. (The reason for this phenomenon was explained by Ratch) ...
  3. LvW

    Good Resource For Learning Bjt Transistors And Amplifier

    Steve, in the first part of your contribution you have mentioned the "current/voltage debate" regarding the BJT control mechanism. It was not my intention to repeat or to extend the discussion about this specific question. If you read my posts again you will notice that I didn`t mention these...
  4. LvW

    Good Resource For Learning Bjt Transistors And Amplifier

    I think, that it is always wise to explain the working principle of a simple pn diode first. And - as far as I can see - nearly each textbook and each electronics course follows this approach. Based on this knowledge, it is a very simple task to explain the basic working principle of the BJT...
  5. LvW

    Good Resource For Learning Bjt Transistors And Amplifier

    Certainly, I will follow davenn`s recommendation not to start another "current/voltage debate" - however, even your last sentence contains a big misunderstanding. If you like, I can explain without any theoretical discourse. Who has recommended such an approach? D you think, that would be the...
  6. LvW

    Good Resource For Learning Bjt Transistors And Amplifier

    Steve - at first, let me say that I totally agree with your first sentence: "There are two (and probably more -- but let me simplify it to two) ways of teaching a topic like this." I have some experience in teaching - and I know that it can be effective (and sometimes: necessary) to start with...
  7. LvW

    Good Resource For Learning Bjt Transistors And Amplifier

    Well - because * it's not really worth - for my opinion - to discuss the whole content of the video, and * the moderator does not want to start "another debate" about BJT properties here is just one comment to the video: A drawing is shown in the video (app. at minute 40) with the mechanical...
  8. LvW

    Good Resource For Learning Bjt Transistors And Amplifier

    davenn, I have the following question to you: When in this forum a youtube video is recommended, which contains wrong, misleading and meaningless information - is it allowed to inform a newcomer to electronics that this video shouldn`t be used? Don`t forget, the questioner has asked for a "good...
  9. LvW

    Good Resource For Learning Bjt Transistors And Amplifier

    For my opinion, it´s better to say: "Font of all kind of information - right and wrong. In this case, I am really surprised about the (last part of the) youtube video dealing with the BJT. I only can say: Wrong explantion of the working principle of the BJT. Don`t use this video!
  10. LvW

    Why don't I get a Sine wave?

    For my opinion, the problem is that nobody from us (who have answered up to now) knows what the questioner needs. Unfortunately he does not tell us if he is interested in a sinewave output only or if he wants a signal generator for different waveforms (triangle, squarewave, sinus). Of course, in...
  11. LvW

    Why don't I get a Sine wave?

    Of course, this recommendation is "correct". That`s the classical method of transferring a squarewave into a "quasi-sinusoidal" signal. However, one should know that there is no lowpass filter that can "block" unwanted harmonics. All you can achieve is to reduce the amplitude of harmonics - and...
  12. LvW

    Transistor amplifier gain

    Without emitter degeneration resistor RE (or when it is bypassed for AC) the gain is A=-gm*Rc. If this value is considered to be "high" depends on the DC current Ic and the collector resistor Rc. Example (Ic=1mA and Rc=2kohms): A=-(Ic/Vt)*Rc=(1E-3/25E-3)*2E3=-80.
  13. LvW

    Transistor amplifier gain

    Yes - there is a difference. Without mentioning other points (power consumption, operational point, collector current,...) it is the correct gain formula which gives the difference: Gain A=-Rc/(RE+1/gm). The transconductance gm is the slope of the Ic=f(VBE) characteristic and can only be...
  14. LvW

    Transistor amplifier gain

    To me, it is a severe misconception to think that re=1/gm would be a resistance belonging to the emitter. Such a view results from a false understanding for the transistors working principle. The bipolar transistor acts as a voltage controlled curent source - and the relation between input...
  15. LvW

    Peenemünde Document Translation (German)

    The second document shows the principle of a "Meissner-Oscillator" - also known as "Armstrong-Oscillator".
  16. LvW

    Peenemünde Document Translation (German)

    Yes - in principle, I agree with Harald K. * The first document deals with subtracting two groups of signals having the same frequency (using a phase-reversal amplifier) , * The second paper seemingly describes a Q-enhanced active bandpass (using a valve and frequency-selective feedback)...
  17. LvW

    NPN Transistor Amp not working!!?!?!

    A load resistor of 8 Ohms? This cannot work. In your circuit diagram you have forgotten to show us one of the most important parts: The load! I suppose you know how such a load determines the gain? Remember: The transistor acts as a CURRENT source - and the output voltage is determined by the...
  18. LvW

    Phase Shift Oscillator Op-Amp Neg Feedback

    "not sure" means you have some rough ideas, don`t you? Tell us about your first approach.
  19. LvW

    Phase Shift Oscillator Op-Amp Neg Feedback

    In short: * A closed-loop gain cannot be defined because the circuit IS indeed a closed loop withoput any input. * The oscillation condition (to be fulfilled at one single frequency only) is Loop gain=1. * This condition must be controlled using the BODE plot. Hence, you must create a BODE plot...
  20. LvW

    Phase Shift Oscillator Op-Amp Neg Feedback

    Three questions: * What do you mean with "closed-loop gain"? Which input? * For which function do you intend to create a BODE plot? * What is the general oscillation condition?
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