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  1. LvW

    German translation

    "messen" means "to measure" and "messe" is the corrsponding imperative ("you should measure") "laden" means "to charge" and "lade" is the imperative . "entladen" means "to discharge" and "entlade" is the imperative!
  2. LvW

    Free online textbooks and video lectures

    Robert - are you interested in some critical comments to your lessons? Example: I strongly disagree to your headline The BJT as a Current-controlled Variable Resistor For my opinion, this is a misleading (and false) statement. In contrast, under certain operational conditions the FET can be...
  3. LvW

    Question about transistor

    For my opinion, this subject could lead us to a - more or less - semantic/philosophical discussion. Just an example: The -3dB point on a lowpass magnitude response can be (and very often is) "defined" as cut-off frequency. Is this correct or is it wrong ? I think, it is suitable and makes...
  4. LvW

    Question about transistor

    OK - no problem. I also was too fast in writing my comment in post#10. I did mention the 19th century - but, of course, I mean the 20th. century.
  5. LvW

    Question about transistor

    Yes, Ratch - as you know, I am completely with you. It is funny and surprising, that even today two different function descriptions can be found in textbooks (current-controlled vs. voltage-controlled). May be it is interesting for you that - as far as I know - the famous Barrie Gilbert has...
  6. LvW

    Question about transistor

    I spoke about DEFINITIONS and the terms we are using during design of transistor-based circuits and corresponding discussions. So - a definition NEVER can be "wrong". It can be suitable or not. I think, for the subject under discussion there is a common agreement to say: (1) We select the...
  7. LvW

    Question about transistor

    It is a matter of definition if the term "results" is equivalent to the term "amplify". To me, there is - of course - a relation between both currents (Ib is a small part of Ic), however I would not use the term "amplification" for these DC quantities. As another example: The drain current Id...
  8. LvW

    Question about transistor

    To understand the procees of amplification (voltage or current) you have to realize that it is possible only to amplify VARIATIONS of the input quantity (voltage or current).
  9. LvW

    How to convert Sallen-Key Low pass filter to Signal Flow Graph

    OK - I know what you mean. But that does not answer the question. The question concerns the corresponding signal-flow diagram (which shows forward and backward ways.). That is the background we are speaking about FEEDBACK. And - it does not matter how the circuit looks like without feedback. It...
  10. LvW

    How to convert Sallen-Key Low pass filter to Signal Flow Graph

    I don`t understand your position. A bandpass is a bandpass - full stop. Just one question, which can be answered with yes/no: Do you agree that - between the ouput pin and the non-inv. input of the opamp - there is the classical four-element ladder network C1-R1-R2-C2 ? And this is the well...
  11. LvW

    How to convert Sallen-Key Low pass filter to Signal Flow Graph

    We are discussing the FEEDBACK network. Hence, you have to look into the circuit from the opamp output. You cannot deny that - in this case - the feedback network resembles the well known highpass-lowpass CR-RC bandpass characteristic. This is a well-known property of a positive-gain Sallen-Key...
  12. LvW

    How to convert Sallen-Key Low pass filter to Signal Flow Graph

    No - it is obvious that the feedback network consists of a band pass (highpass C1-R1, lowpass R2-C2). As a consequence, there is no lowpass -6dB response.
  13. LvW

    How to convert Sallen-Key Low pass filter to Signal Flow Graph

    The circuit consists of a fixed-gain amplifier (opamp with R3, R4) and a positive feedback function. Hence, where is the problem to find the signal-flow graph?
  14. LvW

    Plug-in supply (switched) with ac output

    Adam - thank you so much. I am pretty sure that you have sent me on the right track. The discussion as shown in the referenced link - and in particular, an application note contained in one of the contributions - is very helpful. So I think, my question has been answered. Thank you again. LvW
  15. LvW

    Plug-in supply (switched) with ac output

    I have a small plug-in-supply unit with "220V ac 50Hz" input and "12V rms" output. It is an italian device called "Transformatore elettronico" and the weight is only 70 grams. So it is kind of switched power supply - however with an ac output. It is intended to drive a halogen lamp. However...
  16. LvW

    Oscillator

    In case you are interested in a detailed and comprehensive answer it would be wise to spent a bit more time for explaining your problem.
  17. LvW

    Op Amp

    What is an amplifier? An amplifier processes (amplifies) signals. What kind of signals? What is the most important form of electrical signals? Answer: VOLTAGES (however, in some or certain cases we also have signals represented as currents). So - voltage amplifiers (like the commonly used...
  18. LvW

    Calculate Op Amp Gain

    OK - you win. Congratulation.
  19. LvW

    Calculate Op Amp Gain

  20. LvW

    Calculate Op Amp Gain

    Duke37, Harald and Ratch - yes you are right. Indeed, R1 cancels out - independent on the respective values. I am getting older and older...
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