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  1. LvW

    How does the current flow?

    Yes - and to complicate things: Nearly the same applies to electrons too. What we call "current" is NOT "flow of electrons" (they move very slowly!) but movement of charges (not charged carriers). But that`s pure physiscs and does not have any influence on designing/analysing circuits based on...
  2. LvW

    differential amplifier

    Yes - and more than that, the ground reference is provided as follows: * For inverting applications the pos. input terminal is grounded (0V) * For non-inv. applications the feedback network is grounded.
  3. LvW

    The need for resistance

    Electrical "resistance" is nothing else than a property of each material under influence of an electrical voltage. And this "property" determines how much current can exist - as a result of this voltage. Some materials have very large resistances (so called "isolators" with R>1E12) and other...
  4. LvW

    Pspice and 4538 help

    Don`t blame the program. Since more than 20 years I work with PSpice - and if something went wrong it was ALWAYS a failure of the user (that`s me) and NEVER a malfunction of the program. May I ask: What means "can`t seem to make it work"? Didn`t the program start? Was there any failure message...
  5. LvW

    Kirchof's law with Current?

    Did you ever hear about the superposition theorem? That means: How to calculate the total current through a particular part using superposition of different currents (in our case: 2) caused by different sources (in our case: 2) ?
  6. LvW

    Sine Wave from Square wave

    There are many, many introductory articles accessible through the Internet which can teach you filter design basics. I don`t think that it is possible to do that in a forum like this.
  7. LvW

    Sine Wave from Square wave

    If the frequency is fixed you could use a self-designed lowpass or bandpass filter (the necessary order is determined by your distortion requirements: Quality of the sinus signal). However, a filter that can be tuned together with the varying frequency of the squarewave is harder to realize.
  8. LvW

    Ideal Diode in LTSpice

    I am not quite sure if the term "ideal diode" is a commonly agreed "definition". Therefore, it would be helpful if YOU could specify the properties of the diode model you want (for example: Threshold voltage at V=0 or V>0?)
  9. LvW

    LC circuit in the time domain

    I`ve got the impression that it is your desire to find a way back from the frequency into the time domain. And - solving the diff. equation (time domain) you arrive at the characteristic equation which must be solved. And this equation can be derived also from the transfer function. That`s all I...
  10. LvW

    LC circuit in the time domain

    Perhaps it helps to remember that the denominator of the transfer function (frequency domain) is identical to the characteristic polynominal of the corresponding diff. equation (time domain)?
  11. LvW

    Using all four amplifiers in an LM324

    In principle, you can operate each opamp with a single power supply. But you must know that in this case - for linear amplification purposes - a special circuitry is necessary to bias the opamp properly at 50% of the supply voltage, approximately. Collect some information on single supply...
  12. LvW

    Using all four amplifiers in an LM324

    In most cases, a combination of two (or even three opamps) in form of a "composite amplifier" is used to increase the bandwidth of the resulting circuit. I thappens not very often that "maximum amplification" is the reason for combining amplifiers. But why not? However, if you are going to...
  13. LvW

    help eliminating oscillation in circuit

    I must admit that it is not easy to analyze the diagram as provided by you. For example, it tooks some time to realize that you are working with single supply - and I have problems to see if and how you have realized the dc biasing necessary for single supply linear operation. What is the...
  14. LvW

    Op amp output into op amp input?

    Russbo - pleaase, can you show the circuit? This would make the communication much easier. What is the purpose of the 3-opamp configuration?
  15. LvW

    Summing amplifier

    Gryd3 - if you connect the node labelled as V1 to the output node you simply have Rin in parallel to Rf. Hence, using the node labelled as V2 as an input signal you have an inverting amplifier with a closed-loop gain of (-Rf||Rin/Rin). That`s all. No integrating function at all.
  16. LvW

    Summing amplifier

    Did I understand correctly: You intend to connect Vout with V1 ? Why?
  17. LvW

    AC analysis of common base BJT

    Fastcharlie2 1.) Your calculation of the DC current is correct. 2.) I recommend to split calculation of the AC gain of the circuit into two parts: a) gain between emitter and collector (classical formula involving only re=1/gm and Rc)), b) Input damping between signal input and emitter node...
  18. LvW

    How a BJT Transistor works (base current version)

    Hi Steve - I must admit that I cannot follow you: Vbe is a "constant factor"? And a voltage change across RE "will cause a current change and therefore (according to this model) change Ic." ? Therefore, I repeat my question (see my post#17) that was not yet answered: Are you denying that Re...
  19. LvW

    How a BJT Transistor works (base current version)

    OK - where is your explanation (in words!) for the phenomenon of RE feedback - without using the fact that VBE controls Ic ? I don`t intend to write such a paper. Since several decades, such a description can be found in several books and other resources.
  20. LvW

    How a BJT Transistor works (base current version)

    Steve - really absolutely rubbish? Are you denying that Re implements current-controlled voltage feedback? I have several years experience in teaching electronics - what do you think how students would react upon your method to explain the principle of RE feedback? (The emphasize is on...
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