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    Electrotechnic exercise (help)

    This problem has been setup to ensure that a solution will be found by just searching for a real (not complex) value of Z that will give a v(2) of zero. To rule out the possibility that some complex impedance for Z would also give v(2) of zero, one can plot the voltage V(2) as a surface in the...
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    Electrotechnic exercise (help)

    You say that this is from an exam you took last week, so it's not homework and it should be ok to provide a solution. Laplace has already pointed out that the phase of the current doesn't matter. Furthermore, R1 and C1 don't matter either since they are in series with a current source. The...
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    Electrotechnic exercise (help)

    In post #1 you said that you applied the mesh current method. What result did you get from that?
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    Hi, center tap transformer, how to calculate?

    The Radio Designers Handbook (https://archive.org/details/RadioDesignersHandbook) will probably explain all you want to know.
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    Resistivity question help

    If by the phrase "resistance of the said 1 Metre cube", you mean the resistance measured between two of the plane surfaces of the cube which are on opposite sides of the cube with a perfect conductor used to make the connection to each face, you should be aware that the resistance will be the...
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    Thevenin-Norton conversion

    I think that the problem wants the student to enter the schematic into Pspice and then use Pspice to do the DC analysis, finding all the currents and voltages. Then do some simplification with source conversions. For part 3 I think they want the student to use several different load resistors...
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    Hacking Nodal and Loop Analysis

    If you really want to become proficient, solve problems with both methods; this gives you much practice. Solving with a second method provides a valuable check for your results which I find gives more confidence in the answer than just redoing the problem with the same method.
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    AC Circuit Problem HELP. Urgent.

    Since the OP said his request for help was urgent, and posted last Thursday, I suspect the due date has passed, and we probably won't hear from him again. But, Finnjamin, just in case you see this, would you post the answer here?
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    Output resistance of equivalent op amp circuit

    This seems like a big "if" to me. Getting the transfer function is probably the most difficult part of the problem. If a homework problem wants various gain functions as well as input/output immitances, then the transfer function will have to be calculated to get those gain functions anyway...
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    Phase shift oscillator help

    I was only concerned with Ratch's calculation of the oscillation frequency. He made a mistake in calculating the phase condition which involves setting certain imaginary parts to zero. I should have been more precise and said that "My purpose was to point out that Barkhausen's criterion...
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    Phase shift oscillator help

    The "Together" function just puts everything over a common denominator. Here you can see what the result is before the use of "Together":
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    Phase shift oscillator help

    The key is to learn how to set up the problem so a linear algebra solver on your computer is doing all the work:
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    Phase shift oscillator help

    My purpose was to point out that Barkhausen's criterion applies to the loop gain, Aß, not Aß-1. See: https://en.wikipedia.org/wiki/Barkhausen_stability_criterion The transfer function referred to in that Wikipedia article is the transfer function only of the feedback network ß. But in this...
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    Phase shift oscillator help

    We can proceed like this to find a value of f which makes the imaginary part equal to zero:
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    Phase shift oscillator help

    I don't know how to plot an equation. I only know how to plot a mathematical expression, such as the t of the left side of that equation. The relevant thing to plot here is the loop gain--the gain AB, what you called "the output of A1*A2*A3" which is also t. When the phase shift of a signal...
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    Phase shift oscillator help

    What about the plots of phase vs. value of r2 shown in post #53, showing that the value of r2 has no effect on the phase vs. frequency of t?
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    Phase shift oscillator help

    This is from your post #14, showing r2 being factored out of the expression for t; r2 is involved in the 180 degree phase change, but its effect doesn't change with frequency, so the frequency of oscillation of the circuit won't depend on r2. Whether it oscillates at all will depend on r2...
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    Phase shift oscillator help

    Doesn't the factorization: show that r2 is not a frequency determining component? It's only involved in the gain constant.
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    2 transistor circuit input output question.

    Laplace posted all the complicated expressions for the Wheatstone bridge here: https://www.electronicspoint.com/threads/thevenins-and-nortons-circuit-help.271858/page-2#post-1635807 I gave a link to an even larger set of expressions about it found here (dating from 1947)...
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    Impedance of two stage amplifier

    I know exactly what you're talking about, and the things you mention have no relevance to this homework problem. When the student's education has progressed to the point where he learns to consider component tolerances, temperature variations, etc., then they can be considered. The purpose of...
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