Need help with a nonlinear circuit problem

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Discussion Overview

The discussion revolves around solving a nonlinear circuit problem, specifically finding the Thevenin equivalent for voltage and resistance. Participants explore various approaches to tackle the problem, including modeling techniques and alternative methods.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant reports finding the Thevenin resistance to be 1 ohm and suggests Vth values of -3V and 1V for different questions, expressing confusion about the next steps.
  • Another participant proposes using a piece-wise linear model for the nonlinear element, suggesting to compare the operating point of a simpler model to the nonlinear element's I,V curve.
  • A different approach is suggested, where the problem is split into four parts based on current ranges, with corresponding impedance values for each range.
  • One participant questions the necessity of using Thevenin's equivalent, suggesting that the problem could be solved without it, given that the current is provided.
  • A later reply emphasizes that Thevenin equivalents are typically linear and suggests combining ideal components to model the I-V characteristic instead.

Areas of Agreement / Disagreement

Participants express differing views on the necessity and appropriateness of using Thevenin's equivalent in this context. There is no consensus on the best approach to solve the problem, with multiple competing methods and models being proposed.

Contextual Notes

Some participants highlight the limitations of Thevenin's theorem in nonlinear scenarios, while others suggest alternative modeling techniques. The discussion reflects varying assumptions about the applicability of linear models to the given problem.

akaCrazed
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Hello, I have been working for hours on this single problem, to no avail. I am supposed to find the Thevenin equivalent for Voltage and Resistance, which I found to be 1ohm for resistance, and for question 2, Vth is -3V, and for 3 and 4, Vth is 1V. Any help is appreciated, as I have no clue where to go from here
 

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One way to approach this would be to substitute a simpler model for the non-linear element. It is, of course, a piece-wise linear model composed of a 1ohm resistor and a 2v or -2V voltage source. Try solving for just a resistor, or just a voltage source. Then compare the operating point of that solution to the non-linear element, if the I,V calculated is on the non-linear element's I,V curve, then you have the solution. If not, try a different local I, V model for that element.
 
In my opinion, you may split the problem in 4 parts:
i>2 Z=2/i
0<i<2 Z=1
0>i>-2 Z=1
i<-2 Z=-2/i
Now you have to find I ,vo and v1 in each part.
 
Is it mandatory to use Thevenin's equivalent? You can solve the question without it as well. You've given the current, so that will either give a constant Vo or Vo in the form of an equation.
 
akaCrazed said:
Hello, I have been working for hours on this single problem, to no avail. I am supposed to find the Thevenin equivalent for Voltage and Resistance, which I found to be 1ohm for resistance, and for question 2, Vth is -3V, and for 3 and 4, Vth is 1V. Any help is appreciated, as I have no clue where to go from here
It doen't say to find the thevenin equivalent. Thevenin equivalents aere always linear.
You can combine two ideal 2V zeners, 2 ideal diodes and one resistor to model the i-V characteristic.
 

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