Thevenin Equivalent & Available Power?

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Discussion Overview

The discussion revolves around the application of Thévenin's theorem in circuit analysis, specifically focusing on the determination of the Thévenin equivalent voltage and resistance in a given circuit. Participants are addressing a homework problem that involves setting up equations and interpreting circuit elements.

Discussion Character

  • Homework-related
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant expresses confusion about the setup of their equations, particularly regarding the values of Vx and the implications of obtaining a Thévenin voltage (Vthev) of zero.
  • Another participant questions the identification of a rectangle labeled -Vx, suggesting it is a dependent current source.
  • A further contribution states that a Thévenin voltage of zero is acceptable and discusses the implications for determining the Thévenin resistance (Rth), suggesting an alternative method of injecting current into the circuit to measure the resulting voltage.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the interpretation of the circuit elements or the implications of a zero Thévenin voltage, indicating that multiple views remain on how to approach the problem.

Contextual Notes

There are unresolved questions regarding the definitions and roles of specific circuit components, as well as the mathematical steps involved in determining the Thévenin equivalent.

Marcin H
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Homework Statement


Screen Shot 2016-09-10 at 3.19.22 PM.png


Homework Equations


V=IR
Node Voltage
Thev/Nort

The Attempt at a Solution


So I set up my equations in the picture below, but I'm kinda confused about the Vx's in the equations. First, did I set these up correctly? If so, solving them I get that V2=0 which would mean my Voc is 0V which means Vthev=0. Is that even possible? Am I doing something wrong here?

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That rectangle labelled -Vx, what is it?
 
NascentOxygen said:
That rectangle labelled -Vx, what is it?
What? That's a dependent current source.
 
A Thévenin voltage of zero is okay. This still leaves you trying to determine Rth. There is not much use pretending to short-circuit the output to measure current—because regardless of the Thévenin resistance, that current is going to be zero because its voltage source is zero.

An equally-valid approach is to inject current into your circuit's outputand measure/calculate the voltage this causes at the output. You can then use this data in conjunction with the Thévenin model to calculate Rth.

⏩ So draw an independent current source adding a current Iin at terminal a and determine Vab.

it's a linear circuit model, so on paper you can do whatever you wish to it
 

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