Thevenin equivalent with dependet sources

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Discussion Overview

The discussion revolves around finding the Thevenin equivalent of a circuit that includes dependent sources. Participants are exploring the application of Thevenin's theorem in the context of a homework problem involving diodes and circuit analysis techniques.

Discussion Character

  • Homework-related
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • The original poster presents a circuit and expresses uncertainty about deriving the Thevenin equivalent, specifically mentioning difficulties in formulating the necessary equations.
  • One participant questions the motivation behind the second equation proposed by the original poster, suggesting it may not be valid.
  • The original poster indicates that the second equation is based on an example from a textbook, but struggles to formulate a second equation independently.
  • Another participant provides a suggestion involving the concept of a general Thevenin source and voltage divider, proposing the use of nodal analysis to derive the output voltage.
  • There is a concern raised about how to handle the dependent source within the circuit while applying the suggested methods.
  • A later reply emphasizes the importance of including the dependent source in the analysis and suggests substituting for the current through the resistor as part of the node equation analysis.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the validity of the original poster's equations. There are differing views on how to approach the problem, particularly regarding the treatment of the dependent source and the formulation of equations.

Contextual Notes

There are unresolved aspects regarding the assumptions made in the equations and the specific definitions of the dependent source in the context of the circuit analysis.

elamre
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Homework Statement



Hello, i was studying diodes for my exam on monday, but i had some struggle finding the Thevenin equivalent. Here is the circuit:
http://img411.imageshack.us/img411/5336/schakeling.png

Homework Equations



I have no clue what to put here?

The Attempt at a Solution



I have made 2 equations with which i should be able to solve it (i think?) But i have no clue if I am doing it right! So can somebody check it?

ix = (5-Voc)/1000
and
ix - ix /2 = 5/1000
 
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What is the motivation behind your second equation?
 
Well i tried to follow an example out of my book (electrical engineering fifth edition by allan r hambley) And i need my second equiation to solve the first equation. Its just that i can't think of 2 =/.
 
elamre said:
Well i tried to follow an example out of my book (electrical engineering fifth edition by allan r hambley) And i need my second equiation to solve the first equation. Its just that i can't think of 2 =/.

I see. Well, it doesn't look like a valid equation to me.

Here's a trick that often helps with these types of circuits. If you consider a general Thevenin source it's a voltage supply Vth with a series resistance Rth. When it's connected to some load resistance R, the two resistances will form a voltage divider for the Thevenin voltage source and the voltage across the load will thus be
Vo = V_{th} \frac{R}{R + R_{th}}

Now, if you stick a resistance R onto your circuit on the right as a load, you should be able to apply nodal analysis at the output node and solve for Vo. One equation! If you can then put the result in the form above you can read off both the Thevenin voltage and resistance directly.
 
Well i know that, but what about the dependent source? :)
 
elamre said:
Well i know that, but what about the dependent source? :)

Solve for Vo with the dependent source in place, of course. You'll be finding the expression for the current Ix through the 1000Ω resistor as part of the node equation analysis, so you can substitute for Ix/2 easily.
 

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