Thevenin equivalent circuit help

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Discussion Overview

The discussion revolves around finding the Thevenin equivalent circuit for a given electrical circuit that includes multiple voltage sources. Participants explore methods for determining both the equivalent resistance and the Thevenin voltage.

Discussion Character

  • Homework-related, Technical explanation

Main Points Raised

  • One participant expresses uncertainty about how to approach the problem with two voltage sources and requests step-by-step guidance.
  • Another participant suggests that there are multiple methods to solve the circuit and inquires about the circuit theorems the original poster has learned.
  • A third participant proposes determining the voltage between points a and b as a means to find the Thevenin voltage (Vs).
  • A later reply outlines a systematic approach involving nodal analysis to find the voltage across points A and B (Vab) and suggests using mesh current methods to find the short-circuit current (Isc) to ultimately derive the Thevenin equivalent resistance (Rth).
  • It is mentioned that one can replace voltage sources with short circuits to find the equivalent resistance, indicating alternative methods exist.

Areas of Agreement / Disagreement

Participants do not reach a consensus on a single method for solving the problem, as multiple approaches are discussed and suggested.

Contextual Notes

The discussion includes various assumptions about circuit analysis techniques and does not resolve the specifics of the calculations or the definitions of terms used.

full123
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http://img855.imageshack.us/img855/5369/eehmwk.jpg


I haven't done this before with 2 voltage sources so I'm not sure how I would go about doing it.

If someone could show me step by step how to understand this, I would appreciate it.

Equivalent resistance = 2.5ohms, right?
But what about Vs?
 
Last edited by a moderator:
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full123 said:
http://img855.imageshack.us/img855/5369/eehmwk.jpg


I haven't done this before with 2 voltage sources so I'm not sure how I would go about doing it.

If someone could show me step by step how to understand this, I would appreciate it.

Equivalent resistance = 2.5ohms, right?
But what about Vs?


There are several different ways to solve this circuit. What circuit theorems have you been introduced to?
 
Last edited by a moderator:
full123 said:
But what about Vs?
Can you determine the voltage between a and b on the main circuit? That becomes Vs in the Thevenin equivalent.
 
2 or 3 voltages, it doesn't matter. It is the same approach most of the time :smile:
Find the voltage across AB, that is: Vab (using nodal analysis). Then find the short-circuit current Isc, that is in the direction of the voltage DROP across AB (using mesh current method). Then it is a matter of using Ohm's law to find Rth and constructing Thevenin equivalent circuit.
Of course you don't have to have to find the current Isc (which is cumbersome used often), since you can replace the Voltage sources by short circuits and then find the equivalent resistance Rth. But I was just suggesting to use the formal approach.
 
Last edited:

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