Discussion in 'Homework Help' started by ENG99, Oct 25, 2014.

Feb 13, 2014
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0
hi guys, I do have a question about the more effective method that makes me solve any circuit with out using other methods?

I do have these methods

1- Nodal
2- Mesh
3- Superposition
4- Source Transformation

2. shteii01 AAC Fanatic!

Feb 19, 2010
3,388
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I don't consider source transformation a solution method. If I have some huge circuit that takes 3 pages, changing voltage source into current source on page one using source transformation does not tell me anything about voltage/current at Node X on page 3.

I am honestly more comfortable using Mesh-Current Methode, but I have been taught to use Node-Voltage Methode as well, so it makes very little difference which to use.

Last edited: Oct 25, 2014
3. amilton542 Active Member

Nov 13, 2010
494
64
(1) Enclose the circuit with a closed surface, the current entering this closed surface must leave through this closed surface. Don't feel your restricted to a "junction".

(2) If you want the general solution this is the chosen method, whether that be Gauss-Jordan reduction or Cramer's rule.

(3) The longer of the two methods mentioned, but comes in handy for analysis.

(4) I disagree with the aforesaid. A source transformation has worked wonders for me every time.

4. WBahn Moderator

Mar 31, 2012
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Keep in mind that the reason several methods are taught is because no one method is best. Think of these methods, and your proficiency with each, as tools in a tool box. For any given job, one tool might be considerably better than another but the job can probably be performed perfectly well with several of the tools, and it can probably be finished, but not so well, with others, and there are probably other tools that would make a total hash of things. One of the things that a skilled mechanic brings to the table is the ability to assess a given job and choose the best tools for that job. The same with circuit analysis. Don't forget that you have other tools as well, namely the early methods you learned such as the reduction of series/parallel components and more ad-hoc applications of KVL/KCL and Ohm's Law. Then, too, don't forget delta-wye transformations (if you have learned them yet). Your ability to make good choices when deciding which method to choose in a given situation will come only with experience, and the most valuable experience will likely come from making poor choices when deciding which method to choose.

Oct 9, 2007
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6. WBahn Moderator

Mar 31, 2012
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True, and I didn't read the first post closely enough to see that the question was about which methods could be used to solve ANY circuit without using any other methods.

I don't know that any one method truly can. Even the basic mesh and nodal methods need to be supplemented with such things as supermeshes and supernodes and auxiliary constraint equations for more general circuits, so part of it would depend on whether those augmented techniques are still considered mesh and nodal analysis for the purpose of this type discussion. For circuits with non-planar topologies, nodal analysis is usually easier to employ than mesh because the meshes can be much more difficult to identify. And, of course, we are implicitly limiting ourselves to linear circuits governed both by conservative electric fields and lumped parameters, which seems reasonable for this level discussion.

Last edited: Oct 26, 2014
7. studiot AAC Fanatic!

Nov 9, 2007
5,005
513
Eng97,
it's pie in the sky to look for universal methods, they don't exist.

I am guessing that you are at the stage of studying what is usually called 'circuit theory' in the textbooks, but is really not fair name as it is highly restricted in the components or elements you can have in your circuit.

All these theories are necessary steps on your route and you will see that each has its uses when you come to introduce all sorts of components such as transistors, transformers, antenna, operational amplifiers and many more.

All this is without digital circuitry which is different again.

So knuckle down, do the work, and look forward to reaping the benefit in the future.

Last edited: Oct 26, 2014
8. MrAl Well-Known Member

Jun 17, 2014
2,425
490
Hi,

After reading the first post i seriously doubt that the OP wanted to know the analysis method for EVERY possible or conceivable circuit that could ever possibly be drawn or thought of, it appears they just wanted to know about the basic circuit analysis. For example, they dont care about the physical size of the components used just the basic values of those components, and excluding ideas like electromagnetic radiation from any given component.
So they just seem to want a basic idea of what circuit techniques can be used or not used in the basic analysis.

From that, i would say that nodal analysis is widely applicable to any circuit and i think loop analysis is too, but mesh analysis is not so widely possible as it can not be used (or might not be able to be used) on networks that are not 'planar'. Planar here means a circuit that can not be drawn without having at least two leads cross, no matter how you try to redraw it.

It should also be pointed out that superposition is not as general as we would like to think because it is only applicable for linear networks.

I also think that although source transformations may not be widely applicable, they are nonetheless very valuable, and some circuits can be solved by repeated source transformations.

So of the four methods given in the first post, only Nodal Analysis is universally applicable.