# Thevenin Circuit - Help need from Mentor And Expert

Discussion in 'Homework Help' started by DarrenYeoh, Oct 9, 2013.

1. ### DarrenYeoh Thread Starter New Member

Oct 9, 2013
3
1
Hi Mentor/Expert

Help need an advice and step to solve this circuit using Thevenin Theorem.

Million Thanks

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2. ### WBahn Moderator

Mar 31, 2012
18,087
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First, what is it that you are solving for?

Second, you need to show YOUR best attempt to solve YOUR homework problem.

3. ### w2aew Member

Jan 3, 2012
219
64
Have a look at this video that shows the analysis of an R2R Ladder circuit, which is solved using Thevenin's theorem. You should then be able to apply this to your circuit.

4. ### DarrenYeoh Thread Starter New Member

Oct 9, 2013
3
1
Hi Mentor/Expert,

Million thanks for reply, the circuit is to find Voltage equivalent (Vth) and Equivalent Resistance (Rth). I don't understand how to transform the voltage controlled voltage source that 2Vx and and is it I need to change current source to Voltage source?

Million Thanks.

5. ### WBahn Moderator

Mar 31, 2012
18,087
4,917

What if I gave you that exact same circuit and asked you to simply find the voltage difference from Point A to Point B (i.e., Vab). Could you do that?

Now what if I gave you that same circuit but I added a wire between Point A and Point B and asked you to find the current in that wire (i.e., Iab). Could you do that?

Try to do both of those and, once you have that (and we'll help, as long as you show your efforts for us to work from), we can discuss how those two things relate directly to the Thevenin equivalent circuit.

Last edited: Oct 10, 2013
6. ### DarrenYeoh Thread Starter New Member

Oct 9, 2013
3
1
Hi WBahn,

Thanks for reply , I have no ideal how to start, Could you advice?

djsfantasi likes this.
7. ### WBahn Moderator

Mar 31, 2012
18,087
4,917
You have no idea? None?

You have never learned how to analyze a circuit containing a depedent voltage source?

Okay, let's take a step further back and let's say that I give you the same circuit except that the dependent source is replaced with, say, a 12V independent source keeping the same polarity. Can you find the voltage between Point A and Point B then? If so, then please do so and show your work.

8. ### rxdelta New Member

Oct 11, 2013
2
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WBahn why you are such an angry person?

9. ### shteii01 AAC Fanatic!

Feb 19, 2010
3,505
512
Lots of reason, most of them good too. In my other hobby, on another forum (not related to electricity or electronics) I became sort of resident angry guy, they eventually banned me.

10. ### The Electrician AAC Fanatic!

Oct 9, 2007
2,301
338
It's called "tough love". See:

http://en.wikipedia.org/wiki/Tough_Love

The very first sentence at that page is what applies here.

Last edited: Oct 11, 2013
11. ### WBahn Moderator

Mar 31, 2012
18,087
4,917
No anger at all. Certainly some frustration from time to time.

Go back and re-read that post without assuming an angry tone of voice. Instead, use a conversational and inquisitive tone of voice. You will see a huge difference.

Multiple -- sometimes conflicting -- objectives are at play. Such as:

1) Trying to get a poster to actually make some effort. Lot's of people that can actually make a good amount of progress immediately drop into the, "I don't know how to even start, please show me," mentality. Taking a more jaded viewpoint, there are also posters (and we see them on a regular basis) that have no intention of putting forth any effort but, instead, want someone to just do their work for them and figure that if they just play dumb enough long enough that someone will oblige -- and sometimes someone will (and THAT's when I get REALLY frustrated and closer to being angry).

I don't have any tolerance for the second kind, but the first kind I want to get them to start making the efforts to walk on their own. Someday, hopefully, they are going to have to leave the nest and it sure helps if they've at least learned that those things stuck their sides are wings and that they really can move them if they want.

2) Trying to find out just where to start the discussion. If the poster shows some work, it gives you some insight not only into what they are and aren't doing wrong, but also what their thinking is and what level they are approaching things at. There's a big difference between someone trying to analyze an RC circuit and their approach reveals that they are struggling with the basic algebra and calculus is a foreign word and someone that is struggling with dealing with the initial conditions in taking the Laplace transform of the circuit.

Also, notice that after trying to tease out some indication that they actually do know something about this stuff, that I didn't just leave them to their own devices. I simplified the circuit in order to make it closer to something that they hopefully can analyze. If they can't do that, then we can make it simpler still. It may be like pulling teeth, but eventually we can find a starting point and then work back up from there.

12. ### rxdelta New Member

Oct 11, 2013
2
0
WBahn
You should not be acting like this, with anger.Anybody can become angry  that is easy, but to be angry with the right person and to the right degree and at the right time and for the right purpose, and in the right way  that is not within everybody's power and is not easy.You are very educated grown up man with a child at home.You should set a good example for your child.I understand the fact that you hate lazy people but you should not treat others in ways that you would not like to be treated.

13. ### WBahn Moderator

Mar 31, 2012
18,087
4,917
What are you babbling about? I just got done explaining that there is no anger involved.

How is trying to simplify a problem to something that the poster can handle and using that as a starting point for helping them move forward treating someone in a way that I would not like to be treated? It isn't. When I ask someone a question and I can't understand the level at which they are trying to explain it, I appreciated it if they try to take steps back to a level that I can and then bring my up to speed.

For that matter, how is expecting someone to put forth some effort in coming up with a solution to THEIR homework problem treating someone in a way that I would not like to be treated? It isn't. But then, I'm not someone that thinks that I have a right to expect everyone else to do my work for me.