# Couldn't solve this norton question.

Thread Starter

#### etemeskutCEO

Joined Dec 11, 2022
5

Hey guys. I've been trying to solve this question for hours... Can anyone please just find the Vo and explain it? It's enough for me,i can do the rest.

#### Jony130

Joined Feb 17, 2009
5,445
Can you show us your work?

Thread Starter

#### etemeskutCEO

Joined Dec 11, 2022
5

I know it's really comlicated and written badly,sorry about that. I tried to use supernode theorem. In the bottom right of the paper you can see 2 equations that i got from the theorem. I calculated them and found V1 = 2V and V2= -45 mV. Results are incorrect.

#### Jony130

Joined Feb 17, 2009
5,445
But is this not a Voltage controlled Current source?

Thread Starter

#### etemeskutCEO

Joined Dec 11, 2022
5
Yeah you are right,i forgot about that.What do you suggest about solving this circuit?

#### Jony130

Joined Feb 17, 2009
5,445
In that case, you do not need to use the supernode theorem. And your job is to find Vo (output voltage) or Norton equivalent circuit?

Thread Starter

#### etemeskutCEO

Joined Dec 11, 2022
5
It's to find norton equivalent circuit but if someone can help me with finding Vo, it's enough i will do the rest. No need to do the norton eq. circuit.

#### WBahn

Joined Mar 31, 2012
28,512
It's to find norton equivalent circuit but if someone can help me with finding Vo, it's enough i will do the rest. No need to do the norton eq. circuit.
We won't work your problem, or parts of it, for you. We will try to guide you along a path where YOU can solve YOUR homework, so that YOU learn from it.

Mesh Current Analysis works best when there are current sources in the perimeter, because those meshes are solvable by inspection.

You have two such meshes, leaving you with only one that you have to write a mesh equation for you.

Seems like that is something that is just screaming out to you to at least give it a try.

#### WBahn

Joined Mar 31, 2012
28,512
I know it's really comlicated and written badly,sorry about that.
Don't be sorry, clean it up!

Part of your job is to communicate your thoughts and your work clearly and effectively. It's fine to scribble work on a scratch pad, but don't expect others to decipher your chicken scratchings. They have meaning to YOU because YOU wrote them and you know what your thought process was at different points in the work. But when you have a little work here and a little worth there (such as you have scattered across the page), it makes it nearly impossible for others to figure out.

So rewrite your work with the intent of making it easily followable by the person reading it -- whether it be people that you are asking for free help from on the Internet, or the grader.

#### Jony130

Joined Feb 17, 2009
5,445
Write the nodal equation again, but this time don't forget that you have a VCCS. So you need to treat it as if it were an ordinary current source ( I = Vx/4000 ).
It's to find norton equivalent circuit but if someone can help me with finding Vo, it's enough i will do the rest.
I ask about it because the circuit will be much simpler if you want to find Isc (Norton Current) directly.

#### WBahn

Joined Mar 31, 2012
28,512
View attachment 283647

Note that the voltage-controlled current source is improperly specified. It claims that the output is a voltage (namely whatever voltage appears across Ro divided by 4000).

But the output is a current. This is a transconductance amplifier and the gain has to have units of conductance (or reciprocal resistance).

The almost certainly meant that the current is

Vx * (1/4000) A/V

Which is the same as

Vx * (1/(4000 V/A))

And since the units of V/A are units of resistance (specifically ohms), this can be written very compactly as

Vx / 4 kΩ

If you don't add the proper units (to compensate for the author's sloppiness), then the units in your work can't work out and you will end up just tacking some units onto your answer that you hope are correct.

Instead, track your units through every step of your work. In doing so, you will catch the majority of mistakes you make (and, if you're human, you WILL make them).

Thread Starter

#### etemeskutCEO

Joined Dec 11, 2022
5
Thank you for your help guys. I was in a little bit hurry because i had to deliver the homework. I solved the question like this:

#### WBahn

Joined Mar 31, 2012
28,512
You are being very sloppy with units.

Look at your last equation. You have Va - Vb, which is the difference of two voltages. You then have this equal to the difference of two numbers. You then have this somehow, magically, equal to a resistance.

You are going to get yourself into trouble if you don't start paying attention to your units. But it's evident you won't believe that until it happens. Hopefully that will happen on an exam where the cost is a grade on a transcript and not in the read world where sloppiness with units can have catastrophic consequences, like slamming a hundred-million dollar space probe into a planet, or a having jetliner full of passengers running out of fuel in midflight, or the person standing three feet away from you getting killed.

#### The Electrician

Joined Oct 9, 2007
2,927
Thank you for your help guys. I was in a little bit hurry because i had to deliver the homework. I solved the question like this:
I thought you were supposed to find a Norton equivalent? Do you know how to perform a mesh analysis? A quick and easy method can give the Norton parameters in a very straightforward manner.