Discussion on question by Ghost: How can I figure out the output voltage of this circuit?

Feeds

16:23

Q: How can I figure out the output voltage of this circuit?

I redrew the circuit and tried very hard. But nothing makes sense. I cannot just figure out how I should approach and analyse this circuit. This is as far as I have reached.

Transistor

This looks like homework so you need to show your work and where you are stuck. Otherwise the question will be closed.

Ghost

This is not my homework. I am a university student. Do you need my ID card? Also, I have shown my work. I just redrew the circuit. After that I could not move a single bit. Because I do not have any clue at all.

@Transistor I wonder what type of school or college would give such a thing as homework.

Janka

Forget about those resistors going to the voltmeter. There's no current flow in the voltmeter. It's a voltmeter. Its inner resistance is infinite. Does this help?

Transistor

"I wonder what type of school or college would give such a thing as homework." That's a standard electrical engineering problem so most would, I expect. Your original current has a 100 mA source. Your second circuit has a 10 mA source. Assuming that's an error and both should be 100 mA what will determine how the current splits in the two branches?

Ghost

@Transistor It is actually 10 mA. Sorry My bad. I am going to reupload the picture.

user577547

16:23

The 100uA current will make a voltage across a resistance. What is the total resistance? (2K+4k)||(2k+12K) Add up the 2k and 4k, add up the 2k and 12K, then parallel the two. Now that you know the total resistance as seen by the 100uA you should be able to find the voltage across the current source. Hope that helps? Ask more questions.

Ghost

@Janka There is no voltmeter. There is only a current source and bunch oof resistors.

Justme

What did you try that made no sense? This is a very basic circuit, and if this is an electronics course assignment, you shoud have the tools to solve it. Are you an electronics student, or why do you have to solve an electronic circuit?

Ghost

@ronsimpson How come (2k + 12k) and ( 2k 4k) in series? Are they not connected with another resistor which forms Y connection for them?

@Justme I am an electrical engineering student. And, this is not an assignment. This is an exercise.

Math Keeps Me Busy

I’m voting to close this question because this is academic work, and does not show a serious attempt at solution. Whether or not it gets graded is not something I can independently determine.

Ghost

@MathKeepsMeBusy Does not show a serious attempt? What makes you think of that If I may ask?

Math Keeps Me Busy

16:23

@Ghost the only attempt that you have shown is a redrawing of the schematic. You may have tried other things, but you haven't shown them here. We can only go by what we see.

Ghost

And, what possible things I could have tried? I think I have clarified that I cannot go further than redrawing the schematic.

Transistor

You could work out the total resistance between the upper and lower rails of your circuit. Then you'll have two of the variables in V = IR and be able to work out the third.

Ghost

@Transistor That is the problem. Why can my dumb brain not understand this problem? I can only see them in Y connection. But Y to delta does not work either.

Transistor

I has been pointed out already that since there is nothing connected to the \$V_o\$ terminals that there is no current flowing in the \$V_o\$ resistors. Therefore they can be ignored in your calculations.

Simon Fitch

Can you see in your update that you are measuring the voltage now across the current source? This is not equivalent to your original circuit.

Transistor

16:23

Your updated sketch with a total resistance of 4.2k and 42 V is correct. 1. It was recommended that you number all your components, R1, R2, etc., so we can discuss them. 2. You have included the \$V_o\$ resistors (even though they're irrelevant) but included them in the wrong place. They can't be connected directly to the current source terminals. Remove them. 3. Now work out the current in each branch. 4. Then work out the voltage at the junctions of the potential dividers.

Janka

@Ghost: You should tell the voltage V0 between those dots. How do you do that? With a voltmeter.

Ghost

@Transistor Thanks. I have updated the picture with designators and connected those two output resistors with the equivalent resistor. Now they are not directly connected the current source.

Transistor

16:34

Right, so what is the current through \$R_{AB}\$?

Hmm, MathJAX doesn't work in chat. Let's try HTML markup.
What is the current through R<sub>AB</sub>?

That doesn't work either.

What is the current through R_AB.

2 hours later…