# AC Circuit Problem HELP. Urgent.

Discussion in 'Electronics Homework Help' started by Finnjamin, May 12, 2016.

1. ### Finnjamin

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0
May 12, 2016
Hi There.
I wonder if anyone could help me with the problem I have. I have spent quite a lot of time researching how one should go about doing this problem, however, as of this far, I am still not even close to getting anywhere...
This problem is part of some Homework I have for an Electronics course i do at UCT.

I will post an attached photo of the problem.

Thanks

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2. ### davennModerator

13,674
1,892
Sep 5, 2009
hi there
welcome

so what have you learnt in class so far that you can use to make a start on this problem ?

3. ### Alec_t

2,905
784
Jul 7, 2015
Post you attempts so far, so that we can give guidance.

4. ### Finnjamin

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0
May 12, 2016
Hi. Thanks for much for the quick responses. I will tell you what i think i am meant to do and where i am stuck at the moment.
What i think i need to do is calculate the Z thevinin and the V thevinin, and then the current would be Vth/Zth. Which i can then input the different constraints for I that are given to work out the different values of Z2. (Because the equations for Zth and Vth will both include Z2) . My issue at the moment is I do not know how to work out Vth with the extra current source in the middle there.

Let me know what you think.
Thanks so much!

5. ### Ratch

1,088
331
Mar 10, 2013
Looks like no one but I is going to help you. First you need to get up to speed on the PIT (Port Immittance Theorem). You can find out about that is the link below.
https://www.electronicspoint.com/threads/output-resistance-of-equivalent-op-amp-circuit.278977/ Now look at the attachment below. We first find the transfer function Vo/Vs . Then setting the denominator to zero, we find the -ZL . That is your Thevenin impedance look back from ZL. You can go on from there. I also substituted the parameter values into the Thevenin impedance. Hopefully, I did not make a mistake. Ask if you have any questions.

Ratch

6. ### The Electrician

116
11
Jul 6, 2012
Since the OP said his request for help was urgent, and posted last Thursday, I suspect the due date has passed, and we probably won't hear from him again.

But, Finnjamin, just in case you see this, would you post the answer here?

davenn likes this.