I'm having trouble with this question. Can somebody help?

enter image description here

I know the equation for part a) is:

$$P_{\text{max}} = \frac{1}{4} \cdot \frac{\mid{}V\cdot{}t\cdot{}h\mid{}^2}{R_\text{L}}$$

And I'm sure that I have to cut out the \$R_\text{L}\$ resistor from the circut and just focus on getting the thevenin equiv. for the transformer circuit.

Any ideas?

  • 1
    \$\begingroup\$ While there's nothing specifically wrong with homework questions here it might be better received if you edit the title to include the full word instead of an abbreviation, it took me a moment to work out what 'hmwk' was, or even better mention thevenin equivalents for a transformer. \$\endgroup\$ – PeterJ Mar 2 '13 at 7:04
  • \$\begingroup\$ I just had a related problem on my final exam the other day. What are the initial conditions may I ask or does it not entail this information? \$\endgroup\$ – Shane Yost Mar 3 '13 at 1:38
  • \$\begingroup\$ @ShaneYost there are no initial condition outside of what is given in the problem. I think the gist of the question is to get the thevenin equiv. of the circuit at point a and b which are on opposite sides of R_L. Any idea how to do this? \$\endgroup\$ – eggie5 Mar 3 '13 at 18:21
  • \$\begingroup\$ @ShaneYost it looks like a steady state problem. \$\endgroup\$ – Kortuk Mar 9 '13 at 3:47
  • \$\begingroup\$ What I find confusing about your question is that you have PSpice in the title and yet you questions say that the solution should be derived analytically. The PSpice solution is trivial to setup, the analytical not so much because of the feedback of the Rl. Unless of course you definition of analytical is different than my version of analytical. \$\endgroup\$ – placeholder Mar 10 '13 at 19:27


I have a solution which you might like to look at.

I do not have time to post it in detail here. However it is documented in the LTspice files in the archive:


that I have uploaded and publicly shared here


You'll need to install:


LTspice runs natively on Windows and, using WINE, on Linux and Mac.

Unzip the .asc and .plt files from the .7z into the same folder.

Open the .asc file in LTspice.

BTW: There are two LTspice sims in the archive. One is the detailed solution, the other is a sanity check.

If you can't open .7z archives, Google for 7zip and install that.

You can also find a bit more about solution if you follow the link to your original enquiry on Circuitlab:


If anyone wants to, they are welcome to work through the solution and post an explanation here, rather than have to follow a few links that may or may not survive much beyond the end of eggie5's assignment.

As far as I can see from the Terms of Service page on the CircuitLab site, there are no restrictions on the copying or other forms of reuse of content posted on their site, provided that the original content does not in itself violate copyright laws.

To my knowledge, the content I have posted there does not violate copyright.

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