Finding impedance in an ideal transformer circuit

[m453438]

Homework Statement

This is a review question for my test, but I can't get the right answer, the problem is to find the impedance ab.

Homework Equations

Zin = 1/a^2 * ZL

The Attempt at a Solution

The 10 ohm resistor and the capacitor are in parallel and then add the 50 ohm resistor times 1/9. Doing this, I get 60-0.333j, but it is not the correct answer.

 

[berkeman]

Homework Statement

This is a review question for my test, but I can't get the right answer, the problem is to find the impedance ab.

Homework Equations

Zin = 1/a^2 * ZL

The Attempt at a Solution

The 10 ohm resistor and the capacitor are in parallel and then add the 50 ohm resistor times 1/9. Doing this, I get 60-0.333j, but it is not the correct answer.

Challenging question! I'd approach it by writing the 3 KCL equations for the 3 nodes. Put an AC voltage source at the left feeding terminals ab, label the upper left of the xfmr "1", the bottom of the xfmr "2", and the upper right of the xfmr "3". Write those 3 KCL equations, and see if you can solve for the voltages and currents in the circuit. Once you have those, you should be able to solve for Zin = ______

 

[m453438]

Challenging question! I'd approach it by writing the 3 KCL equations for the 3 nodes. Put an AC voltage source at the left feeding terminals ab, label the upper left of the xfmr "1", the bottom of the xfmr "2", and the upper right of the xfmr "3". Write those 3 KCL equations, and see if you can solve for the voltages and currents in the circuit. Once you have those, you should be able to solve for Zin = ______

Thank You!, I would never thought of that...

 

[The Electrician]

Have you made any progress?

If you already have the correct answer, what is it?

 

[m453438]

Have you made any progress?

If you already have the correct answer, what is it?

I haven't tried solving yet, but the correct answer according to my instructor should be 210 - j2700 ohms. And thank you everyone for helping me out.