Objective: We will learn about transformers and phasor diagrams by setting up and performing measurements with transformer circuits. We will test some of the circuits that were (or will be) discussed in lectures and homework problems.

Lab Activities:

1. Use a 1 volt sinusoidal voltage source at 60 Hz applied to the primary side of your transformer (the 120 V AC plug). Make measurements at the secondary terminals to determine the turn ratios and the "dots" on the primary and secondary sides of your transformer.

   We will see that for an ideal transformer, V₁ / V₂ = N₁ / N₂.

2. Repeat step 1 at frequencies other than 60 Hz, and check whether the turns ratio, a, varies with frequency. You may want to make a plot of a versus frequency. Check a frequency range that spans several decades.

3. Devise measurement procedures that will allow you to estimate the internal resistances of the primary and secondary coils (R₁ and R₂) and the self-inductances (L₁ and L₂). Measure the self-inductances at several frequencies (beginning with 60 Hz).

   Do your measurements agree with the "ideal transformer" assumptions? Compare the ratio L₁ / L₂ with the expected value of [N₁ / N₂]².

   Can you devise a procedure to measure the coefficient of coupling, k? We won't do the measurements this week.

4. Attach a 100 ohm load resistor to the secondary, and measure the impedance at the primary terminals, Z_ab, at various frequencies that span several decades (including 60 Hz). Compare your measurement with analysis based on the linear and ideal transformer models.

5. Set up the circuit shown in Problem 9.82 that you will analyze on Homework 3, and compare your measured results with the analysis. We will use a 10 kohm potentiometer for R_x. Choose R₁ in the kohm range and C = 1 uF at frequency omega = 1,000 rad/sec.

6. If you have time, set up the circuit shown in Problem 9.80 that you will analyze on Homework 4, and compare your measured results with the analysis.

Also, please bring your lab results to class next week and we will discuss them during class.