Download Introduction to PSpice - Portland State University

Version 1.1
Page 1 of 3
Your Name
ECE 201 – Lab 8
Sinusoidal Steady-State Analysis
Date Completed
PRELAB
1. What would you expect the ratio of the resistances in the windings of your transformer
to be? Explain.
2. If we choose to use Vi  10 as our reference for the circuit shown in Figure 1, will the
angle of V1 be positive or negative? Why?
3. If we choose to use Vi  10  as our reference for the circuit shown in Figure 1, will the
amplitude of V1 be larger or smaller than Vi? Why?
4. Suppose you have a 1 V power source at 1 kHz driving a speaker, but the sound
produced is not loud enough. How could you use a transformer to increase the
speaker’s volume? (Remember that the power produced by a speaker is related to the
voltage applied to the speaker’s terminals.)
MAGNETICALLY COUPLED COILS
5. Use the oscilloscope to measure the amplitude of the voltages shown in Figure 1. Use
the primary winding of your transformer as the inductor. Measure the phase of V1 with
respect to Vi. Then use sinusoidal analysis to calculate the inductance of the primary
winding of your transformer. Record the value in Table A. Repeat for the secondary
winding of your transformer
6. Using sinusoidal analysis, estimate the mutual inductance of your transformer and
enter this value in Table A.
7. Measure the inductance of each side of your transformer using the RCL meter. Record
these values in Table A.
© 2001 Department of Electrical and Computer Engineering at Portland State University.
Version 1.1
Page 2 of 3
Primary
Winding
L1
(H)
Secondary
Winding
L2
(H)
Mutual
Inductance
M
(H)
500 Hz
1 kHz
2 kHz
RCL Meter
N/A
Table A. Transformer Coil Inductance
SPEAKER CHARACTERIZATION
8. What is the resistance of your speaker?
9. Record the inductance of your speaker at the specified frequencies in Table B.
Speaker Inductance
(H)
500 Hz
1 kHz
2 kHz
Table B. Speaker Inductance
10. Calculate the amount of power being delivered to the circuit with no compensation
based on the amplitude of the voltage across the speaker and the speaker resistance.
Record your results in Table C.
11. To boost the power delivered to the speaker, should you connect the primary or
secondary winding to the speaker? Which winding should be connected to the function
generator?
12. Based on measurements of the voltage amplitude across the speaker, how much power
is delivered to the speaker with the transformer in the circuit? Record your results in
Table C.
13. Draw below the complete circuit that you designed to maximize the power delivered to
the speaker.
14. Calculate the amount of power being delivered to the speaker with the compensation
circuit. Record your results in Table C.
© 2001 Department of Electrical and Computer Engineering at Portland State University.
Version 1.1
Page 3 of 3
Power Delivered to Speaker
(W)
Without Transformer or Compensation
With Transformer
With Compensation Circuit and
Transformer
Table C. Power Delivered to Speaker
15. Is there an audible difference between the volume produced in question 10 and 12?
16. Is there an audible difference between the volume produced in question 12 and 14?
17. Is there an audible difference between the volume produced in question 10 and 14?
OP-AMPS AND SPEAKERS
18. Does your circuit work? Why or why not?
19. Use the oscilloscope to capture a measurement showing the input voltage signal and
output voltage driving the speaker. Paste a copy of the screen shot here.
© 2001 Department of Electrical and Computer Engineering at Portland State University.