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Your Name
ECE 201 – Lab 2
Lab Equipment Introduction
Date Completed
PRELAB
1. Using Ohm's Law, determine the value of the resistor used in the plot in Figure 2.
2. The current in every household in The United States has a frequency of 60 Hz. What is
the period of this current?
3. If the common wall sockets in the United States supply 120 V (rms), what is the voltage
amplitude? What is the peak-to-peak voltage?
MATLAB
4. Use MATLAB to plot a sinusoidal voltage source with amplitude of 2 V and frequency
of 3 Hz from 0 to 2 seconds. On the same graph plot the rms value. Also, on the same
graph, plot the sinusoidal with an offset of 1.5 V. Add text to each plot, labeling what it
is. For assistance, use the MATLAB help command. Your plot should look like the plot
in Figure 3.
TX1 DIGITAL MULTIMETER
5. When taking DC voltage and current measurements, how would switching the positive
and negative leads at the multimeter's input connectors effect the readings?
6. Would switching the leads effect the resistance reading of an element. Explain.
7. Select 10 resistors that came with the ECE toolkit and use the multimeter to measure
their resistance. Write the nominal resistance as specified by the color bands on the
resistor and the measured resistance using the multimeter in Table 1 of the Lab
Worksheet. Calculate the tolerance (as a percent error relative to the nominal value) of
each resistor and record it in Table 1. Are the tolerances within the nominal specified
range?
© 2001 Department of Electrical and Computer Engineering at Portland State University.
Version 1.1
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Nominal Resistance
(k)
Measured Resistance
(k)
Tolerance
(% error)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Table 1: Measured Vs Specified Resistance.
8. When taking AC voltage measurements, how would switching the positive and negative
leads at the multimeter's input connectors effect the readings? When taking AC current
measurements, how would switching the positive and negative leads at the multimeter's
input connectors effect the readings? Hint: think about what a sinusoid looks like and
whether the RMS value would be affected by a change in polarity. You do not need to
take any measurements to answer this question.
9. Does switching the leads effect the capacitance read by the multimeter?
PS2520G PROGRAMMABLE POWER SUPPLY
10. Suppose the power supply is configured to have a voltage limit of 9.5 V and a current
limit of 0.05 A. If the supply is connected to a 220  load, does it act as a voltage source
or a current source? What if it is connected to a 22  load?
11. With the output enabled, according to the power supply, what are the voltage and
current values of the circuit under test? Explain any differences between the settings
and the actual values.
12. Record the voltage and current values displayed on the power supply with the output
enabled in Table 2 of the Lab Worksheet. Use the multimeter to measure the total
voltage drop and the current through the resistors and record the value in Table 2 of
the Lab Worksheet. Do the values measured by the multimeter match the values
displayed by the power supply? If there is a difference, is it significant?
© 2001 Department of Electrical and Computer Engineering at Portland State University.
Version 1.1
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Voltage (V)
Current (A)
Power Supply
Multimeter
Table 2: Measured vs. Specified Voltage and Current.
13. What is the voltage supplied by the power supply?
14. What is the current according to the multimeter?
15. What is the voltage supplied by the power supply?
16. What is the current according to the multimeter?
17. Calculate the upper and lower values of the potentiometer by using Ohm’s Law.
AFG320 ARBITRARY FUNCTION GENERATOR
18. Recall from the prelab exercise that the VRMS value of a sine wave is VP  P 2 2 .
Calculate the VRMS value of the default sine wave supplied by the function generator.
19. What voltage reading is measured with the multimeter? Do not be surprised if it does
not match the value from Question 13.
20. Change the frequency on Channel 1 of the function generator to 10 kHz. Measure the
voltage output and record it in your lab worksheet. Does the value match what you
expected?
21. Using the formulas from the prelab exercise, calculate the period waveform with a
frequency of 10 kHz.
22. If you needed a signal with a period of 250 s, at what frequency would you set the
function generator?
23. What is the minimum period that a signal can have and still be read with the
multimeter?
24. Calculate the VRMS for a 1 V, 2 V and 5 V amplitude and record them in Table 3 of the
lab worksheet.
25. Change the amplitude on channel 1 to 2 VP-P. Measure the voltage from this signal with
the multimeter and record it in Table 3 in the lab worksheet. Change the amplitude to
5 VP-P and record the measured value in Table 3.
© 2001 Department of Electrical and Computer Engineering at Portland State University.
Version 1.1
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Amplitude (V)
Calculated VRMS (V)
Measure VRMS (V)
1
2
5
Table 3. Calculated Vs Measured VRMS.
26. Channel 1 of the function generator should have a sine waveform with a frequency of
10 kHz and amplitude of 5 V. Add a 1V DC offset and measure the AC voltage using
the multimeter. How does adding a DC offset effect the VRMS value of the waveform?
© 2001 Department of Electrical and Computer Engineering at Portland State University.