EET 150
Introduction to EET
Lab Activity 5
Oscilloscope Introduction
Required Parts, Software and Equipment
Parts
Figure 1, Figure 2, Figure 3
Component /Value
Resistor 10 kΩ, ¼ Watt, 5% Tolerance
Capacitor 1.0 F 25 V or above
Resistor 22 kΩ, ¼ Watt, 5% Tolerance
Quantity
1
1
1
Equipment
Required
On-Campus Students
Solderless Experimenters' Board
Hookup wire (22 AWG)
Wire cutter/stripper
Function Generator
Oscilloscope
10x Scope Probe
BNC-Alligator Leads cable
Optional
2 Banana jack leads red/black
On-Line Students
Analog Discovery 2: Arbitrary Waveform Generator (AWG). Two channel oscilloscope
Optional
BNC adapter board for Analog Discovery 2 Digilent 410-263
available at: http://store.digilentinc.com/bnc-adapter-board-for-the-analog-discovery/
1 BNC to alligator lead test cable
2 10x scope probes Digilent 460-004 or equivalent
available at: http://store.digilentinc.com/bnc-oscilloscope-x1-x10-probes-pair/
2 Banana jack leads red/black
BNC-Alligator Leads cable
Software
On-Campus Students
MS Word
On-Line Students
Waveforms 2015 for Analog Discovery 2
Available for download at : http://store.digilentinc.com/waveforms-2015-download-only/
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MS Word
Introduction
Oscilloscopes are used to analyze and test electric circuits. They are capable of showing
waveforms that vary in time and are present in an electrical or electronic circuit. Modern
oscilloscopes, commonly known as scopes, have the ability to display and measure the
electrical characteristics of signals. The measurement functions on the oscilloscope allow the
user to see and measure peak voltage, frequency, phase shift, and much more. The user can
visually measure the signals using the horizontal and vertical scaling factor or use the
measurement functions of the scope to perform the operation automatically.
When attempting to measure the signal of circuits manually, try to fit the waveform to the
scope display. The larger the waveform is on the screen the greater the accuracy of the
measurement. Adjust the vertical control knob if the wave form is too short or too tall to fit on
vertical axis of the screen. This knob controls the volts per division (volts per box). To change
the scaling on the horizontal axis, adjust the time base of the scope. Expand or compress the
waveform time axis by changing the position of this control. This control changes the time per
division.
Common measurements made on an oscilloscope are signal frequency, peak voltage levels, and
phase shift between to signals. Modern scopes take digital samples of signals and can perform
a number of other measurements. They can also store waveform samples for later analysis
using advanced mathematical functions that can display the frequency content of complex
signals.
Oscilloscopes can measure both AC and DC signals when the scope’s input mode is set to DC,
which stands for direct coupling. Changing the input mode to AC will block any DC signal and
allow only AC signals to pass. Use this mode when there are combined AC/DC levels on a signal.
An example of this use is examining the AC ripple voltage on a DC power supply.
Scopes should always be used with a proper set of probes. The probes should have the same
frequency range as the rating of the scope for best performance. The 10x probe provides a 10
times range increase and also reduces the scopes loading effect on the circuit under test. Scope
probes should be properly compensated before measurements are made. Review the video
presentations that show how to make this adjustment.
All scope measurements are made with respect to the ground reference. The scope will read
incorrect values when place across components that have both leads connected to points other
than ground. It will display correctly when one component lead is connect to ground.
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Objective
The objective of this lab is to further the students’ knowledge in the use of oscilloscopes. The
students will be able to measure the peak voltage and period of different signals and calculate
their frequencies.
Procedure
1. Construct the circuit shown in Figure 1 on the SEB.
Figure 1. Test Circuit 1.
2. On-Campus Students: Inform the TA/Instructor that the circuit is constructed so they
can set up the signal generator. They will set the signal source to 1000 Hz sine wave and
4.5 V peak.
On-line Students: Review the tutorial videos that show how to set the output of the
Arbitrary Waveform Generator (AWG) found in the Analog Discovery 2 (AD2). Set the
AWG to output a 1000 Hz sine wave with a 4.5 V peak value and connect it between
points A and ground.
3. On-Campus Students: Sketch and measure manually the waveform from points A to C
and from B to C. Use the graph pages and tables in Appendix A end of this handout to
document the measurements. Measure the peak-to-peak amplitude of the signal and its
period. Compute the frequency from the measured period. Use the formula below to
find the frequency.
f=
Where:
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T
T = period in seconds (S)
f= frequency in Hertz (Hz)
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Enter these measurements and calculations in Table 1. Review presentation slides for
the details of these measurements.
On-line Students: Use the scope input of the AD2 and the WaveForms 2015 software to
display the scope output. Display the signal from points A to C and from points B to C.
Export the WaveForms display for both measurements to Appendix B of the Word
document version of this lab for later submission. See the tutorial video on exporting
the display for more details. Use the AD2 and WaveForms scope measurement
functions to find the, peak-to-peak amplitude, the signal period and frequency. Enter
these measurements and calculations in Table 1 in Appendix B.
4. Construct the circuit shown in Figure 2 on the SEB.
C
B
R8
22k
C4
1uF
+
R7
10k
1kHz
Figure 2. Test Circuit 2.
5. On-Campus Students: Maintain the signal used in step 2 and connect it between points
A and ground on Test Circuit 2.
On-line Students: Maintain the signal used in step 2 and it between points A and
ground.
6. On-Campus Students: Sketch and measure manually the waveform from points A to C
and from B to C. Use the grids provided in Appendix A and record the horizontal and
vertical scales. Measure the peak-to-peak amplitude of the signal and its period.
Compute the frequency from the measured period. Enter these measurements and
calculations in Table 2 in Appendix A.
On-line Students: Use the scope input of the AD2 and the WaveForms 2015 software to
display the scope output. Display the signal from points A to C and from points B to C.
Export the WaveForms display for both measurements to Appendix B for later
submission. Use the AD2 and WaveForms scope measurement functions to find the,
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peak-to-peak amplitude, the signal period and frequency. Enter these measurements
and calculations in Table 2 in Appendix B.
7. Construct the circuit shown in Figure 3 on the SEB.
AA
C
B
R4
22k
+
1kHz
R3
10k
C2
1uF
Figure 3. Test Circuit 3.
8. On-Campus Students: Maintain the signal used in step 2 and connect it between points
A and ground on Test Circuit 2.
On-line Students: Maintain the signal used in step 2 and it between points A and
ground.
9. On-Campus Students: Sketch and measure manually the waveform from points A to C
and from B to C. Measure the peak-to-peak amplitude of the signal and its period.
Compute the frequency from the measured period. Enter these measurements and
calculations in Table 3 of Appendix A.
On-line Students: Use the scope input of the AD2 and the WaveForms 2015 software to
display the scope output. Display the signal from points A to C and from points B to C.
Export the WaveForms display for both measurements to Appendix B for later
submission. Use the AD2 and WaveForms scope measurement functions to find the,
peak-to-peak amplitude, the signal period and frequency. Enter these measurements
and calculations in Table 3 of Appendix B.
Discussion Points
What does the horizontal control knobs do? What does the vertical control knobs do? What is
the trigger function used for? Why are there little boxes on the oscilloscope screen? What
happened when you put the capacitor in the two circuits?
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Appendix A
On-campus Student Measurements and Graphs
Test Circuit 1 Measurement and Waveforms
Table 1-Figure 1 Circuit Measurements
Measurement
A-C
B-C
Peak-to-Peak Volts Period (seconds)
Frequency (Hz)
Test Circuit 1 Voltage Measurement A-C
Channel 1 Volts/div ______
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Channel 2 Volts/div _______
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Time/div __________
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Test Circuit 1 Measurement and Waveforms
Test Circuit 1 Voltage Measurement B-C
Channel 1 Volts/div ______
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Channel 2 Volts/div ________
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Time/div __________
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Test Circuit 2 Measurement and Waveforms
Table 2-Figure 2 Circuit Measurements
Measurement
A-C
B-C
Peak-to-Peak Volts
Period (seconds)
Frequency (Hz)
Test Circuit 2 Voltage Measurement A-C
Channel 1 Volts/div ______
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Channel 2 Volts/div __________
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Time/div __________
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Test Circuit 2 Measurement and Waveforms
Test Circuit 2 Voltage Measurement B-C
Channel 1 Volts/div ______
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Channel 2 Volts/div _________
9
Time/div __________
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Test Circuit 3 Measurement and Waveforms
Table 3-Figure 3 Circuit Measurements
Measurement
A-C
B-C
Peak-to-Peak Volts
Period (seconds)
Frequency (Hz)
Test Circuit 3 Voltage Measurement A-C
Channel 1 Volts/div ______
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Channel 2 Volts/div _______
10
Time/div __________
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Test Circuit 3 Measurement and Waveforms
Test Circuit 3 Voltage Measurement B-C
Channel 1 Volts/div ______
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Channel 2 Volts/div _____
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Time/div __________
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Appendix B
On-Line Student Measurements and Graphs
Test Circuit 1 Measurement and Waveforms
Table 1-Figure 1 Circuit Measurements
Measurement
A-C
B-C
Peak-to-Peak Volts Period (seconds)
Frequency (Hz)
Test Circuit 1 Voltage Measurement A-C
Remove this box and add the scope plot from Waveforms
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Test Circuit 1 Measurement and Waveforms
Test Circuit 1 Voltage Measurement B-C
Remove this box and add the scope plot from Waveforms
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Test Circuit 2 Measurement and Waveforms
Table 2-Figure 2 Circuit Measurements
Measurement
A-C
B-C
Peak-to-Peak Volts
Period (seconds)
Frequency (Hz)
Test Circuit 2 Voltage Measurement A-C
Remove this box and add the scope plot from Waveforms
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Test Circuit 2 Measurement and Waveforms
Test Circuit 2 Voltage Measurement B-C
Remove this box and add the scope plot from Waveforms
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Test Circuit 3 Measurement and Waveforms
Table 3-Figure 3 Circuit Measurements
Measurement
A-C
B-C
Peak-to-Peak Volts
Period (seconds)
Frequency (Hz)
Test Circuit 3 Voltage Measurement A-C
Remove this box and add the scope plot from Waveforms
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Test Circuit 3 Measurement and Waveforms
Test Circuit 3 Voltage Measurement B-C
Remove this box and add the scope plot from Waveforms
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