ANADOLU UNIVERSITY
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
EEM 102 INTRODUCTION TO ELECTRICAL ENGINEERING
EXPERIMENT 5
OSCILLOSCOPE
Prepared by Prof. Dr. Atila BARKANA
EXPERIMENT 5
OSCILLOSCOPE
OBJECTIVE:
To learn how to use an oscilloscope to observe signals and do various measurements.
PRELIMINARY WORK:
Read the INTRODUCTION carefully. Go to the lab and examine the front panels of the
oscilloscope and the function generator before your lab hour.
INTRODUCTION:
Oscilloscope:
Oscilloscopes are used to display electrical signals for visual observation. Besides seeing the fine
details of the signal, it is possible to make various measurements such as peak-to-peak voltage,
instantaneous voltage, period and frequency, rise time, phase difference, etc. Hence, they are
extremely important for electrical engineers.
The oscilloscopes that you will be using in the lab are Textronix 2205. It is a dual-channel 20
MHz instrument. The front panel is divided into 4 major sections. These sections and the contents,
connections and indicators on the front panel will be explained to you in the lab.
Function Generator:
Function generators are devices that can provide various signals. The Textronix CFG 250
Function Generator that you will use has the following properties:
Frequency range: 2.0 Hz to 2 MHz using the 7 push buttons and the variable control.
Output signals: Square wave, sine wave, saw tooth wave. (Also TTL pulse and sweep
function for all outputs)
Frequency Accuracy: 5% of full scale.
Main Output Amplitude:
1. With the VOLTS OUT button pushed in: 10 mVpp to 2 Vpp (open-circuit).
2. With the VOLTS OUT button pushed out: 100 mVpp to 20 Vpp (open-circuit).
Output impedance: 50Ω 10%
DC Offset: -10 V to +10 V (open circuit)
Duty cycle: 5 to 1 minimum duty cycle change. (50% at max CCW or Cal Position)
PROCEDURE:
Use of the Oscilloscope:
Adjust the function generator controls as follows:
Control
Power button
RANGE
FREQUENCY Dial
DUTY Control
DC Offset
AMPLITUDE Control
INVERT button
VOLTS OUT button
FUNCTION button
SWEEP button
Setting
On
1 KHz button pushed in
1.0
In
In
Centered
Out
Out
Sine wave button pressed in
Out
Turn on the Oscilloscope, connect the function generator output to the CH1 input and set
the VERTICAL MODE to CH1.
A. Peak-to-peak Voltage Measurement
1. Set the VOLT/DIV to 2 VOLT/DIV calibrated.
2. Since 1 KHz signal has a period of 1 ms and there are 10 divisions available horizontally on the
display, set the SEC/DIV to 0.5 ms calibrated. You will observe several cycles on the screen.
3. Adjust the vertical position so that the minimum points of the signal coincides with one of the
horizontal graticule lines.
4. Adjust the horizontal position so that one of the maximum points of the signal coincides with
the center vertical graticule line.
5. Measure the number of divisions of vertical deflection from peak to peak.
6. Calculate the peak-to-peak voltage by multiplying the vertical deflection divisions with the
VOLTS/DIV setting.
B. Time Measurement
1. Adjust SEC/DIV so that you observe only one period in the calibrated (CAL) detent.
2. Position the display in such a way that the signal crosses the center horizontal graticule.
3. Measure the number of divisions that a single period takes (the horizontal distance between the
zero-crossings).
4. Calculate the period by multiplying the horizontal distance with the SEC/DIV control setting.
5. You can also calculate the frequency by dividing 1 to the period ( f
1
).
T
C. Phase Difference Measurement:
1. Set up the circuit below.
2. Adjust the function generator so that f = 1 KHz, Vpp = 1 V and connect it between A and B.
3. Connect CH1 between A and B, and CH2 between D and B to compare the input and output
signals.
4. Adjust the VOLTS/DIV controls of both channels to observe the signals properly.
5. Adjust the SEC/DIV to 0.1 ms to observe about one full period.
6. Set the trigger source to CH1 and adjust the TRIGGER LEVEL until a stable CH1 signal is
observed.
7. Center both signals vertically to be able to measure the distance between them.
8. Measure the distance D between the positive zero-crossings of both signals.
9. Measure the number of divisions p of one period of one of the signals. One period corresponds
to 360 ° of phase.
10. Calculate the phase difference between the two signals using the following formula:
PhaseDiffe rence
360 0
*D
p
Name: …………………………..
No :…………………………......
Table No:……………………….
Group :…………………………..
EXPERIMENT 5
OSCILLOSCOPE
REPORT
A-1. Peak-to-peak voltage of the signal:.......................................................................................
A-2. Set the multimeter to measure AC Volts and measure the voltage.
Multimeter reading:.......................................................................................................................
A-3. Calculate Vrms
Vm
2
where Vm
VPP
2
is the maximum value.
Vrms =...............................
A-4. Compare the results in A-2 and A-3.
.......................................................................................................................................................
.......................................................................................................................................................
B-1. Period = .................. divisions
= ................... seconds
Frequency = .................... Hz.
C.1. What is the phase difference between the two signals?
.......................................................................................................................................................
C.2. Change C to 220 nF. Find the phase difference.
Phase difference = ........................................................................................................................
Date:
Table No:
Name:
No:
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