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ELEX 143 - Lab Exercise 1

CAMOSUN COLLEGEElectronics & Computer Eng. Dept.

ELEX 143 - LAB 1INTRODUCTION TO THE OSCILLOSCOPE

Objectives:

To become familiar with the operation of a bench oscilloscope and function generator.

To become familiar with MULTISIM simulation software.

Discussion:

This lab contains a few exercises to familiarize the student with the function generator and HP54645Aoscilloscopes various controls, menus and other functions. The function generator and DSO (DigitalStorage Oscilloscope) will be used extensively during future labs.

Refer to the HP equipments operator manual when in doubt.

Procedure:

Set the Function Generator Output

1. Set the output to high impedance. Shift-Menu Sys Menu Out Term Enter.This should be done for every lab unless 50ohm output is specifically required.

2. Adjust the function generator to output 1kHz, 1Vrms sine wave output

Display a single waveform

1. Power up the oscilloscope.

2. Connect a probe from channel 1 to the calibration tab.

3. Press the 1 button to turn on channel one of the display.

4. Set the coupling to DC.

5. Turn off channel 2.

6. Set the trigger source to channel 1 and the mode to Auto level.

7. Adjust the Time/Div and Volts /Div to display a stable waveform showing one or two completecycles.

8. Adjust the probe compensation to obtain a square wave without overshoot.

Jan 2010 IB/AB Page 1 of 7

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9. Calculate the amplitude and period of the waveform by counting the number of divisions on thegraticule.

10. Turn on the cursors and using the time and voltage buttons confirm your calculations. Make note ofthese observations below.

VPP = f =

T = Duty Cycle =

AC and DC coupling

1. Connect the scope probe to the function generator using a BNC to crock clip cable or use a directBNC to BNC connection.

2. Capture the waveform on the oscilloscope. You will need to adjust the Time/Div and the Volts/Div.

3. Add a 2V DC offset to the function generator and sketch the waveform using DC coupling and thenAC coupling.

4. Explain in your own words the difference between AC coupling and DC coupling and its effect on thedisplayed waveform.


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Triggering

1. Connect the function generators output to channel 1 and set it to 5Vpp 1kHz sinewave

2. Switch the trigger source between channel 1 and channel 2. What do you observe?

3. Set the trigger mode to normal. Adjust the trigger level control. What do you observe?

4. Return the oscilloscope trigger control to auto-level.

5. What do you conclude is the function of triggering on the oscilloscope?

Screen Capture

6. Follow the instructions posted in the lab to obtain a screen capture of the displayed waveform. Youwill need this function to gather screen captures for future lab reports.

Probe Setting

7. Use the measure function to display the peak-to-peak voltage of the function generator waveform.

8. Adjust the probe setting control under the channel menu and observe the effect on the voltage

displayed on the scope. What do you conclude about effect of the oscilloscope probe setting on thewaveform amplitude measured?

9. Adjust the probe x10 switch and observe the effect of the waveform. What do you conclude about

effect of the probe switch setting on the waveform amplitude measured?


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Testing a simple RC circuit

1. Connect the following circuit on a breadboard. Measure and record the actual values ofR1 andC1 using the LCR bridge instrument.

C10.1uF

R1

1KTo

Oscilloscope

FromFunctionGenerator

Vin Vout

2. Connect channel 1 of the DSO to Vin and channel 2 to Vout.

3. Adjust the function generator as follows:

Function: SineFrequency: 10 Hz ( May be hard to trigger on, try 1 kHz and turn down slowly )Amplitude: 1 Vpp ( Maintain this Vin for each frequency change in step 4 )

Offset: 0 V

4. Changing only the frequency, measure Voutppat: 10 Hz, 100 Hz, 500 Hz, 1kHz, 5kHz, and 10kHz. Plot your results below. Also make special note of the frequencies when Voutppequals0.707 V and 0.50 V.

1.2

1.0

0.8

0.6

0.4

0.2

01 10 100 500 1K 5K 10K

Voutpp

(V

olts)

Frequency (Hz)

5. Based on your data and graph determine the frequency when the output voltage is equal to 0.707volts. Is this point significant?

Simulating a simple RC circuit Using MULTISIM simulation software.


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4. Adjust the settings on the Bode plotter as shown below:

5. Verify that the simulated Bode plot matches the plot obtained with the real components.6. Now adjust the potentiometer to 25% and 75% and restart the simulation. What effect do you

notice on the Bode plot.

Lab Report:


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A. Explain the function of the following oscilloscope controls in your own words:

1. Volts/div2. Time/div3. AC/DC coupling4. Triggering5. Probe setting/probe switch

B. Hand in the two simulated schematics that you produced plus screen captures of theoscilloscope and Bode plot data.


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