ELEC 2010 Laboratory Manual Experiment 2 In-Lab Procedure Page 1 of 5

Experiment 2 In-Lab Procedure and Report (30 points) Before starting the procedure, record the table # you are working at in your Lab Report. Also record the EE Inventory # of any equipment that you use.

(1) Familiarize yourself with the equipment. You will use the oscilloscope:

Time Base controller

DISPLAY

Power

Revised August, 2006

the function generator:

FREQUENCY ADJUST

POWER

FREQUENCY MULTIPLIER

MAIN OUTPUT

AMPLITUDE ADJUST

AMPLITUDE RANGE (HI/LO)

DC OFFSET

Left Channel Controls

Right Channel Controls

ELEC 2010 Laboratory Manual Experiment 2 In-Lab Procedure Page 2 of 5

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and the digital multimeter (DMM):

You should make sure your wire tray has 4 each of the following: • longer black cables • shorter black cables • longer red cables • shorter red cables In addition to these cables, you will need one BNC-to-dual banana plug and BNC-to-BNC cable.

(2) Perform a continuity test on each of your 16 standard banana-plug cables to determine if any are broken. Follow the same procedure you learned in Experiment 1. Let your instructor know if you find any bad cables. After measuring all your cables and replacing any bad ones, you are ready for the rest of the experiment. For your lab report, write a statement such as: “Tested all cables, all were within acceptable resistance range (less than 1.0 Ω),” or “Performed continuity test on all cables, one was found to be defective and replaced.”

(3) Initialize the oscilloscope. This is the procedure you should follow throughout the semester each time you prepare

to use the oscilloscope for an experiment.

(a) Remove any input cables and turn on the main power by pushing the button marked “POWER” on top left of the scope

(b) Just press the AutoSet button to automatically set the scope to the desired state. Further initialization details of the scope can be found in the manual in the lab. [Make sure you have a manual at hand before you start working on the scope.]

(4) Follow your instructor’s directions of the oscilloscope controls and functions. Your instructor may pause to let you practice using the controls at your station.

You may view the in-lab video showing the oscilloscope controls and functions after lab hours.

(5) Re-establish the reference display from step (3). (6) Initialize the Function Generator.

(a) Turn on the power (press in the red button). (b) Press in the Amplitude Range button (select HI range = 0 dB). (c) Set the WAVEFORM to sine wave (leftmost button). (d) Turn the DC OFFSET knob fully CCW so it clicks “OFF.” (e) Set the AMPLITUDE knob to the middle of its range. (f) Set the FREQUENCY knob close to 1. (g) Set the RANGE to 1 kHz.

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Now the Function Generator is producing a 1 kHz sine wave with an amplitude of several volts. (7) Connect the Function Generator to the Oscilloscope and observe the sine wave.

(a) Using a BNC-to-BNC plug cable, connect the 600 Ω output of the Function generator to the input of the

oscilloscope. (b) On the left-channel control panel of the oscilloscope, press the coupling button to the DC. (c) Get a display exactly as shown in Figure 7. You will need to do the following:

• adjust the function generator amplitude carefully until the sine wave extends from 2 divisions below the center line to two divisions above the center line,

• adjust the triggering controls LEVEL and SLOPE until the display appears to freeze on the screen. • change the sweep rate to 0.5 ms per DIV, and carefully adjust the frequency of the sine wave until one period

covers two grid divisions

Now you should have a display just like the one shown in Figure 7.

(d) For your lab report, make a sketch of the display. Your instructor will provide oscilloscope display templates to make your sketching easier. On the sketch, label your axes, including units. An example of a properly labeled sketch is shown in Figure 8.

(e) Using the DMM, measure and record the amplitude of the sine wave. The DMM must be set to “AC.”

The DMM does not display peak value. For sine waves, the DMM gives the RMS (root-mean-square) value. This is a scale widely used in AC measurements. The RMS value of a sine wave is equal to the peak value divided by the square-root of 2 ( = 1.414). Make a table like the one below in your report, and fill in your own readings and calculations. In the table, some typical results are shown in italics as a guide. Replace these with your own readings and calculations. Use the following relation for percent difference:

Percent Difference = ' 100%O scope DMM

DMM− ×

DMM reading (RMS)

Peak amplitude calculated from DMM

reading (= RMS X 1.414)

Amplitude from oscilloscope display = (peak-to-peak) / 2

Percent difference

1.38 V 1.95 V 2.0 V 2.6 % (8) Display the following signals. (The DMM will not be used for this step. It can be disconnected.). For each

waveform, adjust the display controls so that you see at least two full periods on the screen, and the signal extends as far as possible vertically without going beyond the grid area. In your report, make a table like the one shown. Fill in the column labeled “Period.” For each display, have your instructor or an assistant observe your display and initial your table. Make a sketch of each display.

Signal # Wave-shape

Frequency Period Peak Amplitude

Instructor Initials

1 Sine 100 kHz 5 V 2 Square 100 Hz 10 V 3 Triangle 1.8 kHz 3.6 V

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(9) Observe the effect of the function generator DC Offset. (a) On the function generator, turn off all the waveforms (this can be accomplished by pushing any of the “out”

waveform buttons just part of the way in. All three waveform buttons should now be “out.”). Also, set the Amplitude to the "min" position.

(b) On the oscilloscope Left Channel control panel, set the scale to 0.1 V/DIV. Select coupling to GND and check the position of the reference trace. Carefully reposition it to the center of the screen.

(c) Prepare the oscilloscope to display DC as well as AC by setting coupling to DC . (d) Now set the DMM to measure DC volts, and connect it to the function generator output simultaneously with the

oscilloscope. (e) Turn on the DC Offset on the function generator. You should notice the oscilloscope trace shifts vertically, perhaps

even off the screen. Turn the DC offset knob carefully to the point where the oscilloscope display returns to the reference position (the knob pointer should be in the general vicinity of the 12 o’clock position). The DMM should read close to zero. Adjust the DMM range to obtain maximum precision. Record the DC voltage as indicated by the DMM reading and the oscilloscope display.

(f) Using the table below to guide you, set the DC offset as close as possible to each value, then record the oscilloscope reading, the DMM reading, and calculate the percent difference using the DMM as the “correct” value. In each case, obtain the maximum available precision from your instruments by careful choice of scale factors. You must re-zero the reference display on the oscilloscope each time you change the VOLTS/DIV setting. In the table below, some typical values are shown in italics as a guide. You should replace these with your own readings and calculations.

Target value

Actual DMM reading

DMM range setting

O’scope reading

O’scope VOLTS/DIV setting

Percent difference between O'scope and

DMM readings 0.1 V 98.8 mV 200 mV 0.1 V 0.1 1.2 % 1.0 V 1.037 V 2 V 1.0 V 0.2 – 3.6 % 10 V 10.39 V 20 V 10.0 V 2 – 3.8 %

(g) With the DC offset set to near zero, select and display a 1 kHz sine wave with peak amplitude of 2 V. Now rotate the DC offset knob in both directions. What happens? Record your observations in your report.

(h) With the DC offset set at 1 V (measured on the DMM),select coupling to AC so that it will display AC-only. What happens? Record your observation and a brief explanation.

(i) With the DC offset set at 1 V (measured on the DMM), select AC on the DMM. Change the range setting if necessary to avoid an over-range reading. What happens? Record your observation and a brief explanation.

(10) Workstation clean-up.

(a) Turn off the DMM. (b) Turn off the Oscilloscope and the Function Generator. (c) Put all wires back in the wire tray neatly. (d) Discard any trash, and arrange equipment neatly on your table.

Review and Report Completion Finish writing your lab report, following the outline given in the Course Information. Submit your lab report to your instructor before leaving the lab.

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Figure 7 (a) Function generator connected to oscilloscope. A sine wave with frequency 1 kHz and amplitude of 2 V is shown.

(b) Detail of oscilloscope connection.

-4

-3

-2

-1

0

1

2

3

4

0 1 2 3 4 5

Time (ms)

Volta

ge (V

)

Figure 8. Example sketch of oscilloscope display, showing proper labeling.

HORIZ: 0.5 ms/DIV VERT: 1 V/DIV

Experiment 2 In-Lab Procedure and Report (30 points)Review and Report Completion