3.4 Lab Assignment Oscilloscope

docx

School

ECPI University *

*We aren’t endorsed by this school

Course

113

Subject

Electrical Engineering

Date

Apr 3, 2024

Type

docx

Pages

Uploaded by sonofliberty78

Electric Circuits LAB EET113 Unit-3 Lab#6 Familiarization with Signals & the Oscilloscope By: Trevor Davis Date: 01/08/2023 Online EET Department ECPI University I pledge to support the Honor System of ECPI. I will refrain from any form of academic dishonesty or deception, such as cheating or plagiarism. I am aware that as a member of the academic community it is my responsibility to turn in all suspected violators of the honor code. I understand that any failure on my part to support the Honor System will be turned over to a Judicial Review Board for determination. I will report to a Judicial Review Board hearing if summoned. Name Trevor Davis Date 01/08/2023

Familiarization with Signals & the Oscilloscope Direct Current (DC): In EET110 you were introduced to Direct Current (DC) which always flows in the same direction, but it may increase and decrease. Electronic circuits normally require a steady DC supply. The DMM (Digital Multi Meter) is used to measure DC values of voltages and currents. Alternating Current (AC): In EET111 / EET111L, you will be presented with Alternating Current (AC) which flows one way, then the other way, continually reversing direction. An AC voltage is continually changing between positive (+) and negative (-). The rate of changing direction is called the frequency of the AC and it is measured in Hertz (Hz) which is the number of cycles per second. For AC signal measurements, a tool called an Oscilloscope is used where its primary function is to provide a graph of a signal's voltage over time. You will download this file and use it as your lab report. For this lab, most of the experiments are setup for you. You need to verify and understand the experiments. Next, you need to complete the remaining experiments. Finally, submit your lab report and your Multisim files.

Mandatory Lab Conduct Figures All of your lab reports will require a “screenshot” figure containing the MultiSim circuit, the computers system tray, and the file information window. Your instructor needs to see the “Time Stamp” on this screenshot to make sure your work is original. An example of the screenshot is illustrated below with the required items circled in red. This figure with the required components is captured by: 1) Displaying the file information window=>Select “File”, then “File Information.” 2) For Windows based computers, press the Print Screen key on your keyboard and then paste the figure into your Word document. 3) For Mac computers using XenDesktop, press at the same time “Command”, “Shift”, and “3” in order to take a screenshot or press “Command”, “Shift”, and “4” in order to generate cross-hairs with your pointer that can be used to select the area that you want to copy. In either case, the screenshot/desired image will be automatically saved to your computer desktop (Not the XenDesktop). You will need to insert the screenshot/desired image into your Word document. For this lab, the required screenshot figure will be placed in the section labeled, “ Place your screenshot with “Time Stamp” Here ”. For future labs, you will need to place the screenshot in the Method and Procedures section, after the step where you discuss the downloading of the MultiSim file.

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Part 1 Perform the following lab procedure on Multisim and verify your answers 1. Open the MultiSim software (On XenDesktop or on your laptop) and run the downloaded file “OscopeFunctionGenMultimeterUpdated.ms8" (some updated files will be named *.ms14) 2. Place your screenshot with “Time Stamp” Here. For future labs, you will do this. 3. Double click on the Oscilloscope (O’Scope) icon. When the O’Scope opens, review the O’Scope controls in each of the major groups (Timebase, Channel A, Channel B, and Trigger). Also, don’t forget the purpose of the Time Marker and the corresponding readouts. Note-1: In the future, when you are constructing your own circuit, the Oscilloscope is the 4 th tool from the top in Multisim right pane, the DMM is the 1 st tool and Function Generator is the 2 nd tool. 4. Make sure the O’Scope Timebase Scale is set to 5 mSec/Div and the Channel A and Channel B Scales are set to 2V/Div each by clicking on the UP/DOWN arrows inside the Scale field and the AC/0/DC source button pushed AC, and select AUTO triggering button. 5. Next, double click on the Function Generator icon. When the Function Generator opens, review the Function Generator controls in each of the major groups (Waveforms

and Signal Options). 6. Make sure the Function Generator Waveforms has the sine wave ( ~ ) pushed in, with the Frequency set to 100 Hz, the Amplitude set to 10 V Peak and the Offset to 0 V DC . 7. Double click on the Digital Multimeter (DMM) icon. When the Digital Multimeter opens, review the Digital Multimeter controls in each of the major groups (Measurement Selector Buttons and AC/DC Selector Buttons). Make sure the DMM is set to V for voltage measurements, and AC ( ~ ) for type of voltage/current measurements. Verify your settings. 8. Turn on the Multisim circuit using the 1/0 (ON/OFF) switch and verify the DMM reading indicates 3.535 V rms . Turn the circuit off. 9. QUESTION : If the Function Generator has an output set at 10 V P, ( = 20 V PP ) why does the DMM read what it does? Please explain your answer and provide proof. You may need to work the V PP à V P à V rms formulas from your textbook to obtain the correct answer. Keep in mind that a DMM measures the RMS (Root Mean Squared) value of an AC signal where Vrms = 0.707 Vp. DMM Vrms reading = 𝑉 𝑟𝑚𝑠 = 0.707 ⋅𝑉 𝑝 = 0.707 ⋅ 5 = 3.535 𝑉 𝑟𝑚𝑠 10. Now we will use the O’Scope to measure the AC voltage being supplied by the Function Generator. The following steps will guide you: (a) Turn on the circuit using the 1/0 (ON/OFF) switch . When the waveform is almost all the way across the O’Scope display, turn the circuit OFF. (b) Calculate and record the Period (T) of 1 cycle.

Note-2 : Use the formula T = 1 / f (c) Measure and record the Frequency (f), Voltage Peak (V P ), and the Voltage peak- to-peak (V PP ) of the waveform Note-3 : Pay attention to your circuit. There are two resistors (R1=R2=1KΩ) connected in series. Therefore, the supplied voltage from the function generator will be divided equally across the resistors and you are checking the voltage across R2 only. Period (T) = 10ms Frequency (f) = 100 Hz Amplitude of Peak Voltage ( Vp ) = 4.992 𝑉 𝑝 Amplitude of Peak-to-Peak Voltage (Vpp) = 9.984 𝑉 𝑝𝑝 (d) Do your results agree with the Function Generator settings? See Note-2 above. Yes (e) Place your Multism screenshot here. Multisim screenshot for the first row in Table-1

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

11. Set the Function Generator to each value listed in Table 1 (Left column) and record your readings in Table 1. Measure each voltage using the above steps as a guide. The first line of the table has been completed as an example. To obtain accurate readings with the oscilloscope, it is necessary to select the Channel A or Channel B Scale VOLTS/DIV and the Timebase Scale settings. This gives several divisions of change between the ground or zero time reference and still provides a complete waveform that is viewable on the O’Scope display. 12. You can also verify your calculations and measurements by using the Time Markers T1 and T2 (the blue and red triangle at the top of the O’Scope screen that can clicked and dragged) and corresponding readouts. Students will complete the table below. TABLE 1 Function Generator Settings O’Scope Channel VOLTS/DIV Setting Number of O’Scope Display Divisions Deflected O’Scope Measured Voltages (V PP and V P ) DMM Measured Voltage Calculated Vrms With Math Calculations 100 Hz / 10 V P 2 V / Div 5 9.98 V PP / 4.99 V P 3.536 V rms V P = V PP /2 = 10/2 = 5 V P V RMS =0.707*V P =0.707*5=3.535V RMS 500 Hz / 20 V P 5V/Div 5 19.96 𝑉 𝑝𝑝 / 9.98 𝑉 𝑝 7.071 𝑉 𝑟𝑚𝑠 𝑉𝑝 = 𝑉𝑝𝑝 / 2 = 19.96/ 2 = 9.98 𝑉𝑝 𝑉 𝑟𝑚𝑠 = 0.707 ⋅𝑉 𝑝 = 0.707 ⋅ 9.98 ¿ 7.056 𝑉 𝑟𝑚𝑠 1 kHz / 30 V P 10 V/Div 5 29.95 𝑉 𝑝𝑝 / 14.975 𝑉 𝑝 10.606 𝑉 𝑟𝑚𝑠 𝑉𝑝 = 𝑉𝑝𝑝 / 2 = 29.95/ 2 = 14.975 𝑉𝑝 𝑉𝑟𝑚𝑠 = 0.707 ⋅𝑉𝑝 = 0.707 ⋅ 14.975 ¿ 10.587 𝑉 𝑟𝑚𝑠 2 kHz / 50 V P 10 V/Div 10 49.916 𝑉 𝑝𝑝 / 24.958 𝑉 𝑝 17.677 𝑉 𝑟𝑚𝑠 𝑉𝑝 = 𝑉𝑝𝑝 / 2 = 49.916 / 2 = 24.958 𝑉𝑝 𝑉𝑟𝑚𝑠 = 0.707 ⋅𝑉𝑝 = 0.707 ⋅ 24.958 ¿ 17.545 𝑉 𝑟𝑚𝑠

Part 2 Conclusion - Evaluation and Review Questions (Students will complete this part) 1. Compute the percent difference between the DMM measurement and the oscilloscope measurement for each DC voltage measurement summarized in Table 1. % difference = (1- ( V RMS-Scope / V RMS-DMM ) ) x 100 Where, TABLE 2 shows the %difference results: Complete the table below and answer parts 2,3,4 below. TABLE 2 Function Generator Settings %diff between DMM and O’Scope from table-1 100 Hz/ 10V P 0.23% 500 Hz/ 20V P 0.21% 1 k Hz/ 30V P 0.18% 2 k Hz/ 50V P 0.18% 2. Describe the four major groups of controls on the oscilloscope and the purpose of each group. ANS: 3.4*5.0=17V 3. (a) If an ac waveform has 3.4 divisions from peak to peak and the VOLTS/DIV control is set to 5.0V/div., what is the peak-to- peak voltage? ANS: 𝑉 𝑝 = 𝑉 𝑝𝑝 /2 = 17/2=8.5 (b) What is the rms voltage? ANS: 𝑉 𝑟𝑚𝑠 = 0.707 ⋅𝑉 𝑝 = 0.707 ⋅ 8.5 = 6.01 𝑉 𝑟𝑚𝑠 4. If you wanted to view an ac waveform that was 20.0VPP, what setting of the Scale VOLTS/DIV control would we use? ANS: 2V/Div

Part 3 FUTHER INVESTIGATION (Students will complete this part)  Most function generators have a control that allows you to add or subtract a dc offset voltage to the signal.  Set the O’Scope Channel A - AC/0/DC source buttons pushed “AC” and the Timebase Scale to 500 μSec. Connect Channel-B of the O’Scope also across R2, but set the AC/0/DC source buttons pushed “DC”.  Set up the function generator for a 1.0 KHz sine wave signal with 5 Vp, and the Offset to 5VDC. Explain what the Offset control does Note-4 : (You need to toggle between O’Scope Channel A - AC/0/DC source buttons AC and DC to be able to see the DC offset. If you click on AC button, scope will show only AC, but if you click on DC, the scope will show AC+DC)  Turn the circuit ON and once the waveform is almost all the way across the screen from left to right then TURN THE CIRCUIT OFF, and observe the O’Scope display. What happened to the AC waveform? Note-5 : How to change color of a signal on an oscilloscope. Terminal-A shows “RED” and terminal-B shows “Blue” (If both have the same color, it is hard to distinguish between them on the Oscilloscope). In Multisim, click of the wire going to the terminal-A or terminal-B, click on “Segment Color”, then pick a different color.  Explain what you observe and why this happened. (Students will write an explanation) Place your screenshot here.

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Explanation: The Oscilloscope offset changes the channels ref level in relation to ground. It will add +5V to the ac signal. But since scope is across one resistor, it will move up the AC signal across R2 by +2.5V. The red signal on the O-Scope is AC only and the blue signal is AC+DC.  Then measure the signal with your DMM. First measure it in the AC VOLTAGE position; then measure in the DC VOLTAGE position. Explain what you observe, and why this happened. Explanation: The DMM only displays V or I in RMS only. When the oscilloscope in the AC voltage position my readings were 1.768V and in the DC voltage position I showed 2.5V.  Place your Multism screenshot here with DMMs readings

3.4 Lab Assignment Oscilloscope

Related Documents