1 clemson ece laboratories pre-labs for ece 211 created by guneet bedi on 09/03/2012 last updated:...

1 Clemson ECE Laboratories Pre-Labs for ECE 211 Created by Guneet Bedi on 09/03/2012 Last Updated: 12/15/2012

2 Clemson ECE Laboratories ECE 211 - Electrical Engineering Lab I Pre-labs for ECE 211 Guneet Bedi Created: 09/03/2012 Updated: 09/03/2012

3 Clemson ECE Laboratories

4 Introduction This laboratory course operates in co-ordination with the companion lecture course, ECE 202, Electric Circuits 1. It is intended to enhance the learning experience of the student in topics encountered in ECE 202.

5 Clemson ECE Laboratories Lab Objectives Through this lab, students are expected to:- 1.Gain proficiency in the use of common measuring instruments. 2.Compare theoretical predictions with experimental results and explain any differences. 3.Develop verbal and written communication skills through:- a.Maintenance of succinct but complete laboratory notebooks and reports. b.Verbal interchanges with the laboratory instructor and other students.

6 Clemson ECE Laboratories Lab Objectives contd 4.Enhance understanding of the basic electric circuit analysis concepts including:- a.Independent and dependent sources. b.Passive circuit components (resistors, capacitors, inductors, and switches). c.Ohms law, Kirchhoffs voltage law, and Kirchhoffs current law. d.Power and energy relations. e.Thevenins theorem and Nortons theorem. f.Superposition

7 Clemson ECE Laboratories Student Responsibilities The student is expected to be prepared for each lab. Active participation by each student in lab activities is expected. The student is expected to ask the teaching assistant any questions he/she may have. The student should understand the concepts and procedure of each lab. The student should remain alert and use common sense while performing a lab experiment. He/she is also responsible for maintaining a laboratory notebook. Students should report any errors in the lab manual to the teaching assistant.

8 Clemson ECE Laboratories Lab Policy Pre-Requisites:- MTHSC 108 and PHYS 122 Co-Requisites:- ECE 202 Attendance:- Attendance is mandatory and any absence must be for a valid excuse and must be documented. Late Instructor:- If the instructor is more than 15 minutes late, students may leave the lab. Pre-Lab:- Each lab has a Preparation section that should be read and completed prior to each lab.

9 Clemson ECE Laboratories Lab Policy contd Lab Records:- The student must keep all work in preparation of and obtained during lab in an approved notebook and prepare a lab report on selected experiments. Late Work:- All full lab write-ups are due two weeks from the date lab is performed. Late work will NOT be accepted. Final Exam:- The final exam will be given in lab on the last meeting. This exam will be closed-book and closed-notes. Use of calculator is permitted.

10 Clemson ECE Laboratories Grading Policy The final grade is determined using the following criteria:- Participation:- 10% Attendance:- 10% Pre-Lab:- 20% Lab Reports:- 40% Final Exam:- 20% Grade Scale:- A: 90%-100% B: 80%-89% C: 70%-79% D: 60%-69% F: >All Program Files>>National Instrument">

38 Clemson ECE Laboratories NI ELVIS Instrument Launcher Launch the Instrument Launcher by navigating to Start>>All Program Files>>National Instruments>>NI ELVISmx>>NI ELVISmx Instrument Launcher.

39 Clemson ECE Laboratories NI ELVIS Instrument Launcher-DMM 1.Display 2.Modes 3.Connections 4.Acquisition mode 5.Help 6.Run/Stop 7.Null offset 8.Mode

40 Clemson ECE Laboratories NI ELVIS Instrument Launcher-FGEN 1.Frequency Display 2.Waveform Selectors 3.Waveform Characteristics 4.Sweep Settings 5.Manual Mode 6.Signal Route 7.Sweep

41 Clemson ECE Laboratories NI ELVIS Instrument Launcher-VPS 1.Voltage Display 2.Manual Mode 3.Output Voltage Controls 4.Sweep Settings 1.Sweep

42 Clemson ECE Laboratories Procedure-Getting Started 1.Turn on computer. 2.Turn on NI-ELVIS power switch (right corner on the back). 3.Turn on the NI-ELVIS Prototyping Board Power switch (at upper right corner, on top). 4.Launch NI-ELVISMX INSTRUMENTS program. 5.Launch the NI-ELVIS DMM instrument. 6.Launch the NI-ELVIS VPS (Variable Power Supply) instrument. 7.Arrange the instruments on the computer screen for your convenience. 8.Set DMM to measure DC Volts. Specify the range to be 60V.

43 Clemson ECE Laboratories Procedure-NULL OFFSET for Voltmeter Electrical drift sometimes causes shifts in the ZERO point indicated by measurement instruments. To eliminate the shift, the NI-ELVIS provides a NULL OFFSET function that subtracts the value indicated at the instant NULL OFFSET is turned on. To set the voltmeters NULL OFFSET: 1.Plug leads into the DMM V and COM jacks. 2.Clip the leads together, let the voltage reading stabilize. 3.Turn on Null Offset.

44 Clemson ECE Laboratories Procedure-DC Resistance of DMM Voltmeter Set the VPS Supply + voltage to +10.00 Volts. STOP the VPS. Set up the circuit as shown in figure. Use the NI-ELVIS DMM for the voltmeter and the VPS for the power supply. Set the resistor R to 0 by shorting the resistors leads. RUN the VPS and record the voltage indicated by the meter. Remove the short across R.

45 Clemson ECE Laboratories Procedure-DC Resistance of DMM Voltmeter contd Increase the resistance R so that the meter reading drops by one half of the original value. Record the final resistance R and measured voltage. STOP the VPS. Use the DMM ohmmeter to measure the actual resistance R. Record the measured value. From these readings, use voltage division to calculate R Vi, the equivalent internal resistance of the voltmeter.

46 Clemson ECE Laboratories Procedure-DC Resistance of DMM Ammeter Set the VPS Supply + voltage to +10.00 Volts. RUN the VPS and measure the actual voltage using the DMM voltmeter. Record the actual voltage. STOP the VPS. To use the DMM as an ammeter, move the DMM cables to A and COM and switch the DMM to measure DC Amps. Set up the circuit as shown in figure. Use the NI-ELVIS DMM for the ammeter and the VPS for the power supply.

47 Clemson ECE Laboratories Procedure-DC Resistance of DMM Ammeter contd Set the resistor R to 1 M resistance. RUN the VPS. Record the resistance R and the current indicated by the ammeter. Adjust R to 100k. Record the resistance R and the current indicated by the ammeter. Continue to decrease the resistance R until the ammeter reading drops to one half of the original value. Record the final resistance R and measured current. Use the DMM ohmmeter to measure the actual final resistance R. From these readings, use current division to calculate R Ai, the equivalent internal resistance of the ammeter.

48 Clemson ECE Laboratories Procedure-Output Resistance of VPS Supply + Set the VPS Supply + voltage to +0.5 Volts. Use the DMM to measure the actual voltage. Record the actual voltage. Construct the circuit shown in figure.

49 Clemson ECE Laboratories Procedure-Output Resistance of VPS Supply + contd Adjust the resistor R to 10k. RUN the VPS. Record the resistance R and the measured voltage. Adjust the resistance R so that the meter reading drops to one half of the original value. Record the R and V values. From these readings, use voltage division to determine R VPS. Where,

50 Clemson ECE Laboratories Procedure-Output Resistance of FGEN Construct the circuit shown in figure. Set the FGEN to output a sine wave with p-p amplitude of 1.41V and frequency 100 Hz. Set the DMM to measure AC Volts. Keep in mind that the voltmeters display shows the value of RMS voltage, where for a sinusoidal waveform,

51 Clemson ECE Laboratories Procedure-Output Resistance of FGEN contd Adjust the resistor R to 100 k. RUN the FGEN. Record the resistance and the measured voltage. Adjust the resistance R so that the meter reading drops to one half of the original value. Record the R and V values. From these readings, use voltage division to determine RFGEN, the equivalent internal resistance of the Function Generator. Where,

52 Clemson ECE Laboratories Lab 2-Student Tasks Students are required to submit a lab report on this experiment. Students MUST strictly adhere to the format as described in the lab manual. For the Questions section of the lab report, the students are required to solve the problems given as a part of Probing Further section of this lab in the manual. Your report is due in TWO WEEKS from today.

53 Clemson ECE Laboratories Preparations for Next Week Read the introductory material in the ECE 202 textbook describing the passive sign convention for circuit elements. Review the lab manual section Use of Laboratory Instruments. Calculate the values of voltage, current, and power absorbed/delivered for each circuit element in Figure 3.1 (i.e. do Part 0 of the Procedure). Sketch in your lab notebook the circuit diagrams to be used in each part of the procedure and have a table prepared for each part in order to record data.

54 Clemson ECE Laboratories References ECE 211 Electrical Engineering Lab I. Latest Revised July 2010. Otago University Electronics Group-NI ELVIS II Orientation Manual.

56 Clemson ECE Laboratories ECE 211 - Electrical Engineering Lab III Pre-labs for ECE 211 Guneet Bedi Created: 09/13/2012 Updated: 09/16/2012

58 Clemson ECE Laboratories Introduction Voltage and current values may be used to determine the power consumed (or provided) by an electrical circuit. Electric power consumption is a very important factor in all electrical applications, ranging from portable computers to megawatt industrial complexes. Thus, an understanding of power and how it is measured is vital to all engineers.

59 Clemson ECE Laboratories Electric Charge-A Brief Review The charge is bipolar, i.e. electrical effects are described in terms of positive and negative charges. The electric charge exists in discrete quantities, which are integral multiples of the electronic charge, 1.602210 -19 C. Electrical effects are attributed to both the separation of charge and charges in motion.

60 Clemson ECE Laboratories Voltage Whenever positive and negative charges are separated, energy is expended. Voltage is the energy per unit charge created by the separation. It can be expressed in differential form as: where, v=voltage in volts w=energy in joules q=charge in coulombs

61 Clemson ECE Laboratories Current Electric current is defined as the rate of charge flow. It can be expressed in differential form as: where i=current in amperes q=charge in coulombs t=time in seconds

62 Clemson ECE Laboratories Power Power is the time rate of expending or absorbing energy. Mathematically, energy per unit time can be expressed in differential form as: where p=power in watts w=energy in joules t=time in seconds

63 Clemson ECE Laboratories Power in terms of Voltage & Current so, where p=power in watts v=voltage in volts i=current in amperes

64 Clemson ECE Laboratories Passive Sign Convention Whenever the reference direction for the current in an element is in the direction of the reference voltage drop across the element (as shown in figure), use a positive sign in any expression that relates the voltage to the current. Otherwise, use a negative sign.

65 Clemson ECE Laboratories Use of Laboratory Instruments-Ammeter Ammeters are used to measure the flow of electrical current in a circuit. For ammeters, it is important that their internal resistance be very small (ideally near zero) so they will not constrict the flow of current. Ammeters must always be connected in series in a circuit, never in parallel with a voltage source.

66 Clemson ECE Laboratories Use of Laboratory Instruments-Voltmeter Voltmeters are used to measure the potential difference between two points. Since the voltmeter should not affect the circuit, the voltmeters have very high (ideally infinite) impedance.

67 Clemson ECE Laboratories Lab Objective By the end of this lab, the student should know:- o How to make DC measurements of voltages and currents. o How to determine power dissipation/delivery for circuit elements, branches, and various combinations of elements and branches.

68 Clemson ECE Laboratories Equipment Needed NI-ELVIS Series II workstation Two 510 Resistors One 1k Resistor

69 Clemson ECE Laboratories Procedure-Theoretical Calculation of Voltage, Current & Power For the circuit given in figure, calculate the voltages across and currents through each circuit element. Using these values, determine the power absorbed or delivered by each circuit element.

70 Clemson ECE Laboratories Procedure-Experimental Circuit Voltage Measurements Set up the circuit in figure. Adjust the output of the DC power supply to 10V. Using the DMM function in the NI-ELVIS workstation measure the voltage across each individual circuit element. For each measured voltage, determine the percent difference from the theoretical value.

71 Clemson ECE Laboratories Procedure-Experimental Circuit Current Measurements Set up the circuit in figure. Adjust the output of the DC power supply to 10V. Using the DMM function in the NI-ELVIS workstation measure the current through each individual circuit element. For each measured current, determine the percent difference from the theoretical value.

72 Clemson ECE Laboratories Procedure-Experimental Circuit Power Calculation Using your experimental voltage and current measurement data, calculate the power absorbed or delivered by each circuit element. Compare this power obtained with the values obtained through theoretical circuit analysis. Calculate the percent difference from the theoretical values.

73 Clemson ECE Laboratories Lab 3-Student Tasks Students are required to solve the Probing Further section, given in the lab manual, in their laboratory notebooks. Lab notebooks are due on the same day as your report for lab 2.

74 Clemson ECE Laboratories Preparations for Next Week Calculate the voltages and currents for each resistor shown in the circuit of Figure 4.1 in your lab manual (i.e. do Part 0 of the Procedure).

75 Clemson ECE Laboratories References ECE 211 Electrical Engineering Lab I. Latest Revised July 2010. Electric Circuits 8 th Edition by James W. Nilsson & Susan A. Riedel.

77 Clemson ECE Laboratories ECE 211 - Electrical Engineering Lab IV Pre-labs for ECE 211 Guneet Bedi Created: 09/24/2012 Updated: 09/24/2012

79 Clemson ECE Laboratories Introduction B2 Spice v5 is an integrated circuit design, simulation, and analysis software It contains a mixed mode simulator based partly on the Berkeley SPICE simulator and partly on the Georgia Tech XSPICE simulator B2 Spice v5 is an application with two separate subprograms: the B2 Spice main program, and the Database Editor It allows you to perform realistic simulations on your circuit without the need of any physical component or any expensive test equipment

80 Clemson ECE Laboratories Lab Objective This lab should give the student a basic understanding of how to use B2 Spice to simulate circuit operating conditions. After this lab, the student should be able to use B2 Spice to solve or check basic circuit problems.

81 Clemson ECE Laboratories Equipment Needed A computer with B2 Spice loaded and ready to use.

82 Clemson ECE Laboratories Procedure-Theoretical Calculation of Voltage & Current For the circuit given in figure, calculate the voltages across and currents through each resistor.

83 Clemson ECE Laboratories Procedure-Opening Software & Creating New Project Double click on B2SpiceV5 shortcut icon on desktop The following window will appear File->New->Project(Check Schematic & Enter Project Name)->Ok

84 Clemson ECE Laboratories Procedure-Placing Resistors Common parts->Resistor(simple)(R) Place resistor as desired on the workspace Double click on the resistor placed to modify its default parameters Right click on the resistor placed for more options(e.g. rotate clockwise)

85 Clemson ECE Laboratories Procedure-Placing Voltage Source Common parts->Voltage Source(V) Place the voltage source as desired on the workspace Double click on the voltage source placed to modify its default parameters Right click on the voltage source placed for more options(e.g. rotate clockwise)

86 Clemson ECE Laboratories Procedure-Placing Ammeter/Voltmeter Common parts->Ammeter(1)/Voltmeter(2) (Horizontal/Vertical) Place the ammeter/voltmeter as desired on the workspace Double click on the ammeter/voltmeter placed to modify its default parameters Right click on the ammeter/voltmeter placed for more options(e.g. rotate clockwise)

87 Clemson ECE Laboratories Procedure-Placing Ground Common parts->Ground(0) Place the ground as desired on the workspace Ground default parameters cannot be changed Right click on the ground placed for more options(e.g. rotate clockwise)

88 Clemson ECE Laboratories Procedure-Connecting Circuit Components On clicking the draw circuit lines symbol, one can draw circuit lines to connect circuit components together To discontinue drawing the circuit line press esc Press to draw circuit lines

89 Clemson ECE Laboratories Procedure-Running Simulations After setting up the circuit and placing the meters in the proper positions, press Run to simulate the circuit To stop simulation, click Simulation->Stop and Reset Run Pause Simulation

90 Clemson ECE Laboratories Test Circuit 1

91 Clemson ECE Laboratories Test Circuit 2

92 Clemson ECE Laboratories Test Circuit 3 How does V across & I through each resistor vary with the given combinations of resistor values?

94 Clemson ECE Laboratories Preparations for Next Week Read the material in the textbook that describes Kirchhoff's Voltage Law, Kirchhoff's Current Law, voltage division, current division, and equivalent resistance combinations. Before coming to class, analyze each circuit and determine the theoretical values that should be obtained during the lab. Verify your calculations by performing B2 Spice simulations for each circuit. Record both your calculations and simulation results in your laboratory notebook.

95 Clemson ECE Laboratories References ECE 211 Electrical Engineering Lab I. Latest Revised July 2010. B2Spice Version 5 Users Manual by Manual by Thien Nguyen, Christopher Hsiong and Jon Engelbert 1996 - 2005, Beige Bag Software, Inc.

97 Clemson ECE Laboratories ECE 211 - Electrical Engineering Lab V Pre-labs for ECE 211 Guneet Bedi Created: 10/01/2012 Updated: 10/01/2012

99 Clemson ECE Laboratories Introduction An understanding of the basic laws of electrical voltages and currents is essential to electrical engineering. Circuit analysis is dependent upon knowing the nature of the laws governing voltage and current characteristics. This lab studies Kirchhoff's Voltage Law, Kirchhoff's Current Law, voltage division, current division, and equivalent resistance.

100 Clemson ECE Laboratories Series Equivalent Resistance

101 Clemson ECE Laboratories Parallel Equivalent Resistance

102 Clemson ECE Laboratories Voltage-Divider Circuit

103 Clemson ECE Laboratories Current-Divider Circuit

104 Clemson ECE Laboratories Kirchhoffs Current Law The algebraic sum of all the currents at any node in a circuit equals zero. Using the convention that currents leaving the node are considered positive and that entering the nodes are considered negative, the above circuit yields the four equations.

105 Clemson ECE Laboratories Kirchhoffs Voltage Law The algebraic sum of all the voltages around any closed path in a circuit equals zero. Here we elect to trace the closed path clockwise, assigning a positive algebraic sign to voltage drops. Starting at node d leads to the expression:

106 Clemson ECE Laboratories Lab Objective By the end of this lab, the student should understand KVL, KCL, voltage division, current division, and equivalent resistance combinations.

107 Clemson ECE Laboratories Equipment Needed NI-ELVIS workstation Resistance substitution box Individual resistors (510, 1k (2), 1.5k, 2k (2), 3k, 3.9k, 4.3k, 5.1k)

108 Clemson ECE Laboratories Procedure-Equivalent Resistance Set up the circuit as shown in figure. Adjust the output of the DC power supply to 10V. Measure and record the total current into the circuit. Using the measured current and voltage, determine the equivalent resistance of the parallel components in the circuit. Replace the resistors with a resistance substitution box set to the equivalent resistance and measure the current as before. Compare the experimentally determined equivalent resistance to the theoretical value.

109 Clemson ECE Laboratories Procedure-Current Division & Kirchhoff's Current Law (KCL) Set up the circuit as shown in figure. Adjust the output of the DC power supply to 10V. Begin with R 2 =510 and measure the currents I 1, I 2 and I 3. Repeat with R 2 =1k, 2k, 3k, 4.3k and 5.1k. Compare the measured currents to those calculated using current divider relation. Determine whether or not each set of measurements agrees with KCL.

110 Clemson ECE Laboratories Procedure-Voltage Division Set up the circuit as shown in figure. Adjust the output of the DC power supply to 10V. Begin with R=510 and measure the voltage across each resistor. Repeat with R=1k, 2k, 3k, 4.3k and 5.1k. Compare the measured voltages to those calculated using the voltage divider relation.

111 Clemson ECE Laboratories Procedure-Kirchhoffs Voltage Law (KVL) (Single Loop) Set up the circuit as shown in figure. Adjust the output of the DC power supply to 10V. Measure the voltage across each component. Compare the measured voltages to those calculated using the voltage divider relation. Determine whether or not your measurements agree with KVL.

112 Clemson ECE Laboratories Procedure-Kirchhoffs Voltage Law (KVL) (Multiple Loops) Set up the circuit as shown in figure. Adjust the output of the DC power supply to 10V. Measure the voltage across each component in loop 1. Repeat for loop 2 and 3. Compare your measured values with the terms in the KVL equation written for each loop. Determine whether or not your measurements agree with KVL.

113 Clemson ECE Laboratories Lab 5-Student Tasks Students are required to submit a lab report on this experiment. Students MUST strictly adhere to the format as described in the lab manual. For the Questions section of the lab report, the students are required to solve the problems given as a part of Probing Further section of this lab in the manual. Your report is due in TWO WEEKS from today.

114 Clemson ECE Laboratories Preparations for Next Week Read the material in the textbook that describes Thevenin's equivalence theorem and maximum power transfer.

117 Clemson ECE Laboratories ECE 211 - Electrical Engineering Lab VI Pre-labs for ECE 211 Guneet Bedi Created: 10/09/2012 Updated: 10/09/2012

119 Clemson ECE Laboratories Introduction This lab focuses on the Thevenin equivalent and maximum power transfer theorems. Complex circuits are often replaced with their Thevenin equivalent to simplify analysis. Maximum power transfer is also an important concept which allows the designer to determine an optimal design when power is a constraint.

120 Clemson ECE Laboratories Thevenin Equivalent Circuit Thevenin equivalent circuit is an independent voltage source V Th in series with a resistor R Th, which replaces an interconnection of sources and resistors. This series combination of V Th and R Th is equivalent to the original circuit in the sense that, if we connect the same load across the terminals a, b of each circuit, we get the same voltage and current at the terminals of the load. This equivalence holds for all possible values of load resistance.

121 Clemson ECE Laboratories Thevenin Equivalent Circuit contd To calculate the Thevenin voltage V Th, we simply calculate the open- circuit voltage in the original circuit. If we place a short circuit across the terminals a, b of the Thevenin equivalent circuit, the short-circuit current directed from a to b is This short-circuit current must be identical to the short-circuit current that exists in a short circuit placed across the terminals a, b of the original network. Thus the Thevenin resistance is the ratio of the open-circuit voltage to the short-circuit current.

122 Clemson ECE Laboratories Maximum Power Transfer Maximum power transfer occurs when the load resistance equals the Thevenin resistance i.e. R L =R Th The maximum power delivered to R L is

123 Clemson ECE Laboratories Lab Objective By the end of this lab, the student should be able to verify Thevenin's equivalence theorem and the concept of maximum power transfer.

124 Clemson ECE Laboratories Equipment Needed NI-ELVIS workstation Resistance substitution box Individual resistors (220, 330, 680, 1k)

125 Clemson ECE Laboratories Procedure-Thevenins Theorem Set up the circuit as shown in figure. Adjust the output of the DC power supply to 10V. Measure the open circuit voltage between nodes A and B. Now connect the ammeter between nodes A and B and measure the short circuit current between nodes A and B. Using these measurements, determine the Thevenin equivalent circuit. Set up the newly determined Thevenin equivalent circuit and verify that this circuit has the same open circuit voltage and short circuit current as the previous circuit.

126 Clemson ECE Laboratories Procedure-Maximum Power Transfer Theorem Use the Thevenin equivalent circuit developed in Part 1. For a resistance substitution box R L between nodes A and B, measure the current through and voltage across R L for R L =0. Repeat for R L =100, 120 500 (in 20 increments). Determine the power dissipated by the resistor for each value of R L. Plot Power vs. Resistance. At which value is the power a maximum?

128 Clemson ECE Laboratories Preparations for Next Week Review 'XYZs of Oscilloscopes', available at: www.tek.com (60+ pages). Be familiar with the following: o Voltage scaling (Volts/division) o Time base (seconds/division) o Input coupling o Triggering o Measurement probes

131 Clemson ECE Laboratories ECE 211 - Electrical Engineering Lab VII Pre-labs for ECE 211 Guneet Bedi Created: 10/19/2012 Updated: 10/19/2012

133 Clemson ECE Laboratories Introduction Oscilloscopes are indispensable tools for anyone designing, manufacturing or repairing electronic equipment. The digital oscilloscope allows the engineer to examine time varying waveforms to determine the magnitude, frequency, phase angle, and other waveform characteristics which depend upon the interaction of circuit elements with the sources driving them. The usefulness of an oscilloscope is not limited to the world of electronics. With the proper sensor, an oscilloscope can measure all kinds of phenomena.

134 Clemson ECE Laboratories The Oscilloscope The oscilloscope is basically a graph-displaying device. The graph shows how signals change over time. The vertical (Y) axis represents voltage and the horizontal (X) axis represents time. The intensity or brightness of the display is sometimes called the Z axis, as shown in figure.

135 Clemson ECE Laboratories Waveforms A waveform is a graphic representation of a wave. Waveform shapes reveal a great deal about a signal. Any time you see a change in the height of the waveform, you know the voltage has changed. Any time there is a flat horizontal line, you know that there is no change for that length of time. Straight, diagonal lines mean a linear change rise or fall of voltage at a steady rate. Sharp angles on a waveform indicate sudden change.

136 Clemson ECE Laboratories Waveform Measurements-Frequency & Period If a signal repeats, it has a frequency. The frequency is measured in Hertz (Hz) and equals the number of times the signal repeats itself in one second, referred to as cycles per second. A repetitive signal also has a period, which is the amount of time it takes the signal to complete one cycle. Period and frequency are reciprocals of each other,

137 Clemson ECE Laboratories Waveform Measurements-Voltage Voltage is the amount of electric potential, or signal strength, between two points in a circuit. Usually, one of these points is ground, or zero volts, but not always. One may measure the voltage from the maximum peak to the minimum peak of a waveform, referred to as the peak-to-peak voltage.

138 Clemson ECE Laboratories Waveform Measurements-Amplitude Amplitude refers to the amount of voltage between two points in a circuit. Amplitude commonly refers to the maximum voltage of a signal measured from ground, or zero volts. The waveform shown in figure has an amplitude of 1 V.

139 Clemson ECE Laboratories Waveform Measurements-Phase The voltage level of sine wave is based on circular motion. Given that a circle has 360, one cycle of a sine wave has 360. Phase shift describes the difference in timing between two otherwise similar signals. The waveform in figure labeled current is said to be 90 out of phase with the waveform labeled voltage, since the waves reach similar points in their cycles exactly 1/4 of a cycle apart (360/4 = 90).

140 Clemson ECE Laboratories Controls of an Oscilloscope The front panel of an oscilloscope is divided into three main sections: o Vertical: The attenuation or amplification of the signal. Use the volts/div control to adjust the amplitude of the signal to the desired measurement range. o Horizontal: The time base. Use the sec/div control to set the amount of time per division represented horizontally across the screen. o Trigger: The triggering of the oscilloscope. Use the trigger level to stabilize a repeating signal.

141 Clemson ECE Laboratories Probes Even the most advanced instrument can only be as precise as the data that goes into it. A probe functions in conjunction with an oscilloscope as part of the measurement system. Precision measurements start at the probe tip. The right probes matched to the oscilloscope and the device-under test (DUT) not only allow the signal to be brought to the oscilloscope cleanly, they also amplify and preserve the signal for the greatest signal integrity and measurement accuracy.

142 Clemson ECE Laboratories Probe Types Passive Probes Active & Differential Probes Logic Probes Specialty Probes

143 Clemson ECE Laboratories NI-ELVIS Series II Workstation- Additional Features Oscilloscope (Scope) Connectors (Input): o CH 0 BNC Connector: The input for channel 0 of the oscilloscope. o CH 1 BNC Connector: The input for channel 1 of the oscilloscope. SYNC (Output): o 5V TTL signal synchronized to the FGEN signal. o This signal is most used as a trigger signal for the oscilloscope.

144 Clemson ECE Laboratories 1.Scope Graph 2.Channel Settings 3.Probe & Coupling 4.Volts/Div (Vertical sensitivity) & Vertical Position 5.Trigger 6.Log 7.Timebase (Horizontal Sensitivity) 8.Display Measurement 9.Cursor Settings NI ELVIS Instrument Launcher- Scope (Oscilloscope)

145 Clemson ECE Laboratories Lab Objective By the end of the lab the student should be familiar with the controls of a digital oscilloscope and be able to use the instrument to observe periodic waveforms.

146 Clemson ECE Laboratories Equipment Needed NI-ELVIS workstation 100 resistor 1k resistor

147 Clemson ECE Laboratories Procedure-Basic Setup Connect a cable with BNC fitting to the BNC jack for CH 0 of the oscilloscope on the left side of the NI-ELVIS II. Connect the cables red lead to the FGEN output; connect the cables black lead to GROUND. Set the function generator to output a 100Hz sine wave with amplitude = 3.0 VPP and DC offset = 0V. Open the oscilloscope window in the NI-ELVIS software. ENABLE the display for Channel 0. RUN the function generator and the oscilloscope. Turn on the prototype board. Record the measured values for RMS voltage, peak-to-peak voltage, and waveform frequency. Sketch the displayed waveform in your laboratory notebook. Compare your measurements with the expected values based on the function generator output.

148 Clemson ECE Laboratories Procedure-Source Control Connect CH 0 to SYNC (adjacent to FGEN). Sketch this waveform in your laboratory notebook. Reconnect CH 0 to FGEN. Change the function generator output to a square wave. Record the displayed waveform in your laboratory notebook. Measure the peak-to peak output voltage. Repeat this measurement for a triangular wave.

149 Clemson ECE Laboratories Procedure-Voltage Scaling Reset the function generator to output a sine wave. Vary the vertical scale control for Channel 0 using either the control knob or pull-down menu. Record the effect that this control has on the displayed waveform. Set the control to 500mV/div. Measure the peak-to-peak magnitude of the displayed waveform by counting (estimate) the number of peak-to-peak divisions and multiplying by the vertical scale. Compare this result with the measurement given by the oscilloscope.

150 Clemson ECE Laboratories Procedure-Voltage Offset Manipulation Vary the vertical position control in the oscilloscope and record the effects in your laboratory notebook, noting any changes in the measured RMS voltage. Return the offset to zero and add a DC offset of 0.5V to the function generator output. Record the effects in your laboratory notebook, noting any changes in the measured RMS voltage.

151 Clemson ECE Laboratories Procedure-Time Scaling Return the DC offset in the function generator to 0V. Using either the timebase dial or pulldown menu, adjust the timebase of the oscilloscope display to the fastest setting (5s/div). Record the effect that this setting has on displayed measurements for the waveform. Gradually increase the timebase through each available setting until the slowest setting has been reached (200ms/div). Record the effect that this control has on the measurement of voltage and frequency. Return the timebase to a setting where 1-3 full cycles of the output sine wave is viewable. Set the Acquisition Mode to RUN ONCE and press RUN to capture a single sweep of the output waveform. Measure the period of the waveform by counting (estimate) the number of time divisions for a single cycle and multiplying by the time scale. Compare this measurement to the inverse of the frequency measured by the oscilloscope.

152 Clemson ECE Laboratories Procedure-Triggering/Synch Function Return the screen update to 'RUN'. Adjust the triggering pull-down menu to edge and record the oscilloscope response. Vary the function generator peak amplitude to verify that the oscilloscope is continuing to update the display in this mode of operation.

153 Clemson ECE Laboratories Procedure-Cursor Function Set the function generator to output a 100Hz sine wave with peak amplitude = 3.0 VPP and DC offset = 0V. Return the triggering function to 'Immediate'. Display a single screen update of between 1-3 cycles of the output function. Switch the cursors function on and drag the cursors to appropriate points on the waveform to measure the period of the sine wave. Then adjust the cursors to measure the peak-to-peak voltage of the sine wave. Compare these measurements to those expected based on the function generator's output settings.

154 Clemson ECE Laboratories Procedure-Test Circuit Connect the voltage divider circuit shown in figure. Set the function generator to output a 1kHz sine wave with amplitude 2V p-p and DC offset = 0. Display the function generator output on channel 0 of the oscilloscope and the voltage across the 100 resistor on channel 1. Display and measure these voltages simultaneously. Measure the period of both waveforms using the cursor function. + -

155 Clemson ECE Laboratories Procedure-Test Circuit contd Sketch the waveforms in your laboratory notebook and record your settings for Volts/div and seconds/div. Compare your voltage measurements with theoretical calculations based on the voltage divider equation. Compare your waveform period measurement with the theoretical value obtained from the input frequency. + -

156 Clemson ECE Laboratories Procedure-Test Circuit contd Reverse the polarity for the output voltage measurement on Channel 1. Repeat your voltage and period measurements. Sketch the resulting waveforms in your laboratory notebook. Record your settings for Volts/div and seconds/div. - +

157 Clemson ECE Laboratories Lab 7-Student Tasks Students are required to solve the Probing Further section, given in the lab manual, in their laboratory notebooks.

158 Clemson ECE Laboratories Preparations for Next Week Read Appendix C, Fundamentals of Statistical Analysis. Become familiar with the following concepts: o Mean o Standard deviation o Variance and o The formulas used for calculating these quantities.

159 Clemson ECE Laboratories References ECE 211 Electrical Engineering Lab I. Latest Revised July 2010. XYZs of Oscilloscopes-Primer by Tektronix Otago University Electronics Group-NI ELVIS II Orientation Manual.

161 Clemson ECE Laboratories ECE 211 - Electrical Engineering Lab VIII Pre-labs for ECE 211 Guneet Bedi Created: 11/09/2012 Updated: 11/09/2012

163 Clemson ECE Laboratories Introduction A resistorcapacitor circuit (RC circuit) or RC network, is an electric circuit composed of resistors and capacitors driven by a voltage or current source. A resistorinductor circuit (RL circuit) or RL network, is an electric circuit composed of resistors and inductors driven by a voltage or current source.

164 Clemson ECE Laboratories Time Constant-RC Circuit The time taken for the capacitor to charge or discharge to within a certain percentage of its maximum supply value is known as its Time Constant ( ). Mathematically, =RC

165 Clemson ECE Laboratories Time Constant-RL Circuit The time taken for the current in an inductor to grow or decay to within a certain percentage of its maximum value is known as its Time Constant ( ). Mathematically, =L/R

166 Clemson ECE Laboratories Lab Objective By the end of this lab, the student should know how to measure the time constants of RC and RL circuits.

167 Clemson ECE Laboratories Equipment Needed NI-ELVIS workstation Resistance substitution box Capacitance substitution box Inductance substitution box

168 Clemson ECE Laboratories Procedure-RC Time Constant Measurement (1) Set up the RC circuit shown in figure. Set the function generator to give a square wave output with magnitude equal to 500mV. Measure both the source voltage and the voltage across the capacitor with the digital oscilloscope. Adjust the frequency of the function generator so that the waveform shown has definite flat sections at the top and bottom. Using the oscilloscope cursors function, determine when the voltage reaches 0.632 times its final value.

169 Clemson ECE Laboratories Procedure-RC Time Constant Measurement (1) contd Sketch the waveform for a complete cycle in your notebook, recording the voltage scale and time scale values. Clearly label the sketched waveforms, including the initial and final values. Repeat these steps using C=0.047F and C=0.1F. For each circuit the frequency of the waveform generator may have to be changed to achieve the flat sections at top and bottom of the waveforms.

170 Clemson ECE Laboratories Procedure-RC Time Constant Measurement (2) Now modify the circuit as shown in figure. Repeat the measurements in part 1 using C=0.01F, 0.047F, 0.1F while observing the voltage across the resistor. Find the time when the voltage reaches 0.368 times its initial value. Compare your measured values of the RC circuit time constant in Parts 1 and 2 with the theoretical values.

171 Clemson ECE Laboratories Procedure-RL Time Constant Measurement (1) Set up the RL circuit shown in figure. Set the function generator to give a square wave output with magnitude equal to 500mV. Measure both the source voltage and the voltage across the resistor with the digital oscilloscope. Adjust the frequency of the function generator so that the waveform has definite flat sections at the top and bottom. Using the oscilloscope cursors function, determine when the voltage reaches 0.632 times its final value.

172 Clemson ECE Laboratories Procedure-RL Time Constant Measurement (1) contd Sketch the waveform for a complete cycle in your notebook, recording the voltage scale and time scale values. Clearly label the sketched waveforms, including the initial and final values. Repeat these steps using L=400mH, 600mH and 800mH. For each circuit the frequency of the waveform generator may have to be changed to achieve the flat sections at top and bottom of the waveforms.

173 Clemson ECE Laboratories Procedure-RL Time Constant Measurement (2) Now modify the circuit as shown in figure. Repeat the measurements in part 1 using C=200mH, 400mH, 600mH and 800mH while observing the voltage across the inductor. Find the time when the voltage reaches 0.368 times its initial value. Compare your measured values of the RC circuit time constant in Parts 1 and 2 with the theoretical values.

174 Clemson ECE Laboratories Lab 8-Student Tasks Students are required to solve the Probing Further section, given in the lab manual, in their laboratory notebooks.

175 Clemson ECE Laboratories Preparations for Next Week Review the material in the textbook on the RLC circuit response. Review the concepts of overdamped, underdamped, and critically damped response. Calculate the theoretical parameter values of s 1, s 2, , d, and T for the circuit used in the lab (i.e., do Part 0 of the Procedure).

176 Clemson ECE Laboratories References ECE 211 Electrical Engineering Lab I. Latest Revised July 2010. Wikipedia

178 Clemson ECE Laboratories ECE 211 - Electrical Engineering Lab IX Pre-labs for ECE 211 Guneet Bedi Created: 11/16/2012 Updated: 11/16/2012

180 Clemson ECE Laboratories Introduction A series RLC circuit (or LCR circuit) is an electrical circuit consisting of a resistor, an inductor, and a capacitor, connected in series with the voltage source. The RLC part of the name is due to those letters being the usual electrical symbols for resistance, inductance and capacitance respectively.

181 Clemson ECE Laboratories Series RLC Circuit Properties-Circuit Response The differential equation for the circuit has the following characteristic equation or The circuit response or the roots of the characteristic equation is given by

182 Clemson ECE Laboratories Series RLC Circuit Properties-, 0 & is called the neper frequency, or attenuation, and is a measure of how fast the transient response of the circuit will die away after the stimulus has been removed. Damping factor, is defined as the ratio of and 0 0 is the angular resonance frequency.

183 Clemson ECE Laboratories Series RLC Circuit Properties-Time Period (T) Let us define d as Where T=Time Period

184 Clemson ECE Laboratories Transient Response-Overdamped Response If is large compared with the resonant frequency o, the voltage or current approaches its final value without oscillation, and the non-oscillatory response is called overdamped. >1

185 Clemson ECE Laboratories Transient Response-Underdamped Response If is small compared to o, the response oscillates about its final value, and this response is called underdamped. The smaller the value of is, the longer the oscillation persists.

1 clemson ece laboratories pre-labs for ece 211 created by guneet bedi on 09/03/2012 last updated:...

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