Chapter 1
Introduction

This supplement to Circuits by Ulaby and Maharbiz contains 40 additional end-of-chapter problems designed for three-way solution: analytical, simulation, and measurement. After solving the problem analytically the student continues by solving the same problem with NI Multisim and then once again with NI myDAQ computer-based instrumentation and circuit components. By iterating on each dimension of the problem until all three agree students “triangulate on the truth” and develop confidence in their analytical and laboratory skills.

Each problem requests at least one common numerical value for comparison among the three methods. The percent difference between simulated and analytical results as well as measured-to-analytical results indicates the degree to which the student has achieved a correct solution. Normally simulation and analytical results agree to within a percentage point, and measurements often agree with analytical results to within five percent.

The problems are organized as four per chapter for Chapters 2 through 9 and also chapter 12 of Circuits. The table of contents indicates the associated section number of the textbook in parentheses. Each problem contains the problem statement and sufficient detail to guide the student through the simulation and physical measurement steps. Short video tutorials are linked to each problem to provide detailed guidance on Multisim techniques and ELVISmx computer-based instruments for the myDAQ.

This document is fully hyperlinked for section and figure references. All videos are included in-line, and additionally live hyperlinks are included to the on-line versions in case flash or javascript are disabled.

1.1 Resources

• Appendix A details the parts list required to implement all of the circuits and includes links to component distributors.
• Appendix B describes how to implement a variable voltage source and two styles of current sources with the LM317 adjustable voltage regulator. Many of the circuits require a DC voltage other than the standard ±15V and 5V power supplies offered by the NI myDAQ. The adjustable voltage source pictured in Figure B.3 should be constructed at the beginning of the term and left in place for subsequent circuits.
• Appendix C describes the Texas Instruments TL072 dual operational amplifier used in many of the circuits. The op amp is frequently used as a voltage follower to strengthen the 2 mA current drive of the myDAQ analog outputs. Appendix D describes the Intersil DG413 quad analog switch used in many of the transient response problems.
• Appendix E details a laboratory technique to measure time constants while Appendix F explains how to measure amplitude and phase shift for sinusoidal signals.

1.2 Goals for Student Deliverables

Students should document their work in sufficient detail so that it could be replicated by others. Present your work on the “Analysis” section as you would on a standard problem set. Be sure to include a “Given” section with your own drawing of the circuit diagram, a “Find” section that lists the requested results for the problem, a detailed solution process, and a clearly-identified end result. Do all of this work on engineering green paper or in a lab book or as otherwise required by your instructor.

The “Simulation” section presents your work to set up the circuit simulation in NI Multisim and the simulation results you used to obtain meaningful information. Create a word processing document that contains an organized set of screenshots with highlights and annotations as well as text to lead the reader through the screenshots. Include the circuit schematic and dialog box setup parameters for information not already visible on the schematic – circle parameters that you entered or changed away from default values. Also include simulation results, again circling control settings that you changed and highlighting regions where you obtained information. Figure 1.1 illustrates a screenshot from NI Multisim properly highlighted to indicate control settings that were adjusted away from default values as well as regions on the screen where measurements were obtained. Interpret the simulation results by writing them in standard form including units, and write any additional calculations that were necessary to reach an end result for simulation.

NOTE: Screen shots in Microsoft Word 2010 can be easily captured and highlighted as follows:

1. Select “Insert” tab and then “Screenshot,”
2. Choose the desired window or select “Screen Clipping” to define an arbitrary region,
3. Select “Shapes,” and
4. Place circles or boxes to highlight important values.

The “Measurement” section presents your work to set up the physical circuit and NI ELVISmx signal generators and measurement instruments. This section also includes your measurement results. Follow the general guidelines for the “Simulation” section. Your instructor may require a photo of your breadboard circuit and myDAQ connections along with your student ID when you work on the problem outside of scheduled class time. Also include a schematic diagram showing all myDAQ connections.

Finally, the “Summary” section compares the requested numerical results from each of the three methods. Tabulate three results for each requested numerical quantity (analytical, simulation, and measurement) and tabulate two percentage differences for each requested numerical quantity:

• Simulation-to-Analytical: [(X_S - X_A)∕X_A] × 100%
• Measurement-to-Analytical: [(X_M - X_A)∕X_A] × 100%

1.3 Student Deliverables Checklist

1. Engineering paper or lab book – submit directly to instructor:
   1. Analysis
      1. “Given / Find” section including original circuit
      2. Detailed solution
      3. End result clearly identified
   2. Simulation – interpreted results from simulation screen shots
   3. Measurement
      1. Circuit schematic with myDAQ connections
      2. Interpreted results
   4. Results comparison table
2. Word processor document – submit electronically to instructor:
   1. Simulation screen shots
      1. Circuit schematic
      2. Dialog box parameters with circles around entered or modified control values
      3. Simulation results marked up to highlight key results
   2. Photo of circuit on breadboard and myDAQ connections (if required)
   3. Measurement screen shots
      1. ELVISmx signal generator instruments with circles around entered or modified values
      2. ELVISmx measurement instruments marked up to highlight key results and circles around entered or modified control values

1.4 Acknowledgements

I gratefully acknowledge contributions from the following individuals:

• Tom Robbins (NTS Press) for his editorial support throughout this project,
• Erik Luther (National Instruments) for his enthusiastic support of the NI myDAQ product for engineering education,
• David Salvia (Penn State University) for his helpful suggestions regarding the design of this project, and
• Rose-Hulman students in Electrical Systems ES203 (Spring 2011) who offered much helpful feedback on their experience with selected problems.

Professor Ed Doering
Department of Electrical and Computer Engineering
Rose-Hulman Institute of Technology
Terre Haute, IN 47803

doering@rose-hulman.edu