Electronics & Instrumentation (20.422)

Active Announcements BLINK For Emphasis
• (4 May) EVEN MORE OPEN SHOP and the last FINAL EXAMannouncement -- We will be keeping the studio open a couple more hours today (until 5 pm) and will be open tomorrow from 9:30-2 for practical quizzes (this is definitely the last time). For those of you taking the final, there are three copies of the solutions for all four quizzes now in the studio.

• (4 May) Project 4 is graded and can be picked up in the studio during open shop hours on Monday. After that, please see Prof. Connor.

• (28 April) OPEN SHOP TIME and FINAL EXAM ANNOUNCEMENT
  • If you plan to take the Final Exam, you need to tell (email) Prof. Connor by the end of the day on Wednesday.
  • Extra Open Shop Time for Practicals:
    • Thursday, 30 April, 10-12 (JL), 12-2 (RK), 3:30-5 (AAAT)
    • Friday, 1 May, 10-12 (CR), 12-2 (HM), 3-5 (MNK)
    • Monday, 9-10 (DT), 10-12 (KC), 12-1 (DT), 1-3 (JS)

• (24 April) OPEN SHOP TIME CONFLICT! Both Fields and Waves I and Electronics and Instrumentation have Open Shop hours scheduled for the same time on Saturday. (12-3 or 4) Thus, you might find it easier to get something done on Sunday. Their Open Shop on Sunday is after 6 pm. Also, the Open Shop normally held on Friday at 4 pm is cancelled today.

• (24 April) The preliminary grades, based on all assignments, except Project 4 and the Practical Quizzes, have been determined. Since the final course grade will include these last two grades, it was necessary to make an informed guess on what they will be. For the Practical Quizzes, it was assumed that each of you will get essentially all 10 points. You get two tries to get full credit on each quiz and lose only a small amount (10% or 0.2 points) for each additional try after that. So far, nearly everyone has needed only one try. For the Project 4 grade, a good guess is the average of the first two project grades. Then if you add up all your grades as indicated in the course Syllabus (a maximum of 10 points for HW, 40 points for Quizzes, 40 points for Projects, 10 points for Practical Quizzes) you will get your overall preliminary course grade. The grade cutoff points are then very standard, A:90-100, B:80-89, C:70-79, D:60-69. Anyone who has a grade of under 60 will have to take the entire final exam to be sure to pass the course. Once you calculate your grade, if you want to check to be sure we agree, please email Prof. Connor your result. This will also give us one more chance to check the accuracy of our records. Finally, the best strategy on your part to make sure you get the best possible grade, especially if you are close to a cutoff, is to do the best you can on the last project. The practical quizzes can be done after next Wednesday, but the project must be handed in by then.Also, if you have done poorly on a quiz, you can take that part of the optional Final Exam. A prediction for the final grade distribution is 35-40% A, 40-45% B, nearly all the rest C.

• (23 April) There will be some extra Open Shop Hours this weekend, Saturday and Sunday from 12-3, longer if necessary. The deadline for the completion of the Practical Quizzes is 5 May, the day of the optional Final Exam.

• (21 April) Project 4 information is now available. This will be updated somewhat by later today or tomorrow. There needs to be some figures added to it, for example. All parts of the project are now due on the last day of class.

• (20 April) The remainder of the work for this semester has now been posted in the Syllabus. This week we will go over the last quiz, do experiment 15,and begin the practical quizzes. As soon as the experiment and the project are completed, class time can be spent on the practical quizzes. Since these must be done by individual students, each group will have to decide who gets to use the class time and who goes to open shop. The practical quizzes are very short. They should take about 5-20 minutes each. Topics are listed below.

• (20 April) Possible Practical Quiz Questions. Each question will have at least 10 variations. You will be given the particular parameters for each question by a TA or instructor. These questions may change slightly, but the list below should give you a very good idea of what to expect. You might want to think through what some of the practical issues are with these questions. For example, triggering the scope might not always be possible with the push of a single button. Quizzes Will Be Available on Tuesday, 21 April for Open Shop Times.
  1. Set up the function generator to produce a square wave output with a specified frequency, amplitude, offset, duty cycle, ...
  2. Given a protoboard with pre-wired logic gate on it, determine its truth table and identify the logic gate. All identifying marks for the gate have been removed.
  3. Construct a particular op-amp circuit. Given a particualr input signal, show that your circuit works as it should.
  4. Simulate a simple RL, RC, LR circuit with a specified input signal. Do both a transient and AC sweep.
  5. Construct a simple RL, RC, LR circuit and drive it with a function generator.
  6. Measure the electrical noise in the studio classroom using very simple wire antennas.

• (17 April) Final Exam -- Some of you have noticed that there is a Final Exam listed in the Poly for this course, but no Final is listed in the Syllabus. That is because the Final will be optional. If you missed a quiz, you have to take the Final. If you would like to improve your grade on a quiz, you can take the Final. You must let me know by the last day of class if you plan to take the Final.

• (16 April) There will be no extra office hours today. However, if you have any questions and cannot make it to the 6pm open shop, I (KC) will be in my office from around 5-6pm. I have a department meeting from 3:30 - 5pm, so I might be a little late if it runs long.

• (13 April) TYPO in HW#6. The array of logical devices is not correct in the bottom paragraph. I (KC) left out part of the description. It is now correct on the version posted on the web and on the copies on the center table in the studio. Sorry for any inconvenience.

• (13 April) Possible Quiz 4 Questions (Not all will be included). These questions are taken from Experiments 12-14 and from the text (Chapters 6 and 7). Make sure that you understand the basic work done in each of these experiments. The actual questions will be variations of what is listed below. [This list may not be complete until sometime on Tuesday.]
  1. Schmitt Triggers vs Inverters -- Figure 4 of Exp 14 is a PSpice configuration that is to show how Schmitt Triggers do not trigger several times near their turnon threshold, even with noise. The last figure of Part C shows the experiment you were to do to show that Schmitt Triggers and inverters do not trigger the same. You may be given examples of figures taken from scope traces or PSpice simulations for each of these two cases and be asked to identify which is for the Schmitt Trigger and which is for the inverter.
  2. Flip Flop -- For the Flip Flop simulation and experiment (Part D of Exp 14), you might be given several plots showing either simulated output or data from an experiment and be asked to determine what is connected to each of the inputs.
  3. Inductance Measurement -- In Exp 13 you did a simple experiment to find the magnitude of an unknown inductance. You may be given data from another method, in the form of scope traces or simulated output, and be asked to estimate the inductance from this information. The circuit configuration to be used will be a series RLC combination. You may also be given some dimensions for the unknown inductor and be asked to estimate its inductance from an ideal formula. You should know whether or not this ideal formula will over estimate or under estimate the inductance of the coil.
  4. Interaction between magnets and coils -- You should be able to identify which of 3 or 4 possible figures corresponds to the signal one observes on a scope when a magnet is dropped through a coil.
  5. Integrators and Differentiators -- Given a particular input signal, determine which output signal corresponds to a specific differentiator or integrator op amp configuration.
  6. Digital Meets Analog -- A summing amplifier configuration (see Fig. 6.8 of Gingrich) can be used to convert a digital signal to an analog signal. There are two examples of such digital-to-analog convertors (DAC) in the Engineering Sciences 27 webpage at Dartmouth. You may be asked to convert a 3 or 4 digit binary number to an analog number. Remember that the binary number will be represented as ones and zeros but the voltage for a one is 5volts with TTL devices.
  7. Using a logic signal to control an experiment -- A problem like 4 on page 156 of Gingrich. That is, you will be given a set of numbers to produce that are to control some apparatus. You may be given the truth table or be asked to generate it. Then you will be asked to identify which of four given configurations of gates will produce the desired result. The only gates you will be asked to consider are the gates in section 7.3 and 7.4 of Gingrich.
• (13 April) As we approach the end of the semester, we need to check our grade records to be sure there are no errors. Please bring a list of your grades (quizzes, projects, homework) to class on Wednesday or Thursday. A TA will stop by during class to check our records vs yours.

• (8 April) The HP computers in the studio will be rebuilt very soon. Thus, if you have stored anything on an HP hard drive, you should copy it to somewhere else or you will lose it. The drives will be wiped clean.

• (6 April) Some groups have completed the experimental work for Project 3. The results obtained thus far are now available. Please note that to have official results, the motor must be powered by a 1.5 volt battery, there must be a hardcopy of the scope image signed by a TA and the image must show a roughly periodic signal.

• (3 April) Two comments on Project 3. First, the two things that must be done well are the construction of the coil and the testing of the motor. I have asked the TAs to be very careful when they observe your tests and test data. They have to be convinced that you have performed the tests properly before they should sign off. After you convince them of the quality of your results, they are supposed to let me know how well you have done. I will then post the results on the course webpage. That brings me to the second issue. I can post the results by group number according to the studio location where you usually work. However, I would prefer to post the results by group name. If you wish to give your group a name, let me know.

• (1 April) There will be no open shop at 6 pm on Thursday of this week.

  One clarification on the grading for the project report due next week -- The materials from the experiments you have done since the last project report are due with the final report for Project #3. 20 points will still be assigned to these materials. It is the 40 points for the preproject report that you get for nothing.

• (30 March) This week we will be doing Experiment 13 and discussing the next project. Again, as noted below, there should be very little work required outside of class this week.

• (26 March) EXTRA OFFICE HOURS -- I (KC) will be available in JEC 7001 from 4-6 today (Thursday) to help people prepare for the quiz. I will also be at my regular office hour in the studio at 6.

• (25 March) The solution for HW#5 is now posted on the course bulletin board outside the studio.

  In the spirit of Grand Marshall Week, you will not have to write the pre-project report for Project 3. This report will be provided for you next Wednesday. However, there will be a very small number (like 3) pieces of information you will have to add to this report to receive full credit. (This is basically like filling in the blanks.) There will be experiments to perform, but, you will not have to do much work outside of class next week.

• (23 March) There is a minor typo in the writeup for Experiment 12. On the third line before the last figure it should read Decreasing the capacitance increases the RC corner frequency.

• (22 March) Possible Quiz 3 Questions (Not all will be included). These questions are taken from Experiments 9-11. Make sure that you understand the basic work done in each of these experiments. The actual questions will be variations of what is listed below.
  1. Identify the correct output voltage for a half-wave rectifier with smoothing. You might be given the correct plot along with a plot for a circuit without smoothing or the voltage for some other configuration of diode, resistor and capacitor.
  2. Approximately reproduce or identify (as in the previous question) the plots asked for in the PSpice simulations of Experiment 10 involving diode voltage regulation or Zener diode voltage regulation. Note that both DC sweep and transient analysis were asked for.
  3. Experiment 10, part B, number 4. This is a discussion question.
  4. The homework problem handed out with Experiment 11.
  5. Identify the types of op-amp configurations we have seen thus far.In addition, you might be asked to figure out what some configurations do that we have not yet seen. The latter questions will be multiple choice and not worth a lot. However, you might glance through the reading in Gingrich that covers op amps.
  6. Given a copy of the basic receiver and transmitter circuit diagrams from Project 2, identify the function of each section or stage of the circuits. There will be a list of possible answers to choose from with at least two more answers than questions.

• (22 March) At least part of Monday's and Tuesday's classes can be used to complete work on the project. The remainder of the week will be spent on another op-amp experiment and the quiz.

• (20 March) There will be extra open shop hours this weekend to allow people to finish up their projects. The studio will be open from 10-12 on Saturday and from 2-4 on Sunday. Also note that Quiz 3 will be held next Friday rather than Wednesday and Thursday.

• (19 March) The server problems will continue until at least this weekend. If they are not fixed by then, I will move all the class materials to a new location.

• (19 March) At the request of section 1, the due date for the second project is now Wednesday the 25th of March. A piece of advice on the project. Build each section of the circuit separately and make sure it works before you go on. If you have already built everything and it does not work, disconnect the sections and test them separately. Remember that if one section does not work, it may send noise to the other sections of the circuit since they are all connected together via the power busses.

• (6 March) Jerry Lopato has done a PSpice simulation of the transmitter for Project 2. You can find the file xmitter.sch either in my public directory ~connor/public/xmitter.sch or in Jerry's ~lopatg/public/xmitter.sch

• (4 March) The pre-project proposal is due by 5 pm on Friday. Some students have asked if they could hand it in late. To make this possible, we have instituted an increasing late penalty as follows(this is now also in the class syllabus): For each school day late (weekends and vacations are not counted) 2 points per day for the first two days, 3 points per day for the next three days, 4 points per day for the next four days, and so forth. Thus, if the pre-project proposal is handed in 5 days late, the penalty is 13 points.

• (4 March) Please note that there is a Homework assignment included with Experiemnt 11. It is due the day after vacation.

• (2 March) There is a small mistake in Experiment 11. The constant 0.693 was left out of the expressions for the periods in terms of the time constants. The expressions for the two time constants were correct. tau1 = (R1+R2)C and tau2 = (R2)C, but the period of the square wave output from the 555 should be T = 0.693(tau1 + tau2). (I apologize for leaving this out in the writeup -- KC)

• (2 March) Some Comments on Project 1

• (1 March) On Monday this week, we will discuss Quiz 2 and begin an experiment that provides further background for the next project. A demo of the project will be presented in class also. Please note that the date for the pre-project proposal for Project 2 is now Friday, rather than Wednesday. The due date for the final report has also been moved back two days. (Click for details.) Please note that the major activities in this project involve building and characterizing the transmitter and receiver circuits that are posted on the class bulletin board outside the studio.

• (24 February) The solutions for HW#3 and HW#4 are posted on the bulletin board outside the studio.

• (22 February) Possible Quiz 2 Questions (Not all will be included)
  1. In homework problem #4, you analyzed a series RLC circuit. On the quiz, you will be asked to do a small part of a simpler circuit. You will either be given an RC, CR, RL, or LR circuit. You will be asked to find the voltage across the second element in the circuit if it is driven by a sinusoidal source. Your answer will require both the magnitude and phase of the voltage. The method is the same as in HW #4, but there are only two impedances.
  2. Given one of the combinations listed in the first question above, identify whether it is a low pass filter or a high pass filter.
  3. Given a list of standard resistors, capacitors and inductors, choose a combination that will allow an audio signal to pass but will filter out electrical signals produced by mechanical vibrations (like we saw with the cantilever beam) and 60 Hz line noise. You could also be asked to select components that would pass the mechanical signal, but reject the audio signal.
  4. Given a particular diode rectifier circuit and four possible oscilloscope images, select the scope image that would be observed across the output of the rectifier.
  5. Given a simple operational amplifier circuit, choose the components necessary to achieve a specified gain.
  6. Given an op amp configuration, determine whether or not is is working correctly. That is, is it operating like an ideal op amp?
  7. There may be one more question, but the quiz will last no more than one hour.

• (20 February) There are three things you should watch for next week.
  1. Monday and Tuesday -- Project 1 Reports should be back to you on these days. This report has been given extra attention by the course staff to be sure that it is graded consistently and so that you all receive useful feedback that will help you prepare the next report. Please look over your report to be sure that you understand how it was graded and, particularly, look for any items you neglected to include. For this project, you will have the opportunity to submit any missing items.

  2. MONDAY at 4 pm: One of the most useful tools available to engineers these days is Matlab. The person primarily responsible for this very powerful software package will be presenting the next Vollmer Fries Lecture in Sage 3303 at 4 pm on Monday. Please check the Vollmer Fries Lecture website. Besides being an opportunity to hear a dynamic speaker talk about an interesting subject, there are two other motivations for attending. First, the food is really good. This lecture series was well endowed by Mr. Vollmer Fries, which has allowed us to do things properly. Second, you can earn some extra credit points for attending. After you go, email Prof. Connor and tell him what you thought of the lecture (and maybe the food or room or whatever).

  3. Thursday and Friday -- Quiz 2.

• (18 February) This week, there will be only 3 hours of formal class time. The remaining hour on Friday in sections 1 and 2 will be available as time to catch up on things. Course staff will remain to help out, but students will be free to leave.

• (9 February) Should some additional work be required to finish Project 1, do not forget that there are six hours of open shop on Monday and Tuesday each week. Class time this week will be spent on AC circuits, not on this project.

• (5 February) Please note that there is an open shop - office hour added at 6 pm on Thursdays. Also, if you check the staff list, you will see who will usually be in attendance at each time.

  Update on Project 1: The preproject proposal is to be completed in class. This should not take more than 3 hours. When this is complete, it should be checked over by a member of the course staff. Once the proposal is finished, the project should begin. Each group (for the project, the experimental group is the group of people that share the same set of instruments of which there are only nine in the studio classroom) should find an empty protoboard and list their names on the back of it. There are labels available for this purpose. This board should then be used only by this group for the remainder of the project. This will permit a loaded board to be stored at the end of class, rather than reloading a board each time. Once the experimental work for the project is done, each group has to demonstrate that they can sense someone stomping their foot on the classroom floor. The further away, the better. Signals from the amplifier output should be compared with signals from the force transducer coil. They should be of similar, if not identical, amplitude. There should be a phase difference between the two signals. An explanation for this difference must be included in the project report. Note that a good way of doing the phase comparison is to produce a Lissajou pattern. Once the project has been shown to work well, the week's classes are over. There is no need to stay for the entire 6 hours if the work is complete. Your final report should include the PSpice simulations for both your original design and the final design you used. Also, please be sure that you answer all the questions and address all the issues noted in both the pre-project and final project report guidelines.

• (3 February) Some new information has been added to the Helpful Info section below. To help in reviewing for the quiz, there are links to a few course webpages in which you can find tutorials, sample problems, etc.

• (2 February) The solutions to the two homework assignments are posted on the bulletin board outside the studio. Also, you should be sure to check Gingrich for examples of the problems you could see on the quiz. Finding the Thevenin equivalent of the Wheatstone bridge, for example, is discussed on pages 15, 16, 17, 18.
• (31 January) Quiz Info: Here are the questions that could be included on next Wednesday's quiz (Only some of these will be selected):
  1. Reduce a series or parallel combination of resistors to a single resistance.
  2. Find the voltage across a resistor in a voltage divider configuration. The voltage divider can either have a single source voltage or a double source voltage. We saw a divider with a double source voltage in the last experiment on op-amps.
  3. Find the voltage across a resistor in a voltage divider configuration with a load resistor attached.
  4. Find the Thevenin equivalent of a voltage divider or a Wheatstone Bridge configuration.
  5. Given an exact image produced on the oscilloscope (we have the software to do this), determine the mathematical representation of the signal displayed. For example, given a sine wave, find the frequency, the peak-to-peak amplitude, the rms amplitude, and/or the phase.
  6. Be able to answer the question posed when you did the RL and RC circuit analysis: Is an inductor a short circuit or open circuit at very low or very high frequencies? Is a capacitor a short circuit or open circuit at very low or very high frequencies?
  7. Given an image of one of the instruments we have used in this class (function generator, digital multimeter, scope, dc supply), identify the buttons you would push for some specified purpose. Only the most basic functions will be considered.
  Note that these are all questions motivated by our experimental work. It will be a good idea to review the first chapter of Gingrich's notes and the writeups for the experiments we have done.
• (30 January) Extra Open Shop This Weekend. The studio room will be open, with help available, from 12-2 on Saturday and from 3-5 on Sunday. We will try to have such hours available at project time
• (29 January) Several Items
  1. Please check the schedule section for information on Office Hours and Open Shop. Some new hours have been added.
  2. While we will soon be doing some reorganization of groups so that all students have just one partner (see syllabus), you have the option of staying with your present group until the first project is completed.
  3. Information on the first project and the first quiz: Rather than having you do your proposal over the weekend, we will be doing it together during class. This first project is relatively simple. Thus, you should focus on making sure you have completed all of experiments Five and Six (including answering the questions and doing the calculations), since we will need this information. Next week, we will first make sure we have properly characterized the cantilever beam strain gauge output so that we can find an accurate Thevenin representation for it. Ultimately we will connect this bridge to an amplifier made with the 741 op amp so that we can get the signal to a useful level. We will figure out what is useful by looking at the output from the force transducer coil. A simple design will be developed and then simulated using PSpice. Then we will build and test the project and see what else we will need to do to make it work properly. There will then be a few activities in which we use this device as a vibration detector. As for the quiz, sample questions will be posted, so you will know what to expect. Look for these questions sometime on Friday or early Saturday.
  4. As soon as we determine when people are available we will post some open shop hours for this coming weekend. After polling some students in Section 3, it seemed most popular to have two hours available early Saturday afternoon and two hours in the late afternoon on Sunday. We will try to do this if we can.