Active Announcements Are Marked In Red
For Emphasis
(May 7) The final grades (after the optional final exam) are now available. Please check Section 1, Section 2, and Section 3. The grades are calculated the same way as before, the ranges did not change. Again, for example, a grade between 90 and 90.5 is a B unless the quiz average (which includes the Final Exam now) is greater than 90.5. The official course grades will be submitted today.
(May 4) Reminder -- for those of you who are taking the final exam, you may bring four crib sheets, one for each part. The easiest thing to do is to update what you used previously.
(May 3)The grade lists have been updated to reflect corrections and additions since Saturday. Please check Section 1, Section 2, and Section 3 for the latest changes. Remember that you MUST tell us today if you are going to take the final. We also appreciate hearing from those of you who are not taking it.
(May 1)The preliminary grades are now available. Please note that there are very likely some errors in these numbers. You should check them over to be sure that we have the correct info. We will also be checking them over for errors, so there is no guarantee that the numbers will remain exactly as they are. Should you find any errors, please let us know via email asap. The grades are listed by section #, by alias, in decending order. Thus, you will be able to see where you rank in your class. The aliases we have been given are listed at the right. If you have not given us an alias, you can do so now and it will be used when we post the next update of this list. There will be at least one update after Monday's open shop. Other updates will be posted whenever there are significant errors found in our grade list.
The most recent additions to this list are the grades for Exp 12, Proj 4, the practicals, participation and extra credit. The extra credit grade (XC) given is the total change earned following the most generous possible interpretation of the rules listed in the announcement of 12 April (see below). The raw scores remain in each category. The extra credit total may change after Monday if another practical quiz has been completed. No more extra credit assignments were accepted after 5 pm Friday. Project 4 grading criteria are available.
The grade cutoffs are about what they have been all through the semester. Now, however, the exact number means a lot, so we have added a gray area between each grade. We now have 90.5-100 for an A, 80.5-90 for a B, 70.5-80 for a C, 60.5-70 for a D. If your total falls in one of the gaps between the grade ranges, you will receive the higher grade if your quiz average is higher than the grade cutoff. There is a student in section 2 with a corrected total (including extra credit) of 90.08 and a quiz average of 92.5. Thus, this student gets an A. The grades are listed for Section 1, Section 2, and Section 3 in PDF format, which you should be able to read without printing the list. The column marked X-Total is the total grade including the extra credit points. Should you have any trouble looking at them (they have already been tested on two different computers), please let us know.
Again, please note that there may be errors in the grade lists. Final grades will be based on the most correct available information.
(April 28) Some important information regarding the (optional) Final Exam and course grades:
- There will be some open shop time on Friday and Monday. Open shop on both days will be from
10am - 2 pm..
- Preliminary course grades will be posted here on Friday (which might mean by early Saturday). Grades will be posted by alias. If you want to see your grades, you need to give us an alias to use. Most students have already done this in class. If you have not, you can email your alias.Please look over our records and then email and let us know if we are correct and whether or not you will be taking the Final. It makes things much easier if we hear from everyone, not just those people who are taking the Final.
- The last day to hand in extra credit is Friday. We need this info to determine your pre-final grade.
- The Final Exam will be Wednesday in the morning. You must take this exam if you missed any of the quizzes, for whatever reason. Please read over the information in the Syllabus on the Final. If you wish to take the Final, you must email your intentions by Monday at the latest.
- Project 4 is definitely due today (Wednesday, 28 April). Any reports handed in after today will be assessed the late penalty. Project 4 and Experiment 12 will be graded by Friday, so they can be included in the pre-final grade calculation.
(April 19) There are 10 extra statements we would like you to respond to when you fill out your survey.
(April 18) Quiz 4: These questions are taken primarily from Experiments 10-12 and Chapters 6 and 7 of Gingrich. Be sure that you review this material thoroughly before Friday. This list might change a little between today and Wednesday. A copy of Quiz 4 from last semester is available for reference.
- Combinational Logic -- You can be asked a problem like the one in Gingrich problem 4 on page 156. This problem is a classic example of using digital logic devices to control some piece of apparatus. You might have some optical sensors that produce HIGH and LOW signals depending on whether they sense some object. With 2 or 3 sensors, you can have a variety of inputs in a variety of sequences. If a particular sequence of events occurs, then you would want to turn something ON or OFF as a response. Thus, your system would be expected to obey some kind of truth table. You could be asked to identify which of several choices is the configuration of logical devices that would produce the desired truth table. The devices you will be expected to understand are found in sections 7.3 and 7.4 of Gingrich.
- Digital Meets Analog -- A summing amplifier configuration (see figure 6.8 of Gingrich) can be used to convert a digital signal into an analog signal. There are two examples of such digital-to-analog convertors (DAC) in the Engineering Sciences 27 webpage at Dartmouth. There is also a short discussion of DACs available that uses PSpice simulations. 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.
- Schmitt Triggers vs Inverters -- The bottom figure on page 3 of Exp 11 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 (page 7) 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.
- Flip Flop -- For the Flip Flop simulation and experiment (Part D of Exp 11), 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.
- Misc. Experiments -- Given any of the Pspice or hardware configurations in experiments 10-12, you should be able to identify which input/output signal pair goes with which circuit. You should also know the properties of any of the devices used in these experiments.
(April 16) The last project is now posted in the syllabus. Paper copies will not be available until next week. During class Friday and next Monday we will have the grade list available so you can check our records and also see how you are doing. The grade list does not yet include the Practical Quizzes or the Participation grade. If you complete all five Practical Quizzes on time, you will get the full 10 points. The Participation grade will be determined from a combination of the signed boxes on the last few experiments and the judgements of instructors and TAs. We will have this grade available by the last day of class so you can factor it into your decision whether or not to take the final exam. If you have attended almost every class and contributed to the accomplishments of your group, you can expect the full 10 points for this also. There will be a student or two with as few as 5 points and a few with 6-9 points. For now, your present grade total can be determined from the following formula: Total = (2 X Experiment Average) + (Homework Average) + (0.3 X Quiz Average) + (Project Average). The multipliers scale the grades to the percentages listed in the syllabus. The maximum possible total (without the Practicals or Participation) is 80. The highest grade at this point is 76.5. We will have this total calculated for you, but it always pays to check our work. Roughly, then, we have A: 71-80, B: 61-70, C: 51-60. There are no grades below 50.
(April 16) There are now several more extra credit assignments available: 3, 4, 5, 6, 7.
(April 12) Extra Credit: During the last weeks of the term, there will be a few opportunities for some extra credit. The first involves the impact of the material from this course on your job prospects. Extra credit assignments can be used to replace up to 2 homework assignments and/or one practical quiz. To qualify for replacing one practical quiz, you must complete Quiz #4 on Digital Logic. Extra credit points can also be used to add up to 2 points to your participation grade. Some of you already have extra credit points for attending the lecture
on the Petronas Towers.
(April 8) HW#5 is now available.
(April 7) Quiz 3 has now been graded and returned.
(April 1) Please note that the due dates for the practical quizzes have been changed. Please, please to not let them go to the last possible minute. The third project is now also posted on the syllabus. It has been written to be relatively simple, in the spirit of GM/Space week.
(April 1) Please be sure that you go over the quiz from last semester. Essentially, everything on that quiz will be useful for the quiz tomorrow. If you understand the quiz from last term, you should do well. If you have questions this evening, please feel free to email them to me up to about 11 pm. Prof. Connor
A few comments on Exp 7-10
- Exp 7:A forward biased diode will have only a voltage of about 0.7 volts across it. Thus, a diode can limit the voltage at some point in a circuit to no more than 0.7 volts. This is not a particularly useful voltage in many circumstances since it is so small. Fortunately, a reverse biased diode breaks down at a much higher voltage. A zener diode is specifically designed to take advantage of this voltage limit. Zener voltages are typically greater than 4 volts. Placing a zener diode across a DC supply provides some regulation of the voltage as long as enough current is supplied to keep the diode on.
- Exp 8:One of the most useful devices in electronics is the 555 timer. This device can be used to produce a sequence of pulses with a wide variety of duty cycles. The duty cycle can be set or controlled with another signal. The output of the timer circuit configured as an astable multivibrator is very predictable. A sequence of optical pulses can be generated by driving an LED with a function generator. These optical pulses can be turned back into an electrical signal with a phototransistor. Both devices need a DC voltage and a current limiting resistor to work properly.
- Exp 9:Op amps can be used to integrate (capacitor in feedback loop) or differentiate (capacitor in input leg) a signal. A practical integrator requires a resistor in the feedback to have finite DC gain while a practical differentiator must always include the internal resistance of the source in the input leg. Both the integrator and differentiator produce an output scaled by the product of RC and practical devices only work properly in a particular frequency range. One of the best methods available for isolating one stage of a circuit from another is to place a buffer or voltage follower between them. The input impedance of a voltage follower is very, very large.
- Exp 10:The inductance and resistance of simple inductors can be estimated with reasonable accuracy using some simple formulas. Resistance can be measured using the multimeter while inductance can be determined by measuring the reponse of a circuit in which an unknown inductor is combined with a known capacitor. A resonance occurs in such a circuit when the inductive impedance cancels the capacitive impedance. A transformer can be used to step up or down a voltage or a current. They can also be used to transform an impedance up or down. Transformer performance also obeys simple relationships. Simple inductors and transformers can be easily constructed using a magnetic core material and some enameled wire.
(Mar 31) Homework 4 solution is now available.
(Mar 26)Possible Quiz 3 Questions (Not all will be included). These questions are taken from Experiments 6-10. 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. What follows is somewhat preliminary, so watch for updates. A copy of Quiz 3 from last semester is available for reference.
- Approximately reproduce or identify the plots asked for in the PSpice simulations of Experiment 7 involving diode voltage regulation or Zener diode voltage regulation. Note that both DC sweep and transient analysis were asked for.
- Any question included in a Results and Discussion section.
- Homework #4.
- 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.
- 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.
- Inductance Measurement -- In Exp 10 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.
- 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.
- Integrators and Differentiators -- Given a particular input signal, determine which output signal corresponds to a specific differentiator or integrator op amp configuration.
- Transformers -- Given a resistive load connected to a realistic source using a transformer, determine when or whether or not the transformer is working as an ideal transformer. It is also possible to ask this question in a form like the previous question.
(Mar 25) Last weekend on Cartalk (the show was a repeat) there was a very interesting question that relates to the material of this course. The owner of a 1980 Impala from South Boston called to say that when she turns on her high beams her directional signals do not work. The signals come on but do not flash. When she goes back to low beams, the signals work again. The Cartalk guys decided that the voltage output from the alternator is insufficient. The flasher device that makes those clunking sounds is very voltage sensitive. The high beams use more current which pulls the voltage down and the flashers stop working. In older cars and many other systems, old age catches up on various components. The voltage regulator might need to be replaced or the flasher might be old enough that it has become more voltage sensitive. It is partly mechanical and could have become more lossy. In most systems that require a lot of current, like the high beams or the starter motor on a car, one will generally notice that the voltage will drop when they are on. Listen to the show at the Cartalk Radio Show site.
(Mar 18) We will be having some extra open shop time this weekend for Project 2. Times will be announced later today or tomorrow. Also, when you replace the personal stereo output with an audio sensor like the guitar pickup, you have to pay attention to both the voltage level and the internal impedance of your new signal source. If the voltage level is too small, you might have to add some amplification. If the internal impedance is very high, you might have to add a unity-gain follower as a buffer between your sensor and the transmitter
circuit. (See page 13 of the Radio Shack Op-Amp book and section 6.2.1 of Gingrich)
(Mar 14) This week (15-19 March) all class time will be spent on project 2. Please see the syllabus for information on this project. Also recall that there are many hours of open shop time available.
(Mar 5) I have suggested to several people that they download PSpice (it is free for students) so they can work on their simulations at home. The link for this download is in the software list on the Studio Classroom webpage. The key thing to notice is that the name of the software we are using is Designlab.
(Mar 5) Quiz 2 has been graded and will be returned today. The grade distribution is the same as on the first quiz: 90-100 A, 80-89 B, 70-79 C, 60-69 D, 0-59 F. Homework #3 will also be returned today. Experiments 6 and 7 will be graded over the break. Remember that Experiment 8 must be turned in by the Tuesday after break. Also, no class time can be spent finishing up this experiment after today. We will need all of the week we come back to work on Project 2.
(Mar 2) Homework 3 solution is now available.
(Mar 1) Please check the room schedule for additional open shop hours. There are now hours from 6-8 on Monday and from 12-7 on Tuesday.
(Feb 26) Here are the questions that could be included on Wednesday's quiz (Only some of these will be selected). Please recall (see syllabus) that for any test, you can use one formula sheet, but no other reference materials. Note that you will also need to recall some of the more important topics covered in Quiz 1 (voltage divider, bridge circuits, Thevenin equivalents, ...). Quiz 2, from fall 1998 is available as a study guide.
- In homework #2, you analyzed a series RLC circuit. On the quiz, you will be asked to consider such a circuit or part of a simpler circuit. You will either be given an RLC, RC, CR, RL, or LR circuit. You will be asked to find the voltage across the last 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 #2, but there may be only two impedances.
- Convert the result of the first question (or a similar expression) from phasor form to real sinusoidal form.
- Given one of the combinations listed in the first question above, identify whether it is a low pass filter, a high pass filter, a band pass filter or a band reject filter.
- 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.
- Given a simple circuit, set up the differential equation and initial conditions for voltage or current and then identify the solution from among 3 or 4 voltage and/or current plots. This question is, in effect, the transient form of the first question above, except that you do not have to figure out the solution yourself.
- Given a particular diode rectifier circuit (half-wave or full-wave) and four possible oscilloscope images, select the scope image that would be observed across the output of the rectifier. This is the topic of HW#3. If you do this homework problem, you will be well prepared for this question. Since a question like this has appeared on Quiz 2 in each of the last three semesters, there is a good chance it will appear again.
- Determine the gain of one of the three operational amplifier configurations we have studied: inverting, non-inverting and differential. Ideal conditions will be assumed.
- Given any of the circuits you have simulated in experiments 3 - 6, identify which of several choices is the correct voltage or current signal at some point. You could also be asked to explain what information is contained in the figure. This questions could be in the form of a list of possible comments from which you will choose those that are true.
- Given a simple mechanical oscillator or an equivalent simple circuit, determine its natural resonant frequency. You might be given a description of either device or a plot of their response vs. time.
- There may be one more question, but the quiz will last no more than one hour.
(Feb 24) During the remainder of the semester, there will be several opportunities to earn some extra credit points. (Details will follow shortly on how these points can be used.) The first such opportunity is the Vollmer Fries Lecture, next Monday (1 March) at 4 pm in the Sage Lecture Hall (3303). If you attend and send me (Prof. Connor) an email giving your reaction to the talk, you will earn the extra credit.
(Feb 24) Project 1 is now complete and graded. In the four days I spent reading these reports, I collected a lot of comments that you should read over before you forget what you have done. All-in-all, a good job was done by everyone.
(Feb 24)Homework 3 is now posted on the syllabus.
(Feb 21) Please note. Due to further delays and confusion caused by last weekend's schedule and my illness on Wednesday, the first hour of Monday's (22 February) class will be available to finish up Experiment 5. Experiment 6 must start during the second hour. It is short enough that it should still be possible to finish it on Wednesday. If your group finishes up early on Wednesday, one or two of you can use the available time to work on a practical quiz. Experiment 7 will begin, as scheduled, on Friday. The due dates for Experiments 5 and 6 have been changed (see syllabus). If your group finishes its work before the end of Wednesday's class, someone can use the time for a practical quiz.
(Feb 16) The second homework assignment is now posted in the syllabus.
(Feb 13) The details of the schedule for carpet installation on the 4th floor of JEC have now been worked out so that we can have open shop on Tuesday, 16 February from 8am - 8 pm. It is probably best to come as early as possible, since the facilities will be used on a first-come-first-served basis. The main hallway will be closed so you will have to use the stairs at the end of our hallway to get to the room. When you come to open shop, please be sure to get your basic project design working as soon as possible. By basic design, I mean combining the strain gauge bridge circuit of Exp 2 with the differential amplifier circuit of Exp 4. It is best not to add filters or other functionality to your circuit until you are sure that the basic design is working. Also, is it very important that you have a good procedure for testing your design that you can show to one of the course staff for approval. Since part of the specifications call for increasing the level of the bridge signal to that of the coil signal, one of the simplest ways to verify that these are about equal is to produce a Lissajou pattern from their combination.
Regarding the practical quizzes, it appears that one of the questions in the second quiz asks for information that we will not see how to obtain until Exp 5. Up to now, we have only been finding the amplitude of voltages when we have done AC sweeps with PSpice. Since this question also asks for phase, you should look at the first paragraph on page 7 of Exp 5 (second paragraph on page 6 in the version from last semester), where the use of P() for this purpose is discussed. The letter P is more a replacement for the Greek letter Phi than an abbreviation for phase.
(Feb 10) DUE DATE CHANGES It is usual to schedule some open shop time during the weekends of projects. We will do this in the future, but we cannot do it this time. The 4th floor of JEC will be closed through next Tuesday to install new carpeting. To permit at least a little extra time to be spent on this project, the due date is moved to Friday, 19 February. There will be the usual open shop times on Wednesday and Thursday for people who need a little more time. The schedule posted on the syllabus page calls for the first two practical quizzes to be completed by 19 February. This date was set so that these quizzes are not left to the last possible moment in the semester. Unfortunately,very few people noticed that it was coming up. The due date will now be the day before spring break. While this adds two weeks to the time to do these quizzes, no one should wait until the end, since Quiz 2 occurs on Wednesday of that week. Please read the quizzes over outside of class and then work on them as soon as you possibly can. Finally, some additional information has been added to the description of the practical quizzes in the syllabus.
(Feb 9) Quiz 1 has been graded and will be returned this week on Monday or Wednesday. The grade breakdown is A:90-100, B:80-89, C:70-79, D:60-69, F:0-59. All assigments through Experiment 3 and Homework 1 will be graded and returned this week. During class, a TA will check with you to see if our records are accurate. Please note that the deadline for the completion of the first two practical quizzes is coming up in two weeks. You will need to work on these during open shop time. Check the room schedule for available hours.
- (Feb 5) [Update] The Homework #1 Solution is now available. Please note -- There was a small, but significant typo in the solution that was originally posted. It is now correct. We will watch for this mistake when we grade the quizzes. If you make a mistake by following this solution and we miss it, please let us know.
- (Feb 1) Homework #1 was handed out today. It is due Thursday, 4 February. The solution will be posted on the bulletin board outside the studio and here on the website after 5 pm that day.
- (Feb 1) Here are the questions that could be included on Friday's quiz (Only some of these will be selected). Quiz 1, from fall 1998 is available as a reference.
- Reduce a series or parallel combination of resistors to a single resistance.
- Find the voltage across a resistor in a voltage divider configuration.
- Find the voltage across a resistor in a voltage divider configuration with a load resistor attached.
- Find the Thevenin equivalent of a voltage divider or a Wheatstone Bridge configuration.
- Given an exact image produced on the oscilloscope, 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. A decaying sinusoid, like the ones observed in Experiments 2 and 3, is also a possibility.
- Be able to answer the questions: 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? (Hint: think of high-pass or low-pass filters).
- 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. This question will definitely be on the quiz, since every quiz should have a gift on it.
- Given a PSpice Probe plot with two or more time-varying signals on it, identify which points in a circuit (also given) correspond to which signals.
- Given a PSpice Probe plot with time-varying signals on it, show that the signals satisfy the appropriate voltage and current relationships.
- Given that you wish to obtain a particular AC Sweep, DC Sweep, or Transient analysis with PSpice, describe the specific steps you would follow. You will be given blank windows and asked which ones you will use and what numbers you will input.
Note that these are all questions motivated by our experimental work. It will be a good idea to review the first two chapters of Gingrich's notes and the writeups for the experiments we have done. Also note that the circuits in these problems will be taken from the experiments.
- (Jan 28) One of our teaching assistants, Abdul Kader Nazimudeen, has made two excellent suggestions on how to improve the writeups for experiments. I have changed his ideas slightly. You will see this new information on future experiments. However, we would like you to follow these guidelines on your writeup for experiment 3.
- When you attach a PSpice plot to your report, please add some comments to the plot indicating what it is. Include a simple, hand-drawn schematic of the circuit you have simulated. Also, indicated why you think the result makes sense. You should also add comments to any experimental plot you produce.
- After you have answered all the questions, add a paragraph describing the key points of the experiment. Also include any mistakes you made and how you addressed them (eg In PSpice, you tried to use the VAC source to get an AC sweep, but found that you needed to use the VSIN source.) We will be collecting the most common problems encountered with PSpice, the HP instruments or anything else you need to learn how to use in this class. Please include any other comments on the experiment you think would be useful, including such things as typos, confusing sentences, etc.
- (Jan 27) There are now some additional open shop hours. Please see the schedule.
- (Jan 24) Experiment 3 has been updated. You can see the new version by linking to it from the syllabus.
- (Jan 21) The parts/tool kits are now in. They are available in the studio classroom during class times. Please pick up your kit (and pay for it) Friday or Monday. Also, please check the due dates for the experiments listed in the course syllabus. We will accept Experiment 1 a couple days late because the recent bad weather has made it difficult for some students to make it to class. However, in the future, we want to stay on schedule.
- (Jan 19) Most of the open shop times have now been scheduled. 2-4 more hours will be added in the next day or two. Please check the room schedule for the available times.
- (Jan 6) I (Prof. Connor) apologize in advance for missing the first day of class. I have to review proposals for the National Science Foundation at their Arlington, Virginia headquarters. I know I have left you in good hands, but I really like teaching in our great new facility that we have worked so hard to make available to you. I look forward to meeting you all after the 12th. Also, since I am the course coordinator, please send me any questions or complaints generated by your experience in this class.