Physics 364 - fall 2014 - University of Pennsylvania

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Physics 364 : Laboratory Electronics

University of Pennsylvania — Fall 2014

People

  • Bill Ashmanskas — ashmansk@hep.upenn.edu — instructor
  • Jose Vithayathil — vithayat@physics.upenn.edu — lab instructor
  • Tanner Kaptanoglu — tannerk@sas.upenn.edu — teaching assistant
  • Zoey Davidson — zoeysd@sas.upenn.edu — teaching assistant

Why take this course?

Dismantle screenshot1.jpg

Electronic devices are all around us. A smartphone lets you walk around an unfamiliar city without fear of getting lost, of missing an important message from a friend, or of making the wrong subway connection. Somehow the phone can detect the sound of your voice, can produce both speech and music, can sense Earth's magnetic and gravitational fields, can respond to the swipe of your finger, can record and display images, can exchange radio signals with a distant cell tower, can receive and decode GPS signals from orbiting satellites, and more. Learning a bit of hands-on electronics will give you some intuition for what goes on (at least in principle, if not in detail) inside those electronic gadgets that enrich our lives. So even if you have no practical reason for doing so, spending one semester learning electronics may broaden your view of the world, and thus can be a worthwhile part of your liberal-arts education.


If you work in experimental science, it is likely that some part of your research will involve instruments that turn real-world physical quantities (temperature, pressure, acceleration, light intensity, chemical concentration) into electrical signals that can be measured, recorded, or maybe used in some sort of process control (e.g. turning on and off a laser or a vacuum pump). While many labs primarily use commercial electronics modules for data collection, you may still need to amplify or filter a signal before connecting it to a commercial data-acquisition module. Or perhaps your lab's existing commercial module has a spare output that can be switched on or off under computer control, but you need to amplify that output with a circuit that can provide enough current to drive the stepper motor that moves your experiment back and forth on the tabletop. Understanding the building blocks of electronics can give you more flexibility in how you carry out experiments in your own research.


In some fields of research, experiments require huge numbers of custom-designed electronics modules. The High-Energy Physics group here at Penn has designed key parts of the readout electronics for the CDF experiment at Fermilab (e.g. discovery of top quark), the ATLAS experiment at CERN (discovery of Higgs boson), and the SNO experiment in Sudbury, Canada (resolution of solar neutrino puzzle). These experiments could not be done without teams of scientists who understand electronics (and the associated particle-detection instruments, which are also custom-designed). So knowing something about electronics can be pretty handy if you work in experimental particle physics, radio astronomy, etc.

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    CDF (Fermilab: near Chicago)

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    ATLAS (CERN: near Geneva)

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    SNO (Sudbury, Canada)

This is my third time teaching PHYS 364 (fall 2010, fall 2012, fall 2014). (And it's Jose's 12th year co-teaching the course!) In past years, students have learned enough by the end of the term to do some interesting final projects of their own design. One student designed a distortion box for his electric guitar. Another student programmed a robot to move around the room. Two students made a pong-like "video" game with an LED display (video at http://www.youtube.com/watch?v=l45MOT4Ahd0). One grad student built an amplifier sensitive enough to record EKG traces from his own fingertips, then designed a system for getting the traces into a computer for analysis and storage. Another student built an infrared transmitter/receiver pair that could be used to exchange data wirelessly between two devices (e.g. a remote control and a TV set). (He learned enough to get a summer job working on detector electronics with a colleague of mine at Fermilab, near Chicago.) Projects along these lines should be within your reach by the end of the term. If that sort of know-how sounds like fun, then this course is for you.


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    PHYS 364 (fall 2010) student working on final project of his own design

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    immerses hands in salt water (wires go to amplifier inputs)

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    heartbeat visible on oscilloscope

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    and in computer data

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    Pong-like game project

  • Video clip of a 2012 final project — an FPGA-based synthesizer.
    • Playing louder now, using a large speaker and a push-pull transistor buffer!
  • Video clip of another 2012 project — an Arduino playing Mary Had a Little Lamb.
  • Finally, these aren't projects — they're just video clips of Bill and Jose demonstrating some fun circuits we've built in class during the semester.
    • This is a simple ad-hoc AM radio receiver that we've included as a lab exercise most years.
    • This is a push-pull transistor amplifier driving a large speaker we borrowed from Bill Berner's demonstration lab.
    • Here's a FPGA board playing Bach's Invention 13 (right- and left-hand parts together!)
    • Same thing much louder with amplification
    • And from the very end of the course, a simplified ad-hoc microprocessor (to see conceptually how a computer works) is programmed to find prime numbers from 2 through 9997 and display them.


By contrast, if your only goal in taking PHYS 364 is to meet the Physics Department's requirement that you take a lab course (PHYS 364 or PHYS 414), then it is worth weighing the differences between PHYS 364 (Laboratory Electronics) and PHYS 414 (Advanced Laboratory).

  • In PHYS 364, we learn a bit about how real-world signals (e.g. pressure vs. time for a sound wave) can be converted to/from electrical signals (voltages and currents vs. time); we spend a lot of time working with the circuit fragments that are most commonly used for manipulating electrical signals (filters, amplifiers, etc.); and we spend the last 1/3 of the semester learning to connect the analog world of continuous, real-valued signals with the digital world of discrete, integer-valued signals, so that real-world signals can be manipulated by a computer.
  • If instead you take PHYS 414, you will learn to reproduce with your own hands several important measurements from the history of physics, such as Cavendish's torsion-pendulum measurement of Newton's G, the lifetime of cosmic-ray muons, the angular distribution of Compton scattering, the Stern-Gerlach experiment showing the quantum nature of angular momentum, etc. Note that PHYS 364 is no longer listed as a prerequisite for PHYS 414.
  • If you need to choose one or the other, take PHYS 414 if you prefer to learn the experimental underpinnings of modern physics, and take PHYS 364 if you prefer to learn some of the electronics techniques that are used in a wide range of experimental science and in a large number of everyday gadgets.

Course overview

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    classroom

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    workbench

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    breadboard

  • The overall goal is to be a fun and useful course, after which I intend that you will
    • understand what electronic circuits can help you to do
    • know how to use common electronic components & instruments
    • know enough to be confident learning more from a textbook (e.g. Horowitz & Hill)
    • know how to build solutions to lab/project problems you may encounter later in your career
    • have enjoyed time spent in lab — fun change of pace. Pushing little wires into breadboards, measuring signals on an oscilloscope, and debugging misbehaving circuits are very different from the work done in a typical physics course: you may find it a soothing contrast to your other, more equation-centered work.


Like the Harvard course (which was own my favorite course in college, 22 years ago, and which several other Penn physicists tell me they also enjoyed), this course tries to cover "all" of electronics in a single semester. While an electrical-engineering curriculum needs to spend about four semesters on the in-depth study of electronics, this course is a one-semester survey, emphasizing breadth at the expense of depth. My aim is that after taking Physics 364, you can be comfortable looking at a schematic diagram, will recognize familiar circuit fragments, and will generally know enough to be able to confront your own real-life electronics problems with some help from a standard reference textbook (such as Horowitz and Hill).

Workload

  • 6-7 hours/week in lab
    • Regular class meeting time is either MW2-5pm or TR 2-5pm, in DRL 2N25. If you need more time, you can stay a bit late, or you can schedule extra time with Jose.
    • You'll turn in a written record of your lab work at the end of each class, which will mainly consist of filling in blank spaces on the day's lab handout.
    • Lab write-up doesn't need to be beautiful — just needs to convince us that you did the work and took the time to think about the questions embedded in the lab handout.
  • 2-3 hours/week on reading textbook/notes (due each Sunday night)
    • Includes answering some straightforward questions by email, to convince me that you've done the reading, and to let me know what I may need to supplement in class
  • no homework; no lectures; no midterm exams
    • So the total weekly time commitment is about the same as a typical physics course, but in Physics 364 you'll spend a larger fraction of those hours in class. (I estimate that a "typical" physics course requires 3-4 hours in class plus 6-8 hours outside of class per week.)
  • optional final project (for extra credit)
  • take-home final exam emphasizing simple circuit designs — mainly to give me feedback on what you've absorbed, and to give you a chance to review the semester's material

Grading

  • 40% — lab write-ups (work in class & turn in at end of each day)
    • If you occasionally need extra lab time to finish up an assignment, that's no problem. The idea is that you should not normally need to spend any time outside of class writing up lab results.
  • 30% — email/online responses to weekly reading assignments
    • Most questions will simply be to motivate you to think about the reading you just did, and to demonstrate to me that you read it carefully.
    • Sometimes the last question will aim to reinforce material from the previous week's lab.
  • 30% — take-home "final homework," due Friday, December 19
  • up to 5% extra credit — final project, if you choose to do it
    • Main reason to do a project is if you think you'll enjoy the challenge of making your own idea work in the lab.
    • Your having done an interesting project provides me with good material if you later ask me for a letter of recommendation.

Textbook

  • required text: Basic Electronics for Scientists and Engineers, by D. Eggleston
  • My favorite electronics textbook is The Art of Electronics by Horowitz & Hill
    • Alas, many beginning students find it difficult to learn from: it seems to be more widely used as a reference.
    • Also, the 2nd edition (1989) is somewhat dated; a 3rd edition should finally be out in a year or so.
    • Toward the end of the semester, I'll give you a sample to read, covering a few topics left out of Eggleston's text. If you like the authors' style, consider buying the 3rd edition once it exists.

Schedule

Reading (due Sunday night) Mon/Tue Wed/Thu
— — Aug 27/28 lab01: introduction; breadboard; meters; measuring current and voltage
Aug 31 reading01 Sep 1/2 no class (Monday = Labor Day holiday; cancel Tuesday to keep the two sections synchronized) Sep 3/4 lab02: meter imperfections; voltage dividers; Thevenin equivalents
Sep 7 reading02 Sep 8/9 lab03: continue Thevenin equivalents; introduce oscilloscope & function generator Sep 10/11 lab04: RC circuits; impedance; filters
Sep 14 reading03 Sep 15/16 lab05: filters; resonance Sep 17/18 lab06: diodes
Sep 21 reading04 Sep 22/23 lab07: opamps 1 Sep 24/25 lab08: opamps 2
Sep 28 reading05 Sep 29/30 lab09: opamps 3 Oct 1/2 lab10: opamps 4
Oct 5 reading06 Oct 6/7 lab11: opamps 5 Oct 8/9 no class (Thursday = Fall Break; cancel Wednesday to keep the two sections synchronized)
Oct 12 reading07 Oct 13/14 lab12: Bipolar Junction Transistors 1 Oct 15/16 lab13: BJT 2
Oct 19 reading08 Oct 20/21 lab14: BJT 3 Oct 22/23 lab15: BJT 4 / home-made opamp
Oct 26 reading09 Oct 27/28 lab16: PID motor controller Oct 29/30 lab17: Field Effect Transistors 1
Nov 2 reading10 Nov 3/4 lab18: FET 2 / analog switch Nov 5/6 lab19: digital intro / logic gates
Nov 9 reading11 Nov 10/11 lab20: arduino 1 Nov 12/13 lab21: arduino 2
Nov 16 reading12 Nov 17/18 lab22: arduino 3 Nov 19/20 lab23: sequential logic (flip-flops)
Nov 23 reading13 Nov 24/25 lab24: Field Programmable Gate Array 1 Nov 26/27 no class (Thursday = Thanksgiving Break, no class Wednesday due to Friday schedule)
Nov 30 reading14 Dec 1/2 lab25: FPGA 2 Dec 3/4 lab26: FPGA 3
Dec 7 reading15 Dec 8/9 lab27: FPGA 4 Reading Days
— Dec 19 final homework due —

CircuitLab examples

  • I will put up simulation models of many of the circuits we build in the lab, so that you can work with them on your computer if you wish. The simulations will use either CircuitLab (runs in your web browser) or LTspice (runs on your computer).