Unit 3: Circuits

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This unit focuses on the design and analysis of physical systems. General principles are developed in terms of circuit theory and are applied to design a light sensor to enable the robot to seek and follow a moving source of light.

 Photograph of robot with a rotating head that tracks light.

Topics Kirchhoff’s voltage law (KVL), Kirchhoff’s current law (KCL), op-amps, Thevenin equivalents
Lab Exercises

Build robot “head”:

  • motor servo controller (rotating “neck”)
  • photo-transistor (robot “eyes”)
  • integrate to make a light tracking system
Theme design and analysis of physical systems

Looking for something specific in this course? The Resource Index compiles links to most course resources in a single page.

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Session Overview

Part of a circuit diagram.

In this session, we use what we’ve learned in the previous two sessions to allow even further circuit abstraction. We’ll learn about Thevenin equivalence (as well as Norton equivalence) and superposition.

Thevenin equivalence supplies a discipline for abstracting complex systems down into simple, equivalent representations, typically in order to substitute the simple representation back into a larger circuit. Superposition allows us to solve circuits more quickly (and for some, more intuitively).

The overview handout provides a more detailed introduction, including the big ideas of the session, key vocabulary, what you should understand (theory) and be able to do (practice) after completing this session, and additional resources.

Session Content

Readings

Review chapter 6 of the course notes.

Lecture Video

Watch the lecture video. The handout and slides present the same material, but the slides include answers to the in-class questions.

About this Video

This lecture covers other ways of achieving modularity in circuit design. If a circuit only contains linear elements, then it can be represented by a Thevenin or Norton equivalent circuit, and superposition can be used.

Recitation Video

These videos have been developed for OCW Scholar, and are designed to supplement the lecture videos.

Session Activities

The problems in the tables below are taken from the 6.01 Online Tutor, an interactive environment that is not available on OCW. Do not try to answer these questions in the PDF files; answers will not be checked, and cannot be submitted.

Software Lab

Design Lab

Additional Exercises

The optional questions (10.3.6-10.3.9) are provided as additional preparation for Midterm Exam 2.

PROBLEM # QUESTIONS
9.3.1 Thevenin equivalents (PDF)
9.3.2 Thevenin practice (PDF)
9.3.3 More Thevenin (PDF)
9.3.4 Thevenin divider (PDF)
10.3.6 Subtraction action [optional] (PDF)
10.3.7 Op-amp [optional] (PDF)
10.3.8 Op-amp [optional] (PDF)
10.3.9 Endless summer [optional] (PDF)

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Session Overview

Part of an op-amp circuit diagram.

In this session, we start a new unit on circuits. We will explore different motivations for studying circuits, the conventional representations associated with the study of circuits, and Kirchhoff’s voltage and current laws.

The overview handout provides a more detailed introduction, including the big ideas of the session, key vocabulary, what you should understand (theory) and be able to do (practice) after completing this session, and additional resources.

Session Content

Readings

Read sections 6.1-6.5 of the course notes.

Lecture Video

Watch the lecture video. The handout and slides present the same material, but the slides include answers to the in-class questions.

About this Video

Introduction to circuits, including several methods for analyzing circuits (Kirchhoff’s current and voltage laws, node voltages, and loop currents) and common patterns that simplify analysis.

Recitation Video

These videos have been developed for OCW Scholar, and are designed to supplement the lecture videos.

Session Activities

The problems in the tables below are taken from the 6.01 Online Tutor, an interactive environment that is not available on OCW. Do not try to answer these questions in the PDF files; answers will not be checked, and cannot be submitted.

Design Lab

PROBLEM # QUESTIONS
7.1.2 Potentiometer (PDF)

Additional Exercises

PROBLEM # QUESTIONS
7.2.1 Parallel resistors (PDF)
7.2.2 Resistor dividers (PDF)
7.2.3 NVCC (PDF)
7.2.4 Resistor network (PDF)
7.2.5 Argopt (PDF)
7.2.6 floatRange (PDF)

Check Yourself

Nano-Quiz

Nano-quiz problems and solutions are taken from a previous version of the 6.01 Online Tutor. Do not try to answer these questions in the PDF files; answers will not be checked, and cannot be submitted.

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Session Overview

Part of an op-amp circuit diagram.

In this session, we will cover operational amplifiers (op-amps). Op-amps provide new functionality to circuits, introduce dependent sources, and allow modularity and abstraction in our circuit designs and diagrams.

Op-amps enable us to sample a voltage from a particular subsection of a circuit without disrupting the properties of the circuit in that subsection. This is powerful because it allows us to treat that subsection as independent from the rest of the circuit.

The overview handout provides a more detailed introduction, including the big ideas of the session, key vocabulary, what you should understand (theory) and be able to do (practice) after completing this session, and additional resources.

Session Content

Readings

Read section 6.6 of the course notes.

Lecture Video

Watch the lecture video. The handout and slides present the same material, but the slides include answers to the in-class questions.

About this Video

Circuit design is complicated by interactions among elements, but these interactions can be reduced or eliminated by using an op-amp as a buffer. This lecture covers how to analyze and design op-amp circuits.

Recitation Video

These videos have been developed for OCW Scholar, and are designed to supplement the lecture videos.

Session Activities

The problems in the tables below are taken from the 6.01 Online Tutor, an interactive environment that is not available on OCW. Do not try to answer these questions in the PDF files; answers will not be checked, and cannot be submitted.

Software Lab

PROBLEM # QUESTIONS
8.1.1 Describing circuits (PDF)
8.1.2 Modeling resistors (PDF)
8.1.3 Modeling op-amps (PDF)
8.1.4 NodeToCurrents (PDF)

Design Lab

Additional Exercises

PROBLEM # QUESTIONS
8.3.1 Name that node (PDF)
8.3.2 Summer vacation (PDF)
8.3.3 Op-amp practice (PDF)
8.3.4 Voltages (PDF)
8.3.5 Circuits (PDF)
8.3.6 Period of pole (PDF)

Check Yourself

Nano-Quiz

Nano-quiz problems and solutions are taken from a previous version of the 6.01 Online Tutor. Do not try to answer these questions in the PDF files; answers will not be checked, and cannot be submitted.

Homework

PROBLEM # QUESTIONS
8.4.1 Eyes have it (PDF)
8.4.2 Amplifiers with offsets (PDF)
8.4.3 Controller gains (PDF)
8.4.4 Light seeker design (PDF)

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