ELEC 226, Spring 2009
Prof. Rich Kozick

Homework 10

Date Assigned: Thursday, March 26, 2009
Date Due: Wednesday, April 1, 2009 in class at 9:00 AM

  1. Homework 9 is due at the beginning of class on Monday, March 30.

  2. Please see the Announcement on Blackboard for the upcoming guest lectures in Dana 113:
    Monday, March 30 at 10:00 AM
    Friday, April 3 at 9:00 AM
    Monday, April 6 at 10:00 AM

  3. Reading: Continue to study Chapter 7, Sections 7.1 - 7.4.

  4. Exam 2 is scheduled for Monday, April 6. We will discuss the topics for the exam in class on April 1.

  5. Please solve the following problems in Chapter 7:  7.34 and 7.55.

  6. The following circuit is a slightly more general version of the clock circuit from Lab 5, where Ra and Rb may be unequal. Assume that the op amp is powered so that -10 V <= vout(t) <= +10 V, and let T denote the period of the waveform produced by the oscillator circuit.

    • Find the formulas for the capacitor voltage, vc(t), during the time intervals 0 <= t <= T/2 and T/2 <= t <= T. Assume that the circuit is in "steady-state" at time t=0, i.e., the circuit has been oscillating for a long time before t=0. Your formulas will be a function of all of the resistor and capacitor values in the circuit (R, C, Ra, Rb).
    • Use your results for vc(t) to find a formula for the period, T, as a function of the resistor and capacitor values in the circuit.
    • Sketch vout(t) and vc(t) versus time, and indicate the effects of the circuit parameters on the amplitudes and period in your plot.
    • How should Ra and Rb be chosen so that vc(t) is close to a triangle wave? Please explain based on your formulas for vc(t).

Thank you.