ELEC 101, Spring 2005

Prof. Rich Kozick

Prof. Rich Kozick

**Reading:**Please continue to study Chapter 2 in the Bobrow text: Section 2.4 (op amps), Section 2.5 (Thevenin equivalent circuit), and Section 2.6 (superposition).- Before lab on Thursday, February 17, please read the Lab 5 handout and do the pre-lab activities in your lab notebook.
- Please solve problem 2.35 in the Bobrow text. Show the steps that you use in your analysis.
- Design an op amp circuit such that the output voltage
is one-fourth the input voltage, i.e.,

v_{o}= 0.25 v_{i}. (Hint: You may need more than one op amp.) - Specify an op amp circuit whose output voltage is
the
*average*of three input voltage sources:

v_{out}= (v_{a}+ v_{b}+ v_{c})/3. Specify values for all resistors in your circuit diagram. - Consider the electronic ohmmeter
shown below.
To use the ohmmeter,
an unknown resistance
*R*is connected as shown, and then the value of*R*is obtained by measuring the voltage v_{o}and then computing*R*= -1000 v_{o}.

[CIRCUIT DIAGRAM IS NOT AVAILABLE IN HTML DOCUMENT.] - Since v
_{o}is always within the range -10 volts to +10 volts, what is the maximum value of*R*that can be measured with this circuit? - How can the circuit be modified in order to measure
resistance values up to 100 k ohms?
Explain the reasoning behind your modification, and explain
how the value of
*R*is computed from v_{o}in your circuit.

- Since v