Problem 8.7 - CHALLENGE PROBLEM! Time Constant of an Op-Amp Circuit
*
* The circuit for this problem is from textbook Chap. 8, Problem 66.
*
* NOTE: This is a 2 part problem:
* 1. Determine "by inspection" the time constant of the circuit.
* Use .TRAN with a final time of 10 circuit time constants.
* 2. Change the value of resistance R12 so that the circuit time
* constant is double the value calculated in Part 1. Re-run.
*
* Use PROBE to examine each curve individually, then display both
* curves on one graph.
* Write the expression for the responses in both Part 1 and Part 2.
* You should be able to do this "by inspection." Add the expressions
* for the responses to the PROBE plot of the output voltage waveforms.
* If your expressions are correct the four traces will coincide.
*
EAMP 2 0 ??? ??? 1E10 ; Enter control voltage node numbers.
R2 2 0 10K
R12 1 2 100K
C12 1 2 1U IC=10 ; Initial voltage = 10 volts, positive
; a node 1.
R1 1 0 100K
.TRAN ??? 1 ??? ??? UIC ; Enter the parameters for the .TRAN
; command. TSTEP should be TFINAL/40.
; The maximum step size should be
; about TFINAL/100.
; Add .PRINT or .PLOT command for
; listed or plotted output.
.PROBE
.END
Problem 8.7, Part 2. CHALLENGE PROBLEM! Time Constant of an Op-Amp Circuit
*
* Change feedback resistance to double the time constant.
* Obtain a PROBE graph of the source-free responses for Parts 1 and 2.
* Also graph the mathematical expressions for the responses.
*
EAMP 2 0 ??? ??? 1E10 ; Complete the program as above. Complete
R2 2 0 10K ; the .TRAN command statement.
R12 1 2 ??? ; Enter the new value for resistance R12.
C12 1 2 1U IC=10
R1 1 0 100K
.TRAN ??? 1 ??? ??? UIC
.PROBE
.END