Problem 8.6 - Transient Response and Graph of Energy Dissipation
*
* The circuit description is a repeat of Problem 8.5. The purpose
* of this problem is to show the relationship between the speed at
* which the stored energy in a circuit is dissipated and the rate
* of decay of the transient voltage waveforms.
*
* After you have run the PSpice program, run PROBE. Select the menu
* entry for the first program run, R12=25 ohms, to obtain the blank
* graph screen. The variable on the horizontal axis will be TIME.
* Enter the expression V(1)*I(R12) to see a graph of the power
* delivered to the 25-ohm resistance R12 as a function of time.
*
* Change the x-axis range to 0,3m for the balance of this problem.
* Change the y-axis range to 0,3 for the power graphs. You will need
* to select "Y_axis" on the menu and "Auto_range" to reset the Y-axis
* scale for the energy (integral) graph described below.
*
* Use "Exit" to return to the first PROBE screen and select the menu
* entry for R12=325 ohms. Observe the instantaneous power curve again.
*
* The area under the curve of the instantaneous power curve represents
* the energy dissipated by the circuit. The integral of the power
* curve is the area under the curve. The numerical value of the
* integral at any instant of time is the running total of the energy
* dissipated up to that instant.
*
* To obtain the integrals of the three power curves, return to the
* main PROBE menu and select "All_Transient_analysis." The PROBE
* integral function is s(x), which gives the integral of x over the
* range of the x-axis variable. Enter the expression s(V(1)*I(R12)).
* The integrals of the three power curves will be drawn on one graph.
*
* Can you see a correlation between the rate at which all of the
* energy in the circuit is dissipated and the transient response of
* the circuit? (The energy curves reach their maximum value when
* there is no additional area under the curves.) Compare the results
* of the integration with each of the original power curves.
*
VS ??? ??? DC 0 ; Enter node numbers for current-measuring
; voltage source.
F1 0 1 VS ??? ; Enter gain of controlled source. Whether
; the gain is positive or negative depends
; upon your choice of +/- nodes for VS.
R12 1 2 RMOD 1
L1 1 0 .1M IC=20
C1 1 0 100U IC=10
.MODEL RMOD RES(R=1)
.STEP RES RMOD(R) 25 325 150
.TRAN ??? 5M ??? ??? UIC
; Enter the parameters for the .TRAN command.
; TFINAL should be approximately four times
; the period of the undamped natural
; frequency or 4/(natural frequency in Hz).
; TSTEP should be TFINAL/40 and the maximum
; step size should be about TFINAL/100.
.PROBE
.END