Problem 8.3 - Source-Free Response of a Series RLC Circuit
*
* Calculate the undamped natural frequency of the RLC circuit. Set the
* .TRAN final time to approximately 4/(natural frequency in hertz).
*
* NOTE: Always choose a TFINAL in one or two significant figures, such
* as 25 seconds or 2E-4 seconds. PROBE auto-scales each axis of the
* graph to "round numbers." If you use a TFINAL of 317 microseconds,
* for example, PROBE will round it off to 350 microseconds, and your
* plotted data will only be calculated to 317 microseconds, leaving a
* part of the graph unfilled.
*
* Use .STEP command to vary the value of resistance R1 from 100 to 300
* ohms in 100 ohm steps. Obtain a PROBE graph showing on one graph the
* capacitance voltage responses for each of the damping resistances.
*
* ===> For the curious: From the PROBE menu screen, choose the analysis
* for one of the resistance values (such as for R=200). Display the
* PROBE graph of the inductance current and inductance voltage. What
* is the mathematical relationship between these two functions?
* What is the value of inductance voltage when the inductance current
* is at a peak? Why? Answer the same questions for capacitance
* voltage and current. How are the inductance current and capacitance
* current related? Inductance voltage and capacitance voltage?
*
L1 0 1 ??? IC=??? ; Enter inductance value and initial condition.
R1 1 2 RMOD 1
C1 2 0 ??? IC=??? ; Enter capacitance value and initial condition.
.MODEL RMOD RES(R=1)
.STEP RES RMOD(R) 100 300 100
.TRAN ???? 250U ??? ??? UIC
; Enter the parameters for the .TRAN command.
; TSTEP should be TFINAL/40 and the maximum
; step size should be about TFINAL/100.
; Add .PRINT and/or .PLOT commands as desired
; for listed or printer-plot output.
.PROBE
.END