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Friday, October 24, 2008

Pulse response of an RLC Circuit

Using P Spice, for the following RLC circuit, calculate and plot the Transient Response from 0 to 400µs with a time increment of 1 µs .
Solution:-
[The capacitor voltage V (3) and the current R1, I(R1) are to be plotted]

Program

* PULSE (-VS +VS TD TR TF PW PER) ; Pulse input
VIN 1 0 PULSE(-220V 220V 0 1NS 1NS 100US 200US)
R1 1 2 2
L1 5 3 50UH
C1 3 0 10UF
*TRAN TSTEP TSTOP ; Command for Transient Analysis
.TRAN 1US 400US
*.PRINT TRAN V(R1) V(L1) V(C1) ; Prints to the output file
*.PLOT TRAN V(3) I(R1) ; Plots in the output file
.PROBE ; Graphical Wave form analyzer
.END ; End of circuit file

It should be noted that with the .PROBE command, there is no need for the .PLOT command; .PLOT generates the plot in the output file, while .PROBE sends graphical output to the monitor screen that can be dumped directly in to plotter or printer.
By putting asterisk (*) in front of .PLOT or .PRINT, there is no effect.