Problem 9.2 - Complete Response Using Short Time Constant EXP Source
*
* The circuit for this problem is from textbook Example 9.2.
*
* Use the exponential (EXP) source i(t) = 40exp(-3t) as in Problem
* 9.1. Use PROBE to display the response waveform for the circuit.
* Add the expression for the steady-state (forced) response to the
* graph to determine when the steady-state solution is effective.
* It may be helpful, when you add the expression, to select "Y_axis"
* and "Set_range" and change the vertical axis range to -10,10.
*
* ===> Because the time constants of the circuit are longer than the time
* constant of the excitation, the response due to the source is
* swamped out by the transient response.
*
* ===> You can graph the current responses for each of the circuit
* devices. See if you can correctly predict the shape of each of
* the current waveforms: for example, the capacitance should
* initially take all of the current, since it has zero volts at t=0
* and looks like a short circuit. The inductance current cannot
* change instantly, so should gradually increase and then fall back
* to zero. What does the resistance current waveform look like?
*
* UIC is necessary for correct response with this waveform, which
* is discontinuous at the origin.
* Complete response is v(t)=-30exp(-3t)+40exp(-2t)-10exp(-1t).
*
IS 0 1 EXP(40 ??? ??? .33333 ??) ; Enter the source parameters.
R1 1 0 .16667
L1 1 0 .25
C1 1 0 2
.TRAN ??? 6 ??? ??? UIC ; Complete the .TRAN statement.
; The six-second analysis
; period is necessary in this case
; because of the long time constants
; of the natural response of the
; circuit.
.PROBE
.END