==Transient Test==
The transient analysis generates the circuit's behavior as a function of time from t<sub>start</sub> to t<sub>stop</sub> at increments equal to t<sub>step</sub>. The maximum interval between time steps, t<sub>max</sub> or "Step Ceiling", is critical to prevent the simulation from generating incorrect results. If t<sub>max</sub> is too large, then sharp changes in the circuit's voltages may be overlooked by the simulator. [[RF.Spice A/D]] gives you the option to linearize your time-domain simulation results, which will generate a second transient graph, with results linearly interpolated at an interval of t<sub>step</sub>. The Transient Test is similar to the default "Live Simulation", but the time span is rather finite and it is defined and confined by you. Moreover, the simulation results are displayed in a graph instead of [[Virtual Instruments|virtual instruments]].
The default results of a transient test consist of plots of the voltage across each voltmeter in the circuit and the current through each ammeter as a function of time. You can customize the results by choosing any node voltage or device current using "Preset Graph Plots" and "Preset Table Plots". To learn how you can define output voltages or currents anywhere in your circuit, refer to the section on [[B2_output#Setting_Up_Circuit_Observables | "Setting Up Circuit Observables]]". You may also place a voltage probe or a current probe in your circuit to plot its signal as a function of time. To learn more about probes, see the section on [[B2_output#Using_Probes_or_Meters_as_Observables | "Using Probes or Meters as Observables]]".
Sometimes the SPICE engine has trouble converging on solutions in a transient analysis. If this happens, increasing capacitances and internal transistor capacitances specified in the transistor models can sometimes relax the circuit enough to help convergence. Also, increasing the value of the "ITL4" parameter in the [[Simulation Options]] dialog from its default of 10 to around 40 can sometimes help the solution's convergence. The ITL4 parameter specifies the maximum number of iterations in a transient simulation.
As an example, the figure below shows an Op-Amp circuit (inverting amplifier) with a capacitive load. The graph next to it shows the time-domain input and output voltages of the Op-Amp circuit.