Run your first simulation
Pick an analysis, press run, and read the results on the chart or in the table.
Britt Espinosa
Last Update 15 days ago
Running a simulation takes two decisions: which analysis you want, and where you want to read the answer.
Choose the analysis
Open Simulation Settings on the right of the schematic and pick from Simulation Type. Seven analyses are available:
| Analysis | Use it when you want |
|---|---|
| Interactive | To poke at the circuit while it runs |
| Interactive operating point | Steady-state numbers that refresh as you edit |
| Transient | Behavior over time |
| AC sweep | Response across a frequency range |
| DC operating point | Steady-state voltages and currents |
| DC sweep | The effect of varying a source across a range |
| Parameter sweep | The effect of varying a component value across several runs |
DC operating point is the one to start with. It answers what the voltages and currents are once everything settles, which is what most first circuits are asking.
DC sweep and Parameter sweep show a padlock on the free Basic plan and need Standard or Premium.
Press run
The run button is at the top right. While the engine loads for the first time on a page, its tooltip reads Preparing simulation engine..., which takes a moment and then does not happen again.
The status text beside the circuit name tells you where things are:
- Ready means nothing is running
- Simulating: 40% counts through a transient, AC, or DC sweep
- Running appears during an interactive simulation, which keeps going until you stop it
- Running #12 counts frames during an interactive operating point run
The same button becomes Stop while a simulation is going.
Read the results
Turn on Chart to see results plotted, or Table to see them as numbers.
For a DC operating point there is no waveform to draw, so the Table panel is where the answer is: a row per node voltage and per component current.
For transient and AC analyses, the Chart panel is usually what you want. Drop cursors on the trace to read exact values at a point, and use the chart settings drawer to change which traces are shown and how the axes are scaled.
Running automatically
Two settings in Simulation Setup save you pressing the button:
Run simulation on open starts the analysis whenever the circuit is opened.
Simulate on schematic change re-runs after you edit the schematic, which helps while you are tuning values and gets in the way while you are building.
Both are off by default, and both are forced off for parameter sweeps, which only run when you start them.
If nothing happens
The run stops before it starts when the schematic has a problem the simulator cannot work around. Turn on the Info panel: the same badge that appears on the Info button in the top bar corresponds to a message there explaining what is wrong.
The two most common are a missing ground and a pin left unconnected. See My simulation will not run.