First Simulation

This walkthrough takes you from zero to a plotted frequency response using five tool calls. We will create an RC low-pass filter from a built-in template, simulate it, extract the output waveform, measure the bandwidth, and generate a plot.

Create a circuit from a template

The create_from_template tool generates a ready-to-simulate netlist from one of the built-in circuit templates.
```
create_from_template("rc_lowpass")
```
This writes an RC low-pass filter netlist to /tmp/rc_lowpass.cir with default component values (R=1k, C=100n) and an AC analysis directive.
```
// Response
{
  "netlist_path": "/tmp/rc_lowpass.cir",
  "template": "rc_lowpass",
  "parameters": { "R1": "1k", "C1": "100n" },
  "description": "RC low-pass filter, fc ~ 1.59 kHz"
}
```

Run the simulation

Pass the netlist to simulate_netlist. LTspice runs via Wine in batch mode and produces a binary .raw file with the results.

simulate_netlist("/tmp/rc_lowpass.cir")

// Response
{
  "raw_file": "/tmp/rc_lowpass.raw",
  "log_file": "/tmp/rc_lowpass.log",
  "simulation_type": "AC Analysis",
  "variables": ["frequency", "V(out)", "V(in)", "I(R1)"],
  "points": 801,
  "elapsed_seconds": 0.42
}

Extract the output waveform

Use get_waveform to pull signal data out of the .raw file. For AC analysis, this returns complex-valued data (magnitude and phase at each frequency point).

get_waveform("/tmp/rc_lowpass.raw", ["V(out)"])

// Response (truncated)
{
  "variables": {
    "frequency": [1.0, 1.26, 1.58, "...801 points..."],
    "V(out)": {
      "magnitude": [1.0, 0.9999, 0.9998, "..."],
      "phase_deg": [-0.036, -0.045, -0.057, "..."]
    }
  },
  "simulation_type": "AC Analysis",
  "num_points": 801
}

Measure the bandwidth

The measure_bandwidth tool finds the -3dB cutoff frequency from the AC analysis results.
```
measure_bandwidth("/tmp/rc_lowpass.raw", "V(out)")
```
```
// Response
{
  "f_3dB_hz": 1591.5,
  "dc_gain_dB": 0.0,
  "gain_at_cutoff_dB": -3.01,
  "signal": "V(out)"
}
```
The measured cutoff of 1591.5 Hz matches the theoretical value of 1/(2 * pi * R * C) = 1/(2 * pi * 1000 * 100e-9) = 1592 Hz.
Plot the results

Generate an SVG plot of the frequency response with plot_waveform.
```
plot_waveform("/tmp/rc_lowpass.raw", "V(out)")
```
```
// Response
{
  "svg_path": "/tmp/rc_lowpass_V(out).svg",
  "plot_type": "bode",
  "signals": ["V(out)"],
  "format": "SVG"
}
```
The SVG contains a Bode plot with magnitude and phase traces --- suitable for embedding in reports or viewing in a browser.

What just happened

In five tool calls, you:

Generated a complete SPICE netlist from a template
Ran an AC analysis through LTspice (via Wine, in batch mode, with no GUI)
Extracted complex-valued frequency-domain data from the binary .raw file
Measured the -3dB bandwidth automatically
Produced a publication-ready Bode plot

All of this happened without writing a single line of SPICE, opening a GUI, or parsing binary files manually.

Next steps

Try modifying the circuit. You can change component values with the template parameters:

create_from_template("rc_lowpass", parameters={"R1": "10k", "C1": "10n"})

This shifts the cutoff frequency to ~1.59 kHz (same frequency, different impedance) --- or pick entirely different values to explore the design space. See the tool reference for the full list of available operations.