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# SpiceBook

**A notebook interface for SPICE circuit simulation.**

Write the narrative. Run the simulation. See the waveform. All in one document.

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![SpiceBook notebook showing RC lowpass filter with Bode plot and step response waveforms](docs/screenshots/both-sims-complete.png)

## What is this?

SpiceBook is a notebook for circuit engineers. Markdown cells for explanation, SPICE cells for simulation, waveform plots for results -- interleaved in a single document you can re-run, share, and version control.

Think "Jupyter for circuits" except it actually understands SPICE. The editor highlights your `.tran` and `.ac` commands. The waveform viewer knows about dB and degrees. Engineering notation on the axes reads `1.59 kHz`, not `1591.549`.

Nothing else does this. PySpice needs you to write Python. CircuitLab is closed-source and schematic-only. Multisim Live is shutting down. The browser-based ngspice wrappers give you one netlist and one plot -- no narrative, no interleaving, no notebook.

SpiceBook lets you write a document that says: "here's why this filter works, here's the AC analysis proving it, here's the step response confirming the time constant" -- and every claim is backed by a live, re-runnable simulation.

## Features

- **Markdown cells** with rendered preview -- headings, bold, lists, inline math notation
- **SPICE cells** with CodeMirror 6 and custom syntax highlighting:
  - Dot commands (`.tran`, `.ac`, `.dc`, `.model`, `.param`, `.subckt`, ...)
  - Component prefixes (`R`, `C`, `L`, `V`, `I`, `M`, `Q`, `D`, `X`)
  - Engineering notation (`1k`, `10u`, `3.3meg`, `100p`)
  - Comments (`*` and `;`), brace expressions (`{10k*(1-x)}`)
- **Waveform viewer** built on uPlot (~50KB, fast):
  - Multi-trace overlay with color-coded legend
  - Stacked Bode plots (magnitude dB + phase degrees) for AC analysis
  - Time-domain plots for transient analysis
  - Log-scale frequency axis, engineering-notation labels
  - Click-drag zoom, scroll to pan
- **ngspice backend** -- subprocess execution with binary `.raw` file parsing
- **Notebook operations** -- create, open, edit, save, delete, reorder cells, run individually or all at once
- **Keyboard shortcuts** -- `Ctrl+S` save, `Shift+Enter` run cell
- **Clean URLs** -- `/notebook/rc-lowpass-filter` via Astro dynamic routes
- **15 example notebooks** included:

  **Fundamentals:**
  - RC Lowpass Filter Analysis (AC + transient)
  - Voltage Divider (DC operating point + sweep)
  - Common Emitter Amplifier (AC + transient with BJT model)
  - RC Step Response, RLC Bandpass Filter, Diode Rectifier, LED I-V Curve, Inverting Op-Amp, CMOS Inverter

  **Advanced (multi-cell, real-world circuits):**
  - Synchronous Buck Converter -- 12V-to-3.3V switching regulator with startup and steady-state detail
  - Class AB Push-Pull Audio Amplifier -- frequency response, clean output, and overdrive clipping
  - AM Radio Receiver -- envelope detection with carrier and audio waveforms
  - Dickson Charge Pump -- voltage multiplication under light and heavy loads
  - Transmission Line Signal Integrity -- unterminated ringing vs series-terminated clean signals
  - 4th-Order Sallen-Key Butterworth Filter -- active filter vs passive RC comparison
  - Colpitts RF Oscillator -- ~1 MHz oscillation startup and steady-state

## Quick Start

### Prerequisites

- **ngspice** -- the simulation engine
  - Arch: `sudo pacman -S ngspice`
  - Debian/Ubuntu: `sudo apt install ngspice`
  - macOS: `brew install ngspice`
- **Python 3.12+** with [uv](https://docs.astral.sh/uv/)
- **Node.js 20+**

### Local Development (no Docker)

```bash
# Clone
cd spicebook

# Backend
cd backend
uv sync
uv run uvicorn spicebook.main:app --host 0.0.0.0 --port 8099 --reload

# Frontend (separate terminal)
cd frontend
npm install
npx astro dev --host 0.0.0.0 --port 4322
```

Open [http://localhost:4322](http://localhost:4322)

### Docker (Development)

```bash
make dev
```

Frontend at `http://localhost:4321`, backend at `http://localhost:8099`, API docs at `http://localhost:8099/docs`.

### Docker (Production)

```bash
make prod
```

Production mode runs behind Caddy with TLS via `caddy-docker-proxy`. Set `SPICEBOOK_DOMAIN` in `.env`.

### Makefile Targets

| Target | What it does |
|--------|-------------|
| `make dev` | Build and start dev containers with hot-reload |
| `make prod` | Build and start production containers |
| `make down` | Stop all containers |
| `make logs` | Tail container logs |
| `make clean` | Remove containers, volumes, and build artifacts |
| `make backend-shell` | Shell into the backend container |
| `make help` | List all targets |

## Project Structure

```
spicebook/
├── frontend/                # Astro 5 + React 19
│   ├── src/
│   │   ├── pages/           # Astro routes (index, /notebook/[id])
│   │   ├── components/
│   │   │   ├── notebook/    # Editor, cells, output viewers, toolbar
│   │   │   └── ui/          # Button, Badge, Dropdown (shadcn/ui)
│   │   ├── lib/
│   │   │   ├── spice-language.ts   # CodeMirror SPICE mode
│   │   │   ├── waveform-utils.ts   # Engineering notation formatter
│   │   │   ├── notebook-store.ts   # Zustand state
│   │   │   ├── api.ts              # Backend client
│   │   │   └── types.ts            # TypeScript types
│   │   └── styles/globals.css
│   └── astro.config.mjs
├── backend/                 # FastAPI + ngspice
│   ├── src/spicebook/
│   │   ├── main.py          # App factory, health check
│   │   ├── config.py        # Settings from environment
│   │   ├── engine/          # SPICE engine abstraction
│   │   │   ├── base.py      # Abstract base class
│   │   │   └── ngspice.py   # ngspice subprocess + .raw parser
│   │   ├── models/          # Pydantic schemas
│   │   │   ├── notebook.py  # Notebook, Cell, CellOutput
│   │   │   └── simulation.py
│   │   ├── routers/         # API endpoints
│   │   │   ├── notebooks.py # CRUD
│   │   │   ├── simulation.py # Run cells
│   │   │   └── waveforms.py # Waveform data
│   │   └── storage/
│   │       └── filesystem.py # .spicebook file I/O
│   ├── tests/
│   └── pyproject.toml
├── notebooks/
│   ├── examples/            # Shipped example notebooks
│   └── user/                # User-created (gitignored)
├── docker-compose.yml       # Base services
├── docker-compose.dev.yml   # Dev overrides (hot-reload, port mapping)
├── docker-compose.prod.yml  # Prod overrides (Caddy, no ports exposed)
├── Makefile
└── .env
```

## `.spicebook` File Format

Notebooks are JSON files with a `.spicebook` extension. Git-friendly, outputs persisted inline.

```json
{
  "spicebook_version": "2026-02-13",
  "metadata": {
    "title": "RC Lowpass Filter Analysis",
    "engine": "ngspice",
    "tags": ["filter", "passive"]
  },
  "cells": [
    {
      "id": "cell-001",
      "type": "markdown",
      "source": "# My Circuit\nExplanation goes here.",
      "outputs": []
    },
    {
      "id": "cell-002",
      "type": "spice",
      "source": "V1 in 0 AC 1\nR1 in out 1k\nC1 out 0 100n\n.ac dec 100 1 10meg\n.end",
      "outputs": [
        {
          "output_type": "simulation_result",
          "data": { "success": true, "waveform": { "..." : "..." } },
          "timestamp": "2026-02-13T12:00:00Z"
        }
      ]
    }
  ]
}
```

## Tech Stack

| Layer | Technology |
|-------|-----------|
| Frontend framework | Astro 5 (SSR, Node adapter) |
| Interactive islands | React 19 |
| Code editor | CodeMirror 6 (custom SPICE language mode) |
| Waveform charts | uPlot |
| State management | Zustand |
| Styling | Tailwind CSS 4 |
| UI components | shadcn/ui |
| Icons | Lucide |
| Backend | FastAPI |
| SPICE engine | ngspice (subprocess) |
| Data validation | Pydantic |
| Containerization | Docker Compose |
| Reverse proxy | Caddy (via caddy-docker-proxy) |

## API

The backend exposes a REST API. When running in dev mode, interactive docs are at `http://localhost:8099/docs`.

Key endpoints:

| Method | Path | Description |
|--------|------|-------------|
| `GET` | `/api/notebooks` | List all notebooks |
| `GET` | `/api/notebooks/{id}` | Get a notebook |
| `POST` | `/api/notebooks` | Create a notebook |
| `PUT` | `/api/notebooks/{id}` | Update a notebook |
| `DELETE` | `/api/notebooks/{id}` | Delete a notebook |
| `POST` | `/api/notebooks/{id}/cells/{cell_id}/run` | Run a SPICE cell |
| `POST` | `/api/simulate` | Run a standalone simulation |
| `GET` | `/health` | Health check |

## Configuration

All configuration is via environment variables (`.env` file). See `.env` for the full list.

| Variable | Default | Description |
|----------|---------|-------------|
| `ENVIRONMENT` | `dev` | `dev` or `prod` |
| `BACKEND_PORT` | `8099` | Backend port (dev only) |
| `FRONTEND_PORT` | `4321` | Frontend port (dev only) |
| `NGSPICE_PATH` | `/usr/bin/ngspice` | Path to ngspice binary |
| `NOTEBOOK_DIR` | `/app/notebooks` | Notebook storage path |
| `SPICEBOOK_DOMAIN` | -- | Domain for production (Caddy TLS) |
| `VITE_HMR_HOST` | -- | Set when behind reverse proxy |

## Roadmap

### Phase 2 -- Core Features
- Python cells with sandboxed execution and cross-cell data access
- LTspice engine integration (via mcltspice library)
- Measurement cursors in waveform viewer
- SVG/CSV export for waveforms
- Signal analysis: FFT, THD, RMS, bandwidth
- KaTeX math rendering in markdown cells

### Phase 3 -- Advanced
- Schematic cells (SchemDraw backend rendering)
- Auto-schematic generation from netlist
- WebSocket progress for long simulations
- LTspice `.asc` file import

### Phase 4 -- Polish
- Interactive schematic editor (tscircuit integration)
- Parameter sweeps with overlay plots
- Monte Carlo analysis visualization
- Template gallery

## Contributing

1. Fork the repository
2. Create a feature branch: `git checkout -b my-feature`
3. Make changes and add tests
4. Run the linter: `cd backend && uv run ruff check .`
5. Run tests: `cd backend && uv run pytest`
6. Submit a pull request

## Versioning

SpiceBook uses date-based versioning (`YYYY.MM.DD`). The current version is `2026.02.13`.

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Built by [Ryan Malloy](mailto:ryan@supported.systems)