Circuit Codex

An open, machine-readable archive of the circuits that made electric guitar.

Every classic amplifier circuit — redrawn as a clean KiCad schematic, verified as an ngspice netlist against published voltage charts, tagged with structured metadata, and connected to its ancestors and descendants in a navigable lineage graph (5F6-A → JTM45 → 1959 → 2204 …).

An Analog Maker project, live at circuitcodex.com. Guitar-pedal circuits are on the roadmap once the amp corpus is established.

Status: live — circuitcodex.com. The homepage stat block is generated from this repository at deploy time (circuit count, verified count, CC0 tube models, history-tier rows). Do not restate those numbers here — they rot the first time a circuit lands. Every documented amp carries a redrawn KiCad schematic, an ngspice netlist, a redrawn board-layout diagram, structured metadata, and a circuit walkthrough. A verified badge means the netlist landed inside the published voltage chart in CI and a maintainer signed off; everything else is draft, with the blocker named on the page. Browse the live corpus at circuitcodex.com.

Principles

1. Redrawn from facts, never scanned. Every schematic is independently drawn from the underlying circuit — component values, topology, published voltage charts. No factory drawings are reproduced or traced.
2. Circuit-number-first naming. Circuits are identified by their designation (5e3, jtm45, ab763); maker names appear only descriptively ("Tweed Deluxe-style"). This project is not affiliated with or endorsed by any amplifier manufacturer.
3. Verification is earned, not assumed. A circuit is verified only when its netlist simulates within tolerance of the published voltage chart in CI and a maintainer signs off. Everything else is draft.
4. Open forever. The archive is free. The data stays free. See Licensing.

Repository layout

amps/<id>/          one directory per circuit
  schematic.kicad_sch   redrawn KiCad schematic
  netlist.cir           ngspice netlist (references models/)
  meta.yaml             era, tubes, topology tags, lineage edges  → docs/schema.md
  voltages.yaml         published chart vs simulated operating point
  notes.md              history + circuit walkthrough
models/             tube SPICE models, freshly derived from datasheet curves (CC0)
pipeline/           validation + rendering tooling (Python)
docs/               schema and process documentation

Licensing

• Code (pipeline/, site, CI): MIT
• Circuit data (amps/): CC-BY-SA 4.0
• Tube models (models/): CC0 1.0 — to our knowledge the first explicitly open-licensed tube SPICE model set

Contributing

Contributions are welcome from day one — see CONTRIBUTING.md. The short version: redraw from facts (attested in your PR), follow the naming rules, sign off your commits (DCO). The verified badge is assigned by CI + maintainer review only.

Safety

Tube amplifiers operate at lethal voltages (350 V+), and filter capacitors hold charge long after power-off. This archive documents circuits for study; if you build or open an amplifier, learn high-voltage safety practice first. The authors accept no liability for use of this information.