ColijnSPICE

ColijnSPICE is a schematic editor and circuit simulator in the Colijn++ family, written in Rust: draw a circuit, set up the simulation in a window (no directive text), press F5, and read the results in a fast, clear waveform viewer. Simulation is done by ngspice, run as its own process so a simulator crash never takes the editor down.

Status (v0.1, M0): draw circuits from the built-in parts (R, C, L, V, I, D, ground, net labels), run transient, AC and operating-point analyses, probe voltages and currents, zoom and read the plots with cursors. See docs/roadmap.md.

Run it

cargo xtask ngspice          # once: downloads ngspice 47 into tools/ (Windows; checksum checked)
cargo run --release -p colijnspice

Or cargo xtask dist for a folder to hand out: dist/exe/colijnspice.exe with ngspice next to it, and the browser build in dist/web (the editor and plots work in the browser; simulation there is the next milestone).

Using it

Do	How
Place parts	Library on the left, or R C L V I D, G (ground), N (net label); Ctrl+R / Ctrl+E rotate and mirror while placing
Wire	W, click to start, click to bend, end on a pin; Space flips the corner
Edit a value	Select the part: the card top right (values like 4k7, 100n, 1M = 1 MΩ, 10m = 10 mΩ)
Simulation settings	The chip top left, the sliders button in the header, or Simulate › Simulation settings
Run	F5 (Shift+F5 stops)
Plot	P, then click a wire (voltage) or a part (current); or click a net in the sidebar
Read the plot	Hover for live values in the legend; ruler button for cursors A/B with Δ; drag a box to zoom, wheel to zoom, right-drag to pan, double-click to fit
LTspice	File › Open reads .asc (or drop it on the window); Settings (gear) sets your LTspice library folder and vendor libraries; search the library in the sidebar
Select	Drag left to right: what is inside the box · right to left: what it touches
Symbols	Settings › Symbols: American or European
Updates	Help › Check for updates; a new version shows in the footer (Install, then Restart now). Settings › Updates: daily check, channel
Everything else	Ctrl+K

Layout

Part	What it is
crates/ltspice	Standalone LTspice readers: .asc, .asy, model libraries, encodings, orientations
crates/library	Library folders (LTspice and vendor), model lookup, .asc import, vendor zips
crates/schematic	Parts, wires, connectivity, built-in symbols, the netlist with plain-English diagnostics, engineering units
crates/sim	Analysis setup, ngspice jobs (one process per analysis), raw-file reader, results named after the schematic
crates/engine	The document, every edit as a command, undo and redo
crates/ui-egui	The user interface
apps/colijnspice, apps/colijnspice-web	Desktop and browser shells
xtask	ngspice, wasm, web, ci, dist

Documentation

Read	For
AGENTS.md	Rules for contributors and AI agents
docs/roadmap.md	Milestones, the LTspice verification plan
docs/engine.md	Why ngspice, how it is embedded, WebAssembly
docs/model-formats.md	Vendor symbol and model formats (LTspice, PSpice, …)
docs/decisions.md	Architecture decision records

Licence

MIT OR Apache-2.0 (to be confirmed). ngspice is distributed under its own BSD-style licence; Geist is SIL OFL 1.1 and Lucide icons ISC; see ATTRIBUTION.md.