SU.1084 Schematic capture and circuit simulation (a Multisim-style tool)

Asked (#1084, Oct 27): schematic simulation software without a subscription, easy like NI Multisim.

Built 2026-11-06 (session circuit-09): the CadCraft add-on `circuit` (Circuit simulation, off by default) on lib/schematic and lib/em. A schematic editor (resistor, capacitor, inductor, DC, AC and pulse sources, current source, switch, diode, LED, NPN/PNP, N/P MOSFET, op-amp, ground), wiring with junctions, net names, a rule check through Problems (no ground, floating pins, duplicate names, two names joined, bad values, no DC path, source loops). DC operating point, transient and AC sweep, read with a meter, scope and plotter placed on nets. Save/Open, netlist export, example, help in English.

Measured (public_html/assets/apps/cadcraft/a Discord member/addons/circuit/test/test.mjs, 87 passed; errors printed): divider 2e-9, RC step worst 1e-3 V on 5 V, RLC resonance curve 1e-10, rectifier peak vs an independent Shockley solve 6e-12, op-amp stage 1e-13, MOSFET 1e-11, BJT bias 2e-7, LED 1e-8. Real page in Chromium: test/browser.mjs, 30 passed (with the mount added by a route).

Not claimed: equality with Multisim or any program; Multisim files and part models are not read; no real part library (values are typed, generic defaults); op-amp has no rails or bandwidth; no noise, sweeps or Monte Carlo; not tried on a phone or in Studio.

Mounted 2026-11-06: "circuit" in CadCraft's a Discord member addons/index.json (off by default); browser test 30/0 with the real index. SuperCad Studio mounts CadCraft inline from its a Discord member build, so the add-on is listed there too. Not claimed: equality with Multisim.