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Open Model LabCircuit Builder

Circuit Builder

Build a live circuit, then use the same workspace to explain what it is doing.

This page combines a free-build circuit canvas with guided component explanations, live computed values, and bounded DC solver assumptions that stay visible while you work.

Suggested starting points

Presets are there to teach. You can still add, delete, rotate, and rewire every part after loading one.

Current status and export

Nothing selected0 issues

Diagram export stays disabled until the workspace contains at least one component. JSON state export still works for an empty workspace.

Workspace

Drag parts, rotate them in the inspector, and pan the canvas by dragging empty space.

Start with a source and one loadClick a palette item to add it here, then connect terminals with the wire tool.Example: battery -> resistor -> back to the battery for a complete loop.

Inspector

Component details, live readouts, warnings, and graph panels move here on smaller screens.

Inspector

Select a part to inspect it

The inspector explains what each symbol means, which properties you can edit, and how the part is behaving inside the current circuit.

1. Add a source and at least one load.

2. Use the wire tool to connect two terminals at a time.

3. Click any component to edit it and read the live explanation.

The current circuit solves cleanly. Select a component to see its local explanation and computed values.

Solver notes and model assumptions

This v1 builder prefers an explicit, teachable DC steady-state model over perfect electronics fidelity.

Batteries are ideal voltage sources. Resistors, bulbs, thermistors, LDRs, meters, closed switches, and intact fuses are linear or near-linear elements in the steady-state solve.
Capacitors are treated as open circuits after settling. Diodes use a simplified threshold model, bulbs are resistive loads, and fuses trip instantly once the steady-state current exceeds their rating.
Wires collapse terminals into shared nodes, so branch currents and voltage drops come from the same graph-based circuit solve instead of separate per-widget math.
SVG and JSON export both use the same document model, so future formats can reuse this pipeline without changing the builder state shape.