circuitsnap

circuitsnap

Convert a circuit — however the user gave it to you — into a running CircuitJS1 simulation.

The one rule

Never hand-write the CircuitJS1 file format. It is positional and unforgiving: v 128 64 192 64 0 0 40 5 0 0 0.5 has six trailing parameters whose order and units you will get wrong, and the failure mode is a circuit that loads happily and simulates incorrectly — which the user cannot detect. Always go through the build_circuit tool.

Your job is the part that needs judgement: reading the drawing. The tool's job is the part that must be exact.

Workflow

1. Read the circuit into a netlist

Look at what the user gave you and identify every component and what connects to what. Produce a netlist — components plus net names, no coordinates:

{
  "title": "RC lowpass",
  "components": [
    { "id": "V1", "kind": "voltage",   "nodes": ["gnd", "in"],  "value": 5 },
    { "id": "R1", "kind": "resistor",  "nodes": ["in", "out"],  "value": "10k" },
    { "id": "C1", "kind": "capacitor", "nodes": ["out", "gnd"], "value": "1uF" }
  ]
}

Terminals sharing a net name are connected — that is the only connectivity mechanism, and you never supply positions. The server handles all layout.

Key points:

• Ground. Use the net name gnd for the 0 V reference. Almost every circuit needs one; the tool warns if there is none. gnd, ground, 0, vss all work.
• Pin order. nodes is ordered by that element's pins. Call describe_elements if you are not certain — a transistor is [base, collector, emitter] and an op-amp is [minus, plus, out], and swapping them produces a wrong-but-plausible circuit.
• Values. Engineering notation works: "10k", "2.2uF", "4k7", "1M". M means mega and m means milli (schematic convention, not SPICE's).
• Polarity. For a two-terminal source, nodes is [neg, pos].

2. Flag what you were unsure about

Put anything ambiguous in notes rather than silently guessing: