{ "openapi": "3.1.1", "info": { "title": "Ohmforge AC Sweep (Bode plot) API", "version": "1.0.0", "summary": "Frequency response of a circuit: Bode magnitude/phase, −3 dB corner and unity gain.", "description": "Every endpoint performs the same calculation as the human page and returns inputs, result, units, assumptions, sources, warnings and computedAt. MCP endpoint: /mcp." }, "servers": [ { "url": "https://ohmforgeacsweep.usefulweb.site" } ], "paths": { "/api/v1/calculate": { "post": { "operationId": "calculate", "summary": "Frequency response of a circuit: Bode magnitude/phase, −3 dB corner and unity gain.", "description": "Linearises the circuit at its DC operating point and solves the complex MNA equations across a logarithmic frequency sweep. Returns magnitude in dB and unwrapped phase of an output node (optionally relative to an input node), the peak gain, lower/upper −3 dB frequencies, the unity-gain frequency, a Bode chart and CSV.\n\nMethodology:\n- The DC operating point is solved first; every nonlinear device is replaced by its small-signal conductances at that point (diode gd, BJT gm/gπ/go, MOSFET gm/gds, op-amp output slope).\n- Capacitors become admittances jωC, inductors impedances jωL in their branch equations, coupled inductors jωM; the complex system is solved by dense LU with partial pivoting at every frequency.\n- Magnitude is 20·log10|H|, phase is unwrapped to be continuous. The −3 dB points are found 3.01 dB below the peak by logarithmic interpolation; unity gain is the 0 dB crossing.\n\nTeaching-grade simulation: device models are simplified (Ebers–Moll BJT, level-1 MOSFET, behavioural op-amps and 555) and part ratings are typical values. Verify real designs on the bench and against manufacturer data before building anything connected to mains voltage.", "tags": [ "apps" ], "x-mcp-tool": "ohmforge_ac_sweep", "requestBody": { "required": true, "content": { "application/json": { "schema": { "$ref": "#/components/schemas/OhmforgeAcSweepInput" }, "examples": { "example1": { "summary": "RC low-pass (fc ≈ 1.59 kHz)", "value": { "netlist": "* RC low-pass, fc = 1/(2*pi*1k*100n) = 1591.5 Hz\nV1 in 0 DC 0 AC 1\nR1 in out 1k\nC1 out 0 100n\n.ac dec 20 10 1meg", "output": "out", "input": "V1" } }, "example2": { "summary": "Inverting op-amp, gain −10", "value": { "netlist": "* Inverting amplifier, gain -10 (ideal op-amp as VCVS)\nV1 in 0 AC 1\nR1 in m 1k\nR2 m out 10k\nE1 out 0 0 m 100k\n.ac dec 10 10 10meg", "output": "out", "input": "V1" } } } } } }, "responses": { "200": { "description": "Calculation result envelope.", "content": { "application/json": { "schema": { "$ref": "#/components/schemas/OhmforgeAcSweepResult" } } } }, "400": { "description": "Malformed JSON body.", "content": { "application/problem+json": { "schema": { "$ref": "#/components/schemas/Problem" } } } }, "422": { "description": "Invalid input (see errors[]).", "content": { "application/problem+json": { "schema": { "$ref": "#/components/schemas/Problem" } } } }, "429": { "description": "Rate limit exceeded (see Retry-After).", "content": { "application/problem+json": { "schema": { "$ref": "#/components/schemas/Problem" } } } } } } }, "/api/v1/tool": { "get": { "operationId": "getToolDefinition", "summary": "Inputs, output schema and examples for this tool", "responses": { "200": { "description": "Tool definition.", "content": { "application/json": { "schema": { "type": "object" } } } } } } } }, "components": { "schemas": { "Problem": { "type": "object", "description": "RFC 9457 problem details. 422 responses include per-field `errors`.", "required": [ "type", "title", "status", "detail" ], "properties": { "type": { "type": "string" }, "title": { "type": "string" }, "status": { "type": "integer" }, "detail": { "type": "string" }, "code": { "type": "string" }, "errors": { "type": "array", "items": { "type": "object", "required": [ "field", "message" ], "properties": { "field": { "type": "string" }, "message": { "type": "string" } } } } } }, "OhmforgeAcSweepInput": { "type": "object", "additionalProperties": false, "properties": { "netlist": { "title": "SPICE netlist", "description": "Subset: R C L V I D Q M E G K, .model, SIN/PULSE/PWL sources, engineering suffixes (k, m, u, n, p, meg). Node 0 is ground. Leave empty when you pass an Ohmforge project instead.", "type": "string", "maxLength": 60000 }, "project": { "title": "Ohmforge project JSON (optional)", "description": "Alternative to the netlist: a .ohmforge.json project as saved by the app (format \"ohmforge\", version 1).", "type": "string", "maxLength": 200000 }, "output": { "title": "Output node", "type": "string", "maxLength": 64, "default": "out" }, "input": { "title": "Input source (gets AC = 1)", "description": "Name of the V or I source to excite (e.g. V1). Empty = keep the AC magnitudes from the netlist.", "type": "string", "maxLength": 64 }, "inputNode": { "title": "Reference node (optional)", "description": "Report V(out)/V(ref) instead of V(out).", "type": "string", "maxLength": 64 }, "fstart": { "title": "Start frequency", "description": "Empty = .ac line or 1 Hz.", "type": "number", "minimum": 0.001, "maximum": 10000000000, "x-unit": "Hz" }, "fstop": { "title": "Stop frequency", "description": "Empty = .ac line or 10 MHz.", "type": "number", "minimum": 0.001, "maximum": 100000000000, "x-unit": "Hz" }, "pointsPerDecade": { "title": "Points per decade", "description": "Empty = .ac line or 20.", "type": "integer", "minimum": 1, "maximum": 200 } }, "required": [ "output" ] }, "OhmforgeAcSweepResult": { "type": "object", "additionalProperties": false, "required": [ "schemaVersion", "tool", "computedAt", "inputs", "summary", "result", "units", "assumptions", "sources", "warnings", "presentation", "links" ], "properties": { "schemaVersion": { "type": "string", "const": "1.0" }, "tool": { "type": "object", "additionalProperties": false, "required": [ "id", "name", "version" ], "properties": { "id": { "type": "string" }, "name": { "type": "string" }, "version": { "type": "string" } } }, "computedAt": { "type": "string", "format": "date-time" }, "inputs": { "type": "object", "description": "Normalised inputs actually used, including applied defaults." }, "summary": { "type": "string" }, "result": { "type": "object", "required": [ "output", "frequencies", "magnitudeDb", "phaseDeg", "peakDb" ], "properties": { "output": { "type": "string" }, "input": { "type": [ "string", "null" ] }, "frequencies": { "type": "array", "items": { "type": "number" } }, "magnitudeDb": { "type": "array", "items": { "type": "number" } }, "phaseDeg": { "type": "array", "items": { "type": "number" } }, "peakDb": { "type": "number" }, "peakFrequency": { "type": "number" }, "lowGainDb": { "type": "number" }, "lower3dB": { "type": [ "number", "null" ] }, "upper3dB": { "type": [ "number", "null" ] }, "unityGainFrequency": { "type": [ "number", "null" ] }, "diagnostics": { "type": "array", "items": { "type": "string" } } } }, "units": { "type": "object", "additionalProperties": { "type": "string" } }, "assumptions": { "type": "array", "items": { "type": "string" } }, "sources": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "title" ], "properties": { "title": { "type": "string" }, "url": { "type": "string" }, "publisher": { "type": "string" }, "retrievedAt": { "type": "string" }, "note": { "type": "string" } } } }, "warnings": { "type": "array", "items": { "type": "string" } }, "presentation": { "type": "array", "items": { "type": "object" }, "description": "Display blocks used by the human page (same data)." }, "links": { "type": "object", "additionalProperties": false, "required": [ "human", "api", "openapi", "methodology" ], "properties": { "human": { "type": "string", "format": "uri" }, "api": { "type": "string", "format": "uri" }, "openapi": { "type": "string", "format": "uri" }, "methodology": { "type": "string", "format": "uri" } } } } } } } }