Ryan Malloy
8abd7719bf
Phase 1 implementation with ngspice backend and Astro/React frontend: Backend (FastAPI): - ngspice subprocess engine with custom .raw file parser - Notebook CRUD with .spicebook JSON format (filesystem storage) - Simulation endpoints (standalone + cell-in-notebook) - SVG waveform export endpoint - 18 REST API routes, 5 passing tests Frontend (Astro 5 + React 19): - Notebook editor as React island with Zustand state management - CodeMirror 6 with custom SPICE language mode (syntax highlighting for dot commands, components, engineering notation, comments) - uPlot waveform viewer with transient and AC/Bode plot modes - Markdown cells with edit/preview toggle - Notebook list with card grid UI - Dark theme, Tailwind CSS 4, Lucide icons Infrastructure: - Docker Compose with dev/prod targets - Caddy-based frontend prod serving - 3 example notebooks (RC filter, voltage divider, CE amplifier)
43 lines
1.8 KiB
Plaintext
43 lines
1.8 KiB
Plaintext
{
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"spicebook_version": "2026-02-13",
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"metadata": {
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"title": "RC Lowpass Filter Analysis",
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"engine": "ngspice",
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"tags": ["filter", "passive", "beginner"],
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"created": "2026-02-13T00:00:00Z",
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"modified": "2026-02-13T00:00:00Z"
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},
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"cells": [
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{
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"id": "cell-intro",
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"type": "markdown",
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"source": "# RC Lowpass Filter\n\nA first-order passive RC lowpass filter with a cutoff frequency of approximately **1.59 kHz**.\n\nThe -3dB frequency is: f_c = 1 / (2 * pi * R * C)\n\nWith R = 1k and C = 100nF: f_c = 1 / (2 * pi * 1000 * 100e-9) = 1591 Hz",
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"outputs": []
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},
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{
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"id": "cell-ac",
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"type": "spice",
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"source": "RC Lowpass Filter - AC Analysis\nV1 in 0 AC 1\nR1 in out 1k\nC1 out 0 100n\n.ac dec 100 1 10meg\n.end",
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"outputs": []
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},
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{
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"id": "cell-explain-ac",
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"type": "markdown",
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"source": "## Interpreting the Bode Plot\n\nThe magnitude plot should show:\n- **Flat response** (0 dB) below the cutoff frequency\n- **-3 dB point** at approximately 1.59 kHz\n- **-20 dB/decade rolloff** above the cutoff\n\nThe phase should transition from 0 degrees to -90 degrees, passing through -45 degrees at the cutoff frequency.",
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"outputs": []
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},
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{
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"id": "cell-transient",
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"type": "spice",
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"source": "RC Lowpass Filter - Step Response\nV1 in 0 PULSE(0 1 0 1n 1n 0.5m 1m)\nR1 in out 1k\nC1 out 0 100n\n.tran 10u 3m\n.end",
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"outputs": []
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},
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{
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"id": "cell-explain-transient",
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"type": "markdown",
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"source": "## Step Response\n\nThe transient simulation shows the capacitor charging and discharging through the resistor.\n\nThe time constant is: tau = R * C = 1000 * 100e-9 = 100 us\n\nThe output reaches ~63% of the input voltage after one time constant, and ~95% after three time constants (300 us).",
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"outputs": []
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}
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]
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}
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