Open the CircuitLab learning dashboard · The hosted site is private and requires owner access. You can also run your own copy locally.
CircuitLab helps firmware engineers read and review PCB schematics. Start with a circuit, change a component value, and connect the result to a practical question such as whether an ADC input will settle or an I²C line will rise fast enough.
Open Circuit Playground → Voltage divider. Set the supply to 5 V, the upper resistor to 20 kΩ, and the lower resistor to 10 kΩ. The unloaded tap reads about 1.67 V. Switch to Loaded and set the load to 10 kΩ. It sits in parallel with the lower resistor, making the effective lower leg 5 kΩ. The new tap voltage is 5 V × 5 / (20 + 5) = 1 V.
| Area | What’s included |
|---|---|
| Learning path | Seven complete lessons on voltage, current, resistance, Ohm’s law, capacitors, voltage dividers, and MOSFETs. Each includes a worked example, an experiment, and a knowledge check. Future lessons are marked as planned. |
| Circuit Playground | Eleven adjustable experiments covering resistor networks, RC charging and discharging, LEDs, MOSFETs, open-drain signaling, I²C rise time, resistor sizing, regulator heating, and decoupling. |
| Schematic Reading Academy | Click through an MCU reset circuit and an I²C sensor interface to inspect components, follow signal states, and identify datasheet parameters to check. |
| Quick Reference and Review Checklist | Look up formulas and schematic patterns, then check power, reset, clock, GPIO, analog, protection, and interface decisions during a board review. |
Lesson progress, quiz history, bookmarks, and checklist selections are saved in the current browser. Clearing its site data removes those records.
Use Node.js 22.20 and npm. From a terminal with access to this repository, run
git clone https://github.com/arjun7965/circuitlab.git
cd circuitlab
npm ci
npm run devOpen the local dashboard. The app runs entirely in the browser after its assets load.
npm test
npm run buildThe tests check calculator results against independently worked values, exercise operating modes and invalid inputs, and verify numerical examples and quiz answers in the lessons. The production build exports a static site to out/, which can be served by a static web server.
Each experiment documents its equations, assumptions, and sources under Model assumptions & source. For example, the I²C calculator estimates the 30–70% rise time of a passive pull-up and lumped bus capacitance. Its result depends on the capacitance you supply. For a board review, compare the result with the selected bus mode’s timing limits and each device’s guaranteed sink current.
The experiments use analytical models. Validation covers their stated operating conditions. Device-specific switching behavior, PCB parasitics, and board-level performance require the relevant datasheets, simulation models, or measurements.
- Lesson content contains explanations, worked examples, quizzes, and references.
- Reference library contains the curriculum outline, quick-reference entries, and review checklist.
- Circuit equations and experiment definitions implement the calculations, input bounds, and model assumptions.
- Experiment diagrams and schematic walkthroughs render the interactive SVG circuits.
- Calculator tests and lesson tests contain the numerical regression checks.
Built with Next.js, TypeScript, React, KaTeX, and Recharts.