About Inertance
Inertance is an independent educational project created by Lucas Wybrandt. It helps students, teachers and curious engineers explore circuit energy storage and switching power conversion through an interactive hydraulic analogy.
Pressure represents voltage, flow represents current, a flywheel represents inductance and a spring-loaded piston represents capacitance. The editable simulator displays the circuit and its waveforms on a shared timeline.
The simulator is free to use in a web browser. It is an early teaching tool with stated model limitations, rather than a replacement for engineering design validation. The project is not affiliated with any university or manufacturer.
Contact and source code
For questions, feedback or bug reports, open an issue in the public GitHub repository. Reports there are public; please avoid sharing personal information or confidential circuit files.
The website repository includes the published simulator JavaScript and website source. Simulator code is licensed under AGPL-3.0-or-later. Copyright © 2026 Lucas Wybrandt for his copyrightable contributions; other copyright holders retain their rights. Development includes AI assistance and human review. Download preferred release sources, build instructions and licences; third-party notices; changelog. No warranty is provided to the extent permitted by applicable law.
Privacy and browser data
Simulations run in your browser. Circuit and netlist files you open are read locally, and circuit downloads are created locally. The simulator contains no circuit-upload service, account system or advertising.
Community drafts, custom schematics and their private contact fields stay on this device; simulated approval does not upload or publish them. Sharing exports omit private contact. The app saves display and playback preferences in your browser’s local storage. You can remove these by clearing this site’s browser data.
Optional usage analytics helps Lucas Wybrandt understand visits and which features people use. It contacts Umami Cloud and PostHog only after you allow it. Both projects use their EU data regions. The free plans retain six months of Umami data and one year of PostHog data. These are US-based providers; choosing an EU region does not mean all processing is exclusively within the EU.
We send the site hostname, the page path (/app/ or /about/) and fixed action names: starting a simulation, choosing a built-in preset or model mode, editing a circuit, arranging or resetting a view, import preview/apply outcomes and JSON copy/download actions. PostHog also receives random anonymous visit/session IDs and instructions to disable person profiles and location enrichment. We never send circuit contents, component values, filenames, pasted text, error messages, URL queries or hashes, referrers, names, email addresses or account IDs. The redirect page and older demo have no analytics.
Both providers receive your IP address and browser’s User-Agent with normal network requests. Umami uses these to estimate visits, devices and location. Visitor numbers are approximate. PostHog’s random IDs exist only in this page’s memory and are discarded when you leave or withdraw consent. Reloading or opening another tab creates new IDs, so its visitor counts cannot reliably identify returning people. We do not save analytics cookies or persistent visitor IDs, use automatic click capture or session replay, or save identifiers returned by providers. The dashboards are private.
Your allow/decline choice is saved in local storage for 180 days, separately on each domain. Adding PostHog requires a fresh choice from visitors who previously allowed Umami; an existing decline remains off. Do Not Track and Global Privacy Control keep analytics off. Declining does not affect the simulator.
Private feedback
Feedback sent using the app’s Send feedback button goes to Lucas through FormSubmit. It includes the topic, title, message and optional reply email. Circuit documents and playback state are not attached. This is separate from optional usage analytics. FormSubmit processes the message to deliver it by email and retains submissions for 30 days; see its privacy policy. GitHub bug reports are public and are submitted separately on GitHub.
lets you withdraw consent at any time. This aborts outstanding requests and stops future analytics requests; it cannot recall requests already received by either provider. For questions about data handling, contact Lucas through the public repository linked above without posting private circuit files.
GitHub Pages hosts the site and receives normal web requests. See GitHub’s privacy statement for its handling of visitor data. The older buck demo requests fonts from Google Fonts. The simulator’s d3 chart library is served from this website.
For teachers and site reviewers
The site’s purpose is education in electronics and electrical circuits. It offers interactive browser simulations, editable examples and waveform explanations. The canonical address is https://inertance.org/; the working app is at /app/.