About OhmLens

What it is

OhmLens is a free way to learn electronics by doing. Each lesson is a live circuit: you change a part, and the voltages, currents and temperatures update at once. It is written for complete beginners, so every new word is explained in plain English.

Who makes it

OhmLens is made by Jari, a developer who wanted a hands-on way to see how circuits really behave. You can find him on GitHub as zenix.

Why it exists

Most electronics explanations show a formula and a still picture. Seeing a voltage sag, a capacitor fill or a resistor overheat as you move a slider makes the formula stick, so that is what OhmLens does.

How it works

Every simulation is calculated in your browser, not on a server. The maths (Ohm’s law, capacitor charging, diode and MOSFET models, regulator losses and so on) lives in one file, engine/solvers.ts, and is covered by automated unit tests.

The lesson text was written with the help of AI tools and then checked by hand against textbook formulas. The models are simplified on purpose so they stay easy to follow: use them to build intuition, and always check a real datasheet before you build a real board.

Privacy

There is no tracking, no analytics and no cookies. Your progress and settings are saved only on your own device, in your browser, and you can reset them at any time from the lesson list.

Contact

Found a mistake or have an idea? Say hello on GitHub: github.com/zenix.

Last updated: 26 October 2026

Start with lesson 0.1: Your First Circuit: Voltage, Current & Resistance