Pick Examples… at the top, or drag parts from the left.

Time window Trigger

Plots the numbers printed with Serial.print / println (one value per line, or several separated by commas, spaces or label:value).

Time window Show bus value

Shift+click up to 8 pins on the canvas: the Logic tab shows them as a timing diagram, the Scope tab as voltages.

Smart21 Tutor

Share my circuit & sketch with the tutor

Hello, what shall we build today?

Ask about electronics, Arduino code, or your own circuit. I can explain, calculate and debug.

Settings

AI tutor engine

The built-in tutor works offline with no account. For free-form answers, connect your own AI service: Anthropic (Claude), any OpenAI-compatible service, or a local model such as Ollama.

Engine

Model Base URL API key

Your key is encrypted with the operating system’s secure storage and only used from the app’s background process. Nothing is sent anywhere until you choose an online engine and send a message.

Simulator

Play buzzer sound Show hover readouts on pins

About

Smart21 ElectroLab — a circuit and Arduino Uno emulator for studying electronics. The Arduino emulator runs a practical subset of Arduino C++ (variables, arrays, functions, loops, Serial, pinMode, digitalRead/Write, analogRead/Write, delay, millis, tone…). It is a learning tool, not a replacement for real hardware.