Open-source circuit simulator for power electronics with multi-domain simulation: electrical, thermal, and EMI -- all in one tool.

Originally developed at ETH Zurich's Power Electronic Systems Laboratory by Andreas Muesing, Andrija Stupar, and Uwe Drofenik.

• Multi-domain simulation -- electrical + thermal + EMI in a single environment
• Fast simulation engine -- optimized for power electronics (MNA-based solvers: Backward Euler, Trapezoidal, Gear-Shichman)
• Visual circuit editor -- drag-and-drop schematic capture with built-in oscilloscope
• 64+ control blocks -- PI/PID, integrators, limiters, lookup tables, state machines, and more
• Thermal analysis -- junction temperature, loss calculation, heatsink design
• EMI filter design -- common-mode/differential-mode filter analysis
• MATLAB/Simulink integration -- remote control via RMI or memory-mapped files
• Scriptable -- built-in JavaScript (GraalVM) and Java block scripting
• Cross-platform -- runs on Windows, Linux, and macOS

• Java 21 or later (Adoptium Temurin recommended)

1. Download gecko-1.0-jar-with-dependencies.jar from the Releases page
2. Run:

   java -Xmx3G -Dpolyglot.js.nashorn-compat=true -jar gecko-1.0-jar-with-dependencies.jar

3. Open an example circuit from File > Open (see Examples below)
4. Click the Simulate button (or press F5)

Convenience scripts are provided in scripts/:

Add --hidpi for high-DPI / Retina displays.

The resources/ directory contains ready-to-simulate circuits:

# Clone
git clone https://github.com/tinix84/GeckoCIRCUITS.git
cd GeckoCIRCUITS

# Build (produces target/gecko-1.0-jar-with-dependencies.jar)
mvn clean package assembly:single -DskipTests

# Run
java -Xmx3G -Dpolyglot.js.nashorn-compat=true -jar target/gecko-1.0-jar-with-dependencies.jar

# Run tests
mvn test

Requires: Java 21 JDK + Maven 3.6+

GeckoCIRCUITS
├── Simulation Engine (MNA matrix, LU decomposition, 3 solver types)
├── Circuit Components (R, L, C, diodes, MOSFETs, IGBTs, transformers, ...)
├── Control Blocks (64+ calculators: PI, PID, integrator, gain, limiter, ...)
├── Thermal Domain (loss models, thermal networks, heatsink simulation)
├── EMI Domain (CISPR filters, CM/DM analysis)
├── Visualization (oscilloscope, FFT, THD, RMS analysis)
└── Integration (RMI for MATLAB, memory-mapped files, JavaScript scripting)

Full documentation is available at tinix84.github.io/GeckoCIRCUITS:

• Getting Started Guide
• Tutorials (DC-DC, AC-DC, DC-AC, thermal, scripting)
• Examples Library (125+ circuit files)
• API Reference (GeckoSCRIPT, RMI, REST)
• Developer Guide

Contributions are welcome! See CONTRIBUTING.md for the full guide.

# Run tests before submitting
mvn test

# Check code quality
mvn spotbugs:check

This project is dual-licensed:

• Open Source: GNU General Public License v3.0 -- free for academic, research, and open-source use
• Commercial: Contact for commercial licensing terms

Copyright (c) ETH Zurich, Power Electronic Systems Laboratory. Originally developed by Andreas Muesing, Andrija Stupar, and Uwe Drofenik.

• Documentation
• Original SourceForge project
• Technokrat contributions (HiDPI support)