Arduino Uno Design Starter for Scheme-It - Scheme-it - Engineering and Component Solution Forum - TechForum │ Digi-Key
voltage - Designing circuit with Arduino and optocoupler: beginners problem - Electrical Engineering Stack Exchange
Circuit design software that makes it easy to design, document, and debug electronics projects for the breadboard (more info in the comments). Would you find this useful? (x-post with r/ArduinoProjects) : r/arduino
A Guide To The World Of Arduino
Arduino UNO Reference Design | 3D CAD Model Library | GrabCAD
Tinkercad & Arduino: How to Design and Simulate Circuits | All3DP
Total Circuit Design with Arduino and Display | Download Scientific Diagram