Welcome to All About Circuits

This site provides a series of online textbooks covering electricity and electronics. The information provided is great for both students and hobbyists who are looking to expand their knowledge in this field. These textbooks were written by Tony R. Kuphaldt and released under the Design Science License. Interested in contributing to the textbooks? Please click here.

Textbook - Lessons in Electric Circuits

Direct Current

Basic Concepts of Electricity, OHM's Law, Electrical Safety, Scientific Notation...

Alternating Current

Basic AC Theory, Complex Numbers, Reactance and Impedance, Resonance...


Amplifiers and Active Devices, Solid-State Device Theory, Diodes and Rectifiers...


Binary Arithmetic, Logic Gates, Switches, Boolean Algebra, Karnaugh Mapping...


Conversion Factors, Resistor Color Codes, Math References, Periodic Table...


Test Equipment, DC Circuits, AC Circuits, Discrete Semiconductor Circuits...


Our Electronics Forum is a place where hundreds of thousands of students, hobbyists and professionals from around the world share knowledge and ideas. We encourage you to sign-up and become part of our community!


Thanks to a contribution to AAC from Tim Fiegenbaum, we have over 100 Video Lectures based on the textbook "Electronics for Computer Technology". These video lectures cover many of the topics contained within the textbooks, and are an excellent supplement to reinforce concepts.


The worksheets were created by Tony R. Kuphaldt, and contain hundreds of categorized questions and answers. They provide a great way to test your knowledge and prepare for exams.


Thanks for visiting AAC! The community behind this site continues to grow, and so does our traffic. We serve up to 3.5 million pages a month! This is due to our hard working E-Book developers, forum moderators, senior forum members, and site administrators. Be sure to stop by the forums and thank them!