A great reference for hobbyists and professionals in electronic circuit designers.
32 pattern cards provide a quick reference of commonly used circuits.
Circuit Pattern Cards are designed by Arachnid Labs. http://www.arachnidlabs.com
Circuit descriptions and schematics are licensed, and used under the Creative Commons Attribution-ShareAlike 3.0 Unported License ( http://creativecommons.org/licenses/by-sa/3.0/ ). They can be found at https://github.com/arachnidlabs/labs-cards