Blinking LEDs to frequency of music
Originally made by David Wang on Instructables, but I fixed some grounding issues which caused errors for some. Includes breadboard sketch and code.
Plug a 3.5mm aux cord from your project to a headphone splitter that is plugged into your computer. Plug another aux cord on the other side of the headphone splitter for your headphones or speaker. Now play some music and enjoy your lights.
Go to the Instructables for more info on what parts to buy (in external links)
Please let me know if I messed something up!