This is the twelfth book in Elektor's celebrated '300' series. An immense source of inspiration for all electronics enthusiasts and professionals, this book deserves a place not far from the workbench. The book contains circuits, design ideas, tips and tricks from all areas of electronics: audio & video, computers & microcontrollers, radio, hobby & modelling, home & garden, power supplies & batteries, test & measurement, software, not forgetting a section miscellaneous for everything that does not fit in one of the other categories. This book presents complete solutions for numerous problems, as well as starting points for your own creations. "311 Circuits" has been compiled from the 2009, 2010 and 2011 'Summer Circuits' double editions of Elektor magazine. The book is mostly based on readers' contributions, supplemented by circuits engineered and developed in the Elektor Labs.