The book introduces readers to 55 simple and complex electronic devices that can be easily assembled from the MASTER KIT sets. The sets, which are sold in radio stores of Russian cities, contain all the necessary radio parts and boards for assembling devices. The description of electronic devices is presented in four chapters, grouped by purpose of devices - from toys to complex measuring equipment. The book contains a catalog containing more than 300 items of electronic devices that can be purchased in the form of ready-to-assemble sets "MASTER KIT" This book is of interest for schoolchildren and students, beginners and experienced radio amateurs, for service and repair workers, as well as for physics teachers and parents teaching children the basics of radio electronics and digital technology.