A few projects I messed around with 6 years ago. Stair lights are 5 volt and activated via sensor beam located on bottom and top of newel posts. They come in kit form and have a variety of settings. At the time I was buying them for £120.00. Sound activated led's well I was going to fit them by front doors for people hard of hearing as they pick up every knock/beat detected. Star lights are also programable and I incorporated some blue 12v led's in the ceiling for more of an effect!