This is a super simple Joule Thief LED light being powered by a small homemade magnesium and copper water battery. The reason that I call it the “Mosquito Light” is because of the sound that it makes on a radio. The battery and light circuit are assembled into one unit. The battery stops when it dries out so the shelf life of this device is extremely long if it is kept totally dry. The electrolyte in this video was regular tap water.