percolator switch

Most of the timer I Cs which are commonly available provide only relatively short timing intervals. If longer delays, of say, from several minutes up to a few hours, are required then one is faced with something of a problem. The following circuit, which can be used in any number of possible applications (e.g. as a time switch for cookers, heaters, alarms, house lighting, etc.), permits delay times of up to approximately four hours.