MC81LV is a multiple output, calendar programmable solid state master clock. It is used for synchronizing most secondary clocks and for switching electric circuits according to a preset time and date program. MC81LV's auto prompting, alphanumeric display makes programming fast and simple. The outputs can be used to ring bells, to control audio/visual equipment or to control lighting, heating, ventilating, air conditioning and security systems with a variety of programming capabilities, ranging from a simple 7 day plan to a more complex plan utilizing its powerful, alternate annual programming features. Each has a compact wall mount enclosure. Secondary clock correction modes are built-in, and can be selected from the keyboard. If a secondary clock correction mode is selected, MC81LV will dedicate two of its relay outputs for correction, thus an MC41LV becomes a two circuit model with correction, and an MC81LV becomes a six circuit model with correction. If they are not being used for correcting secondary clocks (mode 0), then all output relays are available for timed events. Selected outputs can be independently programmed for momentary operation such as required for ringing bells in schools, churches or industrial facilities. Limited options are available for the MC81LV master clocks including 220VAC, 50Hz power.