The MC3 Master Clock is a cost effective yet powerful master clock. The MC3 comes standard with three solid state 120VAC outputs to directly control clock circuits without the need for additional relays. These solid state outputs are capable of driving up to 3 amps each (7 amps combined) and incorporate zero-cross technology to handle undesirable current surges and inrush. The MC3 uses the power-line frequency to keep accurate time eliminating the inaccuracies of crystal oscillators found in other products. The MC3 can be equipped with a GPS antenna (order separately as MC3-GPS) to keep time with the National Institute of Standards and Technology NIST satellite time base accurate to one second over a million years. The web enabled version (WeMC3) can be ordered providing PC browser based configuration and programming as well as NIST or computer network time synchronization. The MC3 and secondary clocks combine to create a maintenance-free time system automatically synchronizing the clocks and adjusting for daylight savings and power outages. When there is a power loss, the MC3 can keep time internally for over 150 days without the need for batteries or expensive rechargeable battery packs. The MC3 can correct the complete line of National Time & Signal clocks as well as synchronous clock systems by other manufacturers. The MC3 can even transmit National’s On-demand Instant Reset over the existing clock system wiring without affecting the existing clocks. The MC3 will also synchronize time with a sound system, paging system, phone system, media retrieval system or an existing master clock which can provide a synchronizing output. This universal system synchronization is easy with an optically isolated input capable of receiving synchronization pulses of 17-132VAC from other sources. The synchronization pulses can be a simple contact closure at 12:00 or one of many common clock reset formats using National's Automatic Protocol Detection algorithm. A serial port is also available to communicate time information with other equipment.