The ELM440 is an 8 pin digital divider integrated circuit, that provides both 60Hz and 1Hz outputs from a common 3.58MHz NTSC colourburst crystal. Externally, the designer need only provide the crystal and two appropriate loading capacitors, as well as a suitably bypassed power supply. Internal oscillator circuits then use this reference frequency to precisely derive a stable 60Hz signal. This signal is then further divided to provide a 1Hz output. The ELM440 can also be locked in synchronism to an external 60 or 120 Hz line frequency signal. If derived from the electrical grid voltage, this results in excellent long-term stability, as the power generation frequency is traceable to national standards. The transition to or from sync-lock with this external signal occurs automatically.