This latest clock from SILICON CHIP is no ordinary clock. It is based on a PIC microcontroller to provide a number of unique features including the ability to adjust for very accurate timekeeping. For high visibility, it uses super large digits, 57mm high, for the hours and minutes and smaller digits for the seconds. The large digits use high efficiency LEDs which means they are bright and much more visible from a distance than any Liquid Crystal Display (LCD) could ever be.

Nor does this mean they are blinding at night. The circuit senses the ambient light and so the display brightness is maximum in bright light but becomes dimmer in darker conditions. So visibility is good in virtually all light conditions (apart from direct sunlight).

Not only is this clock big but it can also be adjusted for very good long-term accuracy. All crystal-based clocks exhibit some tendency to run fast or slow. Some have a trimmer on the crystal and can be adjusted for better accuracy but they will still drift due to temperature effects over a period of time.

Our new design uses a PIC microcontroller and since this is programmed to provide a counter circuit which is actually a clock, we can incorporate a neat feature in the software to adjust the count for even better accuracy. Carefully done, it should mean that the clock keeps time within a few seconds a year – dramatically better than the average watch or crystal clock.

The adjustment technique requires you to correctly set the clock and wait a few days to see how accurately it keeps time. Then a special adjustment mode is selected on the clock and the number of seconds the clock differs from correct time (calculated over a period of 60 days) is entered in.