TONY NIXON 54964 wrote:
>
> I need to make a clock that is accurate. It will be powered by the
> mains, and I thought of using this as a time base as it is a fairly
> stable waveform.
>
> Does anyone else know of a way which will be more accurate?
>
> Regards
>
> Tony.
Frequency deviation of the ac power line is as you say minimal and
intentionally compensated at the source for just that reason and
connecting a pic to the ac line requires only a resistor. My alarm clock
stays accurate for months or until I turn off it's power.But you did not
say how accurate.Start with a higher frequency and divide it down the
higher the source frequncy the more accurate the clock (generally).