gEDA-user: Using 60Hz mains frequency for timing?

[Ian Chapman]

Crystal usually cut to + or - 100 ppm for a general use like a CPU and it
will not change too much with temperature and age.  Ethernet crystals were
at one time cut to a better spec 50 ppm.  Special communications crystal can
be a lot better.  The mains are very good in most places for the morning
alarm however in remote communities with diesel generators ... no way.