32.768KHz has a nice property that it oscillates 2^15 times per second which makes the timer math easy...I made a calc using the average tolerance of these crystals and came out to an accuracy of around 0.002 % accuracy or better - about 2 seconds a day. This of course does not account for temperature drift....wow...are we splitting hairs or seconds?...lol...regards...
On 28 June, 12:24, "H. Carl Ott" <[email protected]> wrote: > On Tue, Jun 28, 2011 at 11:37 AM, neutron spin <[email protected]> wrote: > > Great idea...sometimes the simple designs are the most > > effective....the only drawback of course for any of these crystals is > > the temperature effect on the crystal and drift. We are not dealing > > with NBS traceable standards here but if you a real stickler....I have > > some Cesium....just kidding...the NRC would frown on > > that!...regards... > > Yeah, temperature might be a bit of a problem. Hopefully the temp > inside a clock is reasonably stable over time. > > But if the point is just to try to get accuracy close to that > currently existing via the mains then maybe we don't need temperature > & aging compensation. > Can anybody translate these charts into a PPM error figure? > > http://www.leapsecond.com/pages/mains/ > > > > > On 28 June, 07:47, "H. Carl Ott" <[email protected]> wrote: > >> I think you could put a 32768 xtal, a trim cap, and an 8 pin AVR (my > >> preference) onto a very small pcb for about dollar or two. > >> The advantage of using a micro is that could also add a simple > >> calibrate function. > > >> For people who like to solder. (but don't like to code). > > >>http://www.8085projects.info/post/60Hz-signal-circuit-using-32768Hz-S... > > >> -carl > > > --- Hide quoted text - > > - Show quoted text - -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
