Those 32KHz watch crystals are very flat in the vicinity of the turnover. They don't age well. But if all you need is temperature stability and you can correct for aging a nice little electric heat pump (heats and cools) to keep the crystals at around the 25C inflection point might be interesting. The heat pump might not take too much power either.
The temp error runs .04 (Tturnover - T)^2 ppm. i.e. .1 deg C from turnover gives .0004 ppm freq change. That is .4ppb. if you can hold .03C (not too difficult) you get 10X better - .04 ppb. Aging of course will be a killer with respect to that. http://www.iqdfrequencyproducts.com/app-notes/timekeeping/ ====== Nice page on cuts: http://www.4timing.com/techcrystal.htm Engineering is the art of making what you want from what you can get at a profit. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
