Picking up the crystal frequency should work with older quartz watches that use a trimmer capacitor to adjust the crystal frequency. But recent quartz watches use a crystal that's deliberately too high frequency, and a divider chain that drops one oscillator pulse every so often to bring the overall rate down to close to the correct value. This all-digital method is cheaper and more stable than using a trimcap. The time between dropped pulses is programmed individually for each watch after measuring the actual crystal frequency.
To measure the timekeeping of such a watch, you pick up the sound or magnetic pulses from the second hand's motor (not the crystal), and observe how they drift compared with a reference 1 Hz source over a period of 10 minutes or 16 minutes or whatever the cycle time of the pulse-dropping process is for that model of watch. If you're watching on a timegrapher, you will see the timing running fast for a while, then jump back periodically giving a sawtooth-shaped display. Dave On Wed, Apr 6, 2011 at 7:33 AM, Greg Broburg <semif...@comcast.net> wrote: > For mechanical watch movements such as Rolex > and Patek quality used a microphone to resolve > the sounds of the escapement reference. They > had a strip chart recorder on the top and displayed > the recovered acoustical signature onto a plot of > against the internal crystal reference which ran a > stepper motor moving the paper. I believe that the > manufacturer was Heuer. Last look was 20 yrs ago. > > Same idea for 32k768 bender time references > different type of acoustical pickup then lots of > gain and a BP filter at 32k8. > > No experience with newer 4M194 style watches. > Maybe build an RF induction pickup with a 4M2 > filter and amplifier to try to find it then more > cleanup to get it to a counter > > Greg > > > > On 4/6/2011 5:32 AM, asma...@fc.up.pt wrote: >> >> Dear Time-Nuts, >> >> I am afraid of being off topic with the following. >> If so, I sincerely apologize. >> >> I would like to know the precision to be expected >> on time keeping from a Tissot mod. J378/478 S wrist >> watch and how could be verified the fulfilment of >> that specification without waiting for a long time >> (probably more than one month) to observe an error >> of one second. >> >> Instructions on how to build a test basket or similar >> layout would be most appreciated. >> >> Thanks in advance, >> Antonio >> CT1TE >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.