Quartz
Created Friday 22 May 2026
Quartz watches
Run at a crystal oscillator frequency of 32.768kHz (2^15)
The crystal measures 3mm long and a thickness of 0.3mm, thus has a fundamental frequency around 33 kHz
frequency divider
This a 15 stage flip-flop, each stage divides the input by 2, the result is a 1 second pulse which drives a stepper motor.
These watches usually run fast by about 10s/day and are adjusted by using 'inhibit compensation'
this is achieved by suppressing oscillator pulses before being sent to the frequency divider before it drives the stepper motor, this is done every 10 or 60 seconds.
For a 10 second correction interval, adjustments of 7.91 seconds per 30 days and for a 60 second interval, adjustments of 1.32 seconds per 30 days are achieved.
It seems likely that even the humblest quartz wristwatch can maintain time accurate to within less than 1 second per day with the aid of inhibition compensation. And due to the surprisingly good stability of 32 kHz quartz crystal oscillators, the accuracy of quartz wristwatches can be expected to change by only a small amount over time.