Dive Inside This Old Quartz Watch

In an age of smartwatches, an analog watch might seem a little old-fashioned. Whether it’s powered by springs or a battery, though, the machinery that spins those little hands is pretty fascinating. Trouble is, taking one apart usually doesn’t reveal too much about their tiny workings, unless you get up close and personal like with this microscopic tour of an analog watch.

This one might seem like a bit of a departure from [electronupdate]’s usual explorations of the dies within various chips, but fear not, for this watch has an electronic movement. The gross anatomy is simple: a battery, a coil for a tiny stepper motor, and the gears needed to rotate the hands. But the driver chip is where the action is. With some beautiful die shots, [electronupdate] walks us through the various areas of the chip – the oscillator, the 15-stage divider cascade that changes the 32.768 kHz signal to a 1 Hz pulse, and a remarkably tiny H-bridge for running the stepper. We found that last section particularly lovely, and always enjoy seeing the structures traced out. There are even some great tips about using GIMP for image processing. Check out the video after the break.

[electronupdate] knows his way around a die, and he’s a great silicon tour guide, whether it’s the guts of an SMT inductor or a Neopixel close-up. He’s also looking to improve his teardowns with a lapping machine, but there are a few problems with that one so far.

15 thoughts on “Dive Inside This Old Quartz Watch

          1. “In an age of smartwatches, an analog watch might seem a little old-fashioned…”

            Does a “smartwatch” not tell time just as a “smartphone” desn’t make nor receive phone-calls?

    1. Regular accutrons (214/218) can be had for under $100. They get more expensive if you go for a Spaceview model, but they’re just a couple of hundred bucks. However, the original 214 Astronauts can command over $1000 and if you get a pristine one with box from a good year, you’ll be paying upwards of $3k.

      Do a google search for electric watches co uk and you can see many of the technologies behind pre-quartz electrical watches. Amazing inventiveness around this time, although the accutron tuning fork watches are my absolute favourite, because they don’t tick, they hum!

  1. Interesting teardown! This is clearly an older type chip, as it doesn’t include more advanced functions that are found in almost all quartz watches these days such as “inhibition” and “asservissement”.

    See also these posts for an interesting explanation:


    and https://omegaforums.net/threads/quartz-watches-some-information-some-may-find-interesting.5475/

  2. Wow! Someone at HaD finally knows about inhibition and asservicement. Nice.

    Next time you stare at a quartz analogue timepiece, like this, or the ubiqitous wall clock- realize that the amount of time physically between the first 59 tics and the last 60th tic of each minute are different.

    You cannot physically see this- but its there. That is a function called “inhibition”, and it is part of a self correcting mechanism built into modern quartz circuitry.

    “Asservicement” is a form of intelligent motor control that is like PWM under a feedback loop that tells the stator of the lavet motor that pulses to power the watch to only use as much current at each tic needed to cog to the next point, and no more- to save battery life. It ups juice when extra functions like calender mechanisms need to be actuated against the resistance of the geartrain.

    These 2 functions, mainly inhibition correction circuitry, are what make quartz based oscillator timekeepers so accurate.

    Funny fact- quartz watches actually gain in rate over their lives. It’s physically unavoidable- the canisters that seal the quartz oscillators are filled with inert gas, and over time the hermetic seal of the case just breaks down. Causes a gaining rate as seal is slowly compromised. You’ll get maybe 25 years, tops, out of ANY quartz watch- no matter if the thing is Rolex, Patek Phillippe, whoever. And yes- both companies make excellent quartz models with very nicely made circuitry. Its just a physical reality of the technology though- impossible to stop it from happening.

    If you’re lucky, 25 years from when you bought it, new circuitry or oscillator can be grafted in- but very few makes offer circuitry components that far out brand new. Even fewer watchmakers have the skill to graft new coils or oscillator canisters onto old circuit boards.

    I know these things because I went to school for watchmaking for nearly 2 years, yes, quartz timekeepers and circuit diagnostics are still taught in watchmaking schools. A lot to it!

    I prefer mechanical stuff- no oscillator to leak. Can always be adjusted by a watchmaker, even 200 years out. But not as accurate as quartz- due to lower vibration frequency, and other factors, like “Q” factor, th me system efficiency against power loss in a geartrain and oscillatory system… that one’s too hard to explain here.

    If you like this stuff- buy a copy of the Theory of Horology!

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