It's the article that keeps on giving! I stumbled upon this article today after burrowing down the OF rabbit hole from somewhere entirely unrelated. Thanks Al, I had no idea there was that much to it.

 

I have a lot of quartz watches my Seikos 1 that's 27 years old runs fine, great article thanks

 

Wonderful write up in the OP and, personally, having never been snobby about quartz watches (as I'm a big, big fan of what Seiko was doing in the 70s... wait, can I say that here? ), I find information about them - like this - to be really interesting. Thank you @Archer

 

I personally wear a quartz watch 90% of the time these days, pretty much due to life getting in the way otherwise. When my son was born, I quickly realized that I needed to know the correct time in the middle of the night, and needed to not worry about it being off. What i decided I wanted was a solar powered atomic radio sync 3-hand watch with no digital component, and no "world time" around the bezel. Sounds like it should be easy to find, but surprisingly it is not, at least for under $500. My step-uncle was visiting and I noticed his watch, which was an Oceanus, which after some quick googling I found was a high end Casio. This started me looking and I found there were a couple US market ones that they had made that fit exactly what I wanted, but had since been discontinued. Eventually I found both the model he had, as well as another model with a bracelet as well. Both have the same movement, with a rather different look.



Both have titanium cases and sapphire crystals, along with dual white LED illumination. In the middle of the night this is good for use as a very dim flashlight, and frankly gets used as this frequently for checking babies in cribs and beds, etc. The only real annoyance is that since I live in Arizona I have to manually change the DST zone twice a year, since there is no "DST adjustment off" setting.

For several years I was anti-quartz, but I definitely have come to appreciate the convenience of just being able to slip a watch on and know it's exactly the right time.

 

Hello,

I'm not sure this is of interest to anybody here, but it's related to the thread and I thought I would post it. I got a new quartz watch last week, and while I'm not a watch collector at all, I thought it would be interesting to read a bit more about it, so I stumbled upon this very interesting post, as well as some others (probably already known to readers of this forum).

The 'inhibition period' piqued my interest, it was something I didn't realize before, as I naively assumed that the quartz crystal itself was trimmed in the factory at 32768Hz, but in most quartz watches, it's running ever so slightly faster, as the OP explained. I got curious about the "inhibition period" of my new watch, and so yesterday created a little 5$ tool to measure this, without actually having to open the watch or damage it in any way, but by measuring the magnetic field created inside the little lavet watch motor that moves the hands. I'm picking up this field with a little spare coil I had lying around (from another clock), which I can just place near the watch. I also created a small amplifier circuit, hooked this up to a microcontroller, wrote a little program to sample the amplified coil signal using the ADC (analog/digital converter) and measured the exact amount of time in between each second tick. It took about a day to make this tool, but now I know that the my new watch (which I believe has a Miyota movement) has an "inhibition period" of 10 seconds, meaning the watch runs every so slightly fast every 9 seconds, and then every 10th second corrects this. My Swatch has a period of 60 seconds. It was a fun project to find this out

Below are some quick photos of my setup (not the best photos, but in one you can see the coil lying on top of a watch (the "coil" is actually taken from the remains of a wall mounted clock, and is in fact still attached to it, but that clock itself has no function, only the coil, which sits at the bottom next to the watch (there's another coil on top which is not connected, but it looks the same).

On the oscilloscope display, you can see the ticking of the watch (during about 10 seconds), and on another zoomed in photo you can see a single tick of the watch, which is a pulse-width-modulated 6ms current going through the watch's coil, moving the stepper.

Some data from the application (running on the microcontroller) also below:

First an old Swatch, with an inhibition period of 60s. Note the times are in microseconds, and can fluctuate slightly due to measurement errors. Sampling rate is currently a leisurely 16kHz, enough to figure out the inhibition period, as the time added during this inhibition (1 - 5ms) is much bigger than the time between samples (62.5us). Note also that, since the microcontroller is using its own simple crystal (not temperature corrected or anything), the base timing may be off a bit, but the inhibition times are clearly visible. E.g. for the Swatch, it can be observed that each minute 4.6ms is added, which means the rest of the minute was 4.6min too fast, but this isn't super clear from the numbers. This is due to measurement errors and/or the crystal's inaccuracy. Each line in the graphs corresponds to one second (time axis horizontal)

Below it, I will show some other watches I tested, including my new watch with the Miyota movement. I hope you enjoyed this little experiment. Are there any cheap tools that do this? I know more expensive (>$200) tools exist, such as the one shown by the OP, but as this (admittedly crude) tool took me only $5 to make, I was wondering if there's anything commercial that's cheaper.

 

Really interesting read @niek.
Many thanks for sharing info and set up.

 

Nicely done. Indeed you don't have to open the watch to determine the inhibition period - many timing machines like mine use an external sensor that tells you this (and much more) just by laying the watch on it.

A $200 tool for working on quartz watches would be a very cheap one - for my machine I don't know the current pricing but it was about $6k when I bought it. You can get a quartz only version of the machine for a bit less (mine is designed for both mechanical and quartz watches) but even that is several thousand. I know you said you did all this with $5, but of course that doesn't include the scope, or the laptop.

Knowing a watch has inhibition and what the period is isn't terribly useful from a diagnostic standpoint - they either have it or they don't, but it doesn't change how an intervention to repair something is done. Being able to measure other things is where the useful information comes in...base and total consumption, checking the LWL and EOL, coil resistance. These are the things that are useful from a practical standpoint when actually working on a watch.

Glad you liked the original post - if you have any specific questions, let me know.

Cheers, Al

 

Thanks for the additional info! It's true that my little device needed a scope and laptop to create, but the parts of the device itself only cost $5, and if I wanted, I could add a little display to it to make it completely stand-alone (for a final cost of around 10$). The ADC sampling measurements and data processing are done on the $2 microcontroller, using the amplifier circuit to get the data out of the watch. But you're of course completely right: it's not terribly useful - I created it mainly just out of interest to confirm whether my watches use inhibition, and figure out their period. A fun way to spend a Saturday afternoon I could make it more accurate with the help of a temperature compensated crystal oscillator (or oven controlled crystal oscillator) and possibly make it more useful for figuring out the exact daily accuracy, etc. Maybe some day! I'm surprised these instruments are that expensive, but I suppose it's because it's for a rather niche market and there's not a lot of competition. And it's refreshing to hear people interested in quartz - mechanical watches are nice, I suppose, but to me a watch is about telling the time, and quartz is just better at it Also I like their relative simplicity.. Simple things are often more elegant.

 

It is a very niche market, and there are really only a couple of companies that are making dedicated high level equipment. As you can imagine, most here are mechanical watch people, and some dislike quartz - one reason I made this thread in the first place is that many people underestimate how much technology goes into a quartz watch. Many think the basic controls have not changed since they were first invented, but they are getting better in that regard all the time, leading to better accuracy and longer battery life.

It may not make fans out of people who prefer mechanicals, but I hope that they at least appreciate the technology involved.

Cheers, Al

 

I see Archer beat me to it - I was about to ask where you found the CRO for under five bucks!

On a related note, I'm thinking of picking up a Mondaine Stop2Go watch. It's a fascinating movement that mimics the behavior of the Swiss Railways station clocks, which are all tied to a central time source and all change at exactly the same moment. The Stop2Go advances its second hand a full rotation in 58 seconds, pauses, then advances the minute hand and restarts the seconds again. Fascinating to watch (pardon the pun), and an interesting way of turning the inhibition period into a feature.

 

I did a few more measurements, this time at a more rapid 32kHz sampling rate, and got some cleaner results, which I'll post in the images below. It's again for a Swatch watch, and a Tsovet (Miyota) watch. What is now very apparent is that the Miyota movement not only slows down (inhibits) once every 10 seconds, but also speeds up once every 10 seconds in between. So, you'll see peaks, but also some (very regular) valleys. I had noticed this in my initial measurements, but thought it might be due to measurement errors, but it's very consistent and regular. So, presumably this gives them 2 parameters to play with when trimming the time.

Maybe Archer knows more about this?

Cool indeed how the seconds hand in that Mondaine watch pauses on the hour mark: our railway clocks do the same thing here in The Netherlands. It would be interesting to measure if this is indeed when they do the actual underlying inhibition as well.

 

I read, somewhere once, that in order that all Swiss Railways trains depart on time all the time, the clocks are set to pause in this way.

 

Yes, the station clocks all behave this way, hence my original comment that the Stop2Go mimics them.

 

I came across this very informative video this morning, it describes how quartz watches work in layman’s terms, and much like some of the great information in this thread it reinforces the fact that quartz watches are fascinating objects in their own right. The flip flop description in particular is very helpful

 

Thanks yet again @Archer

Started researching the 1538 after setting my sights on a Bond Seamaster, and this was very informative. Gave me a better appreciation for quartz, and I’m glad to now have one in the collection.