Sven clock vs mechanical clock in accurace

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5 years 3 weeks ago #6688 by Pacman223
Let me start off with some back ground. My lovely wife decided to give me a new watch for my birthday - a Laco Aachen.

shop.laco.de/en/product/Aachen.html?info=82

(a replica of their WWII German pilots watch).

VERY NICE watch Absolutely love it!! If anyone is thinking of owning a nice mechanical watch, this one is really nice, and it comes with some great history. Laco built Pilot watches for Germany during WWII.
(Other companies that make good WWII German pilot versions are Stowa and IWC)


So I thought about seeing how well it keeps time vs my Sven clock. I have never seen anyone document how well a Nixie clock actually keeps time.

So, I kept track for a couple of weeks of how each did (averaging the weekends while I wasn't at work).

In short..
New mechanical Laco Watch's two week average = +8.27 sec/day
Sven Nixie clock = +.06 sec / week (supper accurate in my book)

I found the Nixie clock was STUNNINGLY accurate. I didn't actually realize how well it was doing.

I read that Mechanical watches, may need about 2 weeks of running before they settle down a bit.
(I will continue to track this and see if thats really true or not)

Each morning I compared the time a web page that claims to be very accurate.


(on a side note... the jump for Sven to +1 sec on 7/1/2015 - I believe this was caused by my office being really hot that day (around 83 F). That day was REALLY hot outside 105+F and it felt like our buildings AC was struggling to keep up, My Sven clock reported temperatures of around 84-86 F. Most days its usually around 78 F)

thought I might pass this info along, might be interesting for someone wondering how accurate Nixie clocks /Sven clock really are. I might try this with some other clocks.

Also, has anyone else ever thought to record how accurate their Nixie clocks are? do temperature compensated quartz crystals really improve the accuracy? Do GPS connected clocks really stay perfectly accurate?
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5 years 3 weeks ago #6690 by Ty_Eeberfest
Very nice watch! I like...

Funny coincidence that your Sven gained 1 second on July 1, since June 30 -> July 1 was a leap second. Your clock did an "anti-leap" second instead. :laugh:

I check accuracy against WWV once in a while and if I'm off by more than 1 second a month I'm dissatisfied and start playing with the "tweak" factors in code. My ITS1-A clock from Mr. Nixie has the tweak factor available as a settable parameter. My original designs have an internal tweak factor that I change by recompiling and reflashing, not ideal but it's just for me - not a commercial product - so it's fine.

My personal opinion is that TCXOs are a good thing and I use them in all my originals. Since they are one-offs, not commercial products, I don't consider the extra cost to be a problem. Are they more accurate? We could probably have a good argument about that question and debate the definition of accuracy, What I can say is that they are very consistent - the frequency does not wander around like plain crystals do. I find that I still need to set a tweak factor with TCXOs but once the factor is correct the clock runs accurate to within about 2 seconds per year.

Look into it later when the dust is clearing off the crater.

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5 years 3 weeks ago #6692 by Pacman223
a leap second would explain the jump for a single day. :)

I will have to fix my numbers to reflect that.

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5 years 3 weeks ago - 5 years 3 weeks ago #6693 by Ty_Eeberfest
I had to think about that one for a second... lol. I guess if your source of "precise time" adjusted for the leap second and your Sven did not (it's not GPS disciplined, right?) then it would look like the Sven gained a second.

BTW, I wonder how precise your "precise time" source actually is. There are methods that compensate for the inevitable net-lag but they aren't perfect. I'm sitting here looking at NIST time ( time.gov ) right now, it says it is compensated for net-lag, and yet it's nearly a second off from my GPS disciplined clock. My clock's Sync LED is telling me it has received a GPS update something less than 2 hours ago (probably much more recently but the LED does not begin signalling "GPS fail" until 2 hours have passed with no updates) so I think it can be trusted. Besides, this clock does better than 1 second per week when running with no GPS at all.

Look into it later when the dust is clearing off the crater.
Last edit: 5 years 3 weeks ago by Ty_Eeberfest. Reason: Typos

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5 years 2 weeks ago #6699 by Pacman223
I used

utctime.org/

as the correct time. but you are correct, I really don't know the delay to my computer, or how reliable it is.

but I figured that is my best bet... I thought about trying to use one of our servers at work to measure against, but then I remember one time where one of our servers was a few minutes off causing all sorts of problems. :)

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5 years 3 days ago - 5 years 3 days ago #6809 by Pacman223
Update...

I decided to continue tracking the accuracy of watch and now my newer nixie clock (with the txco).

for week 1. it hasn't lost/gained any time, at least as far as I can tell (just using the web page and looking at the time of the clock vs web page). It appears to be at least as accurate as the sven clock, we will see if over time its better :)

I'm also keeping track of my watch, and seems to have stabilized to around +7 sec/day.

I'll keep track and post my observations.
Last edit: 5 years 3 days ago by Pacman223.

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