Quartz

[ceagle]

For the last couple of months, I've been conducting a fairly simple test. I found an amazing deal recently, one quartz watch and a digital watch, together for $15! (so I bought four)..
And, I've been keeping tabs on them to see how they fare... because, alas, digital doesn't = accurate.

I used to think "digital, how could it NOT be accurate?", but I've seen so many digital time apparatus phail at being accurate.... VCRs, watches, phones, car clocks, etc...

Quartz though... now THAT is supposed to be accurate. Or at least much closer to it.
I think the standard is that they shouldn't veer off more than a minute a year? Pretty good, but I was hoping to split the difference and find one that is close to dead-on some time. And if anything, I prefer a timepiece that runs a bit fast, rather than slow.

The report so far is: after almost three months, Quartz watch #1 is 7 seconds slow, Quartz watch #2 is 5 seconds slow, digital watch (#3) is 15 seconds slow, and digital watch (#4) is 40 seconds fast.

;P

Drat.

None of them are really all that spot-on, but *sigh* I guess they aren't too bad.

Comments

[atkelar.livejournal.com]

Well... "digital" watches are "quartz" watches too: after all, it's a little quartz crystal that is the timer for the digital chip. As Orv mentioned: Quartz crystals are essentially mechanically tuned to have a certain electrical frequency. They are pretty accurate when compared to almost anything mechanical. Usually they say "16.000MHz" or similar. Three decimals seems accurate but that's MHz - they may be off by as much as 999Hz in both directions. Temperature is also an issue which may very well be why clocks in cars vary soooo much. I made a habit to not adjust my car's clock other than the hour DST - and it's off by about 20-25 MINUTES within a year... funny enough: it stays off by about the same amount then. It's now three years that I've set it and it's a bit over 30 minutes off.
So: The commercials saying: "our watch is off by only x-seconds per year" are talking about the lab conditions, not wear-them-every-day conditions ;-)

[lobowolf.livejournal.com]

They usually rate crystal accuracy in "parts per million" (PPM). So a 6 PPM rated 32.000 MHz crystal can be off +/- 192 Hz, which isn't much in terms of percentage, but it really adds up over time (no pun intended!).

[c-eagle.livejournal.com]

If only modern manufacturing allowed for more testing... but the ratio of needs and acceptability in the consumer market doesn't really justify it in most cases I guess... *wingfuzzles ya*

[c-eagle.livejournal.com]

That's pretty far off... yikes!

But yeah, you got me thinking... heh.. I test circuit boards a lot of the time, and it's rather rare that the chips and circuits come up accurate right down the middle :D