I wonder if it's smart enough to have a sanity check to determine
whether the line frequency is 50 vs. 60 Hz?
BTW -- I have an Ecodrive watch, but it's radio controlled (as well as
solar charging), so haven't seen any reference to this setting method
before.
John
----
On 4/20/2011 10:13 AM, paul swed wrote:
My bet would be flicker and divide by 120. Doesn't really matter. But since
these watches use the light to charge the battery, sensing the frequency is
a byproduct. Nice and simple.
On Wed, Apr 20, 2011 at 10:10 AM, jmfranke<jmfra...@cox.net> wrote:
Do they detect the light flicker or the ambient ac field. Light flicker is
120 Hz.
Very interesting,
John WA4WDL
--------------------------------------------------
From: "tom jones"<epoch_t...@yahoo.com>
Sent: Wednesday, April 20, 2011 9:43 AM
To:<time-nuts@febo.com>
Subject: [time-nuts] 60hz disciplined watch
Most if not all Citizen ecodrive watches are disciplined by 60hz light
flicker that average
the 60hz light flicker over approximately 10 days before a rate adjustment
is preformed.
I have four citizen ecodrives;
Plain jane quartz analogue ecodrive with mechanical calendar that is 60hz
disciplined.
Stainless steel skyhawk ecodrive ana-digital that is 60hz disciplined.
I've monitored this one
for over a week it was holding 13 miliseconds for over a weeks duration
(off the wrist mode) compaired to my cesium and ribidium references and got
distracted from futher measurements of this citizen skyhawk as I was
consumed with other measurements and comparisons between loran gps cesium
ribidium and other watches.
Blue angles citizen skyhawk ana-digital that half the time seems to be
60hz disciplined and other times unsure.
This blue angles citizen skyhawk has the same movement as the stainless
steel skyhawk which is definately 60hz disciplined.
I suspect this blue angles skyhawk that I purchased out of the country
could have 50hz and 60hz dicipline modes?
My fourth citizen ecodrive is the stars& stripes forever yacht timer
ana-digital which is 60hz diciplined.
This watch reboots every feb 28th at midnight to utc time zones and jan 1
2004 (not sure of the exact year is crashes to) some kind of leap year bug!
Only unexpected temperature changes experienced by the ecodrive citizen
watches produce significant error
(.5 to 1 second over several days of temperature varation) there rate will
correct after an approximate 10 day time constant.
Many wrist watch forums make reference to citizen ecodrive rate accuratces
remarking that citizen uses some propriatary rate techniques. It's simply
60hz light flicker received at the ecodrives solarbattery/photocell.
I would recomend when setting your citizen ecodrive watches to set them
2.5 to 3 seconds fast if worn continous because that is approximately how
much time will be lost before its rate gets compensated the first time.
A Great Day to All , Tom
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