Post by Steve WilsonThe clock will drift. Eventually it will be so far off the correct time
to be useless.
https://tf.nist.gov/stations/wwvbcoverage.htm
There are a large number of inexpensive WWVB wall clocks that are large
enough to read from a distance. These will keep time to better than a
second.
If Don wanted a clock that ran forever, he should have so stated.
Although the project notes at:
<https://crcomp.net/pseudocell/index.php>
lack any statement as to what he's trying to accomplish, I would
deduce that not replacing the AA battery at unspecified intervals is
the main problem. You just expanded the project by adding an accuracy
problem. Whether this is a problem worth solving is up to Don and his
client.
I didn't see any mention of replacing an LR44 batteries, so I'll
assume that the clock does NOT have an automagic DST (daylight savings
time) feature. There's also something called "auto-set" which is
intended for areas with WWVB interference or reception problems:
<https://www.clockparts.com/blog/atomic-clock-movement-versus-the-auto-set-movement/>
Unfortunately, it looks like the DST feature is run by a tiny LR44
battery, which will probably also need replacement. Therefore if the
clock requires resetting the time twice per year, I would assume that
accuracy is sufficient between DST resettings to not require a daily
WWVB resetting.
The hands on the clock seem to be a little longer than the top of the
ladder, or about 14 inches long. Such long hands on the clock might
require a high torque drive mechanism. Hard to tell without a size
measurement. I couldn't find one that does both WWVB and has high
torque. I'm sure they exist, but I can't seem to find one.
Post by Steve WilsonYou can even get a kit to convert an ordinary clock to WWVB. Search
Amazon.
Are you suggesting a kit that replaces the existing movement with one
that has a WWVB receiver, or some kind of retrofit kit? I found quite
a few WWVB clock movements on Amazon. The only retrofit kits I could
find were complete replacements of the clock movement.
Post by Steve WilsonI use a HTAWI WWVB clock that is 16 inches in diameter. It is easy to
read from many feet away. It has 3 batteries and will switch
automatically when a cell runs down. I expect it to last 3 years or more
and keep perfect time.
Nice. I had a cheap ordinary wall clock in my office that ran on a
single AA cell for about 15 months. After about 2 years of use, it
started to slow down and drain the battery in as little as 4 months.
So, I tore it apart, cleaned out the accumulated dirt, re-assembled,
and it again ran for about 15 months per AA cell. The bushings that
ran the hands don't like dust. I gave it away when I retired last
month.
--
Jeff Liebermann ***@cruzio.com
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