[time-nuts] Re: Power and heat re: Heathkit WWV clock / where are the good oscillators?

[Joe Duarte]

>
>
> The low power CMOS process turns out to be pretty old. Indeed it is not a
> common thing to see used today or even back a while.


I don't follow. Are you saying that CMOS is obsolete and was succeeded by
something else? What's the connection to the Heathkit? It didn't have CMOS
chips as far as I know.

> Analog watch modules ( so a 32 KHz crystal driving a stepper that moved
> hands) could run for a year on the coin cell battery in the watch back in
> the
> 1970’s. The LCD versions …. not so much.


You mean LCD watches used *more* power than analog? I thought LCDs were
sippers compared to LEDs. The LCD watches I know from the 1980s had 2-year
battery lives, just like today's, e.g. the Seiko "Arnie" divers, original
Casio G-Shocks, etc. (Well, the Arnie was both analog and digital, and some
of today's digital LCD watches promise more than two years battery life,
some up to *ten* years.) The 1970s LCD watch that had battery life issues
was the extreme accuracy Citizen Crystron – it had a super fast oscillator,
at least a few hundred KHz, maybe temperature compensation too. I think it
was better than 1 sec/month stable, but the battery lasted six months.

You said "Propagation is a biggie with WWVB." I figured less than 4 ms prop
from Fort Collins to Tucson, AZ, maybe 8 ms to the San Francisco Bay Area.
That's pretty lean to me, and you can just program in the correction – I
thought it was the shortwave WWV signals that had propagation hassles. WWVB
is ground wave at 60 KHz, not the bouncy-bounce of shortwave. The other
latencies measured by Lombardi in his NIST paper seemed to trump prop delay.

On the GC-1000 power issues, I'm not sure it's explained simply by the era.
It seems like the engineers lacked discipline. In 1983, we were, what, a
decade away from the first WWVB syncing watches? The watches likely used
CMOS IC, but they still had to do all the work of those beefy desktop
receivers. Anything you could do with a trickle from a coin cell battery in
1993 you could easily do with a couple of AAs in 1983. The only difference
is the LED display vs a watch's LCD or analog movement. And WWV shortwave
vs WWVB long wave – I still don't understand why Healthkit chose WWV. I'll
probably settle on a modern WWVB receiver, but it would be interesting to
build something from scratch. I've never tried programming an FPGA before.

I've also thought about using it to robotically sync watches that don't
have radio syncing built-in. I wonder how precise I could get with an
exogenous solenoid or linear actuator run by a WWVB receiver clock, where
it hits the reset buttons on a digital watch (setting the seconds to zero),
or pulls out and presses in the crown of an analog watch (pull it to stop
the second hand exactly at 60/0, press it in to start at exactly the true
start of the minute). I wonder if analog watches have sub-second awareness,
meaning can they be stopped at a partial second or is it always a discrete
second, do they restart at that increment, and whether it's different for
quartz vs. mechanical chronometers, etc. It would be a fun way to learn
about solenoids and electromechanics. At first I was thinking about needing
extremely fast solenoids or actuators, but what I really need is extreme
*consistency* of elapsed time to press the button 2-3 mm or whatever.

Cheers,

Joe