Re: [time-nuts] The need for quartz crystals and mains frequency (was: Mains Frequency)
attila@kinali.ch said:
And, please do not forget that modern mains frequency control is something
quite recent as well. Especially outside (west) Europe. Having mains
frequency powered clocks being off several minutes per month was the norm
50-70 years ago.
I have a (fuzzy) data point from ~60 years ago.
I was in high school and got to tag along with a quick tour through Niagara
Mohawk's control room. They were the power company for a large part of
upstate New York, including Syracuse where I lived.
I remember somebody pointing out a pair of clocks on the wall, one driven by
the line. I wasn't enough of a time-nut to inquire about the source for the
reference clock.
Has anybody seen a good writeup on the history of clocks running off the line
frequency and power lines being used for timekeeping?
Anybody else remember the little red dot that was on a swinging flag behind a
little hole? That was the analog equivalent of blinking 00:00.
When you set the time on a clock, the flag swung up and stuck to a magnetic
part of the motor. The color on the part of the flag visible through the hole
in that position matched the color of the face. When power was lost, gravity
pulled the flag down and that part was painted red.
--
These are my opinions. I hate spam.
That 'flag' feature can be found on the very early (1930s) Telechron
digital display clock, the model 8B01, as a separator between the hours and
minutes digits. A lever on the back panel allowed the user to reset the
flag from red to white when power was applied.
Loss of AC power meant the synchronous motor that drove the digital dial
drum mechanism lost it's magnetic field - which allowed the flag to 'fall'
and display as red. The 8B01 has often been described as the world's first
digital clock-is this true?- Not sure.
DaveB, NZ
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@lists.febo.com] On Behalf Of Hal
Murray
Sent: Saturday, February 13, 2021 18:49
To: Discussion of precise time and frequency measurement
Cc: hmurray@megapathdsl.net
Subject: Re: [time-nuts] The need for quartz crystals and mains frequency
(was: Mains Frequency)
attila@kinali.ch said:
And, please do not forget that modern mains frequency control is
something quite recent as well. Especially outside (west) Europe.
Having mains frequency powered clocks being off several minutes per
month was the norm
50-70 years ago.
I have a (fuzzy) data point from ~60 years ago.
I was in high school and got to tag along with a quick tour through Niagara
Mohawk's control room. They were the power company for a large part of
upstate New York, including Syracuse where I lived.
I remember somebody pointing out a pair of clocks on the wall, one driven by
the line. I wasn't enough of a time-nut to inquire about the source for the
reference clock.
Has anybody seen a good writeup on the history of clocks running off the
line frequency and power lines being used for timekeeping?
Anybody else remember the little red dot that was on a swinging flag behind
a little hole? That was the analog equivalent of blinking 00:00.
When you set the time on a clock, the flag swung up and stuck to a magnetic
part of the motor. The color on the part of the flag visible through the
hole in that position matched the color of the face. When power was lost,
gravity pulled the flag down and that part was painted red.
--
These are my opinions. I hate spam.
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Hi Hal,
I have one of these big (maybe 14" dia) old office clocks, still
working, hanging on the garage wall at the farm, next to a modern WWVB
clock. I don't worry about what time it says, but I sometimes look to
estimate total power outage time (can be quite a lot up there) since the
last reset. I think it's around sixty years old. It has the flag
indicator as described, that resets when you pull the time set knob at
the bottom.
I remember when I was a kid, I either repaired or junked out many of the
Telechron (I think that was GE's brand name for it) clocks, which were
the standard for nearly all AC-powered clocks at the time. There was no
gray area in the failures - the sealed motor either worked or not, and
if it did work, then the problem was in the external gear train (almost
always from dirt and lint). I took apart many of the motors to see how
they worked (or didn't). The usual failure was that the oil fill leaked
out. Sometimes, the little magnetic rotor would loose enough of its
reluctance that it wouldn't start reliably or have enough torque to run
the gearbox.
I also lived in Syracuse (actually Liverpool, one of the burbs) for a
while. I remember in 8th grade, we went on a class tour of NiMo's brand
new nuclear plant at Nine Mile Point, just before it was commissioned.
Fascinating.
Ed