[time-nuts] The need for quartz crystals and mains frequency (was: Mains Frequency)

[Dave ZL3FJ]

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 at 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 at megapathdsl.net
Subject: Re: [time-nuts] The need for quartz crystals and mains frequency
(was: Mains Frequency)


attila at 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.


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