yes, Ulrich's [ Rohde ] Father made a high precision clock around 1940,
which had an electronically tuned mechanical oscillator. The vibrating
400Hz tuning fork is phase locked to a quartz crystal oscillator, that
was the most precise clock at that time, and it worked as I have seen
it at the company as I worked there in the sixties of the past century.
73
KJ6UHN
Alex
On 1/9/2015 9:22 AM, Andy Bardagjy wrote:
From a fascinating (albeit long) article about transatlantic communication
cables
http://archive.wired.com/wired/archive/4.12/ffglass.html
On the bottom of page 45 to the top of page 46
"Each piece of equipment on this tabletop is built around a motor that turns
over at the same precise frequency. None of it would work - no device could
communicate with any other device - unless all of those motors were spinning in
lockstep with one another. The transmitter, regenerator/retransmitter, and printer
all had to be in sync even though they were thousands of miles apart.
This feat is achieved by means of a collection of extremely precise analog
machinery. The heart of the system is another polished box that contains a
vibrating reed, electromagnetically driven, thrumming along at 30 cycles per
second, generating the clock pulses that keep all the other machines turning
over at the right pace. The reed is as precise as such a thing can be, but over
time it is bound to drift and get out of sync with the other vibrating reeds in
the other stations.
In order to control this tendency, a pair of identical pendulum clocks hang next to
each other on the wall above. These clocks feed steady, one-second timing pulses
into the box housing the reed. The reed, in turn, is driving a motor that is geared
so that it should turn over at one revolution per second, generating a pulse with
each revolution. If the frequency of the reed's vibration begins to drift, the
motor's speed will drift along with it, and the pulse will come a bit too early or a
bit too late. But these pulses are being compared with the steady one-second pulses
generated by the double pendulum clock, and any difference between them is detected
by a feedback system that can slightly speed up or slow down the vibration of the
reed in order to correct the error. The result is a clock so steady that once one of
them is set up in, say, London, and another is set up in, say, Cape Town, the
machinery in those two cities will remain synched with each other indefinitely."
Does anyone know any other history about that particular piece of equipment?
Cheers!
Andy ◉ Bardagjy.com ◉ +1-404-964-1641
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