[time-nuts] Mechanical 1PPS Oscillator Disciplining

Tom Van Baak tvb at LeapSecond.com
Fri Jan 9 20:54:33 EST 2015


Now it's time to share some of my favorite vintage time & frequency links.

Some very nice vintage low frequency quartz crystals (20 kHz down to 5 kHz):

Lothar Rohde's revolutionary "portable" quartz-clock type: CFQ

Quartz-clock designed by the “PTR”, Germany’s Bureau of Standard, in the 1920s and 1930s

A British technical report on German Quartz Clocks:

The above ~10 page PDF is a must-read for any of you interested in the early history of quartz timekeeping. Note one of the authors was Louis Essen, who went on to develop the first cesium clock, the guy behind the 9192631770 Hz cesium definition of the second, and one of the first to propose leap seconds. I have more Essen info here:

For that matter, if you have time, the entire German History of Technology web site is fascinating:


----- Original Message ----- 
From: "Alex Pummer" <alex at pcscons.com>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Friday, January 09, 2015 3:27 PM
Subject: Re: [time-nuts] Mechanical 1PPS Oscillator Disciplining

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.

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