Wow! That reference is a nugget of pure gold amongst the chaff. As a
mechanical engineer by training (BSME MIT 1960) and experience
(industrial process control), I am deeply interested in
electromechanical things.
Experience suggests that it is impossible for widely separated pendulum
clocks to
Alex,
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):
http://www.cdvandt.org/luminous_quartz.htm
Lothar Rohde's revolutionary portable quartz-clock type: CFQ
http://www.cdvandt.org/CFQ.pdf
Hi Tom dividing down wasn't always necessary I have sample from the UK GPO
Crystal Factory of NT-cut bars, quartz tuning fork, and Gapped Ring
crystals, the latter marked 400cps (pre Hertz :-)) ) I think these are
post WWII because they are mounted in IO base GT style tube envelopes.
Dividers
Hi
The speed of sound in quartz varies by axis, but only by about 2:1. The same
basic physics that gets you a fundamental 5 MHz crystal that is at thickness Z
gives you some dimension on a 5 KHz crystal that’s close to 1000 * Z. Very low
frequency crystals pretty much have to be designed so
Hi David yes I think I have seen similar but not as low as that. If you
compare the suspension points the different vibrational mode should
obvious.the suspension point is at a node. I think some of these are
quite difficult to excite, I have not seen any suggested circuits but I have
not
Similarly, the Tektronix 647 oscilloscope, uses a 4KHz
quartz crystal oscillator, divided by 4 to form its
1KHz calibrator signal. You can hear the crystal
resonate whenever the calibrator is turned on.
The crystal is mounted in an elongated, hermetically
sealed, HC7 style can.
-Chuck Harris
Get the FTS4065C manual, which is applicable to the PRS-50 according to
page 2. There is also a software you can run to monitor the state of the
Cesium-core, but the manual gives you enough details to roll your own if
you enjoy doing that. We recently touched on that for the PRS-45 some
time
Tom t...@leapsecond.com wrote a few days ago:
Here's a nixie clock using javascript. It includes a leap second count down
which is now active:
http://leapsecond.com/java/nixie.htm
I have always been fascinated with Tom's delightful Nixie Clocks -
how clever !
When I ran the above link a
On 1/9/15 4:57 PM, Henry Hallam wrote:
Such slewing solutions are OK for Google. They wouldn't work well for
one of the systems I work with, which uses system time to calculate
the position of a LEO satellite for purpose of pointing a 7.6 meter
X-band dish. Half a second of error corresponds
Hi
The mounting points are the standard locations for a flexure bar running the
resonance along it’s length. The sandwich blank is a bit unique.
The normal gate feedback style circuits will get the crystal running. The
impedance will be quite high, so you will need a bit of gain. At low
Hi David yes I think I have seen similar but not as low as that. If you
compare the suspension points the different vibrational mode should
obvious.the suspension point is at a node. I think some of these are
quite difficult to excite, I have not seen any suggested circuits but I have
not
Back in about 1962 I joined a government research lab. My boss had bought a HP
voltmeter (I remember it as being about a yard cubed)
and a HP printer (also a yard cubed) and it printed out on 2 inch wide paper,
like a cash register record.
My boss's problem was that he wanted more precision in
On 1/10/15 1:25 PM, Hal Murray wrote:
jim...@earthlink.net said:
Which is why we use TAI in the space business and don't fool with this
Greenwich Mean Time or Coordinated Universal Time which is
discontinuous and potentially non-monotonic.
Does the system clock on your PCs run on TAI or do
mike,
i have a prs-10, software version 3.15, serial number 5351. default lock
mode is 1, default time offset is 0. the fc values have been written to
the EEPROM twice in the last 20 hours. fc!? returns 233,1426,1640,1647.
hans
I have a SR TDS12 which apart from name appears to be a
Hi:
You can see the 4 nodes on the Chinese Spouting bowl in my video at:
https://www.youtube.com/watch?v=k68w3OrPztE
When I got it from Cliff Stoll he had recommended using a wet towel to keep the bowl from moving but that damped the
vibrations.
I got 4 stick-on feet and placed them at the
hol...@hotmail.com said:
Basically the solenoid nudged the pendulum
There was an article in Scientific American many years ago. They used a
magnet mounted on the end of a stick attached to the pendulum arm. The arc
of the magnet swung through a hole in the middle of a solenoid coil. A
Many years ago I built a GPSDPO (GPS Disciplined Pendulum Oscillator). A
friend of mine inherited a grandfather clock built in the late 1700's. She
had the movement cleaned and serviced and got the clock working fairly well,
but it was not all that accurate.
I built up a device using a
jim...@earthlink.net said:
Which is why we use TAI in the space business and don't fool with this
Greenwich Mean Time or Coordinated Universal Time which is
discontinuous and potentially non-monotonic.
Does the system clock on your PCs run on TAI or do they have a separate clock
for space
On 1/10/15 3:08 PM, Hal Murray wrote:
hol...@hotmail.com said:
Basically the solenoid nudged the pendulum
There was an article in Scientific American many years ago. They used a
magnet mounted on the end of a stick attached to the pendulum arm. The arc
of the magnet swung through a hole in
Science Madness has a PDF of the book - Projects for the Amateur Scientist
by SciAm columnist C.L. Stong.
The pendulum is on page 290
http://www.sciencemadness.org/library/books/projects_for_the_amateur_scienti
st.pdf
Dave
-Original Message-
From: time-nuts
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