[time-nuts] Antenna Supply voltage

[Neville Michie]

I have just scanned through the Thunderbolt manual and found no information 
on the supply of power to the antenna.
Is there a standard for the supply of power to the antenna?
Are there 3.3v , 5v and 12v antennae?
Will any antenna work safely on any GPS receiver?
It is just a question that I had never thought of before.
Cheers,
Neville Michie
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Re: [time-nuts] Room temperature control (was: Holdover, RTC for Pi as NTP GPS source)

[Neville Michie]

You would be amazed by the effectiveness of installing a small fan, mounted 
parallel to the wall,
to create a slow whirlpool circulation in the room. Just a 10 w computer fan.
If the air velocity is below 0.3 m/s it is hardly perceptible. That takes about 
30 seconds to get 
around the room. The room becomes a well mixed volume of air. Heat sources 
distribute their burden 
of heat with only small local temperature rise. The room contains a 50 to 100kg 
mass of air and provides
an averaging effect on perturbations.
I have constructed 7 labs using this principle and have little difficulty 
keeping temperature swings below
1.0 degree C. The temperature control sensor must be very small (fast), exposed 
to the air flow, have zero 
hysteresis and be located on the wall that is opposite to the fan (and the AC 
unit).
The temperature sensor directly controls the AC unit, with the overriding logic 
that although a 0.1C deviation 
from the set point can switch the compressor on immediately (not even a second 
of delay), when switched off 
the compressor can not be switched on again for about 2 minutes, the time 
needed for the gas pressure in the AC 
to subside.
The natural cycle of about 2 - 3 minutes of on/off is attenuated by the 
integrated mass of the stirred air in 
the room. 1 Kw of heating or cooling is 1 kJ/s, air has an enthalpy of about 
1kJ/Kg per degree C, so 100Kg 
of air heats/cools at 1/100 degrees per second. The room temperature gently 
cycles by a fraction of a degree
as the AC cycles.
If anything, the service life (10 years or more) of the AC unit is longer than 
conventional hysteresis sensor
dominated chuggers.
All of this occurs because you stirred the air in the room!

cheers,
Neville Michie

> On 2 Nov 2017, at 6:32 AM, Poul-Henning Kamp <p...@phk.freebsd.dk> wrote:
> 
> 
> In message <20171101190841.366058d77e544d256b862...@kinali.ch>, Attila Kinali 
> w
> rites:
> 
>> The best we can do today is to have a well insulated room (no windows
>> with whith unknown power flows) and measure the temperature at a few
>> strategically choosen points. Then control the heat influx and
>> outflux using an approriate control loop. This will still result
>> in deviations of 1-2°C when somone walks in.
> 
> It is a matter of energy balance.
> 
> Humans emit heat on the order of a hundred watts and the only way
> to have that not affect the room temperture, is to "wash" it away
> in airflow with much higher energy content, as is typically done
> in clean-rooms.
> 
> That still leaves you with the thermal radiation imbalance from the
> higher temperature of the human skin, which is why "nano" laboratories
> sometimes are kept at an uncomfortably warm temperatures.
> 
> -- 
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] backfill

[Neville Michie]

It is possible that the ageing of a crystal is associated with the 
redistribution of the surface water
monolayer, under the influence of the minute temperature gradient of an 
oscillating crystal.
Some energy is dissipated in the quartz, so some gradient may exist.
When a crystal is resting, the water may redistribute in the sealed package, 
but when run again, the water 
redistributes due to the temperature differences.
Adsorbed water is in equilibrium with its environment, and, given time, will 
migrate along temperature gradients.
It could be just one more mechanism in frequency drift.
I would try using a reactive metal getter in the package to pick up any mobile 
water molecules.

cheers, 

Neville Michie

> On 10 Jun 2017, at 9:52 AM, Bob kb8tq <kb...@n1k.org> wrote:
> 
> Hi
> 
> You can’t quite process a crystal at 300C, but you can get close.
> 
> Bob
> 
>> On Jun 9, 2017, at 7:38 PM, Neville Michie <namic...@gmail.com> wrote:
>> 
>> My memory of high vacuum work is that you need to pump for 4 hours 
>> at 300C to remove the water monolayer from glass.
>> On top of the that water monolayer is another water monolayer that comes off 
>> more easily,
>> and on top of that another………..
>> 
>> cheers,
>> Neville Michie
>> 
>> 
>>> On 9 Jun 2017, at 10:57 AM, Richard (Rick) Karlquist 
>>> <rich...@karlquist.com> wrote:
>>> 
>>> 
>>> 
>>> On 6/8/2017 5:08 PM, Bob kb8tq wrote:
>>>> Hi
>>>> In this case hydrogen + oxygen (like from oxidized metal) goes to H20. You 
>>>> very much do
>>>> not want water running around inside your crystal holder… Helium is inert.
>>>> Bob
>>> 
>>> Exactly right Bob.  The 10811 guys used to go nuts
>>> about keeping water out of their vacuum system.
>>> There were certain temperatures known as "water
>>> points" at which some water was released.
>>> The retained water was in spite of the temperature
>>> already being above 100 degrees C (boiling).
>>> It has something to do with monolayers of
>>> water molecules not boiling away.
>>> 
>>> Rick N6RK
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Re: [time-nuts] backfill

[Neville Michie]

My memory of high vacuum work is that you need to pump for 4 hours 
at 300C to remove the water monolayer from glass.
On top of the that water monolayer is another water monolayer that comes off 
more easily,
and on top of that another………..

cheers,
Neville Michie


> On 9 Jun 2017, at 10:57 AM, Richard (Rick) Karlquist <rich...@karlquist.com> 
> wrote:
> 
> 
> 
> On 6/8/2017 5:08 PM, Bob kb8tq wrote:
>> Hi
>> In this case hydrogen + oxygen (like from oxidized metal) goes to H20. You 
>> very much do
>> not want water running around inside your crystal holder… Helium is inert.
>> Bob
> 
> Exactly right Bob.  The 10811 guys used to go nuts
> about keeping water out of their vacuum system.
> There were certain temperatures known as "water
> points" at which some water was released.
> The retained water was in spite of the temperature
> already being above 100 degrees C (boiling).
> It has something to do with monolayers of
> water molecules not boiling away.
> 
> Rick N6RK
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Re: [time-nuts] Next Aug 21 eclipse and time flow

[Neville Michie]

Maybe there is an effect when the solar wind is switched off for half an hour.
The ionosphere may shift in that time. This is a great opportunity when an 
impulse 
is applied to the system. The switching off of the solar UV is sure to affect 
the 
ozone layer. You will not have an opportunity to make these observations again 
for
a long time. A good OCXO will keep time for half an hour, will the apparent GPS 
time
show a deviation?

cheers, 

Neville Michie
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Re: [time-nuts] Vintage Frequency Measurement

[Neville Michie]

Back in the early sixties I worked in a lab adjusting filters for line 
transmission.
We had numerous oscillators, built to be boat anchors, and CROs set up for X-Y 
display.
The lab had 100hz, 1kHz, 10kHz standards wired in.
We were expert at recognising lisajou figures. We might have several 
oscillators running together,
and we could establish almost any frequency with precision.
Calibting an oscillator would not have been difficult.

Cheers, Neville Michie



> On 12 Feb 2017, at 5:08 PM, Scott Stobbe <scott.j.sto...@gmail.com> wrote:
> 
> I was inspired recently coming across a Lampkin 105 frequency meter, as to
> how  frequency measurement was done before counters.
> 
> Certainly zero-beating a dial calibrated oscillator, would be one approach.
> 
> Is there a standout methodology or instrument predating counters?
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Re: [time-nuts] Temp/Humidity control systems?

[Neville Michie]

Dew Point measurement technology is limited by surface energy problems,
in the near vicinity of the surface,Van der Waals or London forces create 
uncertainties
in the physical processes and dew point instruments always seem to have these 
uncertainties.
The physical equilibrium on the surface of a water film has proved reliable, 
hence the reliance 
of reference instruments using psychrometery. Dew point technology is mainly 
used for measurement
at extremes of dewpoint well outside the conditions in ambient weather and in 
in-line situations 
in industrial control where precision gives way to convenience.

cheers,
Neville Michie

> On 28 Oct 2016, at 11:05 AM, Poul-Henning Kamp <p...@phk.freebsd.dk> wrote:
> 
> 
> In message <20161027134312.ga18...@panix.com>, Ron Bean writes:
> 
>> And since this is time-nuts: Measuring humidity accurately is tricky. 
>> According to people who have tested them, commercial electronic humidity 
>> sensors, when tested in a lab, have never come anywhere close to the 
>> accuracy claimed in the data sheet.
> 
> The main problem in measuring humidity is physical gradients:  It is
> incredibly hard to create a volume of homogenous humidity on a planet
> which has gravity, and for that reason, a lot of labs are not anywhere
> near as accurate as they think they are.
> 
>> The exception is the "cold mirror" type of sensor, which measures the 
>> dewpoint by cooling a mirror and bouncing a light off it to sense the 
>> temperature where dew condenses on it. Those are expensive, and they 
>> require maintenance to keep the mirror clean.
> 
> And they are comparatively slow, last I saw one it could only do
> a measurement every second minute.
> 
> -- 
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Temp/Humidity control systems?

[Neville Michie]

You are correct to question commercial humidity sensors.
It seems to have come about because no-one can make a dollar by selling 
humidity.
Manufacturers do not tell the truth, they think ours is as good as theirs so we 
should claim the same accuracy. People buy these sensors, believe them, and buy 
more.

It is not hard to measure humidity/temperature. (they should be measured 
together).
Cover the bulb of an ASTM32C thermometer with cotton gauze. Insert it through 
the wall
 of a short length (18”) of 4” metal tube, insert another ASTM32C thermometer 
through the side 
of the tube 4” upstream. Put a computer fan on the outlet of the tube sucking 
air over 
the thermometer bulbs at about 4m/s. Wet the thermometer bulb, but NEVER touch 
it with your fingers.
In about 3 minutes you can take two temperature readings. There are a number of 
tables and calculation methods,
some much worse that others that will convert these values to air temperature, 
Relative humidity,
Dew Point temperature etc. You get accuracy of 1% from temperatures measured to 
0.1C.
If anyone is interested I have basic routines for XCEL spreadsheet use to do 
the hard work.
This is based on the WMO Reference Psychrometer developed by Russel Wylie of 
NML Australia.

> On 28 Oct 2016, at 12:43 AM, Ron Bean  wrote:
> 
>> * You cannot "feel" absolute humidity, always measure it.
> 
> And since this is time-nuts: Measuring humidity accurately is tricky. 
> According to people who have tested them, commercial electronic humidity 
> sensors, when tested in a lab, have never come anywhere close to the 
> accuracy claimed in the data sheet. The best you can hope for is 
> consistent readings, not absolute accuracy.
> 
> The exception is the "cold mirror" type of sensor, which measures the 
> dewpoint by cooling a mirror and bouncing a light off it to sense the 
> temperature where dew condenses on it. Those are expensive, and they 
> require maintenance to keep the mirror clean.
> 
> BTW some of us are more sensitive to humidity than others. I can't tell 
> you the RH of a room, but I can tell you when it's too dry for comfort. 
> I want it as close to 50% as I can get it without growing mold on the 
> walls. Some "experts" claim that 30% is good enough for anyone, but 
> they're wrong.
> 
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Re: [time-nuts] Temp/Humidity control systems?

[Neville Michie]

The nature of air is that when you heat it by one degree Celcius the humidity 
falls by 10%.
That does not change the moisture content of the air, just the activity of the 
same amount of 
water vapour with regards to any material with an equilibrium moisture content.
So it is important to control temperature fluctuation if you are going to 
control relative humidity.
cheers,
Neville Michie


> On 27 Oct 2016, at 8:17 PM, David J Taylor <david-tay...@blueyonder.co.uk> 
> wrote:
> 
> From: jimlux
> 
> You can buy the smallest "window" airconditioner and "plumb" it to your
> chamber (I used dryer vent hose, cardboard, and lots of duct tape)
> 
> Attached is a plot temperature and RH of an insulated box about 1.2
> meter wide, 2 meters tall and 60 cm deep, filled with 100 or so 750 ml
> bottles of liquid.
> 
> The temperature is fairly stable, but the RH varies wildly - basically,
> when the AC unit kicks on, it sucks all the water out of the air in the
> box, and then, when it turns off, the (damp) walls of the box rapidly
> rehumidify the air.
> ___
> 
> Thanks for that, Jim, and for the graph.
> 
> Your graph suggests to me that using /any/ form of artificial control may 
> give worse short-term results than simply leaving an underground, uninhabited 
> room with outside walls just "as-is".  The slow daily variations may be far 
> more tolerable than excursions due to heaters etc. being switched on and off.
> 
> Cheers,
> David
> -- 
> SatSignal Software - Quality software written to your requirements
> Web: http://www.satsignal.eu
> Email: david-tay...@blueyonder.co.uk
> Twitter: @gm8arv 
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Re: [time-nuts] Temp/Humidity control systems?

[Neville Michie]

Hi John,

such a project is quite practical.
I spent a working lifetime in textile physics research.
Air conditioned rooms were in great demand and access was limited.
So I did what I could with what I could get.
In spite of what conventional wisdom (or lack of wisdom ) says you 
can get good performance from a reverse cycle window air conditioner unit.
For humidity control, you should be able to make do with unilateral control 
downwards,
set the room to a humidity that is lower than the lowest ambient humidity. You 
may even compromise
by setting humidity at say 40% and tolerate the rare occasion that it drops 
below. It may be worth it 
so avoid the mess of bilateral control.
Now, so far you have the recipe for a system that produces great swings in 
temperature and humidity,
not what you want.
The important step is the controller and a small fan or two that gently swirls 
the air around the room,
at a velocity about 0.5m/s, which is only just on the threshold of perception. 
The swirling of the air 
means that within a time frame of 30 seconds the air is mixed into one thermal 
mass.
The control has several requirements.
The temperature must have a very rapid response time one or two seconds. A very 
small glass 
encapsulated thermistor in the general air flow are used. Thin film humidity 
sensors can be fast 
enough for humidity control.
The controller is directed at motor control. 
The motors are switched with substantial zero voltage switching solid state 
relays, - no QRM.
The rules are for both motors, the motor can be switched 
on within a second of the control temperature being reached, but only if a 
“decompression time” has elapsed.
No noisy switching is possible because any on signal starts the decompression 
timer.
This would be about 2 minutes for a window unit. This is necessary to avoid 
harm to the compressor through
over frequent cycling, and it does not have to start under load.
This may seem catastrophic for control, but the 
result is benign.
The fan in the window unit and dehumidifier are left running, probably on “low”.
Changeover from heating to cooling on the reverse cycle unit occurs 
automatically when a 6 minute timer 
detects no motor operation. This may seem a bit slow, but it happens at a time 
when heating or 
cooling are hardly needed.
How it works: Your 2 * 3 * 3 metre room contains 18 Kg of air, effectively in a 
single mass.
When the window unit cuts in the temperature rises of falls at a constant rate 
of about 2 degrees per minute. When the 
set point is crossed this ramp will stop within a few seconds. The temperature 
then slowly falls or rises
until after 2 minutes IF it is on the wrong side of the set point the motor 
starts up again.
Typically the motor runs 15 seconds and stays off for 200.
My rooms had an average temperature that did not shift more than a tenth of a 
C. They only used the minimum power 
needed, when required, peak variation was about 0.5C. Remember you have to keep 
the air volume mixed.
The thermometer was mounted in the general air stream about half way around the 
loop from the AC unit around the room.
One of my rooms had 30% windows and double brick walls but not other insulation.
The window units did not have shortened lives because of the “frequent cycling” 
because they were started under the right conditions.
I did publish this 30 or 40 years ago in an Australian electronics magazine.

cheers,
Neville Michie



> On 27 Oct 2016, at 2:59 AM, John Ackermann N8UR <j...@febo.com> wrote:
> 
> I may have the opportunity to build a small "clock room" and am considering 
> whether I could make it an environmentally controlled space.  I'd like to 
> learn about the options for doing this.
> 
> The space would probably be 6x8 feet or so, in a basement with one outside 
> wall.
> 
> Can anyone point me to purveyors of the hardware to do something like this?  
> Because I'll have a limited time to build this, I'm looking for something 
> that uses more-or-less off the shelf gear, and not a whole lot of custom 
> engineering.
> 
> Thanks!
> John
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Re: [time-nuts] Hobbyist grade or homebrew temperature testing chamber?

[Neville Michie]

Constant temperature chambers are not hard to build.
I assume you want stability in the range 0.001 to 0.01 degC.
I have made a few of these chambers, about 1 cubic feet, out of 3/4 inch 
particle board,
it is not a brilliant insulator, but you want some heat loss.
Make a partition at one end with both ends open as a radiation wall.
Behind the radiation wall instal one or two tungsten filament lamps,
about 50 watts for heaters, these have low thermal mass and fast response.
Instal a computer sized fan, behind the wall to reduce any radiant output to 
circulate the air in the box.
You want a small hurricane. On the far side of the box from the partition place 
a small bead thermistor, 
glass encapsulated are good. In the air flow this should have a response time 
of a second.
A proportional controller sets the temperature. Air velocity of up to 1m/s will 
not disturb items being tested 
but ensures low temperature gradients.
The trick is to have fast response in heater and measurement and no hysteresis 
in the controller.

cheers,
Neville Michie




> On 6 Sep 2016, at 12:48 PM, Richard (Rick) Karlquist <rich...@karlquist.com> 
> wrote:
> 
> As we all know, step #1 in making a clock is NOT
> to build a thermometer :-)
> 
> I thought I would check the brain trust here to see
> if anyone has seen a hobbyist grade temperature
> testing chamber or kit or homebrew design.  I
> have some crystals, oscillators, and other
> electronics I would like to characterize over
> temperature.  I know this reflector has discussed
> homebrew stabilization ovens; however, they
> have tended to have very long time constants
> (which makes sense for that application).  I
> need to be able to change temperature in a
> reasonable amount of time, and I don't need
> extreme stability.  Looking for any ideas,
> maybe in the "maker" spirit.  I think the
> size I need would be perhaps 1/2 the size
> of a shoebox.
> 
> BTW, in case someone has a chamber to sell,
> let me know...
> 
> Rick Karlquist N6RK
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Re: [time-nuts] Q/noise of Earth as an oscillator

[Neville Michie]

The discussion of Earth as a system with Q, but which is not resonant,
is a more extreme case than the CONICAL PENDULUM.

The conical pendulum has a simple form of a weight on a string, instead of 
oscillating 
in one plane as a conventional pendulum, it swings around in a circular orbit 
in the horizontal plane. It has a definite resonant frequency.
Now a simple pendulum oscillates kinetic energy and potential energy, but a 
conical pendulum
has constant potential energy and oscillates its energy from North-South energy 
to East-West 
energy.
I believe that a conical pendulum still has the circular error associated with 
amplitude.

But will it be as good a time keeper as the simple pendulum?

A curious fact about the conical pendulum is that whereas the simple pendulum 
has earth 
rotation forces that show in the Foucault Pendulum, the conical pendulum has a 
different 
period depending whether is swings clockwise or anticlockwise due to the earths 
rotation.

What do you think?

Cheers, 
Neville Michie
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[time-nuts] How to run Lady Heather under Windows10

[Neville Michie]

Hi,
a new laptop and a new problem,
I can not find COM1, and the slash command
on Lady Heather provokes a response that spaces and slash 
marks are illegal in file names.
Any ideas?

thanks,

Neville Michie
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Re: [time-nuts] quartz thermometers

[Neville Michie]

It always puzzled me that quartz crystals would be considered prime temperature 
sensors.
I can see that an instrument could be built that reliably showed many decimal 
places of reading,
but I could never accept that a vacuum mounted quartz crystal would be closely 
enough 
thermally coupled to whatever was having its temperature measured.
Sensors like thermistors, thermocouples and platinum resistors can be made of 
the right shape and size to 
thermally couple to solids and liquids and so can make successful measurement 
systems.
Many important measurements rely on having no disturbance of the physical 
system by the 
use of the thermometer.

cheers,
Neville Michie


> On 12 Mar 2016, at 8:21 pm, ken hartman <k...@hartmans.org> wrote:
> 
> Interestingly, the use of AC-cut crystals (high linear tempco of frequency)
> is found in the development of OCXOs. Using a reference AC-cut resonator -
> in place of the final AT/SC resonator - one can learn much about the
> thermal  characteristics of the oven loop performance. While not a precise
> temp sensor, it is a high sensitivity  indicator of  temperature variations
> of the resonator.
> 
> On Fri, Mar 11, 2016 at 11:44 PM, Bill Hawkins <bill.i...@pobox.com> wrote:
> 
>> It may be that the need for that kind of resolution died out.
>> 
>> The next step up from quartz thermometry is resistance thermometry.
>> The linearization equation for platinum has enough terms to make it
>> uncertain around .01 C.
>> Temperature calibration baths usually use platinum resistance sensors.
>> 
>> It may be that the triple point of water does not have the certainty to
>> reach '0.0001C'
>> 
>> Disclaimer: I only worked with industrial sensors from Rosemount, Inc.
>> as an employee.
>> 
>> Bill Hawkins
>> 
>> 
>> -Original Message-
>> From: Alan Ambrose
>> Sent: Friday, March 11, 2016 11:42 AM
>> 
>> Hi,
>> 
>> I hope this is still relevant and not too off-topic...but since it
>> involves crystals and tempco...
>> 
>> Quartz thermometers (e.g. the HP 2804A) with their 'linear cut' crystals
>> and '0.0001C resolution' seem to have been a thing from the mid-60's to
>> the mid-80's:
>> 
>> http://www.hparchive.com/Journals/HPJ-1965-03.pdf
>> 
>> There still appear to be some manufacturers making the crystals:
>> 
>> http://www.statek.com/products/pdf/Temp%20Sensor%2010162%20Rev%20B.pdf
>> 
>> Anyone know why they died out? Did a better technology replace them?
>> 
>> TIA, Alan
>> 
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Re: [time-nuts] PRS10 Heatsink Temperature

[Neville Michie]

The LPRO data manual has a graph of MTBF and operating temperature.
The lower the temperature, the longer it lives.
I would choose a temperature so low that for maybe 5% of the time 
the fan control would not hold it down but let it run 1 or 2 degrees high.
It depends on how you value its life and how much harm escaping from 
thermostasis for an hour or two does to your task.
Cheers,
Neville Michie
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Re: [time-nuts] FLL errors

[Neville Michie]

A PLL locks on to the nearest cycle,
is a Time Locked Loop different?
If the decoded time from a GPS system is used discipline 
an oscillator then leap seconds would have to have 
a frequency transient to maintain lock.
If you use the output to say drive a radio telescope monitoring 
a distant object you would want Earth’s rotation to be phase or 
sidereal Time locked. I realise that for such a task far more complex 
computation would be required.
So is a time locked loop a valid concept?

Cheers,
Neville Michie
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Re: [time-nuts] OXCO insulation

[Neville Michie]

Consider the problems of small detached crumbs of this material
upsetting the interelectrode capacitances of the oscillator.
Fibre material may be more stable.
Just a thought,
Neville Michie



On 26/02/2015, at 6:05 AM, Dave M wrote:

 Great find, Arthur.  I had already convinced myself to use fiberglass 
 insulation to reinsulate my OXCOs, but I'm going to order 2 or 3 sheets of 
 this to play with.
 
 Thanks a bunch!!
 Dave M
 
 
 Arthur Dent wrote:
 If you check the popular auction site you can find several listing
 for Aspen Aerogel SPACELOFT Insulation. One listing has a 10x14x.2
 piece for $7 including shipping and another listing has 481 rolls for
 $1.8 million, in case you have several ovens you need to re-insulate.
 ;-)
 
 http://www.ebay.com/itm/171328843398?
 
 -Arthur
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Re: [time-nuts] Current state of optical clocks and the definition of the second

[Neville Michie]

THe stability /accuracy of lasers is entirely dependent on the cavity length.
Materials used are usually invar or silica, so you are no better off than 
with a quartz crystals.
They are just a resonant cavity.
cheers, 
Neville Michie
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Re: [time-nuts] Mechanical 1PPS Oscillator Disciplining

[Neville Michie]

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 measuring a time 
dependent process. My problem was to trigger the voltmeter/printer to sample at 
exact intervals of time. I found a tuning fork standard (might have been GR) of 
400 hertz, so a I built a divider using neon Dekatrons. These had ten 
electrodes in a circle visible from the end, and subsidiary electrodes would 
steer the glow to the next electrode when the tube was triggered.
Each of these anodes must have had a separate load resistor, because I found 
each one had a voltage drop when it was illuminated. I used this with rotary 
selector switches to select divide integers by using the anode pulse to trigger 
a monostable (12AX7 ) to reset the Dekatron to zero and start counting again.
We did not have logic circuits in those days, this was known as Pulse 
Techniques as used in military radar, which is where I got much of my early 
education.
I have forgotten the voltmeter resolution it might have only been 4, 5, or 6 
digits, but the data from the paper tape was then hand typed into an IBM card 
punch and the cards were couriered to head office to be fed into the main frame 
(probably IBM)
We have come a long way in data acquisition and computing since then.
cheers, 
Neville Michie
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Re: [time-nuts] Practical considerations making a lab standard with an LTE lite

[Neville Michie]

A Hint about avoiding convective cell heat transfer,
If you keep the spacing between two planes less than 5/16 then you will 
be unlikely to have convection cells forming. The stationary air is a good 
insulator
but thermal radiation will be the dominant heat transfer process.
This is true for double glazing, katharometers and generally all devices. 
The suppression of turbulent heat transfer may provide more insulation but also 
less noise and instability.
So it may be a good idea to use a relatively close fitting box with thick walls.
Cheers,
Neville Michie




On 23/11/2014, at 11:37 PM, Charles Steinmetz wrote:

 Dave wrote
 
 But given the TCXOs sensitivity to temperature changes, I don't
 know whether it might be preferable to mount the LTE lite in its own box
 without any power supplies in it - perhaps with some thermally insulting
 material around the LTE lite so the crystal doesn't experience any fast
 temperature changes.
 
 First, mount the LTE in a cast aluminum box (not thin sheet metal, something 
 with some heft).  Use thermally insulating standoffs (teflon or nylon, with 
 no metal through fasteners) to get the board in the middle of the volume of 
 the box.  Use a box a bit larger than you'd first think, so there is at least 
 1 of air on all 6 sides of the LTE board.  Do NOT mount any part of the LTE 
 board (connectors, etc.) directly to the box walls -- use pigtails for all 
 connections.  Do NOT use any insulation between the LTE and the box walls 
 other than the 1+ of air.
 
 The mounting described above will add substantial thermal capacitance to the 
 LTE board (good) without adding significant thermal resistance (bad).  For 
 further discussions of this issue, search the list archives for thermal 
 capacitance and thermal mass.
 
 Now, mount the cast box (plus any thermal mass you add to it -- see below) so 
 that IT is thermally isolated from the overall enclosure (or, if it sits out 
 in the open, thermally isolated from anything solid).  The air space in the 
 enclosure isolates the oscillator from the cast box and the box is 
 sufficiently massive that its temperature cannot change nearly as fast as 
 ambient.  The thermal mass of the cast box can be adjusted by adding thermal 
 mass to it as desired.
 
 The goal is for the box temperature to change only by changes in ambient AIR 
 temperature, and the LTE board to change only by changes in the AIR 
 temperature inside the cast box.  This integrates any changes to the LTE 
 board temperature with a very long time constant, which allows the GPS 
 discipline to track and cancel the temperature changes.
 
 (If you mount an ovenized oscillator this same way, it integrates any changes 
 to the OCXO temperature so that the oven control loop can track and cancel 
 any changes to the crystal temperature.)
 
 You can, of course, improve things even further by making sure the ambient 
 air temperature surrounding the cast box changes slowly, or not at all.  But 
 the technique described above can be counted on to reduce thermal effects in 
 most OCXOs or GPSDOs to better (often much better) than the 1e-13 level 
 unless the ambient temperature changes MUCH more and MUCH faster than any 
 change we wouild consider normal for a living space.  This is true whether 
 the cast box is mounted out in the open, or inside an overall enclosure with 
 other electronics.
 
 Best regards,
 
 Charles
 
 
 
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Re: [time-nuts] Price of LTE Lite GPSDO vs Trimble Thunderbolt.

[Neville Michie]

Hi,
I am interested in your new GPSDO.
How do I find out more about buying the kit?
Is this a USA only deal?
cheers, 
Neville Michie
Sydney,
Australia

On 18/10/2014, at 9:35 AM, S. Jackson via time-nuts wrote:

 LTE Lite GPSDO

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Re: [time-nuts] OT Gel Cell question

[Neville Michie]

To clear up the point,
lead sulphate is very much more soluble in water than sulphuric acid,
and when batteries get flat all the sulphuric acid is reacted leaving
only water. That is why no current will flow when trying to charge them.
It is all well documented, see: 
Vinal.G.W. (1945) Storage Batteries,
John Wiley  Sons, Inc. New York Pp. 464

The sulphate is more soluble at higher temperature, and the daily thermal 
cycling
of an uncharged battery adds to the damage.

There are many popular myths and partial truths abroad, largely, I guess,
because the study of batteries is in few current engineering courses.
Magic additives to restore dead batteries have been around for 100 years,
but none of them are effective.
The only trick I have seen was an old guy who heated car batteries in an oven,
I never found out how long or how hot, he made a living reselling them 
with a money back six months guarantee.
cheers, 
Neville Michie

On 28/07/2014, at 1:59 PM, Chuck Harris wrote:

 A small disagreement on a couple of points
 
 Lead sulfate does not dissolve (in the normal battery chemistry),
 and does not go all over the place. It forms at the lead and the
 lead oxide plates, during discharge, and there it stays
 (unless it breaks off) until you charge the cell.  It is the
 electrolytic cell action that allows the lead sulfate to be
 converted back into lead metal, lead oxide, and sulfuric acid.
 
 Everyone wishes lead sulfate could be dissolved safely, as this
 could be a way of recovering batteries that have been overly
 discharged.
 
 Lots of snake oil remedies have been created that tout to do just
 that... things like lime juice, ETDA, adding more sulfuric acid...
 AFAIK, none of them really work.
 
 Shorting in a wet (flooded) lead acid battery happens because the
 charging/discharging action causes the creation and destruction of
 lead sulfate, and because the lead sulfate is less dense than the
 lead and lead oxide it replaces, it flexes the plates.  The flexing
 causes some of the lead sulfate to break free of the plates, and
 drop to the bottom of the cell.  Because energy density is
 important in a lead acid battery, the manufacturer wastes as little
 space in the battery case as possible by putting the plates as
 close to the bottom of the battery jar as it dares.  This allows
 the lead flakes to build up on the bottom until they reach the
 level of the plates and short them out.
 
 The gel cells, and glass mat cells short because the lead dendrites
 that sometimes grow as a result of charging/discharging, pierce the
 separator and short the plates directly.
 
 -Chuck Harris
 
 Neville Michie wrote:
 
 Hi,
 
 Lead acid cells have lead supports carrying lead oxide and lead metal active 
 material
 in an electrolyte of sulphuric acid.
 When they discharge, the sulphuric acid electrolyte is reacted with the 
 oxides and metal
 to form lead sulphate and the concentration of the acid falls, that is why 
 garages
 used to check batteries with a hydrometer to measure the electrolyte 
 concentration.
 At the same time the terminal voltage drops and the internal resistance 
 rises,
 when the concentration of the electrolyte gets very low, the lead sulphate 
 becomes
 soluble and will re-deposit all over the battery. With gel cells the 
 electrolyte can
 be completely absorbed making the battery resistance infinitely high.
 If you can get some current to flow, you may be lucky enough to get the 
 battery to
 reform some electrolyte, conduct some more, and eventually charge.
 However, when flat the lead sulphate dissolves and redeposits all over the 
 battery,
 and when recharged will convert back to lead and lead oxide, often most 
 inconveniently
 bridging the plates to a short circuit.
 The lesson is to not let the battery ever get flat.
 
 Lead acid batteries have some very good features.
 The terminal voltage rises as the concentration of the acid increases. So a 
 constant voltage will
 charge a cell, and current stops flowing when the electrolyte reaches its 
 proper concentration.
 The catch is, when you have a battery of several cells, if one cell gets 
 weak, the others will be overcharged
 causing gassing and over concentration of the electrolyte.
 There is a judicious voltage that causes an acceptably low rate of gassing
 (the oxygen hydrogen catalytically recombining) that will keep the charges 
 of cells equalised.
 But it only takes one total discharge event to cause enough leakage in one 
 cell
 to bring about failure.
 
 Lead acid batteries are also environmentally excellent.
 They consist of nothing but pure lead and sulphuric acid and water.
 Sulphuric acid is not volatile so you can make batteries out of old batteries
 forever, recycling the acid, lead and water.
 If made on a large scale they are also very efficient (99.9% +) electrically.
 
 cheers,
 Neville Michie
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Re: [time-nuts] OT Gel Cell question

[Neville Michie]

Hi,

Lead acid cells have lead supports carrying lead oxide and lead metal active 
material 
in an electrolyte of sulphuric acid.
When they discharge, the sulphuric acid electrolyte is reacted with the oxides 
and metal
to form lead sulphate and the concentration of the acid falls, that is why 
garages 
used to check batteries with a hydrometer to measure the electrolyte 
concentration.
At the same time the terminal voltage drops and the internal resistance rises,
when the concentration of the electrolyte gets very low, the lead sulphate 
becomes 
soluble and will re-deposit all over the battery. With gel cells the 
electrolyte can 
be completely absorbed making the battery resistance infinitely high.
If you can get some current to flow, you may be lucky enough to get the battery 
to 
reform some electrolyte, conduct some more, and eventually charge. 
However, when flat the lead sulphate dissolves and redeposits all over the 
battery,
and when recharged will convert back to lead and lead oxide, often most 
inconveniently
bridging the plates to a short circuit.
The lesson is to not let the battery ever get flat.

Lead acid batteries have some very good features.
The terminal voltage rises as the concentration of the acid increases. So a 
constant voltage will
charge a cell, and current stops flowing when the electrolyte reaches its 
proper concentration.
The catch is, when you have a battery of several cells, if one cell gets weak, 
the others will be overcharged
causing gassing and over concentration of the electrolyte.
There is a judicious voltage that causes an acceptably low rate of gassing 
(the oxygen hydrogen catalytically recombining) that will keep the charges of 
cells equalised.
But it only takes one total discharge event to cause enough leakage in one cell
to bring about failure.

Lead acid batteries are also environmentally excellent.
They consist of nothing but pure lead and sulphuric acid and water.
Sulphuric acid is not volatile so you can make batteries out of old batteries
forever, recycling the acid, lead and water.
If made on a large scale they are also very efficient (99.9% +) electrically.

cheers,
Neville Michie
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Re: [time-nuts] temperature sensor

[Neville Michie]

To ensure that steam is in a suitable state for temperature measurement
one uses a Hypsometer.
I made one out of tin cans and it sits on an electric hot plate.
It is not rocket science but it really works, my PT100 showed stable 
temperatures within a 
milliKelvin.
It is made so that the splash is separated from the boiling water and the 
shielding surfaces 
are maintained at the wet steam temperature. All that is necessary in the 
design is 
that the pressure drop of the steam is kept below some reasonable number.
The catch is that you must measure the ambient pressure to great precision,
aneroid barometers are hardly good enough except for some specially calibrated 
devices,
solid state barometric sensors are orders of magnitude too insensitive,
and a mercury barometer (Fortin pattern) requires several calculated 
corrections 
including the exact value of gravity at the measurement site.

cheers, Neville Michie

On 23/07/2014, at 5:11 AM, Attila Kinali wrote:

 On Tue, 22 Jul 2014 01:17:03 +0100
 Brian D gro...@planet3.freeuk.co.uk wrote:
 
 Saturated steam at standard pressure will be exactly 212F, or 100C.
 
 Stupid question: How to you ensure that the steam is saturated,
 while keeping a constant pressure?
 
 I think just buying some indium off ebay and use that as a melting/freezing
 reference is easier than the contraption needed to ensure fully saturated
 steam, with a low temperature gradient over the temperature sensor.
 
 That said. My investigations into stability of PT100 sensors reveal,
 that the quality ones can be less than 10mK/year, but hysteresis is
 in the same ball park (see [1]).
 
 
   Attila Kinali
 
 [1] Long term stability and hysteresis effects in Pt100 sensors
 used in industry, by Ljungblad, Holmstein, Josefson, Klevedal, 2013
 
 -- 
 I pity people who can't find laughter or at least some bit of amusement in
 the little doings of the day. I believe I could find something ridiculous
 even in the saddest moment, if necessary. It has nothing to do with being
 superficial. It's a matter of joy in life.
   -- Sophie Scholl
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Re: [time-nuts] new clock

[Neville Michie]

Deep soil temperature stability is a bit of a myth, mainly because not many 
people actually measure it.
I measured a beautiful 0.2C degree annual sine wave 15 metres down in limestone 
in Kentucky.
The catch is the Gauss's Error function drop-off rate of temperature 
fluctuation is a very 
good low pass filter, so all the ambient noise of longer than a year period is 
not well
attenuated. Secular variations, like a warm winter, a warmer than normal 
decade, all appear
with less attenuation. 100 year functions reach 100 metres depth, and that does 
not count effects from 
percolating ground water.
Admittedly a deep cellar made a good clock vault, but a thermistor, a computer 
fan and 
a 100 watt filament lamp in a wooden box can give far more accurate temperature 
control.

cheers,
Neville Michie


On 23/07/2014, at 10:17 PM, Alexander Pummer wrote:

 it does need a different design, but a buried oscillator, 5 to 8 meter deep 
 in the garden has the best temperature stabilization, just don't turn thee 
 power off, but that could be done using the old Greek water-clock principle, 
 the spill over stabilizer. In the Bay Area [California] the soil's 
 temperature is around the year approximately 17C° ±0.01C° if you go further 
 down it will be even more constant, without any heating power and control 
 loop
 73
 KJ6UHN
 Alex
 On 7/22/2014 6:43 PM, Bob Camp wrote:
 Hi
 
 A lot depends on the oscillator. My fine old GR rack mount took most of 9 
 months to settle most of the way. It was still dropping in a year after that 
 when I stopped watching it. Some of my T-Bolts took a week, some took a 
 couple months….
 
 Best thing you can do with any OCXO is just leave it on power.
 
 Bob
 
 On Jul 22, 2014, at 7:53 PM, paul swed paulsw...@gmail.com wrote:
 
 Agree with Marks comments.
 Regards
 Paul
 
 
 On Tue, Jul 22, 2014 at 5:25 PM, Mark Sims hol...@hotmail.com wrote:
 
 An oscillator can take many weeks to settle in after being powered off /
 shipped / abused / looked at cross-eyed / etc.   It typically takes a
 Thunderbolt a month or two to  settle down after being shipped from China.
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Re: [time-nuts] temperature sensor

[Neville Michie]

Hi,
as a bit of a temperature nut, here are some observations.

Diodes work as temperature sensors, but better is the trans-diode,
a bipolar transistor with collector connected to base. Sensitivity
about 2.2 mV/K, I did not use them much in spite of their linearity
and low cost.

PT100 is only useful with a four terminal measurement with an HP3468A instrument
or equivalent measuring 4 terminal ohms. It is stable to one milli-Kelvin and I 
use it for 
measuring the temperature of thermostatic water baths when calibrating 
thermometers.
The sensor has self heating, and is poor in placement on small components, with 
high thermal resistance to measured item and high heat conduction along leads.
Without the HP measuring instrument the PT100 relies on the resistors it is 
compared with.
Although the PT100 specs are good, resistors that can match those specs are 
very expensive,
so to set up a measuring bridge requires a lot of expensive technology in 
resistors 
and stable amplifiers. If you wont go that far you are better off with 
thermistors.

Thermocouples only compare temperatures, so cold reference is a problem 
as are cold junction compensators. With only 40 microvolts/Kelvin they need 
good 
to very good amplifiers. They are small and are not compromised by using 
microscopically fine wire. They can measure tiny items with very little heat 
transmitted along the wires. they have no self heating.I use them in a Pile 
of six elements to measure Relative Humidity to a precision of 0.1% RH in 
an appropriate portable instrument. One logging instrument I have built 
uses three thermocouples with ICL7650 amplifiers and a AD590 common cold 
junction
sensor. A four channel logger produces data that is reduced by spreadsheet
to three temperatures. Copper /constantin is a good pair, sensitive (40uV/K), 
reasonably linear
and the copper solves many switching and amplifier circuit problems.

Thermistors are useful. They are available in tiny packages, sealed in glass.
With high impedance their self heating can be negligibly small. As has been 
pointed out they comply well to a general calibration curve.
If Paralleled with an equal value resistor, or connected in an equal 
value resistance bridge, they are linear over about 20C range.
They are very sensitive (4%/K), and so need no special amplifiers. They prove 
quite stable.

Calibration is done with a known PT100 sensor and a HP3468A in a thermostatic 
bath
(Colora or Haake). Tested devices a placed in a copper tube immersed 10cm (4 
inches)
at least. 

Icepoint cell, in a Dewar flask (Thermos) with shaved ice gives a temperature 
at zero C
to 0.01C. Test thermometer inserted 15 cm.

Hypsometer, a boiling point cell has special splash and radiation shields, 
gives 
measurements stable to 1mK, but after all the corrections needed to a Fortin 
barometer
for temperature etc, relies on knowing local gravity to some accuracy. If the 
local 
geoid is assumed with usual corrections the ice-point is still more reliable as 
an absolute standard.

Conduction along leads is a major consideration, even with fine (0.002 ) 
copper leads,
a typical installation needs 20mm immersion. It is a logarithmic function, the 
immersion error,
I allow about 50mm to be sure with thermocouple sensors into a 3mm hole drilled 
into aluminium plate 
edge wise to measure the plate temperature. You only have to do a few 
experiments to find 
that this is necessary.

cheers,
Neville Michie
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Re: [time-nuts] National Standards labs worldwide - specifically Australia

[Neville Michie]

Hi,
it used to be called NSL, National Standards Laboratory, part of the CSIRO.

Now it appears to be called National Measurement Institute, (NSI)
and seems to be located mainly at Lindfield NSW.
http://www.measurement.gov.au/Pages/default.aspx
See if that works,
Cheers, 
Neville Michie


On 29/06/2014, at 8:33 PM, Dr. David Kirkby wrote:

 I know of NPL in the UK, and NIST in the USA, but is anyone aware of
 other standard labs. In particular I am looking for the Australian
 equivalent. A Google search came across Standards Australia
 
 http://www.standards.org.au/
 
 but I don't know how authoritative this is. There is basically
 nothing stopping any body here setting up a web site claiming to be
 the countries leading non-government standards labs. I have a very
 healthy skepticism of calibration laboratories in general
 
 NIST for example does have a .gov domain, which gives it a bit more
 credibility than a typical .com.
 NPL does not have a .gov, despite we use it in the UK.
 
 I found the The National Measurement Institute (NMI)
 http://www.measurement.gov.au/
 
 which is probably the one I am looking for.
 
 There are people on this list who I would trust to produce a list of
 national standards labs more than I would from a Google search or
 Wikipedia.
 
 There are a couple of things I am looking to find out - neither of
 which are very time-nut related, but both are to some extent as they
 they involve measuring the phase difference between two signals.
 
 1) There was some work done somewhere (I believe an Australian lab),
 which showed that calibrating a VNA with 1/8 and 3/8 offset shorts is
 superior to a flush short and 1/4 spacer. Both give the desired 180
 degree difference in reflected signal, so at first thought they are
 equivalent. I do know the reason the 1/8 and 3/8 are superior, but I'd
 like to find a reference.
 
 2) Who in Australia would be best at measuring the reflection
 coefficient of a 50 Ohm termination?
 
 -- 
 Dr. David Kirkby G8WRB
 http://www.vnacalibration.co.uk/
 Economical  accurate VNA calibration kits.
 Coefficients available for HP, Agilent, Anritsu, Rohde  Schwarz and
 VNWA network analyzers.
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Re: [time-nuts] Loran, GPS, Lightning, Timing

[Neville Michie]

Back on the topic of lightening,
a destructive side of lightening can occur with between-cloud strikes.
Beneath a cloud with a hefty charge on it there is a counter charge, a 
reflection,
on the earths surface. This will have the same amount of charge but in inverse 
polarity.
When the charge in the cloud jumps to another cloud, the counter charge has to 
move to
beneath the new cloud.
This involves currents of equal magnitude to lightening strikes moving in a 
similar 
time frame.
Any water pipe or buried telephone or power cable may be obliged by a potential 
voltage similar to a lightening strike to carry part of this current.
I saw a buried phone line that had been 3 feet underground converted to an open 
trench 100 yards long.
Any conducting cable that cuts the transient magnetic field during one of these 
events
may be a victim.
Fibre optic would seem to be the answer for protection.
cheers,
Neville Michie
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Re: [time-nuts] Loran, GPS, Lightning, Timing

[Neville Michie]

Use a local solar cell and battery power supply.
If it is self contained it should not attract lightning.

Cheers,
Neville Michie

On 29/06/2014, at 1:13 PM, Hal Murray wrote:

 
 namic...@gmail.com said:
 Fibre optic would seem to be the answer for protection. 
 
 Assuming I use fibers for the data, how do I safely get power to the other 
 end?
 
 
 -- 
 These are my opinions.  I hate spam.
 
 
 
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Re: [time-nuts] Loran, GPS, Lightning, Timing

[Neville Michie]

Hi,
the maltese cross is a chopper to interrupt the lines of electrostatic force.
The cross could have a hundred legs, as long as it alternately blocks 
and unblocks exposure to the electric field.
The cross spins in a horizontal plane, maybe half an inch above the sensor 
electrode which is flush or just above the ground plane.
The idea is to get the output signal up to a frequency where the time constant 
of the sensing electrode can be quite short.
If you can get it up to 400 Hz it only needs a 2.5mS time constant.
Even then, since you can calibrate it you can have the signal below the time 
constant.  
A 12 legged cross spinning on a 4 pole motor gives a chopping frequency of 
360 hertz,
(in America), quite convenient for amplification and processing.
If the motor is synchronous, or you put a sensor on the motor shaft you can run 
a phase
sensitive detector and get polarity as well as magnitude.
cheers, 
Neville Michie

On 27/06/2014, at 1:59 AM, Max Robinson wrote:

 How fast does the maltese cross turn?
 
 Regards.
 
 Max.  K 4 O DS.
 
 Email: m...@maxsmusicplace.com
 
 Transistor site http://www.funwithtransistors.net
 Vacuum tube site: http://www.funwithtubes.net
 Woodworking site 
 http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html
 Music site: http://www.maxsmusicplace.com
 
 To subscribe to the fun with transistors group send an email to.
 funwithtransistors-subscr...@yahoogroups.com
 
 To subscribe to the fun with tubes group send an email to,
 funwithtubes-subscr...@yahoogroups.com
 
 To subscribe to the fun with wood group send a blank email to
 funwithwood-subscr...@yahoogroups.com
 
 - Original Message - From: Neville Michie namic...@gmail.com
 To: Discussion of precise time and frequency measurement 
 time-nuts@febo.com
 Sent: Wednesday, June 25, 2014 10:46 PM
 Subject: Re: [time-nuts] Loran, GPS, Lightning, Timing
 
 
 Is anyone using a field mill?
 I have always been going to make one.
 It consists of a horizontal metal plane with a conducting button on the 
 surface
 which is insulated from the ground plane.
 A metallic maltese cross driven by a motor alternately covers and uncovers 
 the electrode
 exposing/not exposing it to the sky.
 The electrode button has capacitance to ground which drops its impedance,
 but across that impedance is an AC voltage proportional to the ambient 
 static field.
 A typical field in fine weather is 300 Volts/metre  so the signal is not 
 trivial.
 You should be able to make a field mill that works continuously except when
 actually shorted by rain.
 This is not a very high impedance device, and should show many marvellous 
 things
 as the clouds float over you.
 You can calibrate it with a metal plate, say 12 inches above it with 50 
 volts on it.
 That should produce a uniform field on the mill.
 cheers,
 Neville Michie
 
 
 
 I know you are talking about measuring lightning strikes but if you get the
 impedance high enough, you can actually measure the earth's electric field.
 (It is about 200V/m if I recall properly.) Interestingly it is affected by
 the solar flux and solar wind.
 
 -- 
 Brian Lloyd
 Lloyd Aviation
 706 Flightline Drive
 Spring Branch, TX 78070
 br...@lloyd.com
 +1.916.877.5067
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 and follow the instructions there. 
 
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Re: [time-nuts] Loran, GPS, Lightning, Timing

[Neville Michie]

Is anyone using a field mill?
I have always been going to make one.
It consists of a horizontal metal plane with a conducting button on the surface 
which is insulated from the ground plane.
A metallic maltese cross driven by a motor alternately covers and uncovers the 
electrode
exposing/not exposing it to the sky.
The electrode button has capacitance to ground which drops its impedance, 
but across that impedance is an AC voltage proportional to the ambient static 
field. 
A typical field in fine weather is 300 Volts/metre  so the signal is not 
trivial.
You should be able to make a field mill that works continuously except when 
actually shorted by rain.
This is not a very high impedance device, and should show many marvellous 
things 
as the clouds float over you.
You can calibrate it with a metal plate, say 12 inches above it with 50 volts 
on it.
That should produce a uniform field on the mill.
cheers,
Neville Michie


 
 I know you are talking about measuring lightning strikes but if you get the
 impedance high enough, you can actually measure the earth's electric field.
 (It is about 200V/m if I recall properly.) Interestingly it is affected by
 the solar flux and solar wind.
 
 -- 
 Brian Lloyd
 Lloyd Aviation
 706 Flightline Drive
 Spring Branch, TX 78070
 br...@lloyd.com
 +1.916.877.5067
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Re: [time-nuts] Weather/units question for European members

[Neville Michie]

There is a great sonic anemometer in:

An inexpensive sonic anemometer for eddy correlation G.S.Campbell and 
M.H.Unsworth, (1979), Journal of Applied Meteorology Vol 18, August 1979, Pp. 
1072-1077.

This unit uses 4000 CMOS, a LM301A and two cheap ultrasonic transducers. It 
operates a phase-locked loop and alternately uses the sensors for transmitter 
and receiver, swapping ends at about 74 Hz, to get a two way signal. This 
method cancels most errors. It has temperature and velocity outputs.

cheers, Neville Michie

On 24/05/2014, at 11:16 AM, Mark Sims wrote:

 I am building a weather sensor that includes a ultrasonic anemometer to 
 measure wind speed, direction, and air temperature.  It uses 4 cheap ($1 
 each) HC-SR04 ultrasonic rangefinder modules that output a pulse width 
 proportional to the time of flight of the sound signal  (topic is time nut 
 related since  it simultaneously measures the speed of sound in 4 directions 
 to a pretty good accuracy/resolution using a cheap-ass microprocessor - 
 ATMEGA328 (like and Arduino)...  and does so without using any counter-timer 
 channels).
 Now the question...  I would like it to be able to output data in imperial or 
 metric units.  In what units is the typical wind speed reported  (meters/sec, 
  km/hour, ?).   Also air pressure (millibars/hectopascals/pascals/?). 
   
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Re: [time-nuts] Equinox and sidereal time

[Neville Michie]

Thanks Paul,
I should be able to get this information online,
but nearly all my attempts to get information from 
USA military sites seem to be blocked to Australia,
or may be just to me.
I click the URL and wait two minutes and it times out.
Any time day or night.
It is very frustrating as the sites appear to be available 
to everyone else.
I bought the Nautical Almanac but it does not have such information.
It is very hard to find alternate sources of the data.
cheers,
Neville Michie

On 24/03/2014, at 11:06 AM, Paul wrote:

 On Sun, Mar 23, 2014 at 7:02 PM, Neville Michie namic...@gmail.com wrote:
 
 can anyone out there point me to a source
 for the exact time of the equinoxes and solstices
 
 
 
 I think you want this: http://aa.usno.navy.mil/data/docs/geocentric.php
 
 e.g. RA 0 is 2014 Mar 20 16:57:07.5 or RA 12 is 2014 Sep 23 02:29:08.5
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[time-nuts] Equinox and sidereal time

[Neville Michie]

Hi,
can anyone out there point me to a source 
for the exact time of the equinoxes and solstices
so that I can synchronise a sidereal clock?
I assume that at some time the Universal Time we use 
is exactly the same as Sidereal time, and so a Sidereal clock
could be set.
I have a Tbolt producing 10MHz, and divide it with one of Tom's 
excellent PICDIV chips, to get sidereal seconds. I would like to 
be able to hear them ticking away as I follow a star with a theodolite, 
and check my local time and position.
If I use published times for the equinox, to one minute, I only get 
about 0.2 second resolution.
There is probably more to this than meets the eye, but where does one 
find out about it?
cheers,
Neville Michie
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Re: [time-nuts] New WWVB modulation format receivers (NOT)

[Neville Michie]

Hi Paul,
could you give a hint how long ago you released the front end to T_N?
thanks 
Neville Michie
(Sydney)


On 21/02/2014, at 8:29 AM, paul swed wrote:

 Chuck thats easy. Because I could make it work. :-)
 That said there was a post on time-nuts about LORAN C receiver in software.
 I responded and have had the great pleasure of communicating with Matthias
 over the last two weeks. I have learned a lot already and he in return has
 a tested LORAN C receiver.
 So with some luck just maybe I can become smart enough to do a better
 design in software on a $15 micro. You still need the RF frontend section
 that I released quite a while ago to time-nuts.
 Regards
 Paul
 WB8TSL
 
 
 
 On Thu, Feb 20, 2014 at 4:02 PM, Chuck Harris cfhar...@erols.com wrote:
 
 At 60KHz, it shouldn't be out of range of most
 general purpose CPU's, and even the most pathetic DSP.
 
 Why bother with a hardware solution when software can
 do it more easily?
 
 -Chuck Harris
 
 
 Florian Teply wrote:
 
 Well, if someone comes up with a circuit, I could check how much chip
 area that would consume in a 250nm SiGe BiCMOS... Shouldn't be out of
 range for a serious time nut ;-)
 
 Florian
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Re: [time-nuts] Local Solar Time Clock

[Neville Michie]

FWIW
If you take a cheap digital analog clock, remove the battery,
connect to the two coil connections, you can drive the clock with a 
0.5 Hz square wave through the series combination of a capacitor and resistor.
Typical values are 100mfd and 200 ohms.
You need to select these values to get certain stepping without pole-ing.
The clock originally used 1.2 volt pulses, alternate polarity about 20 mS long.
You can trade off these values and still get smooth certain operation.
Cheers,
Neville Michie
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Re: [time-nuts] temperature

[Neville Michie]

Hi,
I use a HP3468A multimeter to measure a PT100 platinum resistance thermometer. 
It gives me resolution of one mK, but calibration is another matter.
It is best to use a 4 terminal device, but 2 terminal into the 4 terminal input 
works well. Thermoelectric effects and the requirement for 1 microvolt stability
makes wiring them into your own circuit difficult. One of the great technical 
difficulties is to get a resistor to compare them against, it must be very 
stable,
have no thermoelectric effects and have a temperature coefficient in the order 
of one PPM. I always admire the way HP designed their ohm meters.
There are other issues, however. Whereas a volt meter can connect perfectly to 
a reference, a PRT can only report its own temperature.
That is no problem when you are working in a well stirred water bath, that will 
have the PRT at the same temperature as the object in the same bath.
When you get to measure air temperature you are into serious sampling errors, 
the PRT has some self heating and so is air velocity sensitive, and the air 
you are measuring may not be the same air as is over your OCXO or item of 
interest. There is a personal plume of warm air rising from an observer, so 
you must be careful with your measurement technique.
The same problems occur with quartz crystal thermometers, which is why they are 
not more commonly found in surplus.
A PT100 sensor is quite cheap, and their calibration is little short of 
brilliant. However a they would cost much more if their calibration is 
traceable.
For my use, I use an ice-point cell as a calibration check, with care you get 
10mK accuracy. You only need the knowledge how to set it up, a blender to make 
ice slush,
and a picnic vacuum flask, to make your own calibration reference.
I use thermistors for air measurement, and calibrate them against the PT100 in 
a thermostatic water bath. Thermistors can be run with a very low 
level of self heating and they are very sensitive, their resistance changes 4% 
per Centigrade degree, and they come in high values like 100K ohm. You read 
them in a bridge circuit with a voltmeter, so they are many orders of magnitude 
easier to use than a 100 ohm PRT.
 They are made small enough to get them in close contact 
with the object to be measured. 
If you want to know about humidity measurement I can tell you much about that,
cheers,
Neville Michie

On 08/12/2013, at 12:40 PM, Mark Spencer wrote:

 Sorry if this is somewhat off topic, but I'd be interested in more details re 
 precision temperature measurement devices.   Have been using an inexpensive 
 USB temperature sensor for the last year or so to monitor the temperature in 
 my lab and have been looking at the correlation between frequency shifts in 
 some ocxo's vs temperature changes.   I should also start taking humidity 
 measurements as well at some point. 
 
 
 Any pointers re suitable instruments to accomplish this that can be sourced 
 via the usual surplus sources would be welcome.
 
 Thanks in advance
 Mark Spencer
 
 Sent from my iPad
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Re: [time-nuts] Crude Survey Technique

[Neville Michie]

How do the car mounted GPS guidance devices find North?
Is it by deciding which direction you are moving on the map that they have 
stored?
It is amazing how quickly they show the orientation of the map/your direction 
of travel.
Do they have a sensor to register when you turn a corner?
What they do does not seem possible from just a series of position fixes.
cheers,
Neville Michie





On 22/11/2013, at 7:45 AM, tmil...@skylinenet.net wrote:

 If you want true north, set up a camera that has time or bulb shutter at the 
 south end of your property. Put in a marker stake. take a time exposure at 
 night with the camera facing north. If you expose for about 30 minutes, you 
 will get a landscape with the stars rotating around the north star. You can 
 then mark the north location on your property under the north star.
 
 A compass siting can give the mag north.
 
 
 From: time-nuts-boun...@febo.com time-nuts-boun...@febo.com on behalf of 
 Brian Lloyd br...@lloyd.com
 Sent: Thursday, November 21, 2013 2:04 PM
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] Crude Survey Technique
 
 On Thu, Nov 21, 2013 at 12:52 PM, johncr...@aol.com wrote:
 
 I wish to establish a north south line on my property to an accuracy of
 +/- 2 degrees.
 Could this be done by loading a T-bolt, Antenna, Power source, and laptop
 into my
 little red wagon? The idea being to find two positions several hundred ft
 apart where either LH or T-bolt Mon report the same latitude? Will either
 of these programs report to sufficient accuracy? The base line would be 300
 ft, though more is possible.I realizes that the T-bolt is not a survey
 device, but I can spend several hours fixing each position if required.
 
 
 True north or magnetic north? In any case, a good lensatic compass and
 knowing your magnetic variation should easily get you to within 2 degrees
 and is a lot easier than doing a survey with your GPS.
 
 
 --
 Brian Lloyd, WB6RQN/J79BPL
 706 Flightline Drive
 Spring Branch, TX 78070
 br...@lloyd.com
 +1.916.877.5067
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Re: [time-nuts] Time stamping with a PICPET

[Neville Michie]

I am going to use a Tbolt or an LPRO to source the 10MHz, the nanoseconds are 
not going to be important,
the noise or jitter on the proximity detector or photoelectric detector may 
swamp any 10MHz noise.
In the last few decades I am becoming increasingly computer illiterate, the 
machines and/or operating systems 
that I used to know are all in museums.
All I want is something that works.
I have some great ideas for a pendulum system that will work at atmospheric 
pressure on a bench top, 
eliminating the clock vault 50metres underground and the high vacuum system. 
However I will have to 
test and adjust each element of the system, so I need to log timestamps.
cheers, thanks for the input,
Neville Michie

On 26/10/2013, at 4:48 PM, Hal Murray wrote:

 
 namic...@gmail.com said:
 There used to be all sorts of Monitor programs for PCs but I can not see any
 on recent machines. I want to log one second signals from a pendulum to
 analyse its precision. The device looks ideal for this task. 
 
 What are you going to use as a reference clock?
 
 If you can convert your one-second ticks into a TTL signal and feed that to a 
 Linux box, the PPS stuff will allow you to log the data.  That uses your 
 local clock as the reference which is probably pretty close if you are 
 running ntpd.  (But since this is time-nuts, who says pretty close is good 
 enough?)
 
 Here is a simple python script to log the data:
  http://www.febo.com/pipermail/time-nuts/2011-September/058907.html
 It was targeted at 60 Hz but should work OK at 1 Hz.
 
 
 
 -- 
 These are my opinions.  I hate spam.
 
 
 

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[time-nuts] Time stamping with a PICPET

[Neville Michie]

Hi,
I have some PICPETs made by TVB.
They take a 10MHz clock, and on receiving a pulse trigger, they send out a 
19200 Baud
RS232 time stamp word.
My query is can they be fed straight into a serial port? 
What about logic levels?
Would a serial/USB converter get them into a laptop?
What applications are available to receive the data and make an ASCII file that 
can be read by a spreadsheet
or other data reduction program.
There used to be all sorts of Monitor programs for PCs but I can not see any on 
recent machines.
I want to log one second signals from a pendulum to analyse its precision. The 
device looks ideal for this task.
thanks,
Neville Michie
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Re: [time-nuts] de Witte's Experiment

[Neville Michie]

It should not be difficult to measure the temperature of the co-ax,
if it uses copper, copper has a very high tempco, about the same as  
platinum.
So you could set up an experiment where you compare phase in the two  
legs

then compare resistance of the two legs.
Strain in the legs might be an effect.
Cheers,
Neville Michie
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[time-nuts] Sidereal Time and Lady Heather.

[Neville Michie]

I have just found out how to get sidereal time from Lady Heather.
(You put t=GMST in the command line, or alias target line, and 
the Lady comes up in Sidereal Time, ticking away in Sidereal seconds.)
(Also you can get LMST, LAST or GAST.)
Now, as a time nut, I have questions. How is a leap second handled?
Sidereal time is time observed by watching stars rather than the sun.
In fact it is the source of all knowledge about how fast our planet rotates,
and the basis for all our time scales.
A sidereal second is shorter than a physical second by about one second in six 
minutes,
so as to fit 366.25 sidereal days into the year of 365.25 solar days.
At the Vernal Equinox there is a situation where Solar seconds exactly match
the Sidereal second count, as zero, but how can a time nut know if this 
is in error? How accurate is it? In microseconds, nanoseconds?
My interest in Sidereal time is because I have two pendulum clocks mounted 
on the same brick wall and they interfere with each other.
By running one one sidereal time they are independent.
The problem is to get a source of sidereal time to measure the performance of 
the 
sidereal clock. It is no problem to divide 10 MHz down to sidereal seconds, but 
how do you synch.
the seconds? This is where the Lady helps. But I do not know how I can get 
really accurate 
seconds markers as convenient as the PPS from my Thunderbolt.
cheers, 
Neville Michie
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Re: [time-nuts] MesoAmerican calendars, Solstice, etc.

[Neville Michie]

It is little short of brilliant….
Put t=GMST in the command line, and the Lady comes up in Sidereal Time,
ticking away in Sidereal seconds.
It was not exactly obvious that it would do it. I have had so much difficulty 
trying to set up and regulate a master clock to Sidereal time, and Lady Heather 
would show sidereal time!
It is now just a matter of watching the screen and listening to the ticks of 
the clock.

thanks Mark, and the others, 
cheers, Neville Michie



On 18/12/2012, at 2:33 PM, Mark Sims wrote:

 
 Yes,   you can have a GPSDMC (GPS disciplined Mayan calendar).   You can also 
 specify your preferred calendar correlation constant (a +/- offset to the 
 start of the calendar) to satisfy the whims of when your favorite deity 
 demands sacrifices.
 
 Also,  Lady Heather does sidereal time (LMST or GMST or LAST or GAST)...
 
 
 
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Re: [time-nuts] MesoAmerican calendars, Solstice, etc.

[Neville Michie]

But does it have an output of Sidereal Time?
cheers, 
Neville Michie
A Merry Season to all.

On 18/12/2012, at 11:02 AM, Mark Sims wrote:

 
 BTW,  Lady Heather has support for several versions of the Mayan and Aztec 
 calendars.  Also Druid,  Herbrew,  Islamic,  Indian, and many others. 

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Re: [time-nuts] getting a grip on 10811 drift (trying to read my instruments)

[Neville Michie]

I have had two 10811 with EFC problems that turned out to be lack of soldering 
of one internal joint.
This is a large PTFE ferule with several leads including the varactor and 
trimmer going into it. For many 
years the leads all contacted but finally one lead developed an oxide film. A 
soldering iron fixed them very quickly.
The serial numbers were widely separated, so it was not an unlucky batch 
problem.
cheers, 
Neville Michie

On 16/11/2012, at 1:57 PM, Chris Howard wrote:

 
 You all were right, my targeting of the 50 ohm resistor
 across the oscillator output does not seem to have solved the
 problem.   A good thing to do, probably, but not the answer.
 
 While I was all excited about the resistor change I also
 mapped out the control voltage (EFC) vs frequency change.
 I wrote it out but didn't pay much attention.  Now
 I've been pondering over that a bit.  My next theory
 is that my EFC maybe isn't really doing very much.
 
 First I need to know if I am reading this right.
 My frequency counter is a Racal 1992  It reads
 9.9997^6   as I write.  A total of 9 digits
 with a smaller 6 to the right.
 
 If I read this correctly, I'm looking at
 9,999,999.97  Hz ?  If so, then I've got an EFC problem.
 
 My EFC mapping looks like this (this was done before
 I adjusted the coarse control)
 
 
 -4.94 VDC 9,999,999.95
 -3.70 9,999,999.95
 -1.24 9.999.999.93
 0 VDC   9,999,999.93
 +1.21 9,999,999.92
 +2.44 9,999,999.92
 +3.67 9,999,999.91
 +4.90 VDC   9,999,999.90
 
 It doesn't look to me like I am getting anything
 like 1/2 hertz range using the EFC.  If that's
 the case than my controller card is frantically
 steering but not getting the desired result.
 
 Or, if I'm reading it wrong,  maybe that last digit
 is 0-5 meaning 1/2 a hertz and I am all wet (again).
 
 This particular oscillator came out of an old HP counter
 and I believe the EFC was wired to ground.  So maybe
 the thing has never been exercised.  Are there versions
 of the 10811 that don't have EFC guts inside?
 
 Hope I'm not boring you all to death.
 
 Chris
 w0ep
 
 
 
 On 11/9/2012 11:26 PM, WarrenS wrote:
 Chris
 
 HP 10811 can't drift that much that fast unless something is near broken, or 
 being connected wrong like gnds or PS voltage.
 Check the operation of the oven. 
 
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Re: [time-nuts] getting a grip on 10811 drift (trying to read my instruments)

[Neville Michie]

I have found a pic of the dry joint,
this one was just a dry joint with resin insulating the connection,
the other never had any solder applied.
cheers, Neville Michie






On 17/11/2012, at 11:09 AM, Chris Howard wrote:

 
 Maybe that is my problem.  I definitely have a problem.
 
 I am able to get the EFC to work on some occasions.
 Usually it will work if I run the trimmer all the way
 out and toggle the power.  I can then adjust the trimmer
 and get things working.  But if I give the box a rap
 the frequency jumps and I get into the mode of
 the EFC not working.  I can trimmer it up and it will
 look fine but no EFC.
 
 I will check out that ferule thing.  I'm not sure what you
 are describing but will look for it.
 
 Chris
 
 
 
 On 11/16/2012 5:53 PM, Neville Michie wrote:
 I have had two 10811 with EFC problems that turned out to be lack of 
 soldering of one internal joint.
 This is a large PTFE ferule with several leads including the varactor and 
 trimmer going into it. For many 
 years the leads all contacted but finally one lead developed an oxide film. 
 A soldering iron fixed them very quickly.
 The serial numbers were widely separated, so it was not an unlucky batch 
 problem.
 cheers, 
 Neville Michie
 
 
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Re: [time-nuts] Low power timekeeping

[Neville Michie]

Do not be so sure that a deep hole will give stable temperature.
I measured a nice sinusoid of about 0.3 *C over a year in a cave about 10 
metres below the surface.
The attenuation function depends on the thermal diffusivity of the soil/rock, 
but that does not vary widely.
As you go deeper you get a delayed history of the surface temperature. 
A good oven runs rings around deep earth stability.
cheers, 
Neville Michie



On 26/09/2012, at 3:32 PM, Tom Van Baak wrote:

 How good a clock could you get at much lower power?  I guess I'm looking for 
 something (logarithmically) between a watch and a GPSDO.
 
 This one keeps very good time long-term with no power: http://longnow.org/
 
 /tvb
 
 
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Re: [time-nuts] oscillators

[Neville Michie]

Does anyone know about what technology is used in Swiss watches to get much 
better performance from 
their xtals than you might expect?
I assumed that they had look up lists to insert extra counts to compensate for 
ambient variations,
but I have never heard any details.
cheers,
Neville Michie






On 30/08/2012, at 1:45 PM, Richard (Rick) Karlquist wrote:

 
 On 8/27/2012 11:45 PM, WB6BNQ wrote:
 
 
 A microprocessor controlled XO is a non oven crystal oscillator system that 
 has
 additional computational control providing a bit more than just mere passive
 temperature compensation.  The additional computational capability deals with
 having coefficients of that particular oscillator's behavior pre coded to
 compensate for the nonlinear behavior over a given temperature rang
 
 It doesn't use coefficients.  It has a look up table of frequency vs
 temperature.
 
 
 A microprocessor controlled XO system allows for using cheap crystals with
 minimum processing time and costs.  Because of limited storage space there 
 is no
 
 No it doesn't use a cheap crystal.  It uses a *special* SC cut crystal.
 This crystal could very easily cost more than an OCXO crystal.
 
 way for the system to have enough data to even try to compete with the 
 quality of
 a decent OCXO.  Beyond its initial calibration setup, it has no way of 
 keeping it
 tied to a known reference, like the Thunderbolt is doing.
 
 BillWB6BNQ
 
 An MCXO is a very good, but expensive TCXO.  Only temperature, not aging is 
 corrected.
 
 It has nothing to do with smart clocks.
 
 Rick Karlquist N6RK
 
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Re: [time-nuts] Thunderbolt mounting

[Neville Michie]

You have to go deep into the ground to get stability.
At 15 metres deep there is a lovely pure sine wave of about 0.3C P-P.
I measured it on the roof of a cave, its period one year.
My design for the bolt is to put it in a 1/4 inch thick aluminium box which 
is held at a constant temperature by a fan. Switching control is good enough as 
the 
thermal diffusivity of 1/4 inch aluminium will attenuate any spectral 
components shorter than 
a minute. The aluminium box is so conductive that the box is isothermal, so 
once the bolt 
has established its internal temperature gradients, nothing changes.
cheers, 
Neville Michie
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Re: [time-nuts] Leap second? Yay or nay?

[Neville Michie]

I think a small poke at the system, like inserting a leap second, would save 
lives.
If a system has degraded to a house of cards, the sooner someone pokes it the 
better.
It may also point to those responsible who are not handling their responsibilty 
of providing 
bullet proof code. If you can not make a system reliable enough to insert a 
leap second 
it probably cannot handle any other unexpected insult, and that may have far 
worse consequences. 

Just my 2p worth,
Neville Michie
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Re: [time-nuts] Sidereal time

[Neville Michie]

It started with trying to run two long case regulators on one brick wall. 
Although the wall is founded on bedrock they interfere with each other.
As I want to study their performance I tuned one to sidereal time, now they are 
independent.
I run a TBOLT and a LPRO to maintain a mean time clock for the clock analysis.
I am hoping to get a chip from TVB to divide the TBOLT or rubidium 10MHz down 
to PPS at sidereal rate to observe the 
performance of the sidereal regulator. Now I want to be able to set the 
sidereal time standard so, if I lose power on my 
rubidium, I can reset it so the longterm record of the sidereal long case will 
have no phase jumps.
Also it seemed like a good idea, and the more it seems difficult, the more it 
needs to be done.
cheers, 
Neville Michie




On 16/06/2012, at 5:51 PM, Ken Duffill wrote:

 Hi,
 
 First of all why would you want Sidereal Time to that level of precision?
 
 I know this is the time-nuts so 'because I can' is a perfectly acceptable 
 answer.
 
 These days Sidereal Time is only used to display to humans in a recognizable 
 format an old and outdated approximation to the current ITRF - ICRF 
 transformations that the professionals would use to find or track a celestial 
 object.
 
 See IERS (http://www.iers.org/IERS/EN/DataProducts/data.html) and SOFA 
 (http://www.iausofa.org/index.html) for the details and sample code in 
 FORTRAN and 'C' for these transformations.
 
 I suspect if you want microsecond accuracy you will have to use the SOFA 
 routines, and have access to the IERS EOP Data.
 
 Cheers
 
 Ken
 
 On 16/06/12 07:20, Chris Albertson wrote:
 On Fri, Jun 15, 2012 at 9:49 PM, Mark Simshol...@hotmail.com  wrote:
 
 Lady Heather can do sidereal time.   Specify either the LMST, LAST, GMST
 or GAST time zone (for Local/Greenwich Mean/Apparent Sidereal Time).
 
 I think the question was how to get Sidereal time to the microsecond level.
  A computer display screen only gets refreshed roughly 60 to 100 times per
 second so a screen can be tens of milliseconds off.
 
 How is this done professionally.   Basically they don't.  What you do is
 record a UTC time code on a track parallel to the data.  Or now that
 everything is digital, the time code is sampled and multiplexed with the
 data.   Later the display software can convert the time to whatever format
 is desired.
 
 
 
 
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[time-nuts] Sidereal time

[Neville Michie]

I have been trying to set up a clock on sidereal time. 
My only source of a time calculator is  tycho.usno.navy.mil,
but this seems to be off the air for the last week or more.
Is there any other source of sidereal time?
The basic method needs a current almanac and I can not even find a source of 
one of those.
How you would find ST to a microsecond is not obvious. How do radio astronomers 
do it?
cheers, 
Neville Michie
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Re: [time-nuts] Sidereal seconds

[Neville Michie]

The theodolite is not a problem, I use a distant street lamp (4Km  
away) as a referred object (RO) to set azimuth,
and with the usual levelling it takes moments to set the co-ordinates  
of a chosen star.
The RO is observed by one of several methods to get a good azimuth.  
It is chosen to be visible by day or night.
Then I listen to the clock ticks and watch the star cross the  
graticule. The star co-ordinates are from an ephemeris.

You can repeat with the same star or others at later times.
I have not looked at the sidereal time on Lady Heather yet, I was  
unaware of it.


cheers, Neville Michie

On 02/03/2012, at 10:14 PM, mike cook wrote:


Le 02/03/2012 05:13, Neville Michie a écrit :


A possible solution is to take mean time (from a TBolt 10MHz) and  
divide it by 9,972,695.7 to give a PPS(sid) signal that can run a  
digital clock dial and give one second(sid) ticks to phase the  
pendulum. It may be simpler to divide by 9,972,696 to stay with  
integer division and have an error in the order of a second per  
annum. (which we have from leap seconds anyway).
TVB made some picDIV chips with a synch pin that do a similar  
task, but have I got the number correct?

  number looks ok , at least according to the usual sources.
and are there other nuts that would like to add a sidereal clock  
to their clock vaults to make it worth while to make such a chip?
Yup, I guess that would be a useful extension to the code.  You  
would just need to change the delays to fit a 2493174 instruction  
count for a 10MHz input.
If I set up the sidereal clock then I can use my theodolite to  
check time against the stars.
More of a challenge I think. Harrison is reported to have used  
occultation by buildings from a known observation point. It would  
be probably be easier than keeping a theodolite precisely  
orientated over long periods of time.

cheers,
Neville Michie
Sydney
Australia

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[time-nuts] Sidereal seconds

[Neville Michie]

I have a problem with two pendulum clocks that interfere with each  
other, even though they are bolted to a brick wall on bedrock  
foundations.
A solution to this problem is to run one on mean time the other on  
sidereal time. Then I can analyse the operation of each of them.
Now there is a problem with sidereal time that neither the GPS system  
or WWV transmit reference signals for sidereal time and the
method of converting mean time to sidereal by calculation is  
difficult for clock synchronisation.
A possible solution is to take mean time (from a TBolt 10MHz) and  
divide it by 9,972,695.7 to give a PPS(sid) signal that can run a  
digital clock dial
and give one second(sid) ticks to phase the pendulum. It may be  
simpler to divide by 9,972,696 to stay with integer division and have  
an error in the

order of a second per annum. (which we have from leap seconds anyway).
TVB made some picDIV chips with a synch pin that do a similar task,  
but have I got the number correct? and are there other nuts that would
like to add a sidereal clock to their clock vaults to make it worth  
while to make such a chip?
If I set up the sidereal clock then I can use my theodolite to check  
time against the stars.

cheers,
Neville Michie
Sydney
Australia

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Re: [time-nuts] Morion MV89A Repair

[Neville Michie]

Hi,
I have two of Morion MV89A, one is prominently marked (RoHS 5).
I assume that means lead-less solder. Pure tin solder is much more  
prone to

crystallised joints which break later.
Are these the dodgy units ?


cheers, Neville Michie





On 26/02/2012, at 11:02 AM, John Miles wrote:




-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-
boun...@febo.com] On Behalf Of Bob Camp
Sent: Saturday, February 25, 2012 2:55 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Morion MV89A Repair

Hi

The spectrum you show in the middle is the correct one. It shows  
the 10

MHz
output and the sub-harmonics related to the 5 MHz crystal  
oscillator. The
other two are a bit broken. One appears to have a stage  
oscillating. The
other is more interesting. It has a stage oscillating that is  
injection

locked to
the 5 MHz crystal oscillator. I suspect more than one capacitor  
went bad

in
these OCXO's. Somebody may have sold Morion a bad reel of bypass  
caps.


Bob


Interesting.  The MV89As are very stable, but they have a lot of AM  
noise
and they don't meet their PN specs (about -150 dBc/Hz at 10 kHz  
rather than

-155).  I've tested a few and they all look the same in that respect.
Sounds like replacing all of the SMT caps may be a good move.

-- john


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Re: [time-nuts] nanoseconds in the news

[Neville Michie]

Obviously no one is thinking big enough.
A hyper-super computer on either side of the Atlantic could run a model
of each of the stock markets which could be synchronised by frequent  
data transfer.
The learning power of these models would be very great, and they  
could deliver a real-time
estimate of the other markets that would be hundreds of milliseconds  
better that neutrinos.
The long term veracity of these computers could not be doubted, the  
noise in short terms

would be continually reduced.
A system like GPS could be used to synchronise them so they could  
give nanosecond response.



Would that not be great for huge spikes!

cheers,
Neville Michie

On 17/02/2012, at 9:07 AM, Peter Monta wrote:


Time is money...


I wonder if long-distance neutrino links might be attractive to the
financial community.  The SNRs are currently way too low, but with
aggressive engineering, a link through the Earth would shave off many,
many milliseconds (even at not greater than the speed of light :-) ).
The cost would be very high though.

Cheers,
Peter

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Re: [time-nuts] science projects

[Neville Michie]

Do not be misled by the conventional theory that scientists develop a  
theory

and then do an experiment to prove it.
This theory was dreamed up by some vertical thinker who was incapable
of any scientific progress. It has been reinforced by commentators who
reconstruct the path of discovery after the event, omitting any  
unsuccessful
workers or work from the process as being non-contributors to the  
discovery.
As one who has spent his career in (non-worldshattering) research,  
new science

comes from several directions.
First is just plain hard work, exploring every aspect of anything  
anywhere in an area.
This involves doing the experiment first and developing a theory that  
fits the results.

Then you do another experiment to test the theory.
One of the signs that you look for is some discrepancy in the  
conventional model.

Some experimental result that smells suspicious.
You never know what you might find and what it might mean or be  
useful for.

Directed research is not research but engineering.
Next is when the time has come for an idea. When the time has come,  
it will not

be long before some one tries the combination that leads to discovery.
Equipment and technology is a driver. Forty years ago my research chief
suggested that these new lasers may be useful so we should buy one.
That lead to several steps forward and more than one commercial  
instrument.

Research can be driven by looking for what we do not know. This is
looking for a question that has an uncertain answer.
But research is definitely not developing a hypothesis and then  
proving it.
This must surely have held back progress enormously as bright new  
students get
discouraged by the impossible idea of developing hypothesis about  
something

that has not yet even been thought about.
Maxwell did not hypothesise about radio waves. He just followed his  
genius nose
developing one mathematical expression from another. In this case the  
time had not come,

it took four other scientists years to discover what he had done.
cheers,
Neville Michie

On 10/02/2012, at 3:23 AM, Chris Albertson wrote:


I think it's odd that all these science projects are NOT doing any
science.   They sound like engineering to me.

So you build a neat mouse trap?  That is not science unless you have a
theory about mouse behavior and your trap is intended to test the
theory.Around here we do have these projects but we call them
engineering and they are judged by engineers.


Chris Albertson
Redondo Beach, California

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Re: [time-nuts] telling time without a clock

[Neville Michie]

Surely the proximity of the Moon to the surface of the Earth
makes the timing of an occultation dependent on where you are on the  
Earth's surface. (Parallax error)
The calculations to correct for this must make it a mathematicians  
picnic.
Nevil Maskelyne, tormentor of John Harrison, advocated lunar  
distances but it was not practical,

as is demonstrated by it never being used.

Telling the time on the Earth's surface was commonly done with a sun  
dial, and these can be refined to a fraction
of a minute. With about 30 years of observations this should be able  
to discipline an atomic clock to a second or better,

and reach the limit of stability of the atomic clock.


cheers, Neville Michie


On 29/01/2012, at 3:46 AM, aartmol...@comcast.net wrote:

The star catalog specifically designed for lunar occultations is  
the XZ (I'm guessing it stands for eXtended Zodiacal) Catalog from  
the US Naval Observatory. It's based on the earlier ZC and covers  
the band of brighter stars that can be occulted by the moon. Simbad  
should have these catalogs.



Aart Olsen

- Original Message -
From: Chris Albertson albertson.ch...@gmail.com
To: j...@quikus.com, Discussion of precise time and frequency  
measurement time-nuts@febo.com

Sent: Thursday, January 26, 2012 10:42:00 PM
Subject: Re: [time-nuts] telling time without a clock

simbad is a catalog of catalogs with a built in web based search
engine. It is pretty much what everyone uses to search. You can
define a shape and ask for all objects that meet some criteria that
are within that shape. Other software can plot the result for you as
a chart If it is not in Simbad you have likely discovered something
new.


http://simbad.u-strasbg.fr/simbad/
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Re: [time-nuts] establishing your position w/o gps

[Neville Michie]

Finding your location without GPS is not all that difficult.
You need a quality theodolite, but even an ordinary one will read to  
1 second of arc.
You observe circumpolar stars at night to obtain a true azimuth.  
(North and South)

and also the latitude by the inclination of the pole.
On a time photograph these stars draw circles around the pole, the  
centre of the circle
is the celestial pole and its elevation above the horizon gives the  
latitude.
You can also use an almanac and a calendar to determine your latitude  
by observing stars

with the theodolite.
You observe the sun at noon to find the local time and set your local  
clock. You then
wait for an event like an eclipse of a planets moons to establish the  
relationship

between your local time and the time at a known site.
A theodolite has a telescope that can be plunged i.e. used upside  
down and this
technique is used to get a very accurate level from a striding level.  
No pool of mercury

is needed.
The setting up of a theodolite uses sitings  and reversed sitings to  
set the vertical level.
The main error is the atmospheric refraction which scatters  
individual observations,
so many repeated observations are needed. The local time observations  
need to be

repeated for good accuracy.
A sextant is a less accurate instrument that has the main redeeming  
feature that when
reading it you superimpose the image of a star or the sun with the  
image of the horizon.
Although the image seen may be rolling around, the position of the  
sun on the horizon
is rock steady and is adjusted by the thimble for coincidence. The  
elevation is then
read off the vernier. A theodolite needs a solid base to work from  
and would be useless

on a ship.
cheers,
Neville Michie





On 25/01/2012, at 12:52 PM, Jim Lux wrote:


On 1/24/12 3:19 PM, J. Forster wrote:
Is the USNO almana/ephemeris still published in hard copy every  
year? That

had moon timing, etc.



You can download pieces from the Astronomical Applications website  
at USNO.


Or you can buy a copy of the Nautical Almanac for about $20 from a  
variety of sources.  You could also download the pdf (but printing  
it would cost you more than the $20)..


Amazon has it, for instance.

http://www.usno.navy.mil/USNO/astronomical-applications/ 
publications/naut-almanac


will find it, but the GPO version is more expensive than the  
commercial versions..



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Re: [time-nuts] establishing your position w/o gps

[Neville Michie]

On 26/01/2012, at 2:49 AM, J. Forster wrote:


Finding your location without GPS is not all that difficult.
You need a quality theodolite, but even an ordinary one will read to
1 second of arc.


Ordinary? You mean something like a Wild T-2 or Kern DKM-2. Even then
getting close to 1 arc-second requires a lot of care.


A wild T1 reads directly to 6 seconds, but with repetition will get 1  
second.
Unlike digital instruments you need a little bit of skill and  
persistence to get the best measurement from an analogue instrument.




You observe circumpolar stars at night to obtain a true azimuth.
(North and South)
and also the latitude by the inclination of the pole.


Not quite so straight forward. You have to have accurate siderial  
time and

an almanac. Polaris is only near the pole, not at it.


No need for time, you follow the azimuth of the star until it turns  
around and then again until it turns back. Half the difference gives you
the azimuth of the pole very accurately. Fit your observations to a  
parabola to get a good result.
Works best in Winter when the sun is down for more than 12 hours. A  
good technique as refraction errors cancel.





On a time photograph these stars draw circles around the pole, the
centre of the circle
is the celestial pole and its elevation above the horizon gives the
latitude.
You can also use an almanac and a calendar to determine your latitude
by observing stars
with the theodolite.


Not so easy. At the celestial equator the stars are moving in Hour  
Angle

at 15 arc-seconds per second.



As I said, analogue measurements need some skill and perseverance.
If you added more modern technology you could track your theodolite/ 
telescope with a clock so you would get a longer period to adjust/ 
observe

the observations and set your clock.

Neville


-John

==


You observe the sun at noon to find the local time and set your local
clock. You then
wait for an event like an eclipse of a planets moons to establish the
relationship
between your local time and the time at a known site.
A theodolite has a telescope that can be plunged i.e. used upside
down and this
technique is used to get a very accurate level from a striding level.
No pool of mercury
is needed.
The setting up of a theodolite uses sitings  and reversed sitings to
set the vertical level.
The main error is the atmospheric refraction which scatters
individual observations,
so many repeated observations are needed. The local time observations
need to be
repeated for good accuracy.
A sextant is a less accurate instrument that has the main redeeming
feature that when
reading it you superimpose the image of a star or the sun with the
image of the horizon.
Although the image seen may be rolling around, the position of the
sun on the horizon
is rock steady and is adjusted by the thimble for coincidence. The
elevation is then
read off the vernier. A theodolite needs a solid base to work from
and would be useless
on a ship.
cheers,
Neville Michie





On 25/01/2012, at 12:52 PM, Jim Lux wrote:


On 1/24/12 3:19 PM, J. Forster wrote:

Is the USNO almana/ephemeris still published in hard copy every
year? That
had moon timing, etc.



You can download pieces from the Astronomical Applications website
at USNO.

Or you can buy a copy of the Nautical Almanac for about $20 from a
variety of sources.  You could also download the pdf (but printing
it would cost you more than the $20)..

Amazon has it, for instance.

http://www.usno.navy.mil/USNO/astronomical-applications/
publications/naut-almanac

will find it, but the GPO version is more expensive than the
commercial versions..


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Re: [time-nuts] finding time astronomically.

[Neville Michie]

For those unfamiliar with horology,  look at the Wikipedia under  
equation of time
This is the relationship between solar time and the average or mean  
time.
It is mainly the sum of two sine functions, one of 6 months frequency  
the other

one year. Amplitude 16 - 17 minutes.
This function allows a mean time clock to show the time of noon each  
day (passage of the Sun

through the meridian)
cheers,
Neville Michie





On 24/01/2012, at 3:59 PM, J. Forster wrote:


At the solstices, the derivative of the declination goes through just
about to zero, just like a sine wave.

-John

==



It might be useful to determine the rate of the sun's movement at
the ends of the analemma.

There is a passage grave north of Dublin, Ireland, that has a long
passage from a shadow box above the entrance to a spiral carving on
the rear wall. Light shines on the carving at the winter solstice.

The waiting list to see this event fills up with New Agers about a
year before the event. I asked our guide if that wasn't very hard
on people who could only see the event on one day if that day was
cloudy. Oh, no, she said. The event happens for 3-4 days on
either side of the solstice.

Of course, a passage grave is not the same as a shadow cast by a
fine wire on a microscope. It might take a few years to locate it
properly.

Are there any timenuts that want to be buried in a passage grave?

Bill Hawkins


-Original Message-
From: Chris Albertson
Sent: Monday, January 23, 2012 8:40 PM

On Mon, Jan 23, 2012 at 6:07 PM, J. Forster j...@quikus.com wrote:

I think you'd want a slit, not a pin hole.  The pin hole would be
better but it would only work one day a year.


Actually two days per year, unless it was adjusted for the summer or
winter solstice, then it'd be one.


I still think it is one.  because there are not an integer  
number of
days per year so you don't get and exact repeat in 6 months.
Maybe a

pin hole would only work once ever?  I don't know.  To work the
pinhole has to exactly line up with the detector at the exact same
time of day.

But I'm not liking slits either because I can't see how to adjust  
them

to exact vertical.

I'm back to the first thing I thought of,  a wire with a large  
weight.

 Then you measure the light curve as shadow of the wire sweeps over
the detector.



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Re: [time-nuts] Thermal insulation choice?

[Neville Michie]

Insulation of an object to reduce heat transfer has three main  
components.
Convection, the movement of air which carries heat from place to  
place, this is easily reduced by
small cell (less than 5mm) structures, below this size thermal  
convective circulation does not occur.
Conduction, this is reduced by making the cross-section of any solid  
material very small, the length great

and by choosing a low conductivity material.
Thermal Radiation is very significant, and as many materials are  
transparent to long wave (10 micron)
radiation it is important to design for it. A low emmissivity (very  
shiny) surface reduces radiative transfer,
but shiny surfaces usually tarnish with time. A non transparent  
barrier, like metal foil, will stop radiation,
but the foil will heat up and re-radiate. If you have a setup with  
two parallel metal plates, a certain
amount of heat is transferred which does not change with increasing  
distance. If you add an intermediate
plate, it will heat to half the temperature difference,and as each  
plate sees half the temperature difference
only half the heat is transmitted. So on to 10 layers where only one  
tenth of the heat is transmitted.
So if you want to use polymer foam, make it in thin layers with a  
very thin layer of foil between each layer.
Balsa wood sounds as if it could be good, because it will have  
distributed absorbers of radiation
throughout it, equivalent to many layers of foil, and its conduction  
is low because it is mainly air.
I wonder if TVB knows what the brown foam in 10811 is? Does it have a  
radiation absorbing powder in it?


cheers, Neville Michie


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Re: [time-nuts] FE-5680A Rb Questions

[Neville Michie]

Does the FE-5680A have a similar Rb cell to the LPRO-101?
If so do they have finite lamp life, (can you find the one you buy  
has little life left?)

Or by not reporting the status of the lamp no-one worries about it?
cheers,
Neville Michie

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Re: [time-nuts] metric / English

[Neville Michie]

I have small British lathe (Myford) with a 1/8 inch leadscrew, and a  
127 tooth gear is inconveniently large.
By examining the ratio of every gear for every thread required (with  
a simple basic program) I found

a solution within 50 parts per million for all metric threads.
The wierdest threads are not metric but imperial, 19 threads per inch?
Incidently the Whitworth threads, with included angle of 55 degrees  
and coarse pitch are ideal

for soft materials like Plexiglass (perspex, methyl methacrylate).
cheers,
Neville Michie


On 17/12/2011, at 5:48 AM, J. Forster wrote:


There is no error with the change gears. The ratio of inches to
centimeters is exactly 1:2.54 or 100:254 or 50:127. It is often  
done with
a train of 3 gear pairs to get the center-to-center shaft spacing  
right.


-John

=

Not that hard, actually. My 1984-vintage lathe has an inch lead  
screw, but
the quick-change box that drives the leadscrew will do all of the  
inch and

most metric threads directly. The few weird metric pitches are
accommodated by changing two gears on the input side of the QC box. I
suppose that at some very small level, there is some error in  
the metric
threads produced (and I've never bothered to calculate it for my  
lathe)

but
it's a VERY small error that has never been an issue for me.

73,

geo - n4ua

On Fri, Dec 16, 2011 at 11:48 AM, Brooke Clarke bro...@pacific.net
wrote:


Hi Don:

Sure converting lengths is easy and I have metric, English and weird
taps
and dies, but how do you turn metric threads?

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.**end2partygovernment.com/ 
**Brooke4Congress.htmlhttp://www.end2partygovernment.com/ 
Brooke4Congress.html



Don Couch wrote:

The idea that conversion to metric would require replacing all  
of the
machine tools (lathes, mills, etc) is a myth. Any U.S. machine  
shop has

walls and toolboxes covered in conversion charts, converting drill,
screw,
wire, sheet sizes from one crazy measurement to another. One single
additonal conversion chart, inch to metric, and you can keep  
using your

inch machines on metric projects.

My mill has inch lead screws. I added a low cost digital readout  
with a

little button to show inch or millimeter movements, and now I do
everything
in metric. No problem.

Don Couch

--- On Thu, 12/15/11, Dan
Kemppainendan@irtelemetrics.**comd...@irtelemetrics.com
 wrote:

 From: Dan Kemppainendan@irtelemetrics.**com  
d...@irtelemetrics.com

Subject: Re: [time-nuts] time-nuts Digest, Vol 89, Issue 51
To: time-nuts@febo.com
Date: Thursday, December 15, 2011, 10:29 AM

On 12/14/2011 3:59 PM, time-nuts-requ...@febo.com
wrote:


It's not like metric is totally absent.  We drink


2 liter cokes and defend


ourselves with 9mm pistols.   Our cars


use mostly metric parts.  Even ham


radio operators, arguably the most jingoistic and set


in the past bunch


around, get on the 80, 40, and 20 METER bands.


I agree with you, and funnily enough the rest of the NATO
world uses 7.62mm and 5.56mm rifles. (Both were originally
based on standard inch sized rifle cartridges designed in
the US)

The problem in converting to metric would require replacing
a lot of tools. For example Mills, lathes, and other
machining tools and measurement devices are expensive, and
last for decades. I doubt many of the small tool shops
around here could afford it.It's a great idea to standardize
in theory, but in practice it becomes difficult. Maybe the
whole world should standardize our language. We could all
switch to Spanish or Latin or Chinese to speak with so we
could all talk with each other. That would probably be more
helpful to me on a daily basis, than having to switch
measurement systems.

While we're on the subject, let me throw time back into the
mix. We use months and days for scheduling projects.
Meanwhile some of our counterparts use calendar weeks. This
is much more difficult to convert between than inch and mm.
When is CW 36???

There I threw some wood on the fire too!

Dan

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[time-nuts] Solstice Puzzle

[Neville Michie]

At this time of the year many people look for frivolous puzzles to  
solve.

My puzzle is to design a clock.
This clock consists of 6 cubes, each has a digit display on one face.
It does not matter how you arrange them, if they are in a line they  
will display the
right time. (there may also be a nearby box containing a Rb or GPS  
time standard.)

A second or two may be needed for them to reorganise if they are moved.
It must be possible to design them, but an elegant design has eluded me.

Merry Solstice,
Neville Michie

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Re: [time-nuts] gravity controlled pendulumn clock?

[Neville Michie]

I find the biggest problem in units is when you want to solve a  
physics problem and need
data on typical physical properties of substances, for instance  
design of thermal insulation for an OCXO.
You can look through dozens of books with tables of typical values,  
most of which are in units
of BTU/square foot/inch/hour, and a bewildering mixture of other  
units, and are usually wrong!
Decimal points are slipped, or the values are reciprocals,  or the  
numbers have been lifted from a different

industry book that uses different units.
It is quite messy to have to measure these things from first principles.
At least with metric you can keep looking until you find 5 books that  
agree, you can see the value with
the slipped decimal, and then you may have values that may be  
reliable or at least stolen from the same source.

And you get your answer in Watts.
cheers,
Neville Michie

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Re: [time-nuts] synch for pendulum clock....

[Neville Michie]

There have been several (dont ask me for references) schemes for  
synchronising
observatory clocks. The problem was often complicated by the  
pendulums running in a vacuum or reduced pressure and thus being hard  
to adjust.
The type I remember best was a weak electromagnet under the bob that  
added or subtracted from the force of gravity
on the bob. The field was applied for several cycles until the  
observed error was corrected.

A PLL could use this to correct a pendulum.

cheers, Neville Michie



On 12/12/2011, at 8:32 AM, Brian, WA1ZMS wrote:

This was talked about several years ago, but did anyone get a fully  
functional design running using electromagnets to synch at one or  
both ends of the travel?


In the meantime I am using a sensor to measure the time period of  
the pendulum for this particular new grandmother wall clock and  
from that, I can synthesize a pulse train from one of the 10MHz lab  
clocks to drive the electromagnets to cause a subtle synch at the  
end(s) of the pendulum travel. The pulse train freq is custom for a  
given clock.


Anyway.. that's my scheme for now.
Feedback welcome.

-Brian, WA1ZMS
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Re: [time-nuts] Those pesky Neutrinos again...

[Neville Michie]

Has anyone thought about the fact that verticals converge towards the  
centre of the earth?

The surface distance is greater than the distance at a depth.
A map distance is made less, a few hundred metres underground.
Just another thought,
Cheers, Neville Michie

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Re: [time-nuts] Lady Heather

[Neville Michie]

Thanks John,
I should be able to sort it out now.

thanks,
Neville Michie


On 29/10/2011, at 7:57 PM, John Miles wrote:





-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-
boun...@febo.com] On Behalf Of Neville Michie
Sent: Friday, October 28, 2011 9:30 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Lady Heather

Hi, I have just been rather surprised to find Seattle co-ordinates
appearing in my Lady Heather window.
I, of course, eventually found that the latest version of John's
program is installed with a link to his TBolt.
My problem is how do you apply the /# command to look at particular
serial port# without having to open a DOS window
and write DOS commands? How do you set up shortcut icons on the
screen to activate a chosen implementation
of LH?
I seem to be able to manipulate the COM# numbers so that the USB to
Com converters find the right TBolt.
It is probably something very obvious that I am missing,
cheers,
Neville Michie


Right-click on your shortcut icon and edit the Target line to contain
whatever options you want to associate with that shortcut.

Oddly enough, I seem to have commented out the property dialog  
example on
http://www.ke5fx.com/heather/readme.htm for some reason...  it's  
back now,

just below the main screenshot (click to enlarge).

-- john


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[time-nuts] Lady Heather

[Neville Michie]

Hi, I have just been rather surprised to find Seattle co-ordinates  
appearing in my Lady Heather window.
I, of course, eventually found that the latest version of John's  
program is installed with a link to his TBolt.
My problem is how do you apply the /# command to look at particular  
serial port# without having to open a DOS window
and write DOS commands? How do you set up shortcut icons on the  
screen to activate a chosen implementation

of LH?
I seem to be able to manipulate the COM# numbers so that the USB to  
Com converters find the right TBolt.

It is probably something very obvious that I am missing,
cheers,
Neville Michie

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Re: [time-nuts] Speedy neutrino puzzle solved

[Neville Michie]

Now if tvb had loaded up his van with caesium clocks and driven back  
and forth between the two stations several times, then corrected for  
altitude/gravity effects, would he not have revealed the timing problem?

cheers,
Neville Michie


On 16/10/2011, at 8:46 AM, Jim Palfreyman wrote:

http://nbcu.mo2do.net/s/18488/29?itemId=tag:dvice.com, 
2011://3.83661fullPageURL=/archives/2011/10/speedy-neutrino.php


Comments please!
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Re: [time-nuts] the end of light bulbs as we know it was Re: Safe power-up. was (Solartron 7075 ...)

[Neville Michie]

Incandescent light bulbs are very useful.
They are a high dissipation resistor with a lot of uses.
I have one in series with a bathroom ceiling fan, just kept plugging  
smaller watt values in

until the fan was quiet enough but still fully functional.
I have one in series with a micro drill press, runs with full revs  
but stops when the drill jams.

It will be a pity to see them turn to unobtainium.
cheers,
Neville Michie






On 12/10/2011, at 9:05 AM, Mark Sims wrote:



I now have my house converted over completely to LED bulbs...  over  
300 of them (mostly PAR16/PAR20/PAR30/PAR38 bulbs)!   At retail the  
cost would have been over $15,000 dollars!!!   Totally insane...  I  
have a large closet totally dedicated to light bulbs.When  
incandecents/halogens are no longer made  I'll sell all the ones  
that I have removed and become stinkin' rich.


Then I found an Ebay seller that was selling used bulbs for dirt  
cheap (like $5 for a PAR20 and $10 for a PAR30...  actually less  
than the halogens cost).  They are apparently store/utility company  
returns (Bubba buys a replacement bulb and can't figure out how to  
install it so returns it to the store).  I was replacing a couple  
incandecent bulbs every week (many times they killed a $35 dimmer  
when they blew).  Only one of the LED bulbs has failed in the last  
year.


I did have to build 32 custom fixtures to replace the 900 lumen/50  
watt/12V halogen MR-16 bulbs.   The brightest MR-16 LED bulb  
available is around 300 lumens.


If you use PAR20 bulbs in your house check out:   http:// 
www.ebay.com/sch/new_life_electronics/m.html?_nkw=led_trkparms=65% 
253A15%257C66%253A1%257C39% 
253A1rt=nc_trksid=p3911.c0.m14.l1513_pgn=1
These are some of the best PAR20 bulbs out there and the lots of 10  
usually go for less than $60.  The exact same bulbs sell for $40  
each a Lowes.



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Re: [time-nuts] [Solved] Looking for multiple PPS timestamp logging

[Neville Michie]

That looks like a great solution for monitoring oscillators/GPSDOs.
Where to find an application that inputs RS232 and writes a file?

cheers,
Neville Michie



On 04/10/2011, at 6:54 AM, Tom Van Baak wrote:


Hal, Don,

I too have tried all the PC-based (serial/parallel port) solutions.
As we discussed at lot with the TEC thread, they work pretty
well. But for general use, or stand-alone operation, what I use
for dirt cheap non-nanosecond timing is a TBolt-10MHz-driven
isochronous microcontroller.


tvb came up with just the perfect solution:


Details here:

http://www.leapsecond.com/pic/picpet.htm

/tvb


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Re: [time-nuts] Fast than light neutrino

[Neville Michie]

I may be a bit naive,
but how would physically carrying several caesium clocks
back and forth compare to these fibre optic methods?
cheers,
Neville Michie

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Re: [time-nuts] HP 10811 Response I Replies

[Neville Michie]

Humidity is a confusing subject to many engineers and scientists.
Unlike most parameters it is a quantity with two input variables,
concentration and temperature. There are many ways to combine
these to give different units.
As a research scientist I spent most of my career working with
composite materials which exhibit great sensitivity to humidity.
Most composite materials respond to the Relative Humidity with
only a small temperature dependance. So 80% RH has the same
effect at any temperature. Note that the Absolute Humidity varies
exponentially with temperature.
For a fixed Absolute Humidity (say 10gms /m3) and at 70% RH the
relative humidity changes about 10% per degree celsius. So if you
have a sealed container with some water vapour in it the RH will vary
about 10% per C*.
If you have a fixed ambient humidity, a heated enclosure will have a
humidity that falls 10%/K as the temperature rises.
Now there are many grandiose environmental chambers sold to
scientists and engineers that perform poorly. They have internal
temperature gradients, so even if the concentration of water vapour
is uniform the distribution of relative humidity is not.
If a chamber set to 80% RH has a 2 degree gradient it could have  
internal

condensation.
The problems are made worse by the plethora of nearly useless humidity
probes made by manufacturers who are having a bidding war based on
claimed specs.
Since there are very few facilities to calibrate humidity sensors,  
and no
company can make a dollar by having their humidity measured more  
accurately,

there is no pressure to improve instrument quality and the situation
remains that there is a lot of misunderstanding about humidity.

The instruments I have built have an inaccuracy of less than 0.1% RH,
and I have built isothermal chambers that can be programmed to 0.1% RH.
They are based on calculable processes for calibration, and so have
absolute calibration.

In the case of quartz crystals in ovens, when the oven is 30K above  
ambient

the relative humidity is very low, so you would expect there to be very
little absorbed or adsorbed water to interfere with stability. The  
main effects are
surface leakage on hydrophilic surfaces and dielectric absorption in  
composite
material insulators. There is a second order effect that the  
dielectric constant
of air changes with absolute humidity. Humidity sensitivity would  
seem to me
to be a problem of the measurement system rather than the item being  
tested.


Cheers, Neville Michie





On 23/09/2011, at 9:07 AM, Rick Karlquist wrote:


Perry Sandeen wrote:

Wrote: Doing what you describe will result in a very sensitive  
humidity

sensor, having eliminated the thermometer effect.

I do not understand.  I believed that since the OCXO temperature  
will be
substationally higher than the surrounding temps, any residual  
moisture
would migrate to a lower temperature.  The fiberglass insulation  
inside


Heating up a space does not change the absolute humidity AFAIK.
It only changes the relative humidity.  We did tests where we
sealed a 10811 inside a box that was held together with so-called
hermetic epoxy.  We put it in an environmental chamber at a
constant temperature and constant low humidity and let it stabilize.
We then increased the humidity to something like 80%,
while holding the temperature constant.  Within
minutes the frequency changed more than the spec for the entire
temperature range.  Therefore, you should do your experiment with
the hermetic version of the 10811.  The hermetic version is soldered
shut, rather than using epoxy, which turns out not to be hermetic,
no matter what they claim.

Rick Karlquist


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Re: [time-nuts] From Sundials to Atomic Clocks

[Neville Michie]

Thanks Randall,
It downloaded from you OK,
I too could not get it directly  in Sydney.
cheers,
Neville Michie







On 09/09/2011, at 8:32 AM, Randall Prentice wrote:


Have uploaded a copy in NZ.

http://prento.homelinux.net/1796.pdf

Couldn't download off TelstraClear,  had to use Actrix links  (DNS  
didn't resolve properly).


Regards
Randall   ZL2RJP
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts- 
boun...@febo.com] On Behalf Of Ken , VK7KRJ

Sent: Friday, 9 September 2011 9:04 a.m.
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] From Sundials to Atomic Clocks

Is anyone else having trouble with this url?
I've been trying it since the email came through, it just times out  
waiting for a reply.
I did try to get to it from the parent site, with the same effect.  
No problem with the nist site direct, but no go with tf.nist


I have no trouble with .pdf's from anywhere else, but I can't find  
the file anywhere else.


On 2011-09-08 03:27, Mike Fahmie wrote:

On a visit to NIST Boulder (then known as NBS) many years ago (1978),
I was presented with a copy of NBS Monograph 155, From Sundials to
Atomic Clocks by one of the authors. I found it to be a fantastic
read, it answers all of those questions about Time  Frequency  
that you were afraid to ask.


I stumbled on it again today in PDF form on the NIST website, it has
undergone two revisions and this URL points to the most current  
(1999) edition.


http://tf.nist.gov/general/pdf/1796.pdf

-Mike-
WA6ZTY


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--
Cheers, Ken
vk7...@users.tasmanet.com.au
www.vk7krj.com

'It seems hard to sneak a look at God's cards. But that He plays  
dice and uses telepathic methods  is something that I cannot  
believe for a single

moment.' (Einstein's famous quote on Quantum theory)


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Re: [time-nuts] GPSDO for my rubber duckie

[Neville Michie]

Another possible solution is to use a Rubidium stabilised oscillator  
like a LPRO which has been set to your preferred frequency.
If my aged brain remembers my calculation correctly, it is spec'd to  
be accurate to one second in 30 years,

so you might have to correct your clock every decade or so.
cheers,
Neville Michie

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Re: [time-nuts] Rb cooling

[Neville Michie]

The manufacturers data sheet presents MTBF figures for the LPRO
and they decline considerably with higher temperatures.
Against that the power required decreases with rising temperature,
so that at 19 volt supply and 40-45*C the unit takes  much lower  
power and has

still has most of its expected life.
cheers,
Neville Michie

On 18/07/2011, at 1:59 PM, Chuck Harris wrote:


For all of this attention to cooling the oven on the Rb standards,
has anyone seen any failures that are attributable to heat?

I sort of doubt it.

-Chuck Harris

ewkeh...@aol.com wrote:
I monitor and fan cool the base plate, stays nice and constant at  
45 C
which I can not say with heat sink only. I am considering lowering  
the base
plate to 40 C. I have a heat sink on the base plate with the fan  
blowing over
it. Makes good heat exchanger. I have experimented with heat pipes  
from Lap
Tops  but never fit for mechanical reasons. May work with a  
LPRO's. Al my

Rb's are  Efratom.
A variable speed fan will reduce any ambient temperature  
influence. That is

  why I chose to use a fan.
Use a dual Op Amp for temp. control. Nothing special. Fans are $  
3.00 I
have monitored points inside the Rb's and they are within 1 C over  
time.

Bert Kehren


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Re: [time-nuts] 60 Hz measurement party

[Neville Michie]

In Australia, power is reticulated as three phases of 415V.
In suburban streets, 4 wires provide neutral and 240 Volts,
each house is supplied with  one, two or three phases as they need.
I had 3 phases installed as 2nd hand machinery with 3 phase motors was
cheaper than single phase items because  few homes have 3 phases.
cheers,
Neville Michie

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Re: [time-nuts] No more 60Hz, How do I discipline 120VAC 60Hz from a UPS

[Neville Michie]

An interesting question about making a 50/60 hertz source,
Does a 120 to 12 volt transformer have enough inductance to use as a  
12 to 120 volt transformer?
Remember, the inductance is proportional to the square of the no of  
turns, where as voltage is proportional.

cheers,
Neville Michie

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Re: [time-nuts] Bob Pease

[Neville Michie]

Mine did!

Sad to hear of his departure,

Neville Michie

On 21/06/2011, at 1:05 AM, Poul-Henning Kamp wrote:


In message 4dff5c52.4070...@erols.com, Chuck Harris writes:


One important thing to note is he wasn't wearing his seat belts.


Does a 1969 VW Beetle even have them ?


--  
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20

p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by  
incompetence.


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Re: [time-nuts] locate 6 digit digital clock

[Neville Michie]

TRY http://www.vk7krj.com/ham_stuff.htm

Neville



On 12/06/2011, at 6:58 AM, Ken , VK7KRJ wrote:


Aarghh- it's too early in the morning for thinking- here is the url!!

http://www.vk7krj.com/ham_stuff.html

On 2011-06-12 06:55, Ken , VK7KRJ wrote:
It's not up to time-nuts standard, but here is my gps clock I  
built some years ago. It
uses a Motorola Oncore board for the gps and I didn't bother with  
trying to compensate for
the delay my software causes. I did put in a routine to allow for  
daylight saving (curious
concept- a bit like cutting your head off and standing on it to  
make yourself taller!) but
the politicians keep messing with the dates, so it is an hour out  
for a while twice a year.
Next (electronics) project is the same thing, but with my newly  
acquired thunderbolt.


On 2011-06-12 03:25, Jason Rabel wrote:
Since people are showing off their clocks... I managed to get a  
Datum / Bancomm bc632D

display from eBay a while back and it's
pretty cool.


--
Cheers, Ken
vk7...@users.tasmanet.com.au
www.vk7krj.com

'It seems hard to sneak a look at God's cards. But that He plays  
dice and uses
telepathic methods  is something that I cannot believe for a  
single

moment.' (Einstein's famous quote on Quantum theory)
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Re: [time-nuts] Sidereal timekeeping

[Neville Michie]

I am quite aware of the fact that quartz clocks and watches drive
their movements directly from their supplies with tailored pulses.

What I said was that a 0.5 Hz square-wave from a logic source
will drive these movements if you select  appropriate values of
series capacitor and resistor.

Not everyone has acquired the training to use microprocessors,
which are becoming a blight on the electronics world by being a
cheap way of making insupportable and undocumented devices
that cannot be repaired or adjusted.

The engineering that is invested in these devices does nothing
to enhance the traditional step by step evolution that was a  
characteristic

of electronic technology. You cannot see a bright idea that another
has developed and take it one step further. You have a black box
and when it dies you will be none the wiser, so you will design your
own and make the same mistakes that were in the original.

cheers,
Neville Michie



On 19/05/2011, at 9:35 PM, Chuck Harris wrote:


An actual quartz analog wristwatch wouldn't do something so mundane as
to use a 50uf capacitor to drive the coils.  They do this:

DRIVER-A-COIL-+
..|
DRIVER-B--+


And feed the drivers with these waveforms:

1.5V..+-+.+-+.+-+..
..|.|.|.|.|.|..
A-+ +-+ +-+ +---...

1.5V..+-+.+-+.+-+..
..|.|.|.|.|.|..
B-+ +-+ +-+ +---...

Where the pulses alternately come from A and B every second.

If you use a PIC to drive the clock, the driver is easy to program  
in software.


-Chuck Harris

iov...@inwind.it wrote:
I understand now why most analog wristwatches do tick every two  
seconds when
the battery is low. I believed the logic used this trick to signal  
low battery.


Antonio I8IOV


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Re: [time-nuts] Sidereal timekeeping

[Neville Michie]

Analog quartz clocks may be used as slave clocks.
You do not even have to disconnect the quartz movement.
Just find the coil on the motor and drive it with a square-wave of  
0.5 hertz,

in series with a capacitor (about 50mfd) and a resistor (about 200 ohms)
Each type of clock is different, though they all are driven by  
something like 1.5 V

20ms alternate polarity pulses.
The actual values are not critical but must be determined for each  
type of clock.
If the capacitor resistor combination is wrong it will not work. Too  
much signal
will make motors pole and refuse to rotate. The capacitor charges  
when the
polarity changes and that current operates the clock. The resistor  
sets the length
of the pulse together with the capacitor value, as well as setting  
the maximum current.

Just swap values until the action is quiet, definite and reliable.
I have used this method on at least 4 different types of quartz  
clock, usually from a 5 volt

logic signal.
Cheers,
Neville Michie

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Re: [time-nuts] Sidereal timekeeping

[Neville Michie]

Antonio,
it is quite easy to make an external circuit that uses a 32kHz  xtal  
and divides
it down to siderial seconds. It is also easy to drive most analog  
quartz clock movements from

an external circuit.
Just what signal do you need? What frequency? and what does it drive?  
(an alternate polarity

quartz clock motor?)
It can also be done with a micro if you have the skills.
cheers, Neville Michie


On 16/05/2011, at 8:02 PM, iov...@inwind.it wrote:

The background of my request is an OT story. Just to mention  
briefly, I already
have an ordinary (non-radio-controlled) clock machine which turns a  
miniature
torsion balance in a sealed glass vessel. It runs on a single AA  
battery. No
extreme accuracy needed. I wont to modify the rate to sidereal, and  
might have
to replicate the setup too. I figure that the solution I should  
pursue is

getting the odd crystals.
Now it is clear to me that I have to explore two options, a)  
contacting a

crystal manufacturer, b) modifying 32768 crystals.
Thanks,
Antonio

hmur...@megapathdsl.net wrote:


does anybody out there have any ideas as where to find a 32859Hz  
crystal

(1/
2  that value would be better) to be used to replace 32768  
crystals in
ordinary  clocks? I think that 32768 crystals cannot be dragged  
that much.
I've already  read the JimLux article somewhere on the web, but I  
would be
pleased finding a  simpler solution. Also, I already have  
computer programs

that show sidereal  time.


I think it depends upon what you mean by ordinary clocks.

Most of the recent wall clocks I've seen are battery powered  
(single AA) and

resynchronize nightly via WWVB.

If you want sidereal time, you won't have anything to synchronize  
to.  What
sort of accuracy are you interested in?  If you want reasonable  
accuracy,

you
will need an external signal.  (You can provide power over the  
same cable.)


My straw man would be to send 32859Hz down coax or twisted pair  
and feed it
into the xtal-in pin on the clock chip.  I'm not sure how to set  
the time.
You can cut the lead to the antenna to make sure it doesn't sync  
to WWVB.


You can make 32859Hz from a PIC (or any micro you like) running  
off any

handy
frequency.  Given that this is time-nuts, I'd suggest 10 MHz from  
a GPSDO.


It might be simpler to dump the 32KHz and WWVB chip and drive the  
motor
directly from a 1 PPS signal.  Just use a sidereal second rather  
than a

normal second.





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Re: [time-nuts] Sidereal timekeeping

[Neville Michie]

Hi Antonio,
the 32kHz Xtals are 2mm long tuning forks (that is what I believe  
although I have not opened one).
You would have very little chance of modifying it and still have  
enough Q left for it to oscillate.
As an alternative you could build an external circuit (a few uA at 3V  
supply) and generate a signal to inject into

the existing Xtal osc with the Xtal removed.
The type of circuit that I would build would be a cmos binary divider  
connected to a quad gate.
The 4 gate inputs connect to selected binary stages of the divider.  
When the gate decodes the
selected number, an extra pulse is added to the count chain. The  
output is thus shifted to a higher

frequency.
If you are interested I can try to design the circuit for you, I have  
intend to build a Siderial clock

dial for my TBolt.
cheers, Neville Michie

On 17/05/2011, at 7:58 AM, iov...@inwind.it wrote:


Neville,
at present I have not enough skill with micros to solve the problem.
I think I will try modifying a crystal. This would not be that  
difficult using
a lapping sheet or the like. And opening the can would be quite  
easy using hot
air. This is the fastest way for me, and the device will continue  
to be powered
by a simple AA cell, which is a non negligible advantage in my  
application.

All the best,
Antonio I8IOV


Antonio,
it is quite easy to make an external circuit that uses a 32kHz  xtal
and divides
it down to siderial seconds. It is also easy to drive most analog
quartz clock movements from
an external circuit.
Just what signal do you need? What frequency? and what does it drive?
(an alternate polarity
quartz clock motor?)
It can also be done with a micro if you have the skills.
cheers, Neville Michie



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Re: [time-nuts] Tbolt LCD Monitor - No DAC reading

[Neville Michie]

Hi,
continuing the queries on LCD monitors on TBolts
The I.Fluke illustrations show a message of one, two or three
satellites only being visible. My monitors do not display this message,
is that because of the mode the TBolt is in?
I tried to find the list of display messages in the KO4BB listing of  
the software
for the monitor, but I am finding the relation of the message codes  
in the Thunderbolt

Manual to the software for the monitor very confusing.
I assume the TBolt only sends out some codes under particular  
conditions,

does the monitor software decode all possible message codes?
I have inserted the 3 silicon diodes into the 5V supply line to suit  
the micro.

I hope answers to my questions will help many other TBolt users.
Cheers,
Neville Michie


On 12/05/2011, at 4:40 PM, David Bobbett wrote:

Both myself and a few other time-nuts have had a problem with the  
LCD Tbolt monitor from /fluke.l/ in China not showing a value for  
the DAC voltage. The DAC voltage did appear correctly in Lady  
Heather and the tboltmon.exe program, but the LCD monitor would  
only show 0.. All other values would display on the LCD without  
a problem.


I have contacted fluke.l again and so far he has 1) suggested doing  
a factory reset of the Tbolt and 2) asked me to confirm that the  
data is there in the programs mentioned above.  Today he has asked  
me to send him a photo of the display, which I will do shortly.


I thought it would be useful if I let other 'sufferers' know what  
is happening, in case somebody has something to add to the  
information. Please feel free to contact me off list if you prefer.


David Bobbett, G4IRQ
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[time-nuts] Proton Precession Magnetometer

[Neville Michie]

Hi,
I am boxing up my LPRO rubidium source in a steel box. The device is  
to be thermostated
by controlling a small fan outside the box to keep the LPRO at about  
40*C.
Although the unit is in a mumetal box I assume there may be some  
penetration of earths magnetic field.

The steel box should help that.
To test this I want to build a very stable magnetometer. Now I know  
that all you need is a jar of water or kerosene
to give you protons, and a coil around the jar to kick the protons  
and then listen to them sing.
I have also been told that these instruments do not work in a  
laboratory, as the AC magnetic field

drives them crazy.
I am thinking of lock in amplifiers and phase locked loops.
Also toroidal coil or paired coils.
Can anyone in this group point me to an easy to construct and  
fiercely accurate design to build?


cheers, Neville Michie

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Re: [time-nuts] Result of Earth Quake speeds up earth?

[Neville Michie]

One simple calculation is the ratio of the total rotational energy of  
the planet (which is simple to calculate) to the energy release of  
the earthquake.
The magnitude of the earthquake probably has a relation to the total  
energy release. This must put an upper limit on the change of time.
Since the mass of the planet is conserved, we have the moment of the  
planet and its rotational energy as variables.
The radius of the planet may have changed, so we will eagerly wait to  
see the rate of change of the rotation rate.
It is also possible that the earthquake only caused a phase shift in  
the planets rotation, i.e. the rate of rotation stays the same but  
the time of sunrise has shifted slightly.

Maybe that someone who knows about these things will tell us more.
cheers,
Neville Michie


On 16/03/2011, at 12:29 AM, jimlux wrote:


On 3/15/11 6:20 AM, jimlux wrote:

On 3/15/11 1:49 AM, Chris H wrote:


I hear in the Media that the earth quake sped the rotation of the  
earth

up..
Can anyone confirm this?



No.. the magnitude of the change is parts in 1E11 or thereabouts.

Regular old tidal drag slowing is bigger, and that's what mostly
contributes to leap seconds.




Another, potentially easier to detect, effect is that the axis of  
rotation of the earth might have shifted.


An interesting question is whether earthquakes always lead to a  
speeding up... Off hand, I would think that the general tendency is  
for the gravitational forces to make the earth more smooth, which  
would probably mean that the moment of inertia decreases (speeding  
up the rotation). (that is, mountains fill ocean trenches in the  
long run).


On the other hand, rotational forces make the earth more oblate,  
which increases the moment of inertia.  I seem to recall that the  
inital predictions of oblateness were made by assuming that there's  
an equilibrium between gravitational forces pulling in and  
rotational forces pulling out.



And this doesn't even get into the fact that the earth is somewhat  
pear shaped: wider south of the equator than north. ( most  
certainly not a banana shape as reported by Sir Bedivere, but what  
would a medieval experimenter with swallows know anyway)


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Re: [time-nuts] Thunderbolt Supply

[Neville Michie]

One approach for the Tbolt is to use a low dropout low noise linear  
regulator (I used a LT1764 set to 11.5 volts) for the 12 volt input  
(it is within spec) and a 5V switcher (Recom R-785.0-1.0) for the 5v.  
For the minus 12v I used a ICL7662, these are rare, so a cmos gate  
oscillator and diode pump negative generator could be used. I am told  
the -12V is quite uncritical.
The whole lot runs across a 12V lead acid accumulator which delivers  
about 300mA to run it when the power fails. The battery is floated at  
14.0 volts with a linear regulator from a mains transformer power  
supply.
A 20 AH battery gives more than 2 days backup. As the 12Volt is the  
sensitive input, the linear regulator should keep the noise down. The  
whole setup is designed to use minimum power.

cheers, Neville Michie



On 11/02/2011, at 10:16 AM, Larry McDavid wrote:

Greetings! I am a new member of the mail list. I've been using a HP  
Z3801A GPS-steered standard but have just acquired a Trimble  
Thunderbolt GPS Disciplined Clock.


I'm seeking a recommendation for a power supply for this  
Thunderbolt receiver. There is much discussion about noise from  
some switching supplies and the effect on phase noise of the 10 MHz  
output. The Thunderbolt manual specifies the following supply and  
loads:


+12 vdc  750 mA
+ 5 vdc  400 mA
-12 vdc   10 mA

This combination is somewhat unusual in that the highest current is  
on the 12 volt output rather than the 5 volt output. I'm asking if  
list members have a favorite power supply for this unit, why and  
where I can obtain one.


--
Best wishes,

Larry McDavid W6FUB
Anaheim, CA  (20 miles southeast of Los Angeles, near Disneyland)

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Re: [time-nuts] Clock Calibration

[Neville Michie]

I have a little piezo sounder on the PPS from a t/bolt. It runs off a  
cmos gate, I can not remember whether I put some pulse stretching in,

but it needs an on/off switch or the ticking will drive you mad.
This is great to use with the UTC time on LH. You look at the time,  
then keep counting with the audible ticks to guide you while you  
check your analogue clocks.
I also have a BCD counter dividing the 10MHz from the T/Bolt that  
drives a time display. As well,  the milliseconds, 100 microseconds,  
or 10s of microseconds are counted and
can be latched by a proximity switch into a homebrew BCD DAC which is  
recorded by a HOBO logger to give very accurate logging of phase for  
whichever clock the proximity is clipped to.


It is all low power, saves serious frequency counters, PC et. al. so  
you can log continuously for years without a major power bill.

cheers, Neville Michie


On 30/01/2011, at 4:16 AM, scmcgr...@gmail.com wrote:

Ah now from time nuttery to horology. There are those of us who  
tinker with analog clocks as well...


Generally we 'beat' clocks against 'standard' clocks or more  
recently a pc application with a microphone over long periods of  
time generally at least a week and commonly a month.


Scott
Sent from my Verizon Wireless BlackBerry

-Original Message-
From: Chris Albertson albertson.ch...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Thu, 27 Jan 2011 15:52:49
To: Discussion of precise time and frequency measurementtime- 
n...@febo.com

Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Clock Calibration

On Thu, Jan 27, 2011 at 12:55 PM, Perry Sandeen  
sandee...@yahoo.com wrote:


...how the heck they were able to calibrate a clock to  
milliseconds per day back then?


Let it run for 1,000 days, then you only need to be able to measure to
the nearest second to get to ms per day.  Or maybe you can measure to
0.1 seconds so it only takes 100 days.

The trouble is that using this method you don't know the average
error.  A good example is an eccentric gear that makes a second hand
run fast then slow but if averaged over a long period is near perfect.
 I doubt they were able to catch stuff like that.


--
=
Chris Albertson
Redondo Beach, California

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Re: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit

[Neville Michie]

Rubidium cells with a side arm run the side arm at a lower temperature.
Then the excess rubidium condenses in the side arm.
The vapour pressure in the cell then becomes that vapour pressure that
exists over the solid rubidium in the side arm. If the pressure  
rises, more will deposit in the side arm.
If some is lost/absorbed by walls, then some of the solid sublimes to  
make a more vapour.
By controlling the temperature of the side arm you control the  
pressure in the lamp.
Side arm temperature may be just due to design, i.e. half way between  
the heated cell

and the circuit board temperature.
I have only played with an LPRO which has no side arm and so no  
reserve rubidium.
It has only just enough to make the desired pressure. I think the  
cells with side arms are neat,
you should never run out of gas, and there is always the possibility  
if elevating/depressing

the pressure by by changing the side arm temperature.
cheers, Neville Michie

On 20/01/2011, at 6:55 AM, Magnus Danielson wrote:


On 01/19/2011 06:44 PM, Poul-Henning Kamp wrote:
In messagedbb70463b9d04f6589fbf97b2e4be...@vectron.com, Bob  
Camp writes:



Conventional gas cells have a finite lifetime on the
lamp.


It used to be that Rb's would fail lock because the bulb dimmed  
from Rb
absorption into the glass, but I think they got that fixed with a  
teflon

coating.

Thes days most of them ultimately fail from the high operating  
temperature,

through a variety of mechanisms.

For the CSAC, my bet would be that the laser is the limiting factor.



I agree, for the CSAC I would expect that the laser would slowly  
dim, especially as it sits within the oven. Not optimum to keep the  
junction temperature down.


For my older Rubidium, the Rubidium lamp had splattered the  
Rubidium. When I heated it the first time I did get a dimmed glass,  
but heating it again orienting it properly (so hot gas rising into  
the back where I wanted it) I resolved the problem... within  
minutes. So I really wonder if it absorbs into the glass.


Exactly why splattered rubidium cause a problem for the rubidium  
lamp I am not 100% sure about, but my guess is that maybe it will  
expose too large area and thus causing too large gas-pressure to  
let the RF-field light up the gas. If someone who actually know  
could explain it, I would be happy to learn.


Cheers,
Magnus

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Re: [time-nuts] Completely OT: Removing electrolytics of leaking capacitors from a pcb

[Neville Michie]

Acetic acid is volatile, that is why it is smelly. White spirit  
vinegar is fairly pure,
while other types of vinegar have flavourings,  sugars, salt and  
residues.


That is good, because when you have finished cleaning up
the final traces will evaporate into the air.
Most other acids are non-volatile and the traces remain forever.
That is not true for hydrochloric acid, which is volatile but it is  
very corrosive

and will cause any iron in the room to rust.
Ammonia is a volatile alkali, good for neutralising acids to soluble
salts, and it is volatile so traces after clean up evaporate.

cheers, Neville Michie

On 20/01/2011, at 12:37 PM, Philip Pemberton wrote:


On 19/01/11 14:57, Poul-Henning Kamp wrote:

Try a mild acid like citric (lemon-) or citric (vinegar).


Vinegar would be acetic acid, the same stuff that's used in  
photographic stop bath (although there are some 'non-smelly'  
variants based on citric acid).


/pedantic-comment


--
Phil.
li...@philpem.me.uk
http://www.philpem.me.uk/

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Re: [time-nuts] CS reservoir depletion

[Neville Michie]

It may not be necessary to open a tube to renew the supply of an  
alkali metal.
I remember an experiment where an incandescent light bulb was dipped  
into molten sodium chloride in an iron vessel.
The filament was run and a voltage between the filament and the iron  
vessel caused sodium ions to migrate through the glass

into the bulb. Sodium accumulated in the bulb.
It is obviously a slow process, but then you did not need to put much  
Cs in the bulb.


Why not use it to recharge an alkali metal lamp?

cheers, Neville Michie



On 12/01/2011, at 11:06 AM, scmcgr...@gmail.com wrote:


Now that we are discussing how to restore Rb lamps.

 Has anyone given any thought to refilling or refluxing the Cs in  
depleted Cs tubes?


Obviously opening would require high vaccum equipment - which is a  
totally separate category of nut (Or is it?)


Scott

Scott
Sent from my Verizon Wireless BlackBerry

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Re: [time-nuts] CS reservoir depletion

[Neville Michie]

It sounds like you need to dip a corner of the device in liquid nitrogen
and allow the metal to evaporate and condense in the cold corner.
Or is it sublimation.
I do not know how long it would take.
cheers, Neville Michie




On 13/01/2011, at 11:31 PM, Chuck Harris wrote:

I suppose that would be possible if a C beam standard worked like a  
rubidium

reference, but alas, they are different in virtually all respects.

Think of the C beam as having a small kettle full of cesium that is  
put
on a low simmer.  The kettle keeps the cesium molten, and bubbling  
up minute

amounts of cesium vapor.

How are you going to refill the kettle when it lives in the middle of
a hard vacuum chamber?  The best you could do with your technique  
(assuming
it is even possible) is to coat the walls of the vacuum chamber  
with cesium...


Kind of like trying to fill the gas tank by hosing the car down  
with gasoline.


Besides, if HP can be believed, the kettle never runs out of cesium  
before
the receiving end of the tube gets completely choked on waste  
cesium metal.
That waste cesium needs to be removed, and the electron multiplier  
needs to
be restored, at a minimum and the ion pump is probably full up  
too.


-Chuck Harris

Neville Michie wrote:
It may not be necessary to open a tube to renew the supply of an  
alkali

metal.
I remember an experiment where an incandescent light bulb was dipped
into molten sodium chloride in an iron vessel.
The filament was run and a voltage between the filament and the iron
vessel caused sodium ions to migrate through the glass
into the bulb. Sodium accumulated in the bulb.
It is obviously a slow process, but then you did not need to put  
much Cs

in the bulb.

Why not use it to recharge an alkali metal lamp?

cheers, Neville Michie


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Re: [time-nuts] OT: Rustrak Strip Chart Recorder

[Neville Michie]

Hi Antonio,
The wheel that flicks the chopper bar seems to be a press fit.
The shaft is knurled (ridges have been formed) and the brass insert
in the wheel is pressed over the knurled shaft.
As the other end of the shaft protrudes from the gearbox it is simple to
press the wheel on, but very difficult to remove as there is nothing  
to pull on.


How many 50Hz motors do you need?

I converted several Rustraks to print-on-demand using a quartz clock
to reduce the motor power from 3W down to less than a milliwatt so they
could operate for a year on 4 D cells in remote places.

Since then I have been using off the shelf data loggers instead of  
the Rustraks.


cheers, Neville Michie

On 03/01/2011, at 7:14 AM, asma...@fc.up.pt wrote:


Hello!

I need to change the 60 Hz motors of my recorders for using
them here in Europe. I found a suitable replacement for
230 V/ 50 Hz but I need to re-use the original main drive
plastic wheel. It appears a bit hard to remove.
Since I am not very skilled in micro mechanics, I am afraid
of breaking something.
So that,the advice of someone knowing the inner works of the
above recorders on how to remove that wheel safely would be
most appreciated.

Best wishes for the New Year,
Antonio
CT1TE
CT1TE



Your


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Re: [time-nuts] Got 60HZ?

[Neville Michie]

My general solution to generating clock frequencies of any frequency  
is to
take a middle frequency from the divider chain (say 10kHz) and feed  
it into a PLL
chip with a divider (say 3 or 6 using a Johnson counter which resets)  
in the feedback loop.
This multiplies the VCO output by 3 (30kHz or 60kHz) which will then  
divide down to 60Hz
with very little phase noise. The only difficulty is the need for a  
reset that is synchronised

with the PPS signal. (use a D latch or two)

cheers, Neville Michie





Recently I bought a Efratom Ru frequency standard from eBay and a  
frequency
divider chip that makes 1MHZ,100KHZ,25KHZ,10KHZ,100HZ and a 1HZ  
output.
Today I thought of a way to make a nice 60HZ so you can use a  
mains-powered
clock for the display (using amplifier and transformer wired  
backwards).









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Re: [time-nuts] temperature stability basics

[Neville Michie]

Hi,
I have been looking at a similar problem. What I have found is:
many plastic foam materials have very low conduction but are  
transparent to long wavelength radiation, so thermal heating/cooling  
through them is mainly by thermal radiation.
If you wrap an item in plastic foam, then a radiation barrier like  
aluminium foil, then more plastic then more foil etc. you can  
seriously reduce the heat transfer.
Air is an excellent insulator if it is in cells too small to allow  
convection, (less than say 5mm). However light air filled materials  
transmit thermal radiation. The CFC gasses are used in some foams to  
partly absorb this radiation, but reflective foil is even better as  
it is shiny and emits less radiation in the first place.
The sandwich idea works like this; the amount of radiative transfer  
(in Watts) depends on the temperature difference of two layers of  
foil. The distance between the layers does not affect the quantity of  
energy radiated. So if a shiny box with one inch of air insulation  
around it  losses 8 watts by radiation to a surrounding box, then by  
putting a layer of foil in the middle you halve the temperature  
differences and so only have 4 watts of radiative transfer. Place 3  
layers of foil (with intermediate foam layers) and it drops to 2  
watts. Still in the same one inch space.
Find some closed cell polyethylene that is quite thin and some very  
light aluminium foil and you could make many layers. Just make sure  
that the foil is always normal to the thermal gradient.
The project is not finished yet but the thermal insulation is now  
going to be many times better than with just thick slabs of foam.

cheers,
Neville Michie



On 26/11/2010, at 6:24 PM, beale wrote:

In an attempt to educate myself about temperature stability, I put  
a temperature sensor in a 1 cube of brass wrapped in plastic  
packing-type bubble wrap, and compared that with another sensor  
outside the bubble wrap, with the whole combination in a thin nylon  
case just to slow down direct air drafts. I put it on the bench in  
the office where the ambient temperature varies up and down by a  
few degrees over the day. I recorded both temperatures with milli- 
degree resolution.


Looking at the resulting plots, it looks like my thermal mass and  
thermal insulation on the inside sensor gives me only about a  
half  hour lag at most relative to the outside sensor (hard to  
say exactly, it doesn't look like a simple one-pole filter). Note,  
I am not attempting any kind of ovenized control as yet, just  
measuring some time constants.


I've read that plain bubble wrap has an R value of about 2 ft^2·° 
F·h/(BTU·in), while some types of rigid foam building insulation go  
up to R=8 (at least until the CFC gases used to blow the foam leak  
out). What is done in real instruments that need good thermal  
insulation? I assume dewar flasks are limited to aerospace  
applications.


Photo of the block prior to bubble wrap:
http://picasaweb.google.com/bealevideo/2010_11_18TempExperiment

(live) plot of temperatures:
http://www.pachube.com/feeds/12988

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Re: [time-nuts] temperature stability basics

[Neville Michie]

Dont get the idea that radiation is only significant for large  
temperature differences.
For two parallel surfaces at any distance apart the black body  
radiation between them (around room temperature 300K) is near to 6  
watts per square metre per degree (C*) of temperature difference.  
That is an R rating of 0.14 in parallel  with the conduction through  
the insulation that is IR transparent.
The rate is proportional to the temperature difference. The fourth  
power law only becomes significant when the temperature difference is  
quite large.
If the surface is clean and polished the emmissivity of the surface  
can be significantly reduced, hence the silver lining in a dewar.  
With sheet materials, an oil film, corrosion and dust can rapidly  
increase the emmisivity. Gold is good because of its freedom from  
oxidation and discolouring and ease of flashing onto any surface.
If you make a sandwich with N layers of metal foil, the radiation  
transmission is reduced by 1/N.


Cheers, Neville Michie

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Re: [time-nuts] OT loosing things

[Neville Michie]

Not only losing things..
I have a problem with screw drivers changing sex.
There is never a cross-point screw driver when you find a cross-point  
screw,

just dozens of straight blade screwdrivers.
Next time, when it is a straight slot screw there are dozens of cross  
point

screw drivers but no straight blade screw drivers.

cheers,
Neville Michie

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