[time-nuts] Concrete basement moisture proofing

[Perry Sandeen via time-nuts]

Hi,
I have rehabed three houses that I have owned that have cement basements. All 
three were in Colorado.

Bare concrete will weep moisture.  The solution is to paint (actually spread) a 
product made by UGL.  It is $125 for a five gallon bucket.  It is a latex based 
product that seals the surface.

Any exterior concrete wall will suck out heat in the winter and needs to be 
insulated.

In the two housed with full basements I used 2 x 4 studs on 16 inch centers and 
filled the space with IIRC R 13 fiberglass insulation.  That was all that was 
practical at the time but still cold was conducted to the interior in the 
winter.

The third house we had in the mountains outside of Westcliffe, Co and had a 4 
foot stem wall.  About the upper third part of the shorter back wall was open 
to the elements.
I bought 4 x 8 foot panels of 2 inch foam that was covered on one side with 
aluminum foil at Home Depot.  They were about $25 a sheet.
I covered the stem wall on all sides with two layers of insulation as well as 
the rim joists.
Since we were at 9,000 ft moisture was not a problem.
Even though it was well below zero F much of the winter, the electronic 
thermometer probe on the floor which I monitored all winter stayed a 54F.
Now the fact that we had a 450 gallon water cistern in the crawl space probably 
helped to some extent as the crawl space was 30 x 40 ft.
If I was building a temperature controlled room with an exterior concrete wall 
I'd seal it with UGL and put a 4 inch layer of foam to stop exterior heat 
variations. 
When I had a work shop in TN, I stapled aluminium screening material from Home 
Depot to RF proof my exterior walls. If one chooses this method, an electric 
staple gun or better yet, an air driven staple gun makes it a relatively 
reasonable project.
Remember if one goes the old refrigerator route that  some states (CO, CA) for 
example have extremely strict requirements for the old refrigerant to be 
removed and tagged by  licensed  personal (or else...). Just FFT.
Regards,
Perrier



 
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Re: [time-nuts] disappearance of NIST UT1 time service

[Anders Wallin]

somewhat related: if someone has NTP service distributing TAI, that could
be useful for monitoring how the leap second is added to UTC-distributing
normal NTP servers come December 31st?
might have to set one up myself if there are none in Europe?

AW

On Thu, Oct 27, 2016 at 1:50 PM, Mike Cook  wrote:

> Hi,
>
>   Does anyone know what happened to the NIST UT1 time service managed by
> Dr. Judah Levine?
>
> I lost contact with the server ut1-time.colorado.edu on the 24th this
> month at 20:15 UTC and there has been no response to NTP requests  since.
> I mailed Judah to find out what happened but have not as yet got anything
> back.
>
> Regards,
> Mike
>
> "The power of accurate observation is commonly called cynicism by those
> who have not got it. »
> George Bernard Shaw
>
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Re: [time-nuts] Difference in manufacturing for fundamental tone, 3rd, and 5th overtone crystals

[Richard (Rick) Karlquist]

On 10/27/2016 4:50 PM, Bob Camp wrote:

Hi

Crystals are highly optimized for the specific overtone they are
intended to operate on. In fact, you can fiddle them to the point
that they no longer have a “fundamental” response.

Bob



That's interesting.  Every overtone crystal I have played with
would happily oscillate at the fundamental.  How do they
get rid of the fundamental?

Rick
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Re: [time-nuts] Temp/Humidity control systems

[Van Horn, David]

There is a wax which melts at 70F.  Phase change stores and releases a lot of 
heat.

Somewhat optimistic IMHO
https://www.wired.com/2015/05/table-sucks-heat-lower-ac-bills/

http://www.stacoolvest.com/news/

Technical:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4809117/
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Re: [time-nuts] Temp/Humidity control systems?

[Joe Leikhim]

I am in Florida and my garage gets quite warm and damp. I installed a 
window A/C unit and the results were mixed. It got cooler, but not 
necessarily dryer. And my utility bill suffered. So I built up a simple 
controller to control the 120VAC power to the A/C. It is a thermoplastic 
plastic electrical box containing a humidistat, a relay , low voltage 
transformer (doorbell type) and a mechanical timer.


I set the humidistat to ~ 55% where above that setting the relay turns 
on the A/C load. A mechanical timer allows me to force the A/C to run up 
to an hour if I am working in the garage and need cooling. The A/C is 
set to minimum temperature so it continues to control humidity even if 
the temperature is low. I have a provision to wire a magnetic reed 
switch to the garage door to turn off the A/C if the garage door is 
opened. I still need to run a wire and hook that up.


I am also remodeling an existing storage "shed" attached on the side of 
my house into a walk in closet and intend to replicate this same 
arrangement with a small wall mounted A/C to keep that space dry.


--
Joe Leikhim


Leikhim and Associates

Communications Consultants

Oviedo, Florida

jleik...@leikhim.com

407-982-0446

WWW.LEIKHIM.COM

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Re: [time-nuts] Temp/Humidity control systems?

[F. W. Bray]

Have you looked into wine cellar equipment?

They sell equipment that's designed to control temperature and humidity for 
custom built wine cellars that can be anything from an retrofitted insulated 
closet to a small room.  I think that they also sell prefab cellars to put into 
an existing space.

KE6CD

> On Oct 26, 2016, at 8:59 AM, John Ackermann N8UR  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] Difference in manufacturing for fundamental tone, 3rd, and 5th overtone crystals

[Bob Camp]

Hi

Indeed, there are processes for things like filter crystals that reduce the 
(very) near by responses. There are approaches for things like SC’s to
take out the somewhat further out “bothersome” stuff.

Bob

> On Oct 27, 2016, at 7:53 PM, Magnus Danielson  
> wrote:
> 
> Hi,
> 
> Hmm, such fiddeling could maybe also apply to nearby alternative modes of the 
> crystals, even if I guess it would be harder to do meaningful dents on them.
> 
> Cheers,
> Magnus
> 
> On 10/28/2016 01:50 AM, Bob Camp wrote:
>> Hi
>> 
>> Crystals are highly optimized for the specific overtone they are
>> intended to operate on. In fact, you can fiddle them to the point
>> that they no longer have a “fundamental” response.
>> 
>> Bob
>> 
>>> On Oct 27, 2016, at 6:42 PM, Attila Kinali  wrote:
>>> 
>>> Moin,
>>> 
>>> I have stumbled over another question I am unable to answer using the
>>> tools I have available: Is there any fundamental difference in manufacturing
>>> fundamental and overtone chrystals. Or to be more precise: is there an
>>> optimization process during manufacturing that makes a crystal more suited
>>> for one of the harmonics than for the others or all crystals similarly
>>> well suited to be used as an fundamental crystal as they are for the 3rd
>>> or 5th overtone?
>>> 
>>> 
>>> Attila Kinali
>>> --
>>> Malek's Law:
>>>   Any simple idea will be worded in the most complicated way.
>>> ___
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>> 
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Re: [time-nuts] Temp/Humidity control systems?

[David]

Years ago I had to deal with this and the instruments and sensors we
used matched well against dry and wet bulb measurements.  I suspect
consumer level stuff varies considerably in reliability and accuracy.

The capacitive sensors are tricky to use because they require AC
excitation to prevent damage from electromigration.  I see a lot of
integrated sensors are available now and I wonder how well they really
work

On Fri, 28 Oct 2016 09:39:04 +1100, you wrote:

>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:
>> 
>> 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.
>> 
>> ...
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[time-nuts] Temperature/Humidity

[Dan Zorbini]

Simple, build your room (8 x 12), use a water sealing paint paint, install a 
split mini cooling unit at approx.8,000 BTU, set temperature below oven 
temperature  of the equipment.Carefully choose AC size (not to big). Door at 
far end of room.
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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  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?

[Poul-Henning Kamp]

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] Difference in manufacturing for fundamental tone, 3rd, and 5th overtone crystals

[Magnus Danielson]

Hi,

Hmm, such fiddeling could maybe also apply to nearby alternative modes 
of the crystals, even if I guess it would be harder to do meaningful 
dents on them.


Cheers,
Magnus

On 10/28/2016 01:50 AM, Bob Camp wrote:

Hi

Crystals are highly optimized for the specific overtone they are
intended to operate on. In fact, you can fiddle them to the point
that they no longer have a “fundamental” response.

Bob


On Oct 27, 2016, at 6:42 PM, Attila Kinali  wrote:

Moin,

I have stumbled over another question I am unable to answer using the
tools I have available: Is there any fundamental difference in manufacturing
fundamental and overtone chrystals. Or to be more precise: is there an
optimization process during manufacturing that makes a crystal more suited
for one of the harmonics than for the others or all crystals similarly
well suited to be used as an fundamental crystal as they are for the 3rd
or 5th overtone?


Attila Kinali
--
Malek's Law:
   Any simple idea will be worded in the most complicated way.
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Re: [time-nuts] Difference in manufacturing for fundamental tone, 3rd, and 5th overtone crystals

[Bob Camp]

Hi

Crystals are highly optimized for the specific overtone they are
intended to operate on. In fact, you can fiddle them to the point
that they no longer have a “fundamental” response.

Bob

> On Oct 27, 2016, at 6:42 PM, Attila Kinali  wrote:
> 
> Moin,
> 
> I have stumbled over another question I am unable to answer using the
> tools I have available: Is there any fundamental difference in manufacturing
> fundamental and overtone chrystals. Or to be more precise: is there an
> optimization process during manufacturing that makes a crystal more suited
> for one of the harmonics than for the others or all crystals similarly
> well suited to be used as an fundamental crystal as they are for the 3rd
> or 5th overtone?
> 
> 
>   Attila Kinali
> -- 
> Malek's Law:
>Any simple idea will be worded in the most complicated way.
> ___
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Re: [time-nuts] Temp/Humidity control systems?

[Eric Scace]

   Ha!

   That is the system my brother Greg Scace designed and built while at NIST. 
He has given a lot of papers around the world on its metrology technology.

   On the side, he manufactures the reference calibration tools for espresso 
machines 
.

   Greg is still working there… as is his wife Casey (on cryptography)… and my 
father Bob Scace worked there for 25 years on microelectronics and 
nanotechnology… my other brother Brian retired recently from NIST… and I worked 
there for a few years 1978-1981 on international data networking problems. I 
think the Scace family has the record for maximum number of family members 
employed at NIST.

— Eric Scace

> On 2016 Oct 27, at 13:32 , William H. Fite  wrote:
> 
> Just for the fun of it, here is how NIST measures humidity.
> https://www.nist.gov/sites/default/files/documents/calibrations/sp250-83.pdf
> 

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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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[time-nuts] Difference in manufacturing for fundamental tone, 3rd, and 5th overtone crystals

[Attila Kinali]

Moin,

I have stumbled over another question I am unable to answer using the
tools I have available: Is there any fundamental difference in manufacturing
fundamental and overtone chrystals. Or to be more precise: is there an
optimization process during manufacturing that makes a crystal more suited
for one of the harmonics than for the others or all crystals similarly
well suited to be used as an fundamental crystal as they are for the 3rd
or 5th overtone?


Attila Kinali
-- 
Malek's Law:
Any simple idea will be worded in the most complicated way.
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Re: [time-nuts] Aging and Thermal Correction in Holdover

[Bob Stewart]

  From: Attila Kinali 
 To: Discussion of precise time and frequency measurement  
 Sent: Thursday, October 27, 2016 1:45 PM
 Subject: Re: [time-nuts] Aging and Thermal Correction in Holdover
   
On Thu, 27 Oct 2016 16:13:06 + (UTC)
Bob Stewart  wrote:


> Since I want to keep this as simple as possible, I'll probably stay with a
> simple division of the DAC delta over 3.5 days.  And since the thermal
> impact seems to be 1:1 to the DAC delta under most circumstances, I may
> experiment with modifying the beginning and end points of the calculation
> by the temperature.  But, hopefully with a long enough averaging period,
> it won't make much of a difference.

>I.e. you have a very simple, linear temperature dependence and aging model?
Not quite.  The aging model is linear, sure.  But as mentioned earlier, I'm 
experimenting with a sort of linear-nonlinear thermal model.  What this means 
is that over some set time period I take the difference between the beginning 
temperature and the end temperature, and then I step only one DAC step in the 
direction that the temperature changed.  Why?  Because I noticed a strong 
correlation between small temperature differences which broke down as the 
temperature change curve steepened.  And yet, it was only the value of the step 
that broke down, not the direction.  Putting a limit on it like this seems to 
have improved the result.

> The odd thing about the thermal impact is that if the thermal change
> delta is too high, it's no longer 1:1.  I suspect that may be because
> it's an easy thing for the OCXO's heater to add BTUs, but it can only
> subtract them passively.  And shedding BTUs into a rising temperature
> environment is problematic.

>I guess you are measuring the temperature of the OCXO outside of the can.
Keep in mind that the temperature outside is lower than inside. I.e. you
have a temperature gradient. If the temperature changes, then the gradient
changes as well. As long as the rate of temperature change is low, the
gradient will stay linear (ie the temperature inside the OCXO increases
linearly with the distance from the outer can). If the rate of temperature
change is fast, then the gradient will start to bend. Which in turn means
that the heat transport between inside and outside of the OCXO is not a
linear function of the outside temperature anymore. Or in other words:
your simplistic system model does not capture the dynamic behavior of
the OCXO correctly, which results in discrepances between expected and
observed behaviour.
Yes, and this is what I'm trying to capture; especially when the temperature 
increases.  Because that's when it will bend the most.

>And if I may, please talk about energy (or rather power in this
context), not BTU. The former is a physical term, while the latter
is an outdated unit that shouldn't be used anymore and has no clear
definition.
As I've mentioned many times, I'm not an engineer.  It may be that BTU has no 
clear definition, but you understood what I meant, which is all that's 
important.

Bob
   
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Re: [time-nuts] Temp/Humidity control systems?

[William H. Fite]

Just for the fun of it, here is how NIST measures humidity.
https://www.nist.gov/sites/default/files/documents/calibrations/sp250-83.pdf

On Thu, Oct 27, 2016 at 3:30 PM, William H. Fite  wrote:

> NIST-traceable hygrometers are readily available in the $200-$400 range.
>
> Or you can get a couple of airtight boxes of precisely the same volume and
> go gravimetric...
>
> On Thu, Oct 27, 2016 at 9:43 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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>
>
>
> --
> Intelligence has never been proof against stupidity.
>



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Re: [time-nuts] Temp/Humidity control systems?

[William H. Fite]

NIST-traceable hygrometers are readily available in the $200-$400 range.

Or you can get a couple of airtight boxes of precisely the same volume and
go gravimetric...

On Thu, Oct 27, 2016 at 9:43 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?

[Ron Bean]

>* 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] Aging and Thermal Correction in Holdover

[Attila Kinali]

On Thu, 27 Oct 2016 16:13:06 + (UTC)
Bob Stewart  wrote:

> Thanks for confirming that the thermal impact on the aging rate is minimal.
> I had suspected that that was so, but had no easy way to tell.

It is _probably_ minimal. How large it is depends on your setup.
But from what I know of OCXOs the change is mostly dominated by
the non-linear time dependence. I don't know of any measurements
of the temperature dependend aging for long running crystals.
Probably because aging for old crystals becomes much lower than
temperature effects.

> Since I want to keep this as simple as possible, I'll probably stay with a
> simple division of the DAC delta over 3.5 days.  And since the thermal
> impact seems to be 1:1 to the DAC delta under most circumstances, I may
> experiment with modifying the beginning and end points of the calculation
> by the temperature.  But, hopefully with a long enough averaging period,
> it won't make much of a difference.

I.e. you have a very simple, linear temperature dependence and aging model?

> The odd thing about the thermal impact is that if the thermal change
> delta is too high, it's no longer 1:1.  I suspect that may be because
> it's an easy thing for the OCXO's heater to add BTUs, but it can only
> subtract them passively.  And shedding BTUs into a rising temperature
> environment is problematic.

I guess you are measuring the temperature of the OCXO outside of the can.
Keep in mind that the temperature outside is lower than inside. I.e. you
have a temperature gradient. If the temperature changes, then the gradient
changes as well. As long as the rate of temperature change is low, the
gradient will stay linear (ie the temperature inside the OCXO increases
linearly with the distance from the outer can). If the rate of temperature
change is fast, then the gradient will start to bend. Which in turn means
that the heat transport between inside and outside of the OCXO is not a
linear function of the outside temperature anymore. Or in other words:
your simplistic system model does not capture the dynamic behavior of
the OCXO correctly, which results in discrepances between expected and
observed behaviour.

Depending on what you are actually trying to do, I recommend that you
get a book on control theory and read up on some of the basics.
One of the books I like is "Feedback Control of Dynamic Systems"
by Gene Franklin. It's reasonably simple and has lots of examples.

And if I may, please talk about energy (or rather power in this
context), not BTU. The former is a physical term, while the latter
is an outdated unit that shouldn't be used anymore and has no clear
definition.

Attila Kinali

-- 
Malek's Law:
Any simple idea will be worded in the most complicated way.
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Re: [time-nuts] Temp/Humidity control systems?

[jimlux]

On 10/27/16 8:06 AM, Poul-Henning Kamp wrote:


In message <837330db-2015-4ae5-8c9c-f444f569f...@n1k.org>, Bob Camp writes:


Your “time cave” does not have a specific spec on temperature or on humidity.
You get to pick a number for either one. Anything in the “non condensing” (let’s
call it < 80%) range for humidity is likely ok. Temperature up to 40C is 
probably
ok for any gear that I can think of. As long as you *never* go in and out of the
cave, comfort in the cave is a non-issue.


Danger Will Robinson!

Under no circumstances should your dewpoint be above the temperature on
the other side of the door.

If you have 40C at 80% humidity your dew-point temperature is 35C, which means
that whenever you open the door your clock cave will fog up.

If you run your clock cave at 40C, humidity needs to be well below
30% to hold the dewpoint below room tempreatyre.  That is both hard,
expensive and prone to electrostatic discharges.


Assuming the humidity in the basement is under control (if not, fix that), all 
I need
to do for humidity in the closet is to exchange air with the basement.


"fix that" is usually non-trivial, and from very to horribly expensive.

The cardinal rule is that you should only exchange air (basement/outside,
or cave/basement) when the air outside has lower *ABSOLUTE* humidity.

And I keep stressing that it is *ABSOLUTE* humidity, because people simply
don't pay it enough attention.

25C/40%RH air holds 9.2 g/m³ water ... as does 15C/72%RH air.

This is why a lot of people in costal climates who ventilate their
basement during summer "to dry out the basement" get the exact
opposite result:  The air outside is a lot wetter than on the inside.

One would think that somebody had designed fans to measure this,
but it is expensive: Cheap humidity sensors measure relative humidity
and you need to correct for both temperature and pressure to get
absolute humidity.



And having looked into this in some detail - there's a whole lot of "go 
look at a psychometric chart" when you try and write some code to do the 
conversion.


It's similar to the "steam tables" (in fact, it's identical to the 
problem of generating steam tables, it's all about vapor pressure of 
water vs temperature and such)
There's not some nice equation to solve - It's more done by an iterative 
solution of the equation that goes the other way.



https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4813973/pdf/sensors-16-00398.pdf
has some of the background




And therefore, at the risk of repeating myself again:

If you build your clock cave in the basement, it should be air-tight
and you should manage the humidity in it separately from the rest
of the basement.

PS: Here is a good webcalculator:

http://go.vaisala.com/humiditycalculator/5.0/




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Re: [time-nuts] Temp/Humidity control systems?

[jimlux]

On 10/27/16 8:02 AM, John Hawkinson wrote:

jimlux  wrote on Thu, 27 Oct 2016
at 07:51:37 -0700 in :


(and frankly, if someone made something that opened/closed my
windows, I'd love that too, for the same reason.


http://www.mcmaster.com/#motorized-louvers/=14s2pox


No, the existing  windows - we need to be able to see out of it.. We 
have the usual aluminum frame sliding windows.



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Re: [time-nuts] Temp/Humidity control systems

[Scott Stobbe]

I'm not sure I follow the insulation is bad argument, thermal time constant
= RC, better insulation, longer time constant.

On Thu, Oct 27, 2016 at 12:37 PM, Mike Naruta AA8K  wrote:

> On 10/27/2016 03:41 AM, Poul-Henning Kamp wrote:
>
>> Over insulating is a 100% sure-fire way to get unstable temperature
>> inside,
>> because it amplifies the consequences of any change in power dissipation.
>>
>> It is a classic mistake to build a 100mm insulated enclosure inside an
>> office-like environment and end up having less stable temperature on
>> the inside than the outside.
>>
>> Cinder blocks is a much better material for that scenario, because they
>> have both thermal mass and inertia (= heat capacity and heat impedance)
>>
>
>
> True Poul-Henning Kamp.
>
>
> My application was to ecologically stabilize a room exposed to outside
> weather.  I am pleased to see the heater rarely come on, even on cold
> Winter days.  I attribute that to the insulation and equipment mass
> (half-century old computer, avionics, and amateur radio equipment).  Even
> in the Summer heat, the room stays cooler than air temperature (barn roof
> and day/night averaging?).
>
> John's Georgia basement may also enjoy natural cooling and thermal
> inertia.  Cinder blocks may be optimal.  We really need to know John's goal
> and existing conditions.
>
>
>
> Mike - AA8K
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Re: [time-nuts] Temp/Humidity control systems

[Mike Naruta AA8K]

On 10/27/2016 03:41 AM, Poul-Henning Kamp wrote:

Over insulating is a 100% sure-fire way to get unstable temperature inside,
because it amplifies the consequences of any change in power dissipation.

It is a classic mistake to build a 100mm insulated enclosure inside an
office-like environment and end up having less stable temperature on
the inside than the outside.

Cinder blocks is a much better material for that scenario, because they
have both thermal mass and inertia (= heat capacity and heat impedance)



True Poul-Henning Kamp.


My application was to ecologically stabilize a room exposed to 
outside weather.  I am pleased to see the heater rarely come on, 
even on cold Winter days.  I attribute that to the insulation 
and equipment mass (half-century old computer, avionics, and 
amateur radio equipment).  Even in the Summer heat, the room 
stays cooler than air temperature (barn roof and day/night 
averaging?).


John's Georgia basement may also enjoy natural cooling and 
thermal inertia.  Cinder blocks may be optimal.  We really need 
to know John's goal and existing conditions.



Mike - AA8K
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Re: [time-nuts] Aging and Thermal Correction in Holdover

[Bob Stewart]

Hi Attila,
Thanks for confirming that the thermal impact on the aging rate is minimal.  I 
had suspected that that was so, but had no easy way to tell.  Since I want to 
keep this as simple as possible, I'll probably stay with a simple division of 
the DAC delta over 3.5 days.  And since the thermal impact seems to be 1:1 to 
the DAC delta under most circumstances, I may experiment with modifying the 
beginning and end points of the calculation by the temperature.  But, hopefully 
with a long enough averaging period, it won't make much of a difference.
The odd thing about the thermal impact is that if the thermal change delta is 
too high, it's no longer 1:1.  I suspect that may be because it's an easy thing 
for the OCXO's heater to add BTUs, but it can only subtract them passively.  
And shedding BTUs into a rising temperature environment is problematic.

Bob


  From: Attila Kinali 
 To: Bob Stewart ; Discussion of precise time and frequency 
measurement  
 Sent: Wednesday, October 26, 2016 1:28 PM
 Subject: Re: [time-nuts] Aging and Thermal Correction in Holdover
   
On Wed, 26 Oct 2016 17:01:17 + (UTC)
Bob Stewart  wrote:

> I'm working on the Aging and Thermal Correction algorithms in my GPSDO.  At 
> this point, it's pretty simple: For aging, every X seconds I either 
> increment or decrement the DAC value by 1 as determined by the unit's 
> performance history.  For thermal, every X seconds (user settable) I check 
> to see if the thermistor has increased or decreased and step the DAC one 
> step in that direction.
> So, now I'm wondering if there's any correlation between the temperature and 
> aging.  IOW, if the ambient temperature in the case goes up a degree F, does 
> that change the aging rate by some small fractional value?  I recognize that 
> there is a point of diminishing returns, and I may have already hit that.

Yes, there is a coupling between temperature and aging, but how large it
is and into which direction depends highly on your system. It is also
very likely to change over time. But in general it will be drowned by
all other effects and uncertainties.


In general you don't want to set those parameters by hand, but let the control
loop estimate them. This is called adaptive control and the most common
way to do it is to use a Kalman Filter. There are many tutorials on the
net how to build a simple Kalman Filter. As a system model I suggest to use
the simplest that you can imagine that captures enough of the effects
to reach the results you want. E.g. in your case, I would go for a linear
or quadratic temperature dependence and a linear time aging. If you add
more parameters and make the system more complex, run into the risk that
your control system is unable to get good guesses for the parameters and
thus becomes unstable


            Attila Kinali

-- 
Malek's Law:
        Any simple idea will be worded in the most complicated way.

   
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Re: [time-nuts] Temp/Humidity control systems?

[Paul Alfille]

Use one of the Wine cellar room coolers -- they keep the temperature and
humidity fairly constant. Typically ~55F but can vary it. Breezaire and
others are vendors in this area. The units look like a window
airconditioner.

This will work to keep the temperature in a given range, but with rather
abrupt on/off cycles.

If you want a steady temperature, it seems like you need a  lot of thermal
mass and insulation.

On Wed, Oct 26, 2016 at 11:59 AM, John Ackermann N8UR  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] Temp/Humidity control systems?

[William H. Fite]

Mine were 8' x 10' x 7'. "Local pickup only"  ;)
The -20F chamber was 4' x 4' x 7'.
The -80F chamber was 2' x 2' x 5'.

How much space will you need, John? Chances are you could pick up a small
one on ebay and avoid all the jackleg schemes.


On Thursday, October 27, 2016, Poul-Henning Kamp  wrote:

> 
> In message <
> cany2ixrmyy2e9pbdgcqiuzgne_8rpl4kkuw2j4pdjlbj+j1...@mail.gmail.com
> >
> , "William H. Fite" writes:
>
> >Rick, professional environmental chambers [...]
>
> And they come up on fleabay with surprising regularity.
>
>
> --
> 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.
>


-- 
If you gaze long into an abyss, your coffee will get cold.
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Re: [time-nuts] Temp/Humidity control systems?

[John Ackermann N8UR]

On 10/27/2016 11:06 AM, Poul-Henning Kamp wrote:


This is why a lot of people in costal climates who ventilate their
basement during summer "to dry out the basement" get the exact
opposite result:  The air outside is a lot wetter than on the inside.


I learned this myself last summer.  We have a cottage on northern Lake 
Michigan that is about 100 feet from the water.  There is a walk-out 
basement that gets somewhat damp, though a dehumidifier usually keeps it 
under control.  Last summer I opened the cottage later in the season 
than usual, and the basement was very clammy.  So I decided to open the 
slider doors and turn on a box fan to air things out...


When I came back downstairs a couple of hours later, *standing water* 
had condensed on the cold floor tiles!  I had basically been 
dehumidifying Lake Michigan.  Lesson learned (and I spent the rest of 
the vacation trying to dry things out again).


Thanks for all the other comments in this thread.  I'm absorbing and 
will try to summarize back to the group.


John
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Re: [time-nuts] Temp/Humidity control systems?

[Poul-Henning Kamp]

In message , jimlux writes:

>Disadvantages:
>1) It leaks
>2) It grows stuff (even with additives to prevent it)

Antifreeze prevented that for me.

>3) you've increased the number of thermal transfers: refrigerator coils 
>to air to water to air to contents of box.  Both of the air:water 
>transfers are not particularly efficient in a "cobbled together in the 
>garage" sort of scenario.

Right, it is not a viable method if you want to burn 100+W in your fridge.
I've made it work up to 50W with little trouble.

>However, for a time-cave - I think it would work great  - cheap 
>airconditioner, large thermal mass buffer, well stirred air.

Absolutely.

But the problem in the basement setting is that the heat ends up
in your basement, which means the air can hold more moisture, which
you really do not want.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
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Re: [time-nuts] Temp/Humidity control systems?

[John Hawkinson]

jimlux  wrote on Thu, 27 Oct 2016
at 07:51:37 -0700 in :

> (and frankly, if someone made something that opened/closed my
> windows, I'd love that too, for the same reason.

http://www.mcmaster.com/#motorized-louvers/=14s2pox

--jh...@mit.edu
  John Hawkinson
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Re: [time-nuts] Temp/Humidity control systems?

[Poul-Henning Kamp]

In message <837330db-2015-4ae5-8c9c-f444f569f...@n1k.org>, Bob Camp writes:

>Your “time cave” does not have a specific spec on temperature or on humidity.
>You get to pick a number for either one. Anything in the “non condensing” 
>(let’s 
>call it < 80%) range for humidity is likely ok. Temperature up to 40C is 
>probably 
>ok for any gear that I can think of. As long as you *never* go in and out of 
>the 
>cave, comfort in the cave is a non-issue. 

Danger Will Robinson!

Under no circumstances should your dewpoint be above the temperature on
the other side of the door.

If you have 40C at 80% humidity your dew-point temperature is 35C, which means
that whenever you open the door your clock cave will fog up.

If you run your clock cave at 40C, humidity needs to be well below
30% to hold the dewpoint below room tempreatyre.  That is both hard,
expensive and prone to electrostatic discharges.

>Assuming the humidity in the basement is under control (if not, fix that), all 
>I need 
>to do for humidity in the closet is to exchange air with the basement.

"fix that" is usually non-trivial, and from very to horribly expensive.

The cardinal rule is that you should only exchange air (basement/outside,
or cave/basement) when the air outside has lower *ABSOLUTE* humidity.

And I keep stressing that it is *ABSOLUTE* humidity, because people simply
don't pay it enough attention.

25C/40%RH air holds 9.2 g/m³ water ... as does 15C/72%RH air.

This is why a lot of people in costal climates who ventilate their
basement during summer "to dry out the basement" get the exact
opposite result:  The air outside is a lot wetter than on the inside.

One would think that somebody had designed fans to measure this,
but it is expensive: Cheap humidity sensors measure relative humidity
and you need to correct for both temperature and pressure to get
absolute humidity.

And therefore, at the risk of repeating myself again:

If you build your clock cave in the basement, it should be air-tight
and you should manage the humidity in it separately from the rest
of the basement.

PS: Here is a good webcalculator:

http://go.vaisala.com/humiditycalculator/5.0/


-- 
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?

[jimlux]

On 10/27/16 7:37 AM, Bob Camp wrote:

Hi

Ok, take this with a bit of caution ….

Your “time cave” does not have a specific spec on temperature or on humidity.
You get to pick a number for either one. Anything in the “non condensing” (let’s
call it < 80%) range for humidity is likely ok. Temperature up to 40C is 
probably
ok for any gear that I can think of. As long as you *never* go in and out of the
cave, comfort in the cave is a non-issue.



This is an interesting point.. basically you'd turn your DOCXOs into a 
TOCXO where the third oven is your time cave.. you make the set point 
*above* the surroundings, so all you need to do to hold temperature is 
to add heat - which is much, much more controllable in a gradual way 
than removing heat.


The "two radiators and a pump" approach is appealing - you could set it 
up so that the pump is variable speed. That said, there's a fair amount 
of "custom fabrication" involved: you have to find some suitable 
radiators, make the appropriate fittings and connections to your pump 
and hoses, and arrange for fans to blow through them.  You might be able 
to find something off the shelf - Grainger and McMaster are full of 
interesting things - and things to cool hot water using air blowing 
through the coils are probably a fairly off the shelf item.


And, would using a liquid thermal transfer path be any different than a 
variable speed air vent between inside and outside?



What I'm looking for right now is a suitable controller that will run an 
exhaust fan that fits in a 12x12" (approx) opening when the outside 
temperature is "closer" to my target set point than the inside temp:


In Southern California, the outside air temp moves quite a bit during 
the day and rapidly at the day/night transition, so when the garage is 
hot, and outside is cooler, I'd like to exchange air.  Likewise, if the 
garage is cold (cooled down overnight) and outside is warmer, I'd like 
to exchange air to warm it up.


The standard "differential thermostat" seems to only do one of the 
directions (turn on/off load when T1 -T2 > setpoint and T1 > setpoint), 
and I suppose I could "wire or" two of these,  but it seems there should 
be a 'More clever" off the shelf solution.


(and frankly, if someone made something that opened/closed my windows, 
I'd love that too, for the same reason.. I can cold bias the house in 
the morning, leave the AC off all day with the windows closed, and then 
automatically open the windows in the afternoon/evening when the outside 
temperature drops below the inside temperature setpoint)  In combination 
with Time-of-Use electricity rates (something you should consider in 
temperature regulation of your time cave - "store cold at night"), one 
can cheaply pre-cool the house in "super off peak" time.



(Yes, I could program an Arduino to do this, but then I have to cobble 
up a AC relay, a DC power supply, etc., etc)




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Re: [time-nuts] Temp/Humidity control systems?

[Bob Camp]

Hi

Ok, take this with a bit of caution ….

Your “time cave” does not have a specific spec on temperature or on humidity.
You get to pick a number for either one. Anything in the “non condensing” 
(let’s 
call it < 80%) range for humidity is likely ok. Temperature up to 40C is 
probably 
ok for any gear that I can think of. As long as you *never* go in and out of 
the 
cave, comfort in the cave is a non-issue. 

If I load up the cave with gear that runs up the electric bill, the cave will 
self 
heat to some degree. How much it self heats is unclear. The number will be 
highly
dependent on your situation. Based on things like racks full of gear in out of 
the 
way places, it’s a good bet that it will be 10 to 20 C above the temperature in 
the
rest of the basement. 

Assuming the humidity in the basement is under control (if not, fix that), all 
I need 
to do for humidity in the closet is to exchange air with the basement. Since 
the 
volume isn’t very large and (hopefully) the water flow is modest …. a small fan
should take care of that. 

If the closet is bound by the outside (buried) wall and the basement, both 
should be well
controlled temperatures.  If I plug everything in and let it run, the heat rise 
in August should 
be the heat rise in February. Let’s say that’s a 20C rise. The basement is at 
20 C and
the closet is at 40C. Maybe its more, If it’s less,  you need to buy more 
stuff:)

All I need to do is knock the 40C down to 35C with a small amount of “cooling” 
to 
keep things under control. My “humidity” fan might do that. If not, a very 
simple 
water based heat exchanger with a controlled fan will do the job. You need some 
sort
of fan(s) in the closet anyway. Without them you will never get the gradients 
under
control. A pump, 10’ of tubing and two heat exchangers are not a lot of money. 
There
also isn’t a lot to break if you do it right. 

Why do it this way? No compressors to mess up the local power line and break 
every X years (the fridge in the kitchen died Sunday ….. they do break). No 
super
cold surfaces to mess up humidity. No crazy heat flows to create clod drafts 
and 
fast transients in the closet temperature. 

The obvious downside is that you *do* go in the closet. When you do, everything 
goes a bit off. My guess is that you are actually better off letting it recover 
slowly 
than you are trying to move it back in under 10 minutes …. who knows. One 
solution 
to that would be to sub-divide the closet. The gear to do this is cheap. 

Bob



> On Oct 27, 2016, at 10:06 AM, jimlux  wrote:
> 
> On 10/27/16 6:30 AM, Poul-Henning Kamp wrote:
>> 
>> In message , "David J Taylor" writes:
>> 
>>> 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.
>> 
>> You can do *much* better with an old fridge and a small waterpump to
>> circulate water in the cooling loop.
>> 
> 
> 
> I tried that first...
> 
> Advantage is that the mass of the water (serving as a thermal transfer 
> medium) is much greater than that of air.  You wind up with kilos of water at 
> a relatively constant temperature.
> 
> Disadvantages:
> 1) It leaks
> 2) It grows stuff (even with additives to prevent it)
> 3) you've increased the number of thermal transfers: refrigerator coils to 
> air to water to air to contents of box.  Both of the air:water transfers are 
> not particularly efficient in a "cobbled together in the garage" sort of 
> scenario.
> 
> I think your suggestion of just adding (solid) mass to the system is better - 
> the advice to people with wine cellars is to fill empty slots with bottles 
> filled with wine (actually, the advice is to buy more wine, so your cellar 
> doesn't have any empty slots.. but if that's not possible, fill the empties 
> with water, recork and stow them)
> 
> The challenge with a refrigerator as chiller is that getting decent coupling 
> from the cooler coils to the water is tough: you're pretty much restricted to 
> air as the transfer medium.  In a "real chiller" they put the evaporator 
> coils in the water so there's good thermal contact. Refrigerators/freezers 
> aren't made for this - I tried 3 different approaches of varying complexity:
> 
> 1) Put a 5 gallon plastic bucket of water in the refrigerator - the bucket of 
> water does get cold, but--- it also evaporates inside the refrigerator, and 
> the water condenses on the coils, freezes, and then eventually is lost to the 
> air when the unit is defrosted.
> 
> 2) Put an array of copper tubing in close contact with the cold plate in the 
> freezer, weighted down by bricks to make close contact - well, let's just say 
> I found all sorts of interesting galvanic reactions can occur, even at low 
> temperatures - the other problem is that if the c

Re: [time-nuts] Temp/Humidity control systems?

[jimlux]

On 10/27/16 6:30 AM, Poul-Henning Kamp wrote:


In message , "David J Taylor" writes:


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.


You can do *much* better with an old fridge and a small waterpump to
circulate water in the cooling loop.




I tried that first...

Advantage is that the mass of the water (serving as a thermal transfer 
medium) is much greater than that of air.  You wind up with kilos of 
water at a relatively constant temperature.


Disadvantages:
1) It leaks
2) It grows stuff (even with additives to prevent it)
3) you've increased the number of thermal transfers: refrigerator coils 
to air to water to air to contents of box.  Both of the air:water 
transfers are not particularly efficient in a "cobbled together in the 
garage" sort of scenario.


I think your suggestion of just adding (solid) mass to the system is 
better - the advice to people with wine cellars is to fill empty slots 
with bottles filled with wine (actually, the advice is to buy more wine, 
so your cellar doesn't have any empty slots.. but if that's not 
possible, fill the empties with water, recork and stow them)


The challenge with a refrigerator as chiller is that getting decent 
coupling from the cooler coils to the water is tough: you're pretty much 
restricted to air as the transfer medium.  In a "real chiller" they put 
the evaporator coils in the water so there's good thermal contact. 
Refrigerators/freezers aren't made for this - I tried 3 different 
approaches of varying complexity:


1) Put a 5 gallon plastic bucket of water in the refrigerator - the 
bucket of water does get cold, but--- it also evaporates inside the 
refrigerator, and the water condenses on the coils, freezes, and then 
eventually is lost to the air when the unit is defrosted.


2) Put an array of copper tubing in close contact with the cold plate in 
the freezer, weighted down by bricks to make close contact - well, let's 
just say I found all sorts of interesting galvanic reactions can occur, 
even at low temperatures - the other problem is that if the circulation 
rate slows, the water in the loop can freeze, and once it starts to 
freeze, it has positive feedback - the flow rate slows even more, and 
pretty quickly, you have tubes full of frozen coolant.  - it is a good 
thing I was doing this in the garage.


3) trying to make a cold plate by using two sheets of aluminum, some 
aluminum spacers, plenty of silicone, and some hose barbs is a lot of 
work, and doesn't seem to work much better.


I think one problem is that the refrigerator/freezer control system is 
designed to work off two sensors: one is a air temperature sensor and 
the other is a sensor on the actual evaporator unit (basically, if it 
gets too cold, it shuts off the compressor to prevent low pressure 
damage).  The "design point" for all of this is also probably not 
optimum for moving heat out of your equipment closet.



And that's just the challenge on "improvised water chiller"

Then you have the other "water to air heat exchanger".. serpentine 
tubing would seem to be the best way, but it turns out that this is 
non-trivial to design so that you get even flow rates in multiple loops, 
if you have multiple paths. And, arranging the tubing effectively is 
hard. There's also all the fabrication/leakage/hose connection issues. 
I tried making serpentines out of copper and aluminum tubing that would 
be part of the shelf on which the bottles are piled.  That cools the 
bottom bottles nicely, but the thermal transfer among the bottles is slow.


The best approach to "get cold to all bottles" (or, more correctly, take 
heat from warm bottles" is to have a fan to circulate air among the 
stacked and racked bottles.  Well, once you are rigging up a fan to push 
air through cold tubing (a re-purposed car heating core - more 
fabrication of adapters from one tubing size to another - I had a big 
box of hose clamps, between size adapters, and pieces of hose of all 
sizes).  Remember that this is all wet at one point or another, either 
from leaks or condensation, so stuff corrodes, rusts, etc.


Yep - a $99 window airconditioner bought on sale (about this time of 
year is good, in the Northern Hemisphere) worked just fine.  Plumbing 
air is a lot easier than plumbing water or glycol coolant.  You won't 
get down to <10C because window air conditioners aren't refrigerators - 
the choice of refrigerant and internal components and set point range 
isn't compatible with that (and putting a small heater on the AC's temp 
sensor, which is in the return air flow to the evaporator did not allow 
me to "bias" the set point)



However, for a time-cave - I think it would work great  - cheap 
airconditioner, large thermal mass

Re: [time-nuts] Temp/Humidity control systems?

[Poul-Henning Kamp]

In message , "David J Taylor" writes:

>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.

You can do *much* better with an old fridge and a small waterpump to
circulate water in the cooling loop.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
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Re: [time-nuts] Temp/Humidity control systems?

[Poul-Henning Kamp]

In message <20161027131226.0d5a72e62b2c91f2e13b6...@kinali.ch>, Attila Kinali w
rites:

>> Stop!
>> 
>> Over insulating is a 100% sure-fire way to get unstable temperature inside,
>> because it amplifies the consequences of any change in power dissipation.
>> 
>> It is a classic mistake to build a 100mm insulated enclosure inside an
>> office-like enviroment and end up having less stable temperature on
>> the inside than the outside.
>
>No! Don't Stop! :-)
>
>That's why the next section I wrote described how to get rid of the
>excess heat in a controlled fashio. Of course, simply just insulating
>the room without giving it a lot of thermal mass or any form of control
>of the heat production/exchange will not stabilize the room.

Attila,  I did read that.

You are right in a certain set of circumstances, for instance in a
already climate-regulated office space.

But your model is a recipe for grief and disaster if you do it in
a typical basement, on about 2/3 of the inhabited area of the planet
where you cannot ignore the humidity.

In general in a basement, it is a better idea to set up a closed
space and manage the humidity inside it, than it is to move the
humidity in and out of it.


WRT to humidity, that's a very unlinear relationship, but you can
get far by remembering these five rules:

* Warm air holds more *absolute* humidity (ie: g/m³) than colder air.

* At the same temperture, wetter air is lighter than dryer air.

* The temperature is never the same.

* Condensation should be avoided, period.

* You cannot "feel" absolute humidity, always measure it.

And yes, go ahead and look up number two, it's true.  Dehumidifiers
belong on shelves under the ceiling, not on the floor.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
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Re: [time-nuts] Temp/Humidity control systems?

[jimlux]

On 10/27/16 2:43 AM, Neville Michie wrote:

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,



In this particular case, I did do the calculation of "mass fraction of 
water" from the data - the AC really does pull the water out of the air. 
 The "test article" in this case has relatively small air volume, and a 
large surface area of wood.  Water goes out fast, comes in slow.


There might also be a surface condensation issue on the glass surfaces.

If you look at the wet bulb temperature, it runs a few degrees below the 
air temperature, except when the AC is on, when it plunges several 
degrees in seconds.






Neville Michie



On 27 Oct 2016, at 8:17 PM, David J Taylor  
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?

[jimlux]

On 10/27/16 2:17 AM, David J Taylor 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.




Indeed.. a large mass varies slowly.

(hence the suggestions in previous years for finding caves, digging a 
mine shaft, etc)


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Re: [time-nuts] Temp/Humidity control systems?

[Attila Kinali]

Hoi Poul-Henning,

On Thu, 27 Oct 2016 07:41:48 +
"Poul-Henning Kamp"  wrote:

> >Probably the easiest is to get some glass/mineral wool insulation and
> >put it over all the walls, including ceiling and floor. I do not recommend
> >any foam or styropor based insulation as almost all of them are inflamable.
> >This should get you into the area of 10-100W/K thermal resistance for your
> >closet (assuming something like 4cm thick insulation gets about 40W/K).
> 
> Stop!
> 
> Over insulating is a 100% sure-fire way to get unstable temperature inside,
> because it amplifies the consequences of any change in power dissipation.
> 
> It is a classic mistake to build a 100mm insulated enclosure inside an
> office-like enviroment and end up having less stable temperature on
> the inside than the outside.

No! Don't Stop! :-)

That's why the next section I wrote described how to get rid of the
excess heat in a controlled fashio. Of course, simply just insulating
the room without giving it a lot of thermal mass or any form of control
of the heat production/exchange will not stabilize the room.


Attila Kinali
-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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[time-nuts] disappearance of NIST UT1 time service

[Mike Cook]

Hi,

  Does anyone know what happened to the NIST UT1 time service managed by Dr. 
Judah Levine?

I lost contact with the server ut1-time.colorado.edu on the 24th this month at 
20:15 UTC and there has been no response to NTP requests  since. 
I mailed Judah to find out what happened but have not as yet got anything back. 

Regards,
Mike

"The power of accurate observation is commonly called cynicism by those who 
have not got it. »
George Bernard Shaw

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Re: [time-nuts] FTS-1000A Oscillator - Oven mod

[n2lym]

Kapton tape.



On Thu, Oct 27, 2016 at 12:15 AM, Ed Palmer wrote:


I recently bought an unused FTS-1000A Oscillator.

My previous experience and Christopher Hoover's recent experience 
warned me that with time and heat, the red rubber blanket that 
surrounds the oven will bond the oven assembly to the Dewar flask. It 
occurred to me that this is the perfect time to wrap something around 
the rubber blanket to stop it from bonding to the Dewar. After 
thinking about it for a while, the best idea I can come up with is a 
simple layer of acid-free paper.  The temperature isn't high enough to 
bother the paper and it shouldn't bond to the glass at all.


Any thoughts or suggestions on this?

Ed

P.S.  I have opened the unit and the oven slid out of the Dewar with 
very little coaxing, so it really does appear to be an unused unit.



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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  
> 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?

[David J Taylor]

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?

[Poul-Henning Kamp]

In message <20161026210517.26c0fd397b1cae5ba9c12...@kinali.ch>, Attila Kinali w
rites:

>Probably the easiest is to get some glass/mineral wool insulation and
>put it over all the walls, including ceiling and floor. I do not recommend
>any foam or styropor based insulation as almost all of them are inflamable.
>This should get you into the area of 10-100W/K thermal resistance for your
>closet (assuming something like 4cm thick insulation gets about 40W/K).

Stop!

Over insulating is a 100% sure-fire way to get unstable temperature inside,
because it amplifies the consequences of any change in power dissipation.

It is a classic mistake to build a 100mm insulated enclosure inside an
office-like enviroment and end up having less stable temperature on
the inside than the outside.

Cinderblocks is a much better material for that scenario, because they
have both thermal mass and inertia (= heat capacity and heat impedance)

-- 
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?

[Poul-Henning Kamp]

In message 
, "William H. Fite" writes:

>Rick, professional environmental chambers [...]

And they come up on fleabay with surprising regularity.


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
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Re: [time-nuts] Temp/Humidity control systems?

[Poul-Henning Kamp]

In message <5810d2d2.2070...@febo.com>, John Ackermann N8UR writes:

>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.

You first need to decide what kind of clock room you want:

At one extreme you have a clock vault you never change anything in,
with incredibly stable temperature & humidity, but stabilization
times of days or weeks.

At the other end you have an environmental chamber which hits temperature
and humidity in a matter of minutes after you closed them.

If you want to do this low budget, consider getting a couple of old
fridges or freezers and run water of your chosen temperature
through their cooling loops.  That way you can have multiple different
climates and keep soom stuff stable while you play with other stuff.

-- 
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] WWV receivers?

[Poul-Henning Kamp]

In message <5a002554-8d90-4c75-95da-21db45d61...@kfu.com>, Nick Sayer via time-
nuts writes:

>If you’re in North America, a CHU receiver is a lot easier to make
>than WWV/WWVH. The CHU timecode is just BEL 103 AFSK at 300 baud -
>it was a one-chip solution 20 years ago when I made one in college.

We have CPUs and sounds-cards these days...

Also: The KiwiSDR is nearly perfect hardware, no matter which VLF/HF
station you want:  You can track GPS and four (possibly 8) VLF/HF
stations at the same time.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
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Re: [time-nuts] Timing from Iridium satellites

[Hal Murray]

stewart.c...@gmail.com said:
> I hope this is not too blatantly commercial for this list

Looks good to me.  Thanks.

Are the specs for extracting timing from Iridium available without NDA or $$$?

Page 6 shows several hardware boards/boxes.  The NooElec NESDR Mini 2 USB Stick 
seems like the only one that is both low cost and available.  Is any (free) 
software available?  I assume it would work with similar USB based RF front 
ends.

-- 
These are my opinions.  I hate spam.



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