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

On 10/30/2016 10:18 PM, Bill Hawkins wrote: Think of the fun you'll have determining the heat flow model constants for the system. In particular, there's no air flow sensor because they are expensive. You'll need to determine the relation between fan speed and air flow. You can buy an automotive

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

On 31 October 2016 at 10:37, Poul-Henning Kamp wrote: > > In message gmail.com>, "Dr. David K > irkby (Kirkby Microwave Ltd)" writes: > > >> > [...] so it might be a relatively cheap way to measure humidity. > >> > >> 80m wave-guide is neither cheap, nor in most circumstances, practical

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

Hi A multi mode resonant cavity is probably the “easy” approach. Like the waveguide, it is pressure / temperature / humidity sensitive. The same “can I separate the effects” issue applies. Any enclosed device will have issues with properly representing the humidity in the room. It’s fortunat

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

In message , "Dr. David K irkby (Kirkby Microwave Ltd)" writes: >> > [...] so it might be a relatively cheap way to measure humidity. >> >> 80m wave-guide is neither cheap, nor in most circumstances, practical :-) > >But you don't need 80 m of waveguide. 100 mm or so would be sufficient

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

On 31 Oct 2016 06:07, "Poul-Henning Kamp" wrote: > > > In message < canx10hcpa5sozukqe00c5hcm-zrwkblnsojcoljokdriols...@mail.gmail.com>, "Dr. David K > irkby (Kirkby Microwave Ltd)" writes: > > > [...] so it might be a relatively cheap way to measure humidity. > > 80m wave-guide is neithe

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

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

In message , "Dr. David K irkby (Kirkby Microwave Ltd)" writes: > [...] so it might be a relatively cheap way to measure humidity. 80m wave-guide is neither cheap, nor in most circumstances, practical :-) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org

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

Looking at it as a problem in thermodynamics, which has equations for the flow and storage of heat, it might have a simple solution. If you can have your equipment closet hotter than the basement will ever be, we can use basement air for cooling the closet. The basement air can be held to about +/

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

On 10/27/2016 6:43 AM, Ron Bean wrote: 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

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

On Sun, 30 Oct 2016 20:38:49 + "Dr. David Kirkby (Kirkby Microwave Ltd)" wrote: > I was just reading the Keysight forum on VNAs. Someone was having issues > measuring a bit of waveguide 80 m long. Dr. Joel Dunsmore pointed out that > humidity has an effect in waveguide. > > I'm guessing thi

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

On 28 October 2016 at 01:05, Poul-Henning Kamp wrote: >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 k

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

In message , Chris Albert son writes: >[...] the water comping out of the pipe is always about 58F. Unless you live close to a volcano or an artesian spring, the temperature will be exactly the yearly average air-temperature of your climate. Precisely how deep you need to dig for stab

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

There are people making a lot of money installing heating cooling systems that take advantage of the Earth's thermal stability. What they do is dig a hole the size of a swimming pool and lay out a zig-zag pattern of pipe on the bottom of the hole then backfill the hole. Assuming the pipe is bur

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

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/ _

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

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 elect

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

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.

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

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 dama

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

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

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

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 >accura

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

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

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

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 bu

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

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

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

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.

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

>* 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

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

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

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

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 -

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

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 tem

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

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 an

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

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 ab

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

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:

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

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

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

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

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

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 ___

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

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.

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

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. Temperatu

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

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

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

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 abou

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

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 de

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

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

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

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 mois

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

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

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

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 ar

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

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

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

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 bottl

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

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

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

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 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since

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

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

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

amp Date: 10/26/16 4:00 PM (GMT-07:00) To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Temp/Humidity control systems? HI I would take a look at the “stuff” they make for wine cellars. It’s an application aimed at the same sort of area size and done in mu

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

HI I would take a look at the “stuff” they make for wine cellars. It’s an application aimed at the same sort of area size and done in much higher volume than an electronics closet. Bob > On Oct 26, 2016, at 1:58 PM, John Ackermann N8UR wrote: > > On 10/26/2016 1:00 PM, Richard (Rick) Karl

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

If your instruments/clocks were insensitive to variations in line voltage you could vary your rooms line voltage with a variable auto transformer (end up being a heater with tons of surface area). Or pack enough OCXOs in there so they end up thermally servoing the room. On Wednesday, 26 October 20

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

On 10/26/16 1:39 PM, Mark Sims wrote: There is also the old trick of having an AC unit running continuously, but blowing through a controlled heater. Not the most efficient setup... I think that even TVB has implemented such a contraption... That's how automotive A/C works.. _

[time-nuts] Temp/Humidity control systems?

There is also the old trick of having an AC unit running continuously, but blowing through a controlled heater. Not the most efficient setup... I think that even TVB has implemented such a contraption... ___ time-nuts mailing list -- time-nuts@febo.c

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

On 10/26/16 9:34 AM, David J Taylor 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

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

On 10/26/16 10:58 AM, John Ackermann N8UR wrote: On 10/26/2016 1:00 PM, Richard (Rick) Karlquist wrote: On 10/26/2016 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

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

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 perfo

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

On 10/26/16 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

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

I would start looking at the ductless heat pump systems that are becoming popular now they don't take up much space, have pretty good capacity and are efficient. I have no idea if they can be proportionally controlled or what the temperature hysteresis on them are though, which might be an issue in

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

On Wed, 26 Oct 2016 13:58:10 -0400 John Ackermann N8UR wrote: > This room would be a large closet in my basement where two racks of > various OCXO, Rb, Cs live. There wouldn't be a lot of in-and-out > traffic. I'm not looking for 0.01 degree regulation -- <1 degree C and a > few percent humidi

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

Rick, professional environmental chambers and their contents have a great deal of thermal inertia. In addition, they have overbuilt refrigeration systems, electric heaters, and de/humidifiers. You teach your lab rats to enter the chambers as infrequently as possible, to close the doors as quickly a

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

On 10/26/2016 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 baseme

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

Personally I'd be looking at a commercial ductless heat pump unit Mitsubishi MrSlim comes to mind in your case you would want a 'cartridge' type unit designed for ceiling mount the ones for data center use have humidity control as well. Figure these units will hold +/- 2-3 deg F over long term

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

Hi John. You might want to look at "precision air conditioning" systems (to use the vendors phraseology) designed for small computer rooms for some ideas ? I suspect getting close to your temperature spec may be easier than your humidity spec ? There may also be issues getting commercial uni

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

list: groups.yahoo.com/neo/groups/GFS-GPSDOs/info From: John Ackermann N8UR To: time-nuts@febo.com Sent: Wednesday, October 26, 2016 12:58 PM Subject: Re: [time-nuts] Temp/Humidity control systems? On 10/26/2016 1:00 PM, Richard (Rick) Karlquist wrote: > On 10/26/2016 8:59 AM, J

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

On 10/26/2016 1:00 PM, Richard (Rick) Karlquist wrote: On 10/26/2016 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.

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

I have always wondered how large the market for those hydroponic/indoor gardening stores really is, maybe they have something to fit the bill. 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 co

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

On 10/26/2016 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 basemen

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

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 pu

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

Hoi John, On Wed, 26 Oct 2016 11:59:14 -0400 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. What is the available bu

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

Hi Bill -- That's a bit more than I had in mind, but very cool. :-) What I really meant was a heat pump or other unit with good control loop that I could use in a standard insulated space, just to keep "nominal" conditions (ie, not wide-range testing). Thanks, John On 10/26/2016 12:09

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

John, this is what I bought for the Orlando VA Medical Center when I was setting up the research lab there. Not cheap, though. 🤑 https://www.thermalproductsolutions.com/products/walk-in-temperature-humidity-test-rooms On Wed, Oct 26, 2016 at 11:59 AM, John Ackermann N8UR wrote: > I may have t

[time-nuts] Temp/Humidity control systems?

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 t