Author Topic: SHT45 in Barani/Comet/MetSpec shelters  (Read 569 times)

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Offline tobyportugal

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SHT45 in Barani/Comet/MetSpec shelters
« on: November 15, 2022, 03:14:38 PM »
Hello,

After some difficulties, the SHT45 project is coming to fruition.
As a reminder, 10 SHT45s will be in service, 5 at Toby in Portugal and 5 at Antonio in northern France.
They will be mounted in Barani Pro3, Comet F8004 at 190mm and Metspec Rad14.
The others will be mounted according to our comparison objectives, it is essential to be able to compare in two different locations with quite different climatic conditions.
The choice of the other additional shelters will be : Barani Pro Ventiled, MetSpec Rad02, ...
The choice of the SHT45 is quite simple, compared to the SHT35 we gain precision on a very frequent temperature range in spring and autumn.

SHT35



SHT45





When analysing the characteristics of the SHT35/45, two parameters are very interesting for our purposes:
1/ The response time of the relative humidity measurement goes from 8sec to 4sec!
2/ The repeatability in RH and t gains a little.
The declared repeatability is equal to 3 times the standard deviation (3σ) of several consecutive measurement values under constant conditions, on the physical output of the sensor.
The progress of the SHT45 opens up an additional avenue of investigation: absolute humidity.     
As this is calculated using the formula recommended by the WMO (thanks to Barani for the information), it will be possible to see whether condensation occurs in certain contexts.
It goes without saying that a rigorous assembly is necessary to exploit this SHT45.     
Assembly without silicone, glue, brass support, etc...
We started with this support:



The choice was dictated by its length (126mm), its removable filter (for future investigations), and its chamber where the SHT45 is located is isolated from the rest without glue, silicone.
This allows the sensor to be mounted at a strictly identical height on all sensors.



Each sensor is mounted on a PTFE tube for standardised mounting on Barani/Comet/MetSpec.
As the PTFE tube is not a thermal conductor, no external thermal influences are transmitted to the shelter chamber.



The continuation in a few days with examples of assemblies in a Barani and Comet, as well as a system of case housing the transmitter and external connectors for an easy intervention,
exchange, maintenance without having to dismount everything.



Offline tobyportugal

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Re: SHT45 in Barani/Comet/MetSpec shelters
« Reply #1 on: November 16, 2022, 05:41:46 AM »
Origine Ecowitt (Barani MeteoShield)



By Toby  [tup] (Barani MeteoShield)
Mounting the cable gland in the correct direction.

« Last Edit: November 16, 2022, 05:48:13 AM by tobyportugal »

Offline tobyportugal

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Re: SHT45 in Barani/Comet/MetSpec shelters
« Reply #2 on: November 16, 2022, 06:03:38 AM »

Offline bianconero57

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Re: SHT45 in Barani/Comet/MetSpec shelters
« Reply #3 on: November 18, 2022, 09:08:39 AM »
Thanks Toby for the above update :)
Note the common approach taken by both, therefore, we will be working with the same data acquisition process: Meteobridge Red Pro.
But above all regardless of the comfort certainly offered by the embedded system [MB-Pro] in compiling for example the various dynamic graphs at will (therefore abandoned by me due to the inactivity of the main sensors) I think the important thing will be to concentrate on the RH humidity and HA with the T (especially on rainy or dewy days) in order to verify (or not) the theoretical post to us in the joint presentation of the project by Barani in the continuation (update with the sht45) of the comparaison with the MetPro3 vs./ other sheilders !

Lets see what happens .... [tup]

Offline bianconero57

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Re: SHT45 in Barani/Comet/MetSpec shelters
« Reply #4 on: November 23, 2022, 06:09:04 AM »
 [tup] Hello everyone, I'm updating the step of our common project subject to subsequent integration for those interested in the question. Have a good day

Offline hmderek

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Re: SHT45 in Barani/Comet/MetSpec shelters
« Reply #5 on: November 23, 2022, 07:08:37 AM »
Before I'm going to dive into all the links in your PDF, do you have a quick summary? Is there any obvious difference in behavior between the SHT35 and 45?
Davis VP2
Davis WeatherLink
Sensirion SHT35
PT100
NTC Thermistors
DS18B20
Apogee Instruments TS-100
Barani Meteoshield Pro
Davis 7714
MetSpec RAD14
Davis AirLink
Wemos D1 Mini micro controllers
https://blog.meteodrenthe.nl
https://meteodrenthe.nl
https://twitter.com/meteodrenthe

Offline bianconero57

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Re: SHT45 in Barani/Comet/MetSpec shelters
« Reply #6 on: November 23, 2022, 10:16:46 AM »
it is indicated in the preamble of the document  [tup] the operating voltage range is different, and the SHT45 sensor measurement is more stable !

Offline tobyportugal

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Re: SHT45 in Barani/Comet/MetSpec shelters
« Reply #7 on: November 23, 2022, 01:40:25 PM »
Before I'm going to dive into all the links in your PDF, do you have a quick summary? Is there any obvious difference in behavior between the SHT35 and 45?

Hello Holland  [tup]

I still have some memories of Dutch studied at school (I am Belgian from Brussels)  #-o
I don't have many graphs because the 1st SHT45 moved around a lot in my house in Portugal and then in Antonio's house in France.
The daily graphs will be published following this example:
https://u.pcloud.link/publink/show?code=XZYlXBVZN6yoGusQFtYtrqCfcMpIL4tRiaek
https://u.pcloud.link/publink/show?code=XZidXBVZNFelrfy7gQR59AYxFcMkLudayKYV

I don't know yet if the little website I made will be public.
Example:



Attention: the links in the PDF are not about the SHT45, but about the demonstration of a problem with the "Ecowitt" style filters. 
I like your work very much, I have a little difficulty with the usefulness of a PT100 for an amateur.
Knowing the extreme very low resistance to measure without a very accurate power supply, it seems to me as accurate as a SHT35/45 in a well thought out holder.
Have a great evening, I look forward to hearing from you.   :grin:

Offline hmderek

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Re: SHT45 in Barani/Comet/MetSpec shelters
« Reply #8 on: November 24, 2022, 05:12:37 AM »
I don't know yet if the little website I made will be public.

Would love to know if it does go public. I'd enjoy digging into the data generated by your setup.

Wondering at the moment how long it will take before certain parties will start selling the SHT45 with probe a piece like with the SHT35. If it takes too long, I may very well get that set of those 5 presoldered + wired SHT45s you have.

I like your work very much, I have a little difficulty with the usefulness of a PT100 for an amateur.
Knowing the extreme very low resistance to measure without a very accurate power supply, it seems to me as accurate as a SHT35/45 in a well thought out holder.

It's slightly more troublesome than some other sensor types. But Adafruit has a great breakout board called the MAX31865 which can read any PT100 with great results. I've compared it with standard 4-20mA PT100 transmitters and the results are pretty much identical.

If you do ever get into the PT100, I've tried several and I this is the one I've been using mostly: https://www.aliexpress.com/item/32868816875.html
Davis VP2
Davis WeatherLink
Sensirion SHT35
PT100
NTC Thermistors
DS18B20
Apogee Instruments TS-100
Barani Meteoshield Pro
Davis 7714
MetSpec RAD14
Davis AirLink
Wemos D1 Mini micro controllers
https://blog.meteodrenthe.nl
https://meteodrenthe.nl
https://twitter.com/meteodrenthe

Offline tobyportugal

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Re: SHT45 in Barani/Comet/MetSpec shelters
« Reply #9 on: November 24, 2022, 07:50:54 AM »


Wondering at the moment how long it will take before certain parties will start selling the SHT45 with probe a piece like with the SHT35. If it takes too long, I may very well get that set of those 5 presoldered + wired SHT45s you have.


This is a personal opinion, in a search for precision you should discard the ready to plug in SHTxx probes sold on the net.
The filters are of poor quality, often not equal to each other, the PCBs are fixed with silicone/glue, and the heights are not always similar.
Example of a month of data (Barani Pro2 SHT35 without filter, Barani Pro2 SHT35 with chinnese filter, Barani Pro3 SHT35 without filter) it is clear that it is always the SHT35 with filter that causes problems in changing or unusual conditions:

https://u.pcloud.link/publink/show?code=kZ4t0WVZ4OBd25cfgqVKV1ouUpE2HyX6TG37

The holder I use (see above) allows for optimal mounting and replacement without having to throw away each time.
I believe you have a Barani, so it can be mounted with a gland in the right direction.



 

Offline hmderek

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Re: SHT45 in Barani/Comet/MetSpec shelters
« Reply #10 on: November 24, 2022, 08:54:48 AM »

The holder I use (see above) allows for optimal mounting and replacement without having to throw away each time.
I believe you have a Barani, so it can be mounted with a gland in the right direction.

I have something similar, but mostly use the fixed probes. Though I have a bunch of spare empty probes I use for testing as well. Question: what lead you to those probe casings? Do you have a specific reason why those would be better than other options available?
Davis VP2
Davis WeatherLink
Sensirion SHT35
PT100
NTC Thermistors
DS18B20
Apogee Instruments TS-100
Barani Meteoshield Pro
Davis 7714
MetSpec RAD14
Davis AirLink
Wemos D1 Mini micro controllers
https://blog.meteodrenthe.nl
https://meteodrenthe.nl
https://twitter.com/meteodrenthe

Offline bianconero57

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Re: SHT45 in Barani/Comet/MetSpec shelters
« Reply #11 on: November 24, 2022, 09:09:35 AM »
I have something similar, but mostly use the fixed probes. Though I have a bunch of spare empty probes I use for testing as well. Question: what lead you to those probe casings? Do you have a specific reason why those would be better than other options available?

 [tup] Hello
thank you for your feedback
i leave it to my friend Toby to reply in more detail on the technical questions
but it is true that we have noticed that these filters are very probably filters that significantly reduce the responses of the sensor
especially on humidity
so we hope that the filters used in our upcoming tests could be better
without effect actually better still would be to use "SF2" filters which are practically those recommended by Sensiron
unless otherwise noted ....
have a good day
BR

Offline tobyportugal

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Re: SHT45 in Barani/Comet/MetSpec shelters
« Reply #12 on: November 24, 2022, 10:59:24 AM »
My choice was made for several reasons.
1/ its length 120mm
2/ its filter is removable
3/ the insulation of the chamber where the PCB is located is without glue/silicone.
4/ the lower part of the tube is good to mount two sensors (SHT35+SHT45) without having a big cable coming out.
5/ identical support for all shelters.
6/ reusable support.
This assembly was seen by Jan Barani and was not subject to any doubts or remarks (His only remark was a photo to make sure the chamber was closed).
I ordered 20 of them to limit shipping costs.

As Antonio says, the best choice is the SF2. But I've never seen a PCB designed for an SF2 to clip on. I don't want the glue-on stuff.
We may have a lead, but we need a constructive dialogue.


Offline hmderek

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Re: SHT45 in Barani/Comet/MetSpec shelters
« Reply #13 on: November 26, 2022, 04:34:55 AM »
I have decided to order the SHT45s as well. Should be an interesting winter project! I will be housing one in an identical probe casing as the SHT35, and put them both in a Barani shield.
Davis VP2
Davis WeatherLink
Sensirion SHT35
PT100
NTC Thermistors
DS18B20
Apogee Instruments TS-100
Barani Meteoshield Pro
Davis 7714
MetSpec RAD14
Davis AirLink
Wemos D1 Mini micro controllers
https://blog.meteodrenthe.nl
https://meteodrenthe.nl
https://twitter.com/meteodrenthe

Offline bianconero57

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Re: SHT45 in Barani/Comet/MetSpec shelters
« Reply #14 on: November 26, 2022, 04:44:31 AM »
I have decided to order the SHT45s as well. Should be an interesting winter project! I will be housing one in an identical probe casing as the SHT35, and put them both in a Barani shield.

 [tup] hello happy that you can share this project with us and wishing (above all) a constructive collaboration :) have a nice weekend BR

Offline tobyportugal

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Re: SHT45 in Barani/Comet/MetSpec shelters
« Reply #15 on: November 26, 2022, 04:48:36 AM »
I have decided to order the SHT45s as well. Should be an interesting winter project! I will be housing one in an identical probe casing as the SHT35, and put them both in a Barani shield.

Goed nieuws!  ;)
Out of curiosity, where will you order the SHT45?
The ones I have were made at my request.
If you want a stand (support/filter) like ours -> PM

Offline hmderek

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Re: SHT45 in Barani/Comet/MetSpec shelters
« Reply #16 on: November 26, 2022, 06:31:50 AM »
I have decided to order the SHT45s as well. Should be an interesting winter project! I will be housing one in an identical probe casing as the SHT35, and put them both in a Barani shield.

Goed nieuws!  ;)
Out of curiosity, where will you order the SHT45?
The ones I have were made at my request.
If you want a stand (support/filter) like ours -> PM

Went for this one:
https://a.aliexpress.com/_mNSUrfA

I will be using this casing to start with in order to get a fair comparison with the SHT35.
https://a.aliexpress.com/_mseNZwU

But I like the idea of trying different casings. Since I have also realized that the response time of the sensor is greatly affected by the casing.
Davis VP2
Davis WeatherLink
Sensirion SHT35
PT100
NTC Thermistors
DS18B20
Apogee Instruments TS-100
Barani Meteoshield Pro
Davis 7714
MetSpec RAD14
Davis AirLink
Wemos D1 Mini micro controllers
https://blog.meteodrenthe.nl
https://meteodrenthe.nl
https://twitter.com/meteodrenthe

Offline tobyportugal

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Re: SHT45 in Barani/Comet/MetSpec shelters
« Reply #17 on: November 26, 2022, 07:00:27 AM »
The two orders are mine.  :grin:
I asked them in September to make me SHT45s, the configuration (colours/cable length) is at my request.
I think they are serious people, they warned me at the time of long delay, then confirmed my choices.
If you make an order, tell them that it's after the "tobyportugal" orders.
For the future it's good for evolutions like PCBs with SF2.  :lol:

Brackets/filters, heated debate that many people don't want to admit/understand. A SHT35 with low cost filters is like a SHT20!
Great weekend.