Author Topic: Sensirion SHT-75 is now unavailable  (Read 5633 times)

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Offline jgentry

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Re: Sensirion SHT-75 is now unavailable
« Reply #25 on: March 14, 2019, 10:18:30 PM »
Using my Kestrel DROP to guide me in this process, I decided to do an offset on my console for humidity by subtracting 3% and my DP is now accurate. Yes, my high humidity readings will be off but overall, my DP will be accurate.
With my 31 I use -2% and it works very well between ~3 to 90%. If I expect significant time outside those extremes, I'll take the correction out then reapply it when necessary.

With the 31, I had to do 8%. So you must have a good 31
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Offline CW2274

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Re: Sensirion SHT-75 is now unavailable
« Reply #26 on: March 14, 2019, 10:57:07 PM »
Using my Kestrel DROP to guide me in this process, I decided to do an offset on my console for humidity by subtracting 3% and my DP is now accurate. Yes, my high humidity readings will be off but overall, my DP will be accurate.
With my 31 I use -2% and it works very well between ~3 to 90%. If I expect significant time outside those extremes, I'll take the correction out then reapply it when necessary.

With the 31, I had to do 8%. So you must have a good 31
After all the chat on here about the 31, I think it's pretty much a foregone conclusion that it's a much better overall performer (humidity wise) in drier climates, and it doesn't get much drier than it does here. It's also been in service over 2.5 years.

Offline hwcorder

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Re: Sensirion SHT-75 is now unavailable
« Reply #27 on: March 15, 2019, 01:49:35 AM »
Using my Kestrel DROP to guide me in this process, I decided to do an offset on my console for humidity by subtracting 3% and my DP is now accurate. Yes, my high humidity readings will be off but overall, my DP will be accurate.
With my 31 I use -2% and it works very well between ~3 to 90%. If I expect significant time outside those extremes, I'll take the correction out then reapply it when necessary.

With the 31, I had to do 8%. So you must have a good 31
After all the chat on here about the 31, I think it's pretty much a foregone conclusion that it's a much better overall performer (humidity wise) in drier climates, and it doesn't get much drier than it does here. It's also been in service over 2.5 years.

We have recently had a few very dry days here. Most of the time my 75 runs about 4-7 percent lower than my 31.  Once you get to the lower 20% though the 31 rapidly catches up. By the mid to upper teens RH% they read very close to each other.  Of course this doesn't occur too much here in the southeast so the 75 is overall supperior sensor her IMHO.

Offline CW2274

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Re: Sensirion SHT-75 is now unavailable
« Reply #28 on: March 15, 2019, 03:11:52 AM »
Using my Kestrel DROP to guide me in this process, I decided to do an offset on my console for humidity by subtracting 3% and my DP is now accurate. Yes, my high humidity readings will be off but overall, my DP will be accurate.
With my 31 I use -2% and it works very well between ~3 to 90%. If I expect significant time outside those extremes, I'll take the correction out then reapply it when necessary.

With the 31, I had to do 8%. So you must have a good 31
After all the chat on here about the 31, I think it's pretty much a foregone conclusion that it's a much better overall performer (humidity wise) in drier climates, and it doesn't get much drier than it does here. It's also been in service over 2.5 years.

We have recently had a few very dry days here. Most of the time my 75 runs about 4-7 percent lower than my 31.  Once you get to the lower 20% though the 31 rapidly catches up. By the mid to upper teens RH% they read very close to each other.  Of course this doesn't occur too much here in the southeast so the 75 is overall supperior sensor her IMHO.
No doubt the 75 (humidity wise) is better for you, and most likely about everyone else. As far as "catching up", I can't really say on the spot as I don't have a side by side comparison, but have a pretty good idea.
As I look at my last year's records, at this time, I was already in the teens to single digits daily for humidity, and it would remain there for the next four months until the monsoon arrived.

Offline ValentineWeather

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Re: Sensirion SHT-75 is now unavailable
« Reply #29 on: March 15, 2019, 07:47:03 AM »
The 75 was made for metrological use and was the standard sensor for Campbell Scientific  https://www.campbellsci.com/cs215-l 

The 75 is superior IMO to the 31 except possibly extreme cold but even there it was within 1.3° at around -15°.  The 75 was phased out because it doesn't use the I2c protocol but other than that great accurate fast responding sensor meant to be used outdoors unlike the 31.  It's not perfect with prolonged high humidity like all sensirion sensors but does perform better overall with high humidity vs the 31 with faster recovery time and doesn't display the high bias in upper dewpoint range above 58° like the 31 does.

There is no doubt in my mind which sensor I'll be using once sub-zero temperature are no longer a threat.
« Last Edit: March 15, 2019, 08:01:23 AM by ValentineWeather »
Randy

Offline johnd

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Re: Sensirion SHT-75 is now unavailable
« Reply #30 on: March 15, 2019, 08:00:46 AM »
Just as a footnote and it's probably not very relevant to anyone here because it involves using EM, but:

A sensor with an SDI-12 output is in principle compatible with a Davis Enviromonitor node. It would still have to implemented as a recognised sensor by the EM team at Davis and that night well take some time to prioritise and then to achieve, but in principle it could work.
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Sorry, but I don't usually have time to help with individual issues by email unless you are a Prodata customer. Please post your issue in the relevant forum section here & I will comment there if I have anything useful to add.

Offline jgentry

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Re: Sensirion SHT-75 is now unavailable
« Reply #31 on: March 15, 2019, 06:39:43 PM »
Just as a footnote and it's probably not very relevant to anyone here because it involves using EM, but:

A sensor with an SDI-12 output is in principle compatible with a Davis Enviromonitor node. It would still have to implemented as a recognised sensor by the EM team at Davis and that night well take some time to prioritise and then to achieve, but in principle it could work.

Hey John, I emailed Davis a few days ago about an idea of switching the use of Sensirion sensors to the HYT 221 sensor but they never gave a response? Typically they respond to me within a day or two so I’m curious why they didn’t respond?
Davis Vantage Pro2 & WeatherFlow Tempest. WU: KXALJEMI2, KALJEMIS7, KFLPANAM363 & KALTHORS2. CWOP/APRS: C6353 & E6358

Offline CW2274

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Re: Sensirion SHT-75 is now unavailable
« Reply #32 on: March 15, 2019, 06:58:15 PM »
Just as a footnote and it's probably not very relevant to anyone here because it involves using EM, but:

A sensor with an SDI-12 output is in principle compatible with a Davis Enviromonitor node. It would still have to implemented as a recognised sensor by the EM team at Davis and that night well take some time to prioritise and then to achieve, but in principle it could work.

I’m curious why they didn’t respond?
Not John here, but my 2cents is that it would appear incriminating on pointing to the fact that the 31 has issues. They haven't addressed anything prior to this, why start now.
I truly doubt you'll get a response.

Offline johnd

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Re: Sensirion SHT-75 is now unavailable
« Reply #33 on: March 16, 2019, 05:03:30 AM »
Hey John, I emailed Davis a few days ago about an idea of switching the use of Sensirion sensors to the HYT 221 sensor but they never gave a response? Typically they respond to me within a day or two so I’m curious why they didn’t respond?

I really wouldn't read too much into that. My guess is that it's a typical company situation in that the support people are in a completely different group to the developers/engineers for new products.  Support is trained and set up to deal with all the common support questions (which this isn't and so support would struggle to answer this one directly) while product development is not customer-facing. Suggestions for new products are - again I can only guess at the likely scenario - probably forwarded into a different mailbox and read by someone at intervals, but hardly ever answered individually. And priorities for new products might only be reviewed maybe once or twice a year?

One other point that perhaps bears repeating: For better or worse I'm afraid that this is not a high profile or commonly raised issue. To the best of my recollection I've _never_ had a user complain much about RH accuracy (other than maybe a failure to reach exactly 100%). Users I deal with are much more exercised about other priorities for product development like a more consistently accurate rain gauge or a better console or better local software (though that bus has sailed). I'm not doubting the issue for a second but it just doesn't seem to rank as a major unprompted concern for many users and it's the majority concerns that Davis will inevitably respond to.
« Last Edit: March 16, 2019, 09:03:48 AM by johnd »
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Includes many details on 6313 Weatherlink console.
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Sorry, but I don't usually have time to help with individual issues by email unless you are a Prodata customer. Please post your issue in the relevant forum section here & I will comment there if I have anything useful to add.

Offline jgentry

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Re: Sensirion SHT-75 is now unavailable
« Reply #34 on: March 16, 2019, 08:56:01 AM »
Hey John, I emailed Davis a few days ago about an idea of switching the use of Sensirion sensors to the HYT 221 sensor but they never gave a response? Typically they respond to me within a day or two so I’m curious why they didn’t respond?

I really wouldn't read too much into that. My guess is that it's a typical company situation in that the support people are in a completely different group to the developers/engineers for new products.  Support is trained and set up to deal with all the common support questions (which this isn't and so support would struggle to answer this one directly) while product development is not customer-facing. Suggestions for new products are - again I can only guess at the likely scenario - probably forwarded into a different mailbox and read by someone at intervals, but hardly ever answered individually. And priorities for new products might only be reviewed maybe once or twice a year?

One other point that perhaps bears repeating: For better or worse I'm afraid that this is not a high profile or commonly raised issue. To the best of my recollection I've _never_ had a user complain much about RH accuracy (other than maybe a failure to reach exactly 100%). Users I deal with are much more exercised about other priorities for product development like a more consistently accurate rain gauge or a better console or better local software (though that bus has sailed). I'm not doubting the issue for a second but it just doesn't seem rank as a major unprompted concern for many users and it's the majority concerns that Davis will inevitably respond to.


Thanks! Just wished they would’ve emailed me back saying that they passed it along to the right folks. Had one tech question in there that could’ve been answered but oh well.

But I do think if they switch to the HYT 221 sensor, it would be a huge step (along with fixing rain gauge issues) in making Davis VP2 a really viable option for research, etc.  That’s just IMO.
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Offline jerryg

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Re: Sensirion SHT-75 is now unavailable
« Reply #35 on: March 22, 2019, 12:56:18 PM »
Update, well finally got some dense fog and the sensor has been doing real well in following my main sensor. Humidity topped out at 99% on both stations and temp has been right on so it looks like these sensors are a good batch and not seconds or knock offs.

Offline jgentry

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Re: Sensirion SHT-75 is now unavailable
« Reply #36 on: March 22, 2019, 08:49:35 PM »
I’ve finally given up on Sensirion in general. I have the good fortune of having held on to my old analog temperature/humidity sensor from the pre2006 VP2 days (the 7346.029). At 14 years old, I wasn’t sure what kind of performance I’d get from it, although for most of that time it hasn’t been exposed to the extremes of outdoor conditions. I plugged it in and it worked and the temperature matched my other sensors. I placed a wet cloth over it and it read 100% humidity within 5 mins. I installed it as my primary sensor on 23Feb. We’ve had unusually dry weather in western Washington for this time of year (humidity down near 30%) the last 2 days. It has performed well.
 
Previously I was using the SHT75, which for humidity was performing better than the Davis 31, but with the continuous wet conditions, it still suffered from a pretty bad wet bias when things would dry out. I used an offset and calibration on the SHT75 of (1.061x)-5 in Cumulus. With the analog, I am using no calibration or offset. It’s really a shame Davis could not source these humidity elements any longer. I’ll see how it does over the long term, but if you’re interested to see how it compares, the nearest NWS ASOS is KTIW. KSEA and KBFI aren’t too far (see link). Everything prior to 23Feb was the SHT75 with calibration setting. Everything after is the old analog.

https://weather.gladstonefamily.net/qchart/C7491?date=20190227&addnl=KTIW&addnl=KSEA&addnl=KBFI

05Feb really gives a good demonstration of the wet bias after a long wet period with the Sensirion:
https://weather.gladstonefamily.net/qchart/C7491?date=20190206&addnl=KTIW&addnl=KSEA&addnl=KBFI

Man I wish I had that same analog sensor. Looking at your data and comparing it to the ASOS tells me it’s a great sensor. Even though the 75 is better than the 31, I’m still having to do an offset of -3-4%. Even though the sensor has “dried” out for a few days.  I wish there was a way to obtain those old temp/hum sensors. If anyone knows the makers of those sensors, please let me know. 
Davis Vantage Pro2 & WeatherFlow Tempest. WU: KXALJEMI2, KALJEMIS7, KFLPANAM363 & KALTHORS2. CWOP/APRS: C6353 & E6358

Offline CW7491

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Re: Sensirion SHT-75 is now unavailable
« Reply #37 on: March 23, 2019, 01:17:02 AM »
I’ve finally given up on Sensirion in general. I have the good fortune of having held on to my old analog temperature/humidity sensor from the pre2006 VP2 days (the 7346.029). At 14 years old, I wasn’t sure what kind of performance I’d get from it, although for most of that time it hasn’t been exposed to the extremes of outdoor conditions. I plugged it in and it worked and the temperature matched my other sensors. I placed a wet cloth over it and it read 100% humidity within 5 mins. I installed it as my primary sensor on 23Feb. We’ve had unusually dry weather in western Washington for this time of year (humidity down near 30%) the last 2 days. It has performed well.
 
Previously I was using the SHT75, which for humidity was performing better than the Davis 31, but with the continuous wet conditions, it still suffered from a pretty bad wet bias when things would dry out. I used an offset and calibration on the SHT75 of (1.061x)-5 in Cumulus. With the analog, I am using no calibration or offset. It’s really a shame Davis could not source these humidity elements any longer. I’ll see how it does over the long term, but if you’re interested to see how it compares, the nearest NWS ASOS is KTIW. KSEA and KBFI aren’t too far (see link). Everything prior to 23Feb was the SHT75 with calibration setting. Everything after is the old analog.

https://weather.gladstonefamily.net/qchart/C7491?date=20190227&addnl=KTIW&addnl=KSEA&addnl=KBFI

05Feb really gives a good demonstration of the wet bias after a long wet period with the Sensirion:
https://weather.gladstonefamily.net/qchart/C7491?date=20190206&addnl=KTIW&addnl=KSEA&addnl=KBFI

Man I wish I had that same analog sensor. Looking at your data and comparing it to the ASOS tells me it’s a great sensor. Even though the 75 is better than the 31, I’m still having to do an offset of -3-4%. Even though the sensor has “dried” out for a few days.  I wish there was a way to obtain those old temp/hum sensors. If anyone knows the makers of those sensors, please let me know.

I realize information on these old analog sensors is largely irrelevant, but I thought I’d provide an update. After being gone for several weeks, I’ve been back for a few days and combined with what I was seeing remotely and after numerous spot checks with my psycho-dyne, I found that the analog sensor was about 3-4% too dry. The temperature has been very accurate, but in a temperate range from about 43-75F.

The good news about the dry humidity sensor is that it read 3-4% low across the entire scale and topped out at 97% (although I have been able to force it with a warm damp cloth to 100%). I’ve applied a +4% humidity offset, which allows the sensor to easily hit 100% and it has been +/-2% of my psychro-dyne with humidity all the way down into the upper teens (which we just experienced here recently). It recovers from high humidity much quicker than the Sensirion. Sometimes the sensor reads a little wet, other times a little dry. It’s nice to see this random error versus the constant systemic high humidity bias I was used to.

With that said, I did make a side by side comparison with the SHT75 with humidity down in the 20s. They read almost identical (with the +4% offset on the analog) and right on with the psycho-dyne, but with the caveat that the SHT75 had been indoors in a very dry environment and not exposed to the prolonged high humidity that seems to be that sensor’s weakness.

Compared to the nearest ASOS (KTIW), the analog compares favorably. Local effects here can be extreme in warm, dry conditions with proximity to water, wind direction and down and upsloping winds. My psycho-dyne always matches ASOS nearly exactly when I’ve done side by side comparisons, so as a sort of transfer standard, I trust it more than comparing to an ASOS with unique differences over 4 miles away
« Last Edit: March 23, 2019, 01:21:28 AM by CW7491 »

Offline ValentineWeather

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Re: Sensirion SHT-75 is now unavailable
« Reply #38 on: March 23, 2019, 01:49:20 PM »
I made my sensor swap over to the SHT75 yesterday.  I'll go back on the SHT31 when below zero F is a threat again come November. 
I'm running both in same AC aspirated shield, the 75 dp averages 2° lower vs the 31 even with mid 30's dewpoint unless it's raining like today the 75 is running higher by 1 degree responding to the added moisture in the air. It's just the better sensor humidity wise IMO.
Randy

Offline jgentry

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Re: Sensirion SHT-75 is now unavailable
« Reply #39 on: March 23, 2019, 04:03:03 PM »
I’ve finally given up on Sensirion in general. I have the good fortune of having held on to my old analog temperature/humidity sensor from the pre2006 VP2 days (the 7346.029). At 14 years old, I wasn’t sure what kind of performance I’d get from it, although for most of that time it hasn’t been exposed to the extremes of outdoor conditions. I plugged it in and it worked and the temperature matched my other sensors. I placed a wet cloth over it and it read 100% humidity within 5 mins. I installed it as my primary sensor on 23Feb. We’ve had unusually dry weather in western Washington for this time of year (humidity down near 30%) the last 2 days. It has performed well.
 
Previously I was using the SHT75, which for humidity was performing better than the Davis 31, but with the continuous wet conditions, it still suffered from a pretty bad wet bias when things would dry out. I used an offset and calibration on the SHT75 of (1.061x)-5 in Cumulus. With the analog, I am using no calibration or offset. It’s really a shame Davis could not source these humidity elements any longer. I’ll see how it does over the long term, but if you’re interested to see how it compares, the nearest NWS ASOS is KTIW. KSEA and KBFI aren’t too far (see link). Everything prior to 23Feb was the SHT75 with calibration setting. Everything after is the old analog.

https://weather.gladstonefamily.net/qchart/C7491?date=20190227&addnl=KTIW&addnl=KSEA&addnl=KBFI

05Feb really gives a good demonstration of the wet bias after a long wet period with the Sensirion:
https://weather.gladstonefamily.net/qchart/C7491?date=20190206&addnl=KTIW&addnl=KSEA&addnl=KBFI

Man I wish I had that same analog sensor. Looking at your data and comparing it to the ASOS tells me it’s a great sensor. Even though the 75 is better than the 31, I’m still having to do an offset of -3-4%. Even though the sensor has “dried” out for a few days.  I wish there was a way to obtain those old temp/hum sensors. If anyone knows the makers of those sensors, please let me know.

I realize information on these old analog sensors is largely irrelevant, but I thought I’d provide an update. After being gone for several weeks, I’ve been back for a few days and combined with what I was seeing remotely and after numerous spot checks with my psycho-dyne, I found that the analog sensor was about 3-4% too dry. The temperature has been very accurate, but in a temperate range from about 43-75F.

The good news about the dry humidity sensor is that it read 3-4% low across the entire scale and topped out at 97% (although I have been able to force it with a warm damp cloth to 100%). I’ve applied a +4% humidity offset, which allows the sensor to easily hit 100% and it has been +/-2% of my psychro-dyne with humidity all the way down into the upper teens (which we just experienced here recently). It recovers from high humidity much quicker than the Sensirion. Sometimes the sensor reads a little wet, other times a little dry. It’s nice to see this random error versus the constant systemic high humidity bias I was used to.

With that said, I did make a side by side comparison with the SHT75 with humidity down in the 20s. They read almost identical (with the +4% offset on the analog) and right on with the psycho-dyne, but with the caveat that the SHT75 had been indoors in a very dry environment and not exposed to the prolonged high humidity that seems to be that sensor’s weakness.

Compared to the nearest ASOS (KTIW), the analog compares favorably. Local effects here can be extreme in warm, dry conditions with proximity to water, wind direction and down and upsloping winds. My psycho-dyne always matches ASOS nearly exactly when I’ve done side by side comparisons, so as a sort of transfer standard, I trust it more than comparing to an ASOS with unique differences over 4 miles away

Thanks for the input!  Really, if Davis would let their pride go and switch their temp/humidity sensor to the HYT 221 or one that is good, then I’ll have nothing much to complain about the Davis station. Lol

But I’m curious to know if the transmitter needed changing in order to take the I2C or does the console need reprogramming?
Davis Vantage Pro2 & WeatherFlow Tempest. WU: KXALJEMI2, KALJEMIS7, KFLPANAM363 & KALTHORS2. CWOP/APRS: C6353 & E6358

Offline CW2274

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Re: Sensirion SHT-75 is now unavailable
« Reply #40 on: March 23, 2019, 04:15:05 PM »
I’ve finally given up on Sensirion in general. I have the good fortune of having held on to my old analog temperature/humidity sensor from the pre2006 VP2 days (the 7346.029). At 14 years old, I wasn’t sure what kind of performance I’d get from it, although for most of that time it hasn’t been exposed to the extremes of outdoor conditions. I plugged it in and it worked and the temperature matched my other sensors. I placed a wet cloth over it and it read 100% humidity within 5 mins. I installed it as my primary sensor on 23Feb. We’ve had unusually dry weather in western Washington for this time of year (humidity down near 30%) the last 2 days. It has performed well.
 
Previously I was using the SHT75, which for humidity was performing better than the Davis 31, but with the continuous wet conditions, it still suffered from a pretty bad wet bias when things would dry out. I used an offset and calibration on the SHT75 of (1.061x)-5 in Cumulus. With the analog, I am using no calibration or offset. It’s really a shame Davis could not source these humidity elements any longer. I’ll see how it does over the long term, but if you’re interested to see how it compares, the nearest NWS ASOS is KTIW. KSEA and KBFI aren’t too far (see link). Everything prior to 23Feb was the SHT75 with calibration setting. Everything after is the old analog.

https://weather.gladstonefamily.net/qchart/C7491?date=20190227&addnl=KTIW&addnl=KSEA&addnl=KBFI

05Feb really gives a good demonstration of the wet bias after a long wet period with the Sensirion:
https://weather.gladstonefamily.net/qchart/C7491?date=20190206&addnl=KTIW&addnl=KSEA&addnl=KBFI

Man I wish I had that same analog sensor. Looking at your data and comparing it to the ASOS tells me it’s a great sensor. Even though the 75 is better than the 31, I’m still having to do an offset of -3-4%. Even though the sensor has “dried” out for a few days.  I wish there was a way to obtain those old temp/hum sensors. If anyone knows the makers of those sensors, please let me know.

I realize information on these old analog sensors is largely irrelevant, but I thought I’d provide an update. After being gone for several weeks, I’ve been back for a few days and combined with what I was seeing remotely and after numerous spot checks with my psycho-dyne, I found that the analog sensor was about 3-4% too dry. The temperature has been very accurate, but in a temperate range from about 43-75F.

The good news about the dry humidity sensor is that it read 3-4% low across the entire scale and topped out at 97% (although I have been able to force it with a warm damp cloth to 100%). I’ve applied a +4% humidity offset, which allows the sensor to easily hit 100% and it has been +/-2% of my psychro-dyne with humidity all the way down into the upper teens (which we just experienced here recently). It recovers from high humidity much quicker than the Sensirion. Sometimes the sensor reads a little wet, other times a little dry. It’s nice to see this random error versus the constant systemic high humidity bias I was used to.

With that said, I did make a side by side comparison with the SHT75 with humidity down in the 20s. They read almost identical (with the +4% offset on the analog) and right on with the psycho-dyne, but with the caveat that the SHT75 had been indoors in a very dry environment and not exposed to the prolonged high humidity that seems to be that sensor’s weakness.

Compared to the nearest ASOS (KTIW), the analog compares favorably. Local effects here can be extreme in warm, dry conditions with proximity to water, wind direction and down and upsloping winds. My psycho-dyne always matches ASOS nearly exactly when I’ve done side by side comparisons, so as a sort of transfer standard, I trust it more than comparing to an ASOS with unique differences over 4 miles away
Really, if Davis would let their pride go
I highly doubt it has anything to do with pride.

Offline jgentry

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Re: Sensirion SHT-75 is now unavailable
« Reply #41 on: March 30, 2019, 03:51:31 PM »
Finally got a response back from Davis. They are forwarding my email to their design team. So hopefully they will look into the HYT-221 sensor and give it a shot.
Davis Vantage Pro2 & WeatherFlow Tempest. WU: KXALJEMI2, KALJEMIS7, KFLPANAM363 & KALTHORS2. CWOP/APRS: C6353 & E6358

Offline jgentry

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Re: Sensirion SHT-75 is now unavailable
« Reply #42 on: March 30, 2019, 04:02:25 PM »
Finally got a response back from Davis. They are forwarding my email to their design team. So hopefully they will look into the HYT-221 sensor and give it a shot.

Looks like Newark has them on sale.
https://www.newark.com/ist-innovative-sensor-technology/hyt-221/sensor-humidity-digital-w-filter/dp/44W8408
Davis Vantage Pro2 & WeatherFlow Tempest. WU: KXALJEMI2, KALJEMIS7, KFLPANAM363 & KALTHORS2. CWOP/APRS: C6353 & E6358

Offline johnd

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Re: Sensirion SHT-75 is now unavailable
« Reply #43 on: March 30, 2019, 05:19:08 PM »
Finally got a response back from Davis. They are forwarding my email to their design team. So hopefully they will look into the HYT-221 sensor and give it a shot.

But how can Davis do that without a significant redesign of the SIM board (which perhaps isn't very likely at this stage of the VP2's life-cycle)?
Prodata Weather Systems
Prodata's FAQ/support site for Davis stations
Includes many details on 6313 Weatherlink console.
UK Davis Premier Dealer - All Davis stations, accessories and spares
Cambridge UK

Sorry, but I don't usually have time to help with individual issues by email unless you are a Prodata customer. Please post your issue in the relevant forum section here & I will comment there if I have anything useful to add.

Offline jgentry

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Re: Sensirion SHT-75 is now unavailable
« Reply #44 on: March 30, 2019, 08:41:01 PM »
Finally got a response back from Davis. They are forwarding my email to their design team. So hopefully they will look into the HYT-221 sensor and give it a shot.

But how can Davis do that without a significant redesign of the SIM board (which perhaps isn't very likely at this stage of the VP2's life-cycle)?

Will Davis come out with a new station or just continue in improving the VP2?
Davis Vantage Pro2 & WeatherFlow Tempest. WU: KXALJEMI2, KALJEMIS7, KFLPANAM363 & KALTHORS2. CWOP/APRS: C6353 & E6358

Offline johnd

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Re: Sensirion SHT-75 is now unavailable
« Reply #45 on: March 31, 2019, 04:44:44 AM »
Will Davis come out with a new station or just continue in improving the VP2?

I genuinely don't know - either outcome is possible, at least in the shorter term, there being no real rumours of an imminent VP3 at this stage AFAIAA.

AFAICT Davis's focus is currently on enhancements to data handling from the existing sensors and stations with Weatherlink Live and further progress with the weatherlink.com features roadmap, which still has some way to run, plus some tweaks eg to the VP2 rain gauge, which we know about.

But I can't see into 2021 and beyond, and surely at some point there will be a new station model. It wouldn't surprise me if this was based around an EM node (though that's wild speculation based on zero inside knowledge). Of course if you had a temp/hum sensor that you liked with an SDI-12 interface then that is compatible electronically with an EM node already, though you'd still have to persuade Davis to build in software support, but that's potentially easier than a hardware redesign.

Edit: Speculating further, one thing that wouldn't surprise me would be to see a version of WLL that had receiver circuits for the Zigbee wireless that EM uses, in place of the VP2-type protocol. This would provide a mechanism for local data handling for EM nodes rather than requiring the EM gateway for remote 3G uploads. Or another way of doing something similar would be a modified EM gateway where the 3G modem board was replaced by a VP2 multi-transmitter board capable of beaming back all the data to an existing WLL unit.
« Last Edit: March 31, 2019, 06:01:53 AM by johnd »
Prodata Weather Systems
Prodata's FAQ/support site for Davis stations
Includes many details on 6313 Weatherlink console.
UK Davis Premier Dealer - All Davis stations, accessories and spares
Cambridge UK

Sorry, but I don't usually have time to help with individual issues by email unless you are a Prodata customer. Please post your issue in the relevant forum section here & I will comment there if I have anything useful to add.

Offline jgentry

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Re: Sensirion SHT-75 is now unavailable
« Reply #46 on: March 31, 2019, 08:05:40 AM »
Will Davis come out with a new station or just continue in improving the VP2?

I genuinely don't know - either outcome is possible, at least in the shorter term, there being no real rumours of an imminent VP3 at this stage AFAIAA.

AFAICT Davis's focus is currently on enhancements to data handling from the existing sensors and stations with Weatherlink Live and further progress with the weatherlink.com features roadmap, which still has some way to run, plus some tweaks eg to the VP2 rain gauge, which we know about.

But I can't see into 2021 and beyond, and surely at some point there will be a new station model. It wouldn't surprise me if this was based around an EM node (though that's wild speculation based on zero inside knowledge). Of course if you had a temp/hum sensor that you liked with an SDI-12 interface then that is compatible electronically with an EM node already, though you'd still have to persuade Davis to build in software support, but that's potentially easier than a hardware redesign.

Edit: Speculating further, one thing that wouldn't surprise me would be to see a version of WLL that had receiver circuits for the Zigbee wireless that EM uses, in place of the VP2-type protocol. This would provide a mechanism for local data handling for EM nodes rather than requiring the EM gateway for remote 3G uploads. Or another way of doing something similar would be a modified EM gateway where the 3G modem board was replaced by a VP2 multi-transmitter board capable of beaming back all the data to an existing WLL unit.

Gotcha. I’m definitely no electronics expert but could they design an adapter and sell it to those who want to use I2C sensors? I’m glad they are improving the rain gauge, but I do think they need to resolve their humidity issues ASAP. Which their main problem is that they use Sensirion sensors.
Davis Vantage Pro2 & WeatherFlow Tempest. WU: KXALJEMI2, KALJEMIS7, KFLPANAM363 & KALTHORS2. CWOP/APRS: C6353 & E6358

Offline drew1021

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Re: Sensirion SHT-75 is now unavailable
« Reply #47 on: March 31, 2019, 10:07:48 AM »
I want to share my experiences so far with switching over to the 75. I brought my ISS inside and after letting the sensor acclimate to the inside environment and comparing with my Belford 566 I had to input a +1 degree offset for temp. Humidity runs about +5% so no change from my 31, at least at room temperature. My 31 runs dry, however never exceeded 97%. I installed both the 31 and 75 into my ISS leaving the 75 hooked up. The only reason I can think why I had to input a +1 offset for temp may be because I'm using the very latest version transmitter. The ISS is back outside now so we'll see how it tracks.
« Last Edit: March 31, 2019, 10:35:24 AM by drew1021 »
VP2 with 24 hour FARS. WU: KNCLEWIS2. CWOP/APRS: DW4712, COCORAHS: NC-FR-7

Offline jerryg

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Re: Sensirion SHT-75 is now unavailable
« Reply #48 on: March 31, 2019, 11:05:33 AM »
That's right if you are using a new iss and install an older sensor then you have to put in a +.9 offset, just the opposite when putting a 31 into and older iss.

Offline drew1021

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Re: Sensirion SHT-75 is now unavailable
« Reply #49 on: March 31, 2019, 11:22:15 AM »
Thanks Jerry! Good to know what I figured out on my own turned out to be right. Now if I can figure out the humidity issue.
VP2 with 24 hour FARS. WU: KNCLEWIS2. CWOP/APRS: DW4712, COCORAHS: NC-FR-7