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Weather Station Hardware => Other Weather Station Hardware => Topic started by: ValentineWeather on August 04, 2017, 03:27:28 PM
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There was a thread somewhere about looking for accurate probe thermometers, at time I couldn't find link on units I purchased some years ago with now expired certification. gvmelbrty PM link so here it is. I'm not sure of stock or wait time because it says call for availability. They are certified at 4 different temperatures so pick temperature before ordering. I've drilled a hole in bottom of Davis shield up into sensor chamber and have cross checked against sensor using these handy probe thermometers.
https://www.coleparmer.com/p/digi-sense-extreme-accuracy-digital-thermometer-with-calibration/59080
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Called about stock there is 5-6 week delay on any of the models. The EW-90000-29 is certified .05C accuracy at 3 different temperatures 0.00/25.00/37.00C instead of just 1 for almost the same cost.
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Found same thermometer with different name on Amazon. Called Thomas Traceable Extreme-Accuracy Thermometer, 6.25" Stem
The combination of all 3 temps is cheaper here for some reason. and in stock. https://www.amazon.com/gp/product/B006H8MDO0/ref=oh_aui_detailpage_o00_s00?ie=UTF8&th=1
The 6-1/4" Stem is the all 3 combo. Currently listed cheaper than specific ranges.
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The one shown on the Amazon link seems the same in many ways, but then the display is different for the max min, apparently those from Amazon need to be switched back and forth. Doesn't make mch difference for my way of using it, but will study it. And the prices listed when I went to the site are as high or higher than from Cole.
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Cheaper for the combination unit of all three temps calibrated on Amazon.
$113.40USD / EACH + shipping on Cole plus a 5-6 week wait.
Amazon $92.55 free shipping if Prime member and receive 2 business days.
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I gotcha.
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I asked question to seller why they had the 3 point calibration listed cheaper, waiting for an answer.
I checked my digi-sense unit (0.0C 32F) in crushed ice bath while stirring it read 32.2F so it's still on even though NIST certificate expired couple years ago.
Nice little units and only way to field check SHT sensors with any kind of accuracy.
Hanging an accurate outdoor thermometer nearby just doesn't work because of radiational cooling at night or daytime sun exposure.
Temperature needs sampled with same aspirated air SHT is experiencing so these sensor probes ability to go into sensor chamber is the best way I've found.
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Randy, how long does it take for the probe reading to "settle down" to the actual temp?
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Randy, how long does it take for the probe reading to "settle down" to the actual temp?
It's very responsive to any change so complete settle down it really doesn't.
A couple people on phones remembering the Davis lag time 2.5 seconds doing a direct comparison would work.
The way I do most stuff is alone so taking advantage of thermometer max and minimum comes in handy, resetting so you don't need to stay with it.
I also like to start archiving data every 10 seconds with envoy8x and compare with max and minimum temperatures captured by thermometer during specific time.
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Randy, how long does it take for the probe reading to "settle down" to the actual temp?
It's very responsive to any change so complete settle down it really doesn't.
Thanks, but what I'm after is for instance if the probe is in the house at 70F and you take it outside where it's 30F, how long before it gets to 30?
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Randy, how long does it take for the probe reading to "settle down" to the actual temp?
It's very responsive to any change so complete settle down it really doesn't.
Thanks, but what I'm after is for instance if the probe is in the house at 70F and you take it outside where it's 30F, how long before it gets to 30?
I see. :lol:
Well it's fast just estimating within 2 minutes it would reach 30°. Batteries died, they last about a year and no shut off on unit.
I need to get some AAA's I'm fresh out and I'll do a test from freezer to room temperature.
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Excellent, thanks!
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Going down was faster. 78-26: in 75 seconds. Going up from 26-78:135 seconds.
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Going down was faster. 78-26: in 75 seconds. Going up from 26-78:135 seconds.
That's a rather w-i-d-e hysteresis loop time.
Conditions were different inside freezer, compressor was running blowing cold air on probe, outside probe was just exposed to dead still air. If I was to put some kind of aspiration on probe I'm sure it would of recovered much faster.
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Oh no! Now a discussion of FARS on temperature probes. Just kidding
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How does the response time compares between the Thomas sensor and the SHT-31 in the FARS?
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How does the response time compares between the Thomas sensor and the SHT-31 in the FARS?
It's still faster with 1 second update. The probe thermometer does have a switch for slowing response down some may want to use. I tested for 8 hours one day and temperature difference never exceeded .2F max and it occurred outside one of the 3 points certified ranges.
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How does the response time compares between the Thomas sensor and the SHT-31 in the FARS?
It's still faster with 1 second update. The probe thermometer does have a switch for slowing response down some may want to use. I tested for 8 hours one day and temperature difference never exceeded .2F max and it occurred outside one of the 3 points certified ranges.
Nice! I think the SHT 3x updates every two seconds but the transmitter only sends an update every 10-12 seconds