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Author Topic: Beware the THN132N  (Read 6974 times)

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Offline aweatherguy

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Beware the THN132N
« on: March 05, 2013, 01:56:11 AM »
I've discovered a problem with the THN132N temperature-only sensors. I have not seen this problem with other OS sensors. Unlike many OS sensors, this unit operates with a single 1.5V AA battery.

The problem is that temperature readings are significantly affected by battery voltage. These errors depend on how far you are from a "golden point" of 25C. In other words, if the temperature is 25C, battery voltage is irrelevant. On the other hand, if the temperature is 0C or 40C, errors can be as much as 0.8C. And at -20C the errors can reach 1.4C or more.

I've attached a graph showing measurements I've made of changes in reported temperature as battery voltage is varied between 1.2V and 1.6V. These errors are relative to the reported temperature with a battery voltage of 1.5V. This sensor is not functional at 1.1V and below.

I have performed similar tests on OS temperature/humidity sensors which run on two 1.5V batteries (THGR122NX, THGN123N, THGR801N, THGR810) and they are rock-solid. No change in reported temperature for battery voltages over the range from 2.0 to 3.0V.


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Offline Old Tele man

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Re: Beware the THN132N
« Reply #1 on: March 05, 2013, 01:04:53 PM »
Now you know why I dumped my OSI WMR200 system--(in my best Popeye the-sailor-man voice) "...you GETS whats you PAYS for..."
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Offline Skywatch

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Re: Beware the THN132N
« Reply #2 on: March 05, 2013, 01:51:17 PM »
Wouldn't be so sure. My WMR200 has been a good little boy  :-)
You probably got stuck with a bad seed.

Davis will always be my first pick but Oregon Scientific follows a 2nd place after Davis in my books.
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I live in an apartment and for the moment am not a home weather watcher.

I am a storm chaser.

Offline mackbig

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Re: Beware the THN132N
« Reply #3 on: March 05, 2013, 07:22:26 PM »
Interesting find.  Not as bad as the BTHR968 on the wmr 968.

When it gets low you have a few weeks to act.  The temp and humidity will continue to report fine, then all of a sudden the barometer will swing wildly.  It will all of a sudden spike to 1074mb, then tank to 624mb and stay there for several days.

I would much prefer it just turn off, and show --- for all three measures.

Andrew



old thread.
http://www.wxforum.net/index.php?topic=3558.msg28940#msg28940

Andrew
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Andrew - Davis VP2+ 6163, serial weatherlink, wireless anemometer, running Weather Display.  Boltek PCI Stormtracker, Astrogenic Nexstorm, Strikestar - UNI, CWOP CW8618, GrLevel3, (Station 2 OS WMR968, VWS 13.01p09), Windows 7-64

Offline Old Tele man

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Re: Beware the THN132N
« Reply #4 on: March 06, 2013, 11:29:47 AM »
IMHO wx-gear should, like a Doctors' Hypocritic Oath, "...show no erroneous data..."
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• SYS: Davis VP2 Vue/WL-IP & Envoy8X/WL-USB;
• DBX2 & DBX1 Precision Digital Barographs
• CWOP: DW6988 - 2 miles NNE of Cortaro, AZ
• WU - KAZTUCSO202, Countryside
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