Geller voltage reference schematic ??

[CalibrationGuy]

@guenthert: My unit was shipped with batteries. If you don't remove them or replace them periodically, they can leak and destroy the device. That's one thing to check. If that's not it, sounds like maybe a bad capacitor. Sometimes they go bad and need a period of applied voltage before starting to work correctly again. If it's worth your time, have a look. Unfortunately, the binding posts are soldered to the board, so you'll have to do some "surgery" to get the board out. I can see from the side that mine has a reference in a SOIC8 package.

Also, if it's of any value, mine starts at 10.000491Vdc and slowly moves down to 10.000097Vdc over the course of anywhere between 30-60min.

Off all night. Turned on, here's the results:

Temp: 74.5 DegF
6:58PM - 10.000491
7:05PM - 10.000298
7:14PM - 10.000162
7:28PM - 10.000125
7:40PM - 10.000117
7:52PM - 10.000116
8:06PM - 10.000113
8:20PM - 10.000112
8:23PM - 10.000110
8:32PM - 10.000108
8:44PM - 10.000108
8:50PM - 10.000106
Turn A/C On High
Temp: 70.9 DegF
9:23PM - 10.000097
Temp: 71.0 DegF
9:59PM - 10.000090

TomG.

[guenthert]

@guenthert: My unit was shipped with batteries. If you don't remove them or replace them periodically, they can leak and destroy the device. That's one thing to check. If that's not it, sounds like maybe a bad capacitor. Sometimes they go bad and need a period of applied voltage before starting to work correctly again. If it's worth your time, have a look. Unfortunately, the binding posts are soldered to the board, so you'll have to do some "surgery" to get the board out. I can see from the side that mine has a reference in a SOIC8 package.

Also, if it's of any value, mine starts at 10.000491Vdc and slowly moves down to 10.000097Vdc over the course of anywhere between 30-60min.
[..]

    Just recently I found the courage to open the box.  All nice and clean, the (Amazon branded) batteries are still fine.  Just prior, it actually settled quicker.  I don't monitor humidity in-house yet, only occasionally stare in disbelief at the weather app's report for local outside humidity.  Having lived for some twenty years in the southwest USA, 95% or more (!) rel. humidity as found frequently here in Ammerland seems outlandish.