I have an outside humidity and temperature sensor that uses the AM2302. Some month ago the humidity value it showed went up to 99% and sort of stayed there. Replaced it.
Now the new one, all of the sudden, same problem.
These are 'capacitive sensors', could not find anything wrong with my circuit and software (serial ink), so was wondering... What could cause a capacitive sensor to have a high humidity reading all of the sudden? Sure, leaking capacitor?
A magnifying glass showed what looks like a little on chip PCB with a gold electrode, and 2 tiny wires. But no air dielectricum, some other material.. Also a black blob, vertical.
One thing in the datasheet took my attention, had not noticed that before (datasheet is in Chinglish) something about a steady airstream:
[2] to achieve an order of 63% of the time requiredDelphi Oracle (Pythia) would be proud of that statement....
Nowhere a reference to [2], so what did they mean? No 'airflow', I would have thought the storms of the past few days would have fixed that ...
*BULB* and indeed it was now at 98 % humidity, but the housing screens it a lot from sidewinds, and 100 % from rain.So took it inside, blew at it strongly, back at normal value. Conductive? dust it must have been.
Good thing I kept the old one too.