DHT22 AM2302

After 2 months suddenly it stopped registering humidity.The reading for a few days were very high. I chalked it off as the humidity factor as we enter the rainy season. But today was 45-50% humidity.Even the wash area sensor registered 60.Something was wrong.It seemed to be recovering a little but i no longer felt it was accurate. So I swapped it for the DHT22 in my staircase lamp as I really don’t need a humidity sensor between floors, though good to have.It was still dead as the humidity was at a constant reading of 99.9%.I read it was for indoor use only afterward. Something about a dew point. Which got me thinking about attaching an old 5v CPU fan. My thoughts on the issue are that condensation/condensing humidity/dew point may have been a contributing factor to the humidity part of the sensor.As my old computer had recently died I tried to scavenge its parts. I was surprised to find that the fans use 12v… wait I wasn’t surprised but I thought the cpu fan might be so.Then I realized there would be no reason it would be 5v.Plan B. I remembered I had a laptop cooling pad with 2 fans powered by USB. As I don’t need it I attached it to the vcc and ground pin spliced ground with the PIR AM312.I attached a mosquito net behind the extraction fan and and the inlet of the air to the makeshift case.From the front of the mesh (intake)And the back of the multi sensor (exhaust)A few days later and it’s working great.–A week later with many days of constant almost 100% humidity and it’s still going strong.The constant noise is an issue.I’m thinking of sticking in a resistor to limit the speed & sound

—-Couple weeks later. It would seem the rainy season is back. The weather news had it wrong. My outdoor humidity sensor is flatlining again… even with constant wind… hmm time to rethink things again perhaps. _____Update 3There’s been a 24+ hour break in the rain… the sun was out yesterday and today. The evenings being more (very) humid don’t help much. This morning there were signs of life. Perhaps the humidity was 100 at the sensor placement. (Unlikely). The current weather humidity prediction is 65%. The sensor is outside placed high under a veranda so perhaps more humidity as evaporation is collecting there. Time will tell.

___Next day. Today is sweltering hot and sunny. According to the weather forecast the humidity levels should be about 70%. This is on par…


Weeks after the initial panic. It just seems that the reading are high as the area is super humid. 90+ seems to be a regular occurrence lately.

All is well.


Update a year later.

All is not well. The DHT22 isn’t very good and I’ve tested the BME280 which is so far great. Part 1 of the BME280 entry here.

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