Hi all, I have 3x DHT11 temp / humidity sensors. (datasheet: http://www.micropik.com/PDF/dht11.pdf) These are great, inexpensive, digital sensors, however I am having trouble with the RH value varying wildly between different sensors. For example, of the 3 sensors I have, one reads 11%, second one reads 27%, and 3rd reads 34%, all sitting right next to each other. The temp readings all match each other. For each of them, I can "blow on them" and watch the RH reading climb. The datasheet indicates the RH is accurate +/- 5%, which is fine, however my results are showing a 24 point spread! Beyond that, if I place any of the sensors in a known humidity environment, for example I have several cigar humidors that are held at a relatively precise 70% RH, the sensors never show anything near that, typically topping out at around 40%. Unfortunately, an inaccurate reading is completely useless.
I'm wondering if anyone else has experienced this before, and also by contrast if the supposedly more accurate DHT22 yields much better results. If so, I wouldn't mind spending the money for a better sensor, but I don't want to throw money at the problem either.
As far as code, I am testing with the DHT11 example library, I am running this on an ATmega328, and I have switched to several different digital pins, with consistent results.