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3D printed Stevenson screen for the DHT22

Added by dzach almost 6 years ago

Hi all

I’m trying to set up a simple temperature/humidity/light meter in the boiler room. The Jeenode will be housed on a DIN rail inside the room and the sensors, DHT22 and photoresistor, will be located outdoors, and will be housed in something like this:

The above 3D printed housing is a failure, because there is not enough air circulation inside, despite the fact that the bottom was intentionally left open:

I’ll have to put some openings on the cylindrical surface to allow more air circulation. The problem I have is different though. Running the dht_demo.ino sketch gives:

[dht_demo]
temperature = 8
humidity = 17

temperature = 8
humidity = 17

These readings are wrong. Temperature is measured with a thermocouple: 19°C:

The JeeLabs article linked above says:

The DHT11 and DHT22 sensors measure temperature and humidity, and are easy to interface 
because they only require a single I/O pin. They differ in their measurement accuracy, 
but are in fact fully interchangeable.

but I read elsewhere on the internets that The hardware pins and handshake are identical but it uses a different dataformat. . In fact, running the code from that link gives me:

DHT TEST PROGRAM 
LIBRARY VERSION: 0.1.05

Type,   status, Humidity (%),   Temperature (C)
DHT22,  OK, 45.3,   21.9
DHT22,  OK, 45.3,   21.9

which is a lot closer to the expected values.
Any suggestions on what might be wrong?


Replies (26)

RE: 3D printed Stevenson screen for the DHT22 - Added by xz81 almost 5 years ago

dzach: Thank you very much!

I will print them asap.

(26-26/26)