Temperature and Humidity way off

[alphatech]

I have several of these boards in the basement, unfortunately none of them they register the right humidity and temperature on them. Do I need to put some kind of resistor on the sensor or the sensors do not work on these boards? On the attachment, it shows the humidity taken from Temp08 controller and the other from Arduino. The humidity should be around the 50% like as the temp08 board.

[joegr]

My understanding is that the DHT11 sensors are very bad in terms of accuracy. The DHT22 are better, but still really bad. I use BME280s because I need pressure readings too. They are pretty good, but not perfect either.

[alphatech]

Thank you Joegr. I went to Amazon and is funny they say that the accuracy for DHT22 is

• Temperature measurement accuracy: +/- 0.5℃ degree celsius
• Humidity measuring range: 0~100%RH, Humidity measurement accuracy: ±2%RH

Do you think that buying the DHT22 would improve the readings and closer to the actual humidity? It has been a long time since I play with these, same wires correct? would do code change?

[Cor]

If you want good and reliable temperature measurements I suggest you use Platinum Resistance Temperature Detectors (RTDs). You will find enough info on the web how to use them, including example code.

[alphatech]

Great suggestion, I will look into it. In the meantime, do you know if I need a resistor on these temp/humidity devices?

[Cor]

No, what you do need is a current source i.e. the Max31865. You will find several places on the web with examples. Search on 'pt100 on esp8266'.

Another suggestion - if you do not need to measure with high accuracy - is the Dallas DS18B20 temperature sensor. Here too, a lot of examples on the web. They come in several packages. I find them reasonable stable.

For air quality measurements I use the Cozir-A sensor for temperature, relative humidity and concentration CO2.

[alphatech]

You are the best, I will look into those.

Thanks

Sent from my SM-G973U1 using Tapatalk

[dmurphy]

In general I would have said none of the listed devices are that bad.....actual 50% reading 99%.....i would suspect something else.Power supply are u using correct 5v or 3v with or without regulator? The I2c devices do not require a resistor the one-wire ds18b20 does size of resistor will depend on voltage and wirelength to sensor....

[alphatech]

Sorry about the delay, there are canakit Model DCAR-RSP-1A
Output 5.1V DC 1A