Wemos D1 mini+DHT22 shield - Heat from chip influence on dht22

[vojtishek]

Hi all,

Do you have any idea how to isolate dht22 shield from heat of esp8266 chip?

I´ve just discovered that temperature is like +3C° comparing to other reliable sensor.
Root cause possibly will be heat from esp8266.

It is slightly changing so I don´t want to reduce that by formula.

Any help appreciated.

Thanks
V.

[costo]

You can be sure that the wemos is generating some heat that will warmup the DHT sensor on the shield.

many solutions possible:
Make the distance between the DHT shield and the wemos itself larger with a set of extra pinheaders.
Move the air with a ventilator so heat of the Wemos will be blown away.

[Shardan]

This will be a problem at every given time.

The ESP gets warm and the voltage regulator on the WeMos D1 (or any similliar board like node MCU too) gets warm.
As costo said you need to get some distance between the sensor and the WeMos.
This can be done by pin headers or Dupont cables.
Another possible solution might be the double and triple base from WeMos:

https://www.aliexpress.com/store/produc ... 33925.html

https://www.aliexpress.com/store/produc ... 33164.html

Regards
Shardan

[vojtishek]

Thank you guys.
I like double/triple base solution, didn´t know something like that exist.

Just testing deep sleep mode to reduce heat on chip, currently temperature little bit more accurate.
Let´s see what will be the best solution.

I will report here then.

[vojtishek]

So I have another dht22 on wemos D1 next to wemos D1 mini for comparsion.

Solution seems to be to run wemos D1 mini in deep sleep mode, awaking every 60 second to send data, to reduce heat from chip.
Just tested for one hour and there was a difference +1C° on d1 mini in comparsion to d1. So I've applied formula -1 on d1mini.
Results are currently same. Only humidity differs 8%.

I will leave that setting over night and let's see.

[Shardan]

Hello,

if you want accurate measurement i recommend to use a somewhat precise thermometer directly besides the sensor.
I use something like this: http://www.alexmo-cosmetics.de/bilder/p ... ometer.jpg
These lab thermometers are sold for around 5..6€ for a non gauged version.

Why this?

The DHT22 datasheet from the original manufacturer Aosong gives a temperature accuracy of +/- 0,5°C.
https://www.sparkfun.com/datasheets/Sen ... /DHT22.pdf
So in worst case you're measuring the same temperature even if your readings say 1°C differendce.
Or the other way round, you see 1°C difference but it is 2°C in real.

Regards
Shardan