DIY A reliable and accurate humidty and temperature sensor.

[steelrat]

I see a lot of people get the same, cheap hygrometers for their growspaces. Having done six grow i've gone through a few of these and found them to be WAY off when it comes to humidity.

I happen to be a hobbyist electronics enthusiast so thought i'd try rolling my own (pun completely intended!).

What you need :

1. An Arduino.



Arduino - HomePage

These are cheap and readily available on Amazon, Ebay etc ...

2. A temperature/humidity sensor.

I use the DHT11, it sense temperature to within 2 degrees and humidity to within 5%, accurate enough for our needs. Available at Amazon, Ebay etc ...



3. A USB AB cable, just like the cable printers use.



The cable is needed so that you can log the data to your PC/Laptop whatever.

4. Some connecting wires, when you buy an arduino you usually get a few of these.



5. Some breadboard to plug in the DHT11 and connecting wires.

Method.

The DHT11 has 4 pins but, as you can see in the picture above, only three are used, in the following fashion :

1. The VCC pin goes to +3 volts on the arduino.
2. The Data pin goes to one of the Arduino's digital in sockets.
3. The ground pin goes to the arduino ground pin.

Very easy to connect.

The software setup is also very easy, just a matter of copying/pasting some text files to your Arduino directories.

Full instructions can be found here :

Arduino Playground - DHT11Lib

Once it's up and running, the unit outputs the readings every two seconds, these can be accessed via the serial monitor in the Arduino software interface.

This is the unit in operation in my current growbox :

https://www.autoflower.org/f5/grow-...r-one-critical-cheese-26571-3.html#post513197

Since we know it outputs every two seconds, it's easy to put the results in a spreadsheet and get detailed info, rather than just the min/max readings from a cheapy hygrometer.


steely

 

[steelrat]

To make it easier to import data into a spreadsheet, i've altered the program so it just reads out the temperature and humidity.

The program is attached.

View attachment DHT11.zip


steely

 

[CGR]

:five:........how cool is that +......can you recommenced one that fits in jars.

 

[KUDO]

Steelrat let me pass some that cool iv just order some bits im going make me own,i drop back ones i get it,but it look easy to put to giver,but i let you no how i get on :smokebuds:as this just work out just right for me,

 

[steelrat]

Hey thanks Glad if it helps.

It can fit in standard mason jars but would be a bit difficult to drill a hole through glass for the USB cable ;+}


steely

 

[steelrat]

Hey Kudo, thanks, i've zipped up the library folder and files for ya

Just unzip it to your 'My Documents/Arduino/Libraries' folder, so you should end up with 'My Documents/Arduino/Libraries/DHT11'.


steely

 

[KUDO]

Hey Kudo, thanks, i've zipped up the library folder and files for ya

Just unzip it to your 'My Documents/Arduino/Libraries' folder, so you should end up with 'My Documents/Arduino/Libraries/DHT11'.


steely

"Sharing One":five: thanks brv let me pass you a nice fat "Share a Joint..?" im on two it know

 

[wwwillie]

Yes, yes, yes!!!
This is the way to do it. Nicely done.
I have been toying with this plan for a while. Have grand plans to extend it to soil moisture and perhaps even control of fan and humidifier/de-humidifier.
This might be the impetus I was looking for.

 

[steelrat]

Nice one glad it's of help, i'm not using it in my current grow as temps and humidity are now stable and known but it's gonna get colder so i may have to put it in there again to make sure the girls aren't getting the wrong kind of frost ;+}


steely

 

[KsjAuto]

And i must say they work.

:hug:
Peace