Leaf Wetness

Hello,
My name is Elisavet and I am a newbie in Arduino.
I have a Leaf Wetness sensor and I have to connect it to an Arduino Pro Mini.
My sensors is this Leaf wetness sensor

I know that it makes analog measurements.

Did anyone have this sensor or any idea about the soldering procedure?

Looks to me like it's just a switch: moisture shorts the "wires" and thus shorts the connections on the board. It's not analog at all: simple on and off, so use it like it's just a push-button switch.

the leaf wetness sensors measures "resistance ranges".
e.g. if the resistance is 5KOhms, it means "heavy rain"... if the resistance is 200KOmhs is "very dry"...
something like this... It measures particular values ... not only on/off....

One specific question is, if I can solder two wires to the sensors and then these wires to the
arduino board directly, in order to measure the values.

I may be wrong but I think you are a component missing. Moisture sensors like this usually come with a control board.

http://www.ebay.co.uk/itm/1-Rain-detector-module-and-sensor-board-kit-for-easy-arduino-interface-DIY-/161375533241

Perhaps this could work (untested):

dannable:
I may be wrong but I think you are a component missing. Moisture sensors like this usually come with a control board.

http://www.ebay.co.uk/itm/1-Rain-detector-module-and-sensor-board-kit-for-easy-arduino-interface-DIY-/161375533241

I dont have the control board. They just give me the sensor. So, I have to make it work without the specific board.

dlloyd:
Perhaps this could work (untested):

Thank you, I will try this. But I dont know "1μF"? What is that mean?

Its a one microfarad capacitor. Digi-Key

elisavetgrig:
the leaf wetness sensors measures "resistance ranges". .... It measures particular values ... not only on/off....

Ah ok, that makes sense. I did wonder after I posted, if a tiny droplet would actually turn it on.

In that case have a look at this..... the LDR there is a variable resistor just like yours is, so although your sensor's not an LDR the idea of the voltage divider as shown in dllloyd's post, is the same.

Did you mean something like the attached figure? Or I only need to connect one resistor to one wire and the other wire to another pin in the Arduino, without resister?

Different ways of connecting the sensor (includes JimboZA's suggestion).
A capacitor is needed because the input impedance is >10K and it will help stabilize readings.

I have some issues:
My Arduino supply only 3.3V not 5V.
And (until now) I have only 10K resistors.

Do you suggest me to buy and connect 47K resistors and 1μF capacitors?

Thank you very much for your help!

You could connect several 10K in series to get 20K. The capacitor can be anything from 0.1µF to 2.2µF.

Voltage Divider Calculator

Edit: 10K would also work, but would limit the range somewhat. Try the voltage divider calculator to see.