Someone can help to measure with a watermark moisture sensor

[pierrot10]

Good day.

Since a couple of day, I am trying to use a watermark sensor without bug success.
I got servreal documentation
First I found good information on
SMX datasheet
read paragraph 2 and 3.
I also look at this article and I worked on the schema b) under the title "Reading the Watermark 200SS Sensors".

Unfortunately, I can not get a reliable value.

I also found this good schema .

Finally, I also found this another alaterative

Which look nice but apparently there is a condensator in a bad sens.

I spent about four days, trying with Voltage divider.
I specially follow this tutorial, But I never got a correct value and I do not know if I am doing something else wrong or if I missed a detail.
I have two new Watermark. One is wet and the second is fully dry. I also have a WATERMRK digital reader and when I measure it with the reader, I got the value 199 for the dry sensor, and 0 for the wet sensor.

When I take the measure with my Adafruit Trinket Pro by alernating the polartity 10 time, I never get a value similar to the digital reader. The value are close 300 and more.

Now I am going to try the second schema, but as I sepnd so many time on this issue, I would like to know if some one as a good expertise with WATERMAK and adafruit or arduino board and how you develop you schetch t measure a Soil Water potetial in Kpa?

If you develop a such sensor with Arduino or adafruit, sharing your experience (Any links, exemple, titorial, recommandation), will help a lot.!

Many thank
Cheers

[A Former User]

This post is deleted!

[secantscope]

Hi there! Reading the Watermark sensor is no easy task indeed. Took us a while to get accurate and reliable data out of these sensors.

First of all, take a look at the official documentation provided by Irrometer: https://www.irrometer.com/200ss.html
Especially the pseudo-AC excitation is very important and make sure you calibrate the readings using the soil temperature.

There's quite some off-the-shelf hardware on the market already. Look for a device that has a low power consumption so you can measure throughout the year, for example:
https://www.crodeon.com/blogs/news/connecting-a-watermark-sensor-to-the-cloud

Let me know if you have any more questions!