Capacitive Soil Moisture Sensor V.2

torben 2023-07-14 09:17:43 774 Views13 Replies
Hi,
If I take consecutive readings every 3 minutes after having watered an indoor pot without flowers, the readings may start with, say, approx. 245 and continue with that for, maybe, 8 hours. Then the readings start climbing over a period of approx. 3 hours till they reach approx. 256 at which point they start going down again.
I had expected a steady increase because of the drying out of the pot.
Can anyone explain?
Best regards
torben

2023-07-30 22:58:52

Hi bidrohini.bidrohini,

No, I am sure nothing like that happened. Conditions were stable.

Best regards

torben

torben

2023-07-29 04:50:04

Hi Jenna,As far as I can see you start to have some fluctuations in the beginning. Then it drops from 510 to 490 rather fast when you water and then stays stable for a long time after which it suddenly increases 5 points.I give the sensor 15 min. to stabilize before I take as a base reading the avg. of 10 readings. I then take readings until I get a value 3 above the base and I take that value as the point at which I should stop watering. I think I have taken reasonable precautions.Still, at one point the readings jump upwards 48 points - which throws the system off balance - and a bit later the readings drop 48 points.The difference between watering and stop watering (10 points) is chosen arbitrarily in order to get experience.

You see what bothers me: The instability of the sensor - if the problem is the sensor. But taking readings is such a simple thing.Best regardstorben

torben

2023-07-28 02:46:39

Hi bidrohini.bidrohini,

I did not touch the sensor while I took the readings.

Since I have done quite a few sequences and finally the sensor started perform normally - ie. slowly and steadily increasing the reading as the pot dried out.

That is worrying. Was there a fault in the sensor that disappeared or do sensors have to be “run in”?

Best regards

torben

torben

bidrohini.bidrohini wrote:

Maybe there was water on the sensor's body or something like that. Maybe the readings were effected by its surrounding.

2023-07-30 06:25:28 1 Replies

2023-07-26 04:08:51

The final output value is affected by probe insertion depth and how tight the soil packed around it is. We regard "value_1" as dry soil and "value_2" as soaked soil. This is the sensor detection range. For example: Value_1 = 520; Value_2 = 260. The range will be divided into three sections: dry, wet, water. Their related values are:

Dry: (520 430]Wet: (430 350]Water: (350 260]

Check if the depth or tightness is varying.

bidrohini.bidrohini

2023-07-20 13:14:17

Hi R2D2C3PO,

Here is a series of readings taken without first watering the system (approx. 3 min. interval):

For 8 hours the readings stayed at approx. 268

For 51 min the readings went from 268 to 279

For 75 min the readings went from 279 to 266

when the system stopped.

Best regards

torben

torben

jenna wrote:

Hi！

Is there an update on data on dry soils?

Compared with my test data, the data difference between your three intervals is not that big.

The sensor data fluctuates over a long period of time.

It is recommended that you try to increase the contact area between the sensor and the soil, refer to this picture. This may have something to do with the amount of water given to the soil.

2023-07-29 02:00:00 1 Replies

2023-07-19 01:37:44

Hi Jenna and R2D2c3PO,I am sorry it took some time to come back.I have an indoor pot with earth (no flower) which I wet befor beginning to get a series of readings. I am sorry I could not see how to attach a file. I take a reading aprox. every 3 minutes over a period of approx. 15 hours. The readings vary between approx. 255 and 267 in waves.In Water I read 1 and in air I read 637. In earth I read approx. 255 corresponding to input 4,6 V and output 1.14 V.For readings I use Picaxe readadc10.I cannot figure out what is wrong - can it be a problem that there is no flower in the pot?

It is OK that the readings stay at about 255 for 3 hours - I assume that is the time it takes to get rid of excess water, but then the reading should start to climb steadily.

Can you help?Best regardstorben

torben

jenna wrote:

Hi!

I use Arduino UNO to test. (reference voltage 5V, ADC 10 bit)

about 2.5V

about 1.8V

The depth to which the sensor is inserted into the water is the depth to which it will be inserted into the soil.

I will continue to update the data.

2023-07-19 23:39:34 jenna wrote:

It's normal for the sensor data to exhibit some fluctuations. For instance, when I placed the sensor in water, it showed minor variations in the output data over a few hours.

in water 497~501