Soil moisture sensor

BHUVANESWARI R · Oct 24, 2017

Hi geeks,
i am doing a project under the title "smart plant irrigation". For my project, i am using a soil moisture sensor to read the water level of the soil every minute.I bought this one for my project initially - https://www.amazon.in/KitsGuru-Mois...ag=f6c9b37a-4b59-4bb6-a592-46e644d320fd.After 2 weeks, the soil moisture sensor reads wrong value due to corrosion.After that I prepared my own the soil moisture sensor using resistor and two nails.As a result, the nails also get corroded.I don't know to resolve the problem.so please guide me.
Thanks in advance

Bluejets · Oct 24, 2017

Feed the sensor with ac or a reversing dc, will need a different circuit from what you already have( no idea here)
The dc is currently causing electrolysis.
Plenty of circuits already out in Google.
Current sensor you are using will never last, use stainless probes in conjunction with new circuit.
Perhaps also only read the moisture once or twice a day, surely that would be enough.

Harald Kapp · Oct 24, 2017

Corrosion is to be expected from the electrochemical reaction between the metal and the moist soil.
Use stainless steel electrodes or gold plated electrodes (probably too expensive).

BHUVANESWARI R · Oct 24, 2017

Bluejets said:

Feed the sensor with ac or a reversing dc, will need a different circuit from what you already have( no idea here)
The dc is currently causing electrolysis.
Plenty of circuits already out in Google.
Current sensor you are using will never last, use stainless probes in conjunction with new circuit.
Perhaps also only read the moisture once or twice a day, surely that would be enough.
Click to expand...

how to play with AC ?and do you have any idea about coating(galvanicing) to avoid corrosion?.

BHUVANESWARI R · Oct 24, 2017

Harald Kapp said:

Corrosion is to be expected from the electrochemical reaction between the metal and the moist soil.
Use stainless steel electrodes or gold plated electrodes (probably too expensive).
Click to expand...

Thank you.

Harald Kapp · Oct 24, 2017

AC is a good idea, but this sensor board does not seem to be fitted for AC operation.
Galvanisation is possible, the coating needs to be chemically inert, e.g. gold.

BHUVANESWARI R · Oct 24, 2017

Harald Kapp said:

AC is a good idea, but this sensor board does not seem to be fitted for AC operation.
Galvanisation is possible, the coating needs to be chemically inert, e.g. gold.
Click to expand...

apart from gold any another possible chemical available?

duke37 · Oct 24, 2017

Gold plated wire has been used for electronic organ contacts and a meter of this should be affordible. It is very small diameter though so the resistance to soil may be too high.

Platinum and platinum/rhodium wire should also do but you may need to sell your tiara to buy it.

kellys_eye · Oct 24, 2017

I recall seeing soil moisture sensors as part of Arduino-like kits - they offer this assurance...

One commonly known issue with soil moisture senors is their short lifespan when exposed to a moist environment. To combat this, we’ve had the PCB coated in Gold Finishing (ENIG or Electroless Nickel Immersion Gold).
Click to expand...

At $4.95, certainly worth a punt....https://www.sparkfun.com/products/13322

Alec_t · Oct 24, 2017

You could try carbon rods (from old zinc battery cells) as electrodes.

Soil moisture sensor

BHUVANESWARI R

Bluejets

Harald Kapp Moderator Moderator

BHUVANESWARI R

BHUVANESWARI R

Harald Kapp Moderator Moderator

BHUVANESWARI R

duke37

kellys_eye

Alec_t

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