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Soil moisture sensor

Discussion in 'Sensors and Actuators' started by BHUVANESWARI R, Oct 24, 2017.

  1. BHUVANESWARI R

    BHUVANESWARI R

    6
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    Aug 17, 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
     
  2. Bluejets

    Bluejets

    3,520
    714
    Oct 5, 2014
    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.
     
    BHUVANESWARI R likes this.
  3. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    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 likes this.
  4. BHUVANESWARI R

    BHUVANESWARI R

    6
    0
    Aug 17, 2017
    how to play with AC ?and do you have any idea about coating(galvanicing) to avoid corrosion?.
     
  5. BHUVANESWARI R

    BHUVANESWARI R

    6
    0
    Aug 17, 2017
    Thank you.
     
  6. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    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 likes this.
  7. BHUVANESWARI R

    BHUVANESWARI R

    6
    0
    Aug 17, 2017
    apart from gold any another possible chemical available?
     
  8. duke37

    duke37

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    726
    Jan 9, 2011
    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.:)
     
  9. kellys_eye

    kellys_eye

    4,281
    1,144
    Jun 25, 2010
    I recall seeing soil moisture sensors as part of Arduino-like kits - they offer this assurance...

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

    Alec_t

    2,695
    712
    Jul 7, 2015
    You could try carbon rods (from old zinc battery cells) as electrodes.
     
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