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Soil moisture sensor outdoors
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Soil moisture sensor outdoors

by Gerymake on Sat Apr 06, 2019 11:29 am

Hello,

I am planning on installing a capacitive soil moisture sensor outdoors (https://www.adafruit.com/product/4026). I will be straightforward: is it possible to install this sensor outdoors? If possible, do I have to protect it (add a cover, seal the wiring...) or is it completely weather-proof on its own? If not, what should I do to sort it out?

Thanks in advance,
Gerard

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Re: Soil moisture sensor outdoors

by adafruit_support_bill on Sat Apr 06, 2019 11:37 am

The circuitry and connectors on the top end of the board are not weatherproof. You can protect it with a conformal coating - preferably one rated for UV exposure. Conformal coatings are available from any of the larger electronics suppliers like Mouser or DigiKey. You can probably find some on Amazon as well.

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Re: Soil moisture sensor outdoors

by Gerymake on Sat Apr 06, 2019 12:28 pm

adafruit_support_bill wrote:The circuitry and connectors on the top end of the board are not weatherproof. You can protect it with a conformal coating - preferably one rated for UV exposure. Conformal coatings are available from any of the larger electronics suppliers like Mouser or DigiKey. You can probably find some on Amazon as well.


I have made some research. Despite the fact that it seems a great option it may not adjust to what I'm looking for. I need to get it done for a final school project while keeping the budget as low as possible. I have read an option wich may well be viable in my case: using silicone directly, The main downside is temperature, I live in an area where we can reach 35 celsius degrees. Therefore, would you recommend sticking with the conformal coating or cosindering another option?

Thanks,

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Re: Soil moisture sensor outdoors

by adafruit_support_bill on Sat Apr 06, 2019 7:26 pm

Silicone is an option. But avoid the 'acid cure' type since the acid will attack the electronic components. Acid cure silicone is easily recognized since it smells like vinegar.

Look for silicone sealant that is rated as safe to use for electronics or for aquariums. The electronics-safe type can be found in some hardware stores. The aquarium-safe type can be found in pet-stores.

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Re: Soil moisture sensor outdoors

by Gerymake on Sun Apr 07, 2019 12:08 pm

Thank you so much! One last question, shall I apply the silicion/coating to all the electronic components area or omit certain areas? What about the JST pin, how may I seal it (I will buy this JST 4-pin to female socket cable https://www.adafruit.com/product/3950)? And finally, after having applied X substance, is it a good idea to cover the upper part of the sensor with a box (any type of enclosure) or take any other precautions?

PD: Finally I am going to opt for the conformal coating since it seems to be the most reliable and durable method.

Thanks,

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Re: Soil moisture sensor outdoors

by adafruit_support_bill on Sun Apr 07, 2019 12:36 pm

The conformal coating should cover all of the electronic components. But be sure to attach the JST cable before applying the coating. Otherwise, the JST connector will get filled with the coating and you will not be able to plug the cable in.

If you have the sensor and jst plug of the cable well coated, it should be weatherproof enough and not require any additional protection.

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Re: Soil moisture sensor outdoors

by flightlead404 on Sun Sep 15, 2019 2:44 am

IDK if you have any luck with that sensor but AFAIAC its useless.

I've tried it with multiple boards, moteino, arduino pro mini, huzzah feathers......the results are nowhere near stable or repeatable enough to be useful. In free air you can tell when it's not being touched, e.g. readings in the low 100's for bone dry, typical room humidity, untouched, up to just over 1000 for a human touch, and higher if you wrap in a soaking towel.

But stick it in damp soil its useless. I take 100 readings 10 msec between them, and they vary wildly. And no, it's not a power issue I've tried with multiple boards and also tried with regulated power delivered externally from the board.

Useless for soil moisture sensing as far as I can tell.

Maybe I got a bad board, idk, I ended up just building a timing mechanism and calibrating to deliver x ml/day.

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