I always had doubts on which one of these sensors to use. Thanks for explaining so well and solving my dilemma.

@AndreasSpiess

4 жыл бұрын

Glad to help

As expected, another superb exposition! Thank you Andreas.

Thanks for the video. I ordered a capacitive sensor and will add it to my projects queue.

Hi Andreas! You can not imagine how valuable this video is for me! I know programming but almost nothing about electronics. I have started about a month ago and your videos are helping me a lot (I still don't understand a lot but it's a way to know what to study). I will try to reproduce your sensor and connect it in an esp32! Again thanks a lot!

@AndreasSpiess

6 жыл бұрын

Thank you for your feedback and good luck with your build!

Great job, Andreas. I love the detail you've gone into, even finding the schematics for these unknown models.

@AndreasSpiess

6 жыл бұрын

I wanted to understand how they work myself!

@abdulrahmanismailali1064

Жыл бұрын

@@AndreasSpiess can you help me in my Arduino project

@AndreasSpiess

Жыл бұрын

@@abdulrahmanismailali1064 i am a KZreadr and do not do consulting.

I know it's one of your old videos, but this is incredibly helpful. Thank you again Andreas!

@AndreasSpiess

3 жыл бұрын

Glad it was helpful! This video still gets lots of views.

the quality of your content is unmatched! a comprehensive walk through the circuit diagrams and a solution -- what more could you ask for

@AndreasSpiess

2 жыл бұрын

Glad you liked the video!

Nice video Andreas.

@AndreasSpiess

6 жыл бұрын

Thank you!

After a heck of a lot of failed tests, I went to an AC drive detection scheme initially seen from National Semiconductor in the later '70s. My version drives a Ti electrode at around 100khz and 12v peak to peak capacitor coupled (a 555) - neither value is too critical - and senses via a voltage doubler (or a few of them for water level in a tank) consisting of two diodes and two .1uf caps loaded by 100k and directly driving an arduino or ESP logic input for water level, or with different loading to suit your electrodes, an a/d converter. Water has a dielectric constant around 80 - so here we are using the capacity change as water is more or less present between the electrodes. I'm using titanium wire for those (pure) as in most cases it wouldn't corrode even electrolytically, and have had one system (for cistern water level) in continuous use for around 10 years now with no maintenance required. Nothing else ever survived even a whole year - floats stick, optics cloud up, any DC stuff corrodes and so on. Sadly, I didn't do a full documentation on this yet - it's so simple I just remember it, maybe I should and share it - or maybe Andreas can, he'd do a nicer job. Nice pics/plots of what I did do are here: www.coultersmithing.com/forums/viewtopic.php?f=59&t=904&p=5584&hilit=water+level#p5584

@AndreasSpiess

6 жыл бұрын

Sounds like an alternative concept. It would be good if you document it one to be used by others.

@DCFusor

6 жыл бұрын

I will. Your skills in explaining would probably be superior re telling people how to tune the parameters for a given task...

@DCFusor

6 жыл бұрын

Here you go, folks. Let's bug Andreas to do this up right! www.coultersmithing.com/forums/viewtopic.php?f=7&t=1098&p=6438#p6438

@seamusdemora5598

3 жыл бұрын

@@DCFusor Great article - thanks for writing that up, and sharing it here. One point that I'm not clear on: You use alternating current (ac) to drive your "water tank capacitors", and you use titanium wire as the "conductive plates" of those capacitors. The ac will stop electrolysis - as long as the driving current has no dc component. Does the titanium stop some other from of corrosion that is unrelated to electrolysis?

@DCFusor

3 жыл бұрын

@@seamusdemora5598 Yes, it's nearly immune to pretty much all corrosion from water based chemistry. It's widely used in things like salt water for that reason. FWIW, while mine grows a little fuzz (algae?) now and then, it's good as new after more than a decade. Nothing else ever came close to that level of reliable longevity.

It is always a pleasure to learn something from you sir. Keep it up :)

@AndreasSpiess

6 жыл бұрын

:-)

Thanks Andreas! If I'm studying to develop a lora connected watering system for my plants is only because of you. Thank you for inspiring and explaining things in a way that is both fascinating and simple!

@AndreasSpiess

2 жыл бұрын

Glad you like the content of the channel!

Totally unbiased analysis showing which of the sensors really work. Thanks for the improved content.

@AndreasSpiess

2 жыл бұрын

You are welcome!

I didn’t know there was a non-rusting sensor solution. Thanks for sharing

@AndreasSpiess

5 жыл бұрын

You are welcome!

As we don't live on the surface of the sun the moisture does not need to be measured multiple times per second. Limiting measurements even to once every 5-10minutes increases the lifespan of the cheap sensor drastically as the lack of constant dc current means the copper corrodes much slower. Of course the time frame between measurements could be increased even more for a longer lifespan.

@FamilienSoelberg

6 жыл бұрын

Water and other things in the soil will react with the metal even when no current is flowing, so a capacitive sensor is a much better option as it is 'non contact'. But you are correct the lifespan can be increased.

@KucharJosef

6 жыл бұрын

And the capacitive sensors are like 3$, so it's not that bad

@labomat

6 жыл бұрын

There are a lot of Arduino sketches out there where a digital pin is used to power the sensor only when needed.

@zolatanaffa87

6 жыл бұрын

WKD: what you say is right but to be sure to stop the galvanic corrosion you should electrically disconnect the sensor when you do not take the measurement, this should be done using another Arduino channel and maybe a bipolar relay

@eric-janvandenbogaard9415

6 жыл бұрын

why make things complicated, one should try to keep sketches small, so one can add usefull code when neeeded

Hello Andreas, this is an excellent video. I am Electronic Engineer but never had the opportunity to practice it. I love how you explain the principle with the electronic schema. This video has been very useful for me since I was doing the same type of research as you by comparing different probes. I am typing to make a wifi watering system (possibly solar) and this was very helpful. Now, I have heard that the consumption of this device was abnormally high and that better solutions should be found (unless you don't mind about consumption).

@AndreasSpiess

3 жыл бұрын

I do no more remember the consumption. But maybe a small solar panel can help. And you do not need it on the whole time. One or two measurements a day should be ok.

This is just what i needed. Now i can start my garden without flying blind. Thank you Andreas!

@AndreasSpiess

6 жыл бұрын

You are welcome!

Your Swiss Guy intro convinced me!! 😅😁😁😁 Great video!!

@AndreasSpiess

6 жыл бұрын

Thank you!

To extend the lifespan of the cheap sensors, you can use 2 analog pins one as a digital output to power the sensor and one as analog input, you take the reading and then turn off the output pin. On the next measurement you just swap the pins. This way you are simulating an AC behavior. The copper will eventually corrode for chemical reactions over time, but it will not be accelerated by flowing current.

@AndreasSpiess

6 жыл бұрын

Good idea!

@CoolKoon

6 жыл бұрын

thesimbon - The copper (plus the other metal that's plated onto the copper, if you're lucky it's tin, if not, it's nickel and there's a much greater chance for the latter) will not only corrode, but also leach into the soil. Sounds like just the right thing to make your plants happy....

@thesimbon

6 жыл бұрын

CoolKoon I only suggested how to extend the life of sensor, I am not a chemist or a biologists so I don't know what will happen to the plant 😁

@CoolKoon

6 жыл бұрын

thesimbon - Well, soil moisture sensors are usually used in order to be able to water plants properly. Which kinda presumes that the goal is to make the plants thrive and avoid poisoning them as much as possible, don't you think? I mean what else would you use a soil moisture sensor for?

@juanferreira5931

6 жыл бұрын

Use AC-driven stainless steel probes. I´ve seen that used on a water tank level sensor, and it seems to work.

Thank You! I went through EXACTLY the same problem. There is an ON-OFF trick how to slow down the unavoidable corosion, but all attepmts will lead "everyone" to capacitive sensors. Thank You again and more, more, more videos.

@AndreasSpiess

6 жыл бұрын

You are right, I should have mentioned this trick.

Thank you for taking the time and effort to make and publish this. I was looking for a soil moisture sensor and this was very helpful I'm the decision making process.

@AndreasSpiess

2 жыл бұрын

Glad the video was helpful!

capacitive sensing is a good idea. Also: Don't forget to protect the whole sensor, including the electronic components with lacquer, not only the sensing part.

@AndreasSpiess

5 жыл бұрын

You are right!

@BurkenProductions

4 жыл бұрын

That is if you stick the components in the ground, which you do not do :) Also don't water the components!

One more minute to see the finished protected sensor with the material you mentioned would have been a nice touch. Overall it was a very interesting and informative video. Thank you.

@AndreasSpiess

6 жыл бұрын

Unfortunately I do not have the material at hand. But one of my trusted colleagues gave me the tip.

@northshorepx

6 жыл бұрын

what about nail varnish?

@AndreasSpiess

6 жыл бұрын

I also thought about that. But I do not have it in my lab ;-) Maybe somebody tried?

@AndreasSpiess

6 жыл бұрын

Big Clive proposed Nail varnish. (Tip from a Patreon)

@ristomatti

6 жыл бұрын

Another thing that should be considered is how long these suggested protective coatings will last. And if they will release toxic substances in the long run. I doubt this would matter for decorative plants but if used for edible plants/vegetables it might. Of course this applies for the stuff that would be released from the exposed PCB also.

Perfect timing... I couldn’t understand why my plants were being over watered. I’ve ordered the recommended sensor. Thanks again.

@AndreasSpiess

6 жыл бұрын

You are welcome!

I love all your videos. But especially the ESP & sensor ones 😁. Thx for all the effort you put in your videos.

@AndreasSpiess

6 жыл бұрын

You are welcome!

I laugh when you said "this is not a channel about good looks and makeup" at 8:42 . Brilliant and informative video as always Andreas!

@AndreasSpiess

6 жыл бұрын

Thank you!

Well explained. I have made various moisture sensors, including resistive sensors and capacitive sensors. Both have their pro' s and cons. You already mentioned most of the disadvantages of the resistive sensors. Those can be minimized by interrupting the power to the sensor and only switch it on for a few milisec when you measure and that can be done say 4-6 times/day. More than enough. I also do not use copper, but Iron. This way sensors last several seasons I found the capacitive sensors (made with 555 or HC14) a bit sensitive to surroundings, apparently their wires pick up stray capacitance. I was surprised about your sensor working with a plastic bag around it, it will, but probably not well with so much airspac around it. I tried with heat shrink.... that didnt really work. Lacquer and plastidip (expensive) do. One more thing about that various resistive models. If you use the analog output, the 'module' that comes with it is usually superfluous,as it connects directly to the sensor

@AndreasSpiess

6 жыл бұрын

I thought iron starts to rust. No problem with that? Or do you use stainless steel? Concerning the plastic bag: Plastidip arrived too late for the video:-( But as you saw, it worked with the bag.

@Ed19601

6 жыл бұрын

Usually galvanized I use. Yes it builds up some corrosion, but I just wipe it down end of season, doesn't really influence the reading throughout the season. Yes I saw it worked. I used a plastic bag too during some tests, but I never expected it to still work with so much air in between :-) My bad

@DaveMody

6 жыл бұрын

I've been using 316 SS threaded rod. No problem with corrosion that I can detect.

@damianbutterworth2434

Жыл бұрын

You got the same solution I found. Cool someone else thinks like me.

This is brilliant... thanks! Love the circuits you separate to understand what it actually does! Kind regards from Croatia!

@AndreasSpiess

3 жыл бұрын

Glad it was helpful!

Great video! I've had this problem a few years ago with water level detectors. Even with small voltages the electrodes disappeared after a few days. I tried replacing them with stainless steel electrodes, it appeared it didn't corrode, at least not as fast, but I now realize it might create even more toxic waste as a result because of chromium. I wish I knew about the capacitive sensors back then.

@AndreasSpiess

6 жыл бұрын

Thank you for sharing your experience!

You could also just switch the power to the sensor on for just a splitsecond fir a measurement

@AndreasSpiess

6 жыл бұрын

You are right.

Great video! Ive learnt new things. Anyway, instead of using capacitive sensors, what about using graphite as sensor probes? Graphite are used in many electrolytic cells as electrodes so they won't corrode away like copper does. Plus, i think graphite can be cheap too as it can be found in pencils.

@AndreasSpiess

6 жыл бұрын

Graphite was suggested also by other viewers. It is a good idea.

@fooballers7883

Жыл бұрын

yes it is good... but electrolysis will still take place.

Very interesting. I’m not that versed with hydration systems but work on a lot of automation systems dealing mostly with HVAC. I like your simplified explanation and appreciated field data. I am certain that this technology will become more apparent as people are continually looking to automate processes. Keep up the good work.

@AndreasSpiess

5 жыл бұрын

Thank you! I think water will become more and more important.

Muchas gracias profe, muy educativo e interesante el video, para este tipo de sensores tan útiles. El sensor de patas delgadas y macizas es útil para una ecualización del riego en la fase de diseño, por su características físicas, permiten una fácil penetración a la tierra, pero no dejarlo expuesto por periodos prolongados, debido a lo que usted expone en el video, y el sensor recubierto si sera útil para dejarlo en la tierra, claro incluyendo la mejora que usted menciona, recubriendo el borde, para así garantizar un riego proporcional a la humedad del suelo en todo momento. Saludos.

@AndreasSpiess

3 жыл бұрын

Yes, you can use the simple sensors for a short time and for tests.

of course i believe you master! and i proved it

Resistive measurement works perfectly fine. I use two Stainless steel rods that are sampled for 1ms every hour. Inbetween sampling there is no voltage. It is running for 5 years now without issue.

@andraskatona9766

5 жыл бұрын

In analytical chemistry for cunductometry this whole issue is managed by the use of alternateing current (and platina electrodes but stainless steel, copper or graphite should be fine for this). I don't know a damn about eletronics but why don't they just use alternating current, it reverses every chemical changes it makes? Sorry for the spelling.

@thomasrode7938

5 жыл бұрын

I to did the same thing. Using Stainless steel rods have worked in my soil for years now. I also did not want add more circuity (even though I like the capacitive approach) to my project design. I have my Microcontroller pulse for a few milliseconds make a ADC read then average these raw reads, off the rest of the time. No electrolysis effect.

@angelovalerio9984

5 жыл бұрын

I also use stainless steel rods, the only issue I have with resistive measure is the dependence from temperature, anyway I don't know if the capacitive have same issue

thank you Andreas. Yet another phenomenal video. I will be purchasing a few of those moisture sensors soon.

@AndreasSpiess

6 жыл бұрын

You are welcome!

Dear Andreas, your study is priceless. Saved me tons of work and some money (and I'm afraid a friend of mine is not going to receive any payment of a device he was going to build me...) Thanks for this. A Venezuelan exiled in Lima, looking to come back soon to my country, once freed. Cheers!

@AndreasSpiess

3 жыл бұрын

Glad to help! And sorry for your colleague.

Electrolytic corrosion is the death of almost all electronics. That is the reason why it is important to block direct current. Those cheap moisture sensors are actually a nice learning tool and included in almost all arduino-kits. And the rapid electrolytic destruction is a feature, it shows beginners the importance to think about these problems and how to avoid them. :) The naive approach is, to add a resistor to make a voltage divider and put them between Vcc and GND and measure the voltage drop with the built-in ADC. This makes them corrode away in no time. The next less naive approach is to put the voltage divider between a port-pin and GND and enable them only a few times to measure the value. This slows it down but doesn't solve the problem. Third approach is, putting it between two port-pins and to take measurements they are driven with alternating current ( alternate between high and low on those two port-pins, always one pin high and the other low and taking measurements in between). This remove almost all direct current, but some direct current might be still present if the program takes longer when one specific pin is high (i.e. when taking a sample only in one code path). Then you can fix the program, maybe add a capacitor in series with the voltage divider and so on. Then you might introduce the capacitive sensor. It is a learning tool. :) And when all flowers are dried up, you can build electric neon flowers: kzread.info/dash/bejne/pJamzM2zfajWgLg.html www.bigclive.com/nixie.htm (and they don't need water) Edit: The other thing I wanted to mention is: Conformal coating helps a lot and it is extremely easy to retrofit, just get a spray bottle of kontaktchemie plastik 70 (or similar product), clean the PCB, and spray it (be careful with connectors). Conformal coating could be done in the factory, it is very cheap but it isn't done to increase the chance for water damage. Water damage means no warranty and the customer has to buy a new product and that is what some vendors of some products want (Especially the vendor of particularly hard to repair laptops that get turned into a PC when a corroded trace or pad is replaced with a wire). The easy way to make your own, and more robust, moisture sensor is a screw terminal with two nails in it. I mean the screw terminals used to install light fixtures (They are called Lüsterklemme in German, this should give good results in google image search).

@AndreasSpiess

6 жыл бұрын

Thank you for summarizing all connection methods. Maybe I should have mentioned it.

@zvpunry1971

6 жыл бұрын

Now I have mentioned it. Maybe it helps some readers. :) I also edited the comment and mentioned conformal coating that can cheaply added. You mentioned it too, but isn't that plasti dip stuff really thick? That is why I mentioned a product that is especially made for conformal coating and it is old, very old, I know that I used the kontakt chemie stuff almost 20 years ago. ;)

@AndreasSpiess

6 жыл бұрын

My second choice „Tropenlack“ seems to be a conformal coating. But not easily available. Thanks for your proposal.

@zvpunry1971

6 жыл бұрын

Wow. That big yellow/blue can with its big letters worked perfectly. It kept the better suited, but less prominently presented, product under the perception threshold... Somebody should tell this to the marketing people from electrolube. ;)

@eric-janvandenbogaard9415

6 жыл бұрын

making the learning curve steeper, while this is not needed ? i think these subjects are some of the basics of electronics, making a battery, galvanic properties, etc...

What about using AC to measure the moisture? I would expect that the simple sensors should life much longer. Also a pulsed current, only measuring the moisture a few milliseconds every hour or so should help. It is not neccessary to measure all the time. What do you think?

@user21XXL

6 жыл бұрын

AC is the best way to do it. It avoids a problem - electrode polarisation and allowes for even electrode aging

@AndreasSpiess

6 жыл бұрын

You are right. There is a comment summarizing the different possibilities with their advantages and disadvantages.

@uwezimmermann5427

6 жыл бұрын

AC will not remove the corrosion which the metal electrodes will experience in the soil. The DC current only accelerates this degradation - even without DC current a copper trace in soil with or without tin plating will be gone after a very short while. And copper salts - while an essential micronutricient - will kill your plants quickly.

@korishan

6 жыл бұрын

Uwe: I was thinking the same thing. Copper in high concentrations is bad. And coming from a PCB, that is probably high enough concentration to weaken the plant. Especially if you replace the sensor every month. Frank: Pulsed DC is exactly what Andreas showed in his example with the last sensor and the signal generator. It create a capacitance effect. Pretty neat in how that works considering there isn't any touching parts.

@publicmail2

6 жыл бұрын

Actually copper is a fungicide won't hurt the plant.

Thank you Andreas for those explanations !

@AndreasSpiess

4 жыл бұрын

My pleasure!

Thank you for this informative video. I am happy that I have opted for the capacitive sensor on Ali. Now, I also understand why it works without corrosion :)

@AndreasSpiess

5 жыл бұрын

You are welcome!

Just switch polarity every time you check moisture. Second thing - buy only gold plated sensors.

@mustafayasiraydin

3 жыл бұрын

They ll corrode anyways but a little bit slower and switching wont help until you saturate the soil with copper salts. Additionally platinium would be a much better choive then gold.

@mustafayasiraydin

3 жыл бұрын

Decreasing sampling frequency and reducing sampling time would improve cheap sensors lifespan considerably.

the green stuff is probably mostly oxidized copper.

@AndreasSpiess

5 жыл бұрын

You are right!

@pwnmeisterage

5 жыл бұрын

I don't really know plant biology. But I think some copper ions dissolved in the soil will be harmless or even necessary/beneficial. Although too much coppper in the soil will change the pH or reach toxic levels. And some species may be more sensitive than others (for better or for worse).

@paulg.3067

5 жыл бұрын

I dont think so, because copperoxide(s) are not green. The copper somehow goes into some kind of copper-salts, maybe copperchloride/carbonate/hydroxide... they are all nice greenish colors

@williefleete

4 жыл бұрын

@@paulg.3067 tap water would have some chlorine so copper chloride, and hydroxide would be likely. the plating will probably be tin so you might get some stannous chloride as well (not sure if you can get tin hydroxides, not a chemist).

I used the striped sensor as christmas tree water sensor, it corroded in only 2 weeks totally. Thanks for the video, really concise and clear information here!

@AndreasSpiess

5 жыл бұрын

Fortunately, Christmas was over till then ;-) You are welcome!

An informative video that points out the short comings of the different types of commercial sensors that can be purchased. It would of course be easy enough to elongate the life of these but because they rely on conductivity, they do need to be exposed to the soil, whereas a capacitive sensor, does not so can be coated to protect it. 2 nails would suffice to replace the copper electrodes if you wanted longevity, or because of the price of these types you could just replace them every year. Thanks for the video, it gives people insight into the different types to use

@AndreasSpiess

2 жыл бұрын

You are right. There are many other comments on the different solutions and suggestions...

Just bury an ESP8266, the water will change the signal strength. 😎

@zmeygavrilych

6 жыл бұрын

:o)

@AnonyDave

6 жыл бұрын

Make sure you add a LiPo battery so it's self drying. Bonus is that the plant will add to the "heating" effect (read: fire!)

@korishan

6 жыл бұрын

😆😜😂

@AndrewSanjanwala

6 жыл бұрын

Interesting tangent opportunity here, doesn't the ESP32 offer onboard capacitance sensing intended for touch detection? I imagine it wouldn't be too much of a rework this for a buried soil probe along the lines of what Andreas came up with. I might give this a shot when mine arrives!

@GRBtutorials

6 жыл бұрын

@Andrew Sanjanwala Yeah, that should be possible. I believe the working principle is the same, except that with a capacitative touch sensor, one of the plates of the capacitor is your finger (or whatever you're touching the sensor with), and with soil moisture sensors, you have to put another plate.

The green stuff should be copper oxide, which is classified as a hazard to the environment. Considering though, that there are a lot of copper pipes out there that also oxidize, I guess it's not all to bad. Fun fact: the statue of liberty is made of copper and oxidized over the years, that's what gives it its distinctive green color

@AndreasSpiess

5 жыл бұрын

You are right.

@PMeeuws

2 жыл бұрын

@@AndreasSpiess CuO = black CuCO3 = green Cu(OH)2 = bluish green

Thanks! That is informative. Bought some of the bad sensors, didn't thought about it, but it totally makes sense.

@AndreasSpiess

6 жыл бұрын

You are welcome!

Very valuable information through this very clear explained test ! A must know for everybody who wants to do this kind of moisture measurements ! Thankyou !

@AndreasSpiess

6 жыл бұрын

Thank you. This was my goal.

@eric-janvandenbogaard9415

6 жыл бұрын

It also proves one should be selective at what you buy, and not always go for the cheap stuff, if one is seriuos with the hobby, getting good results, with projects that last.

10:32 I love like he talks to us like we are computers, and he is the software running us. Finally someone who speaks my language 💜🤖

@jakubstanicek6726

3 жыл бұрын

Relationship goals

@josephboen178

3 жыл бұрын

Where is the else condition. Where is the ELSE

Hi, I really like your videos. But this time I am a little bit disappointed. I thought you will bring a "real" solution. I got the same problem like you and I found a way to solve the problem forever without any toxic stuff (plastics, softener, etc). And without having any materials that can corrode. I took two graphite electrodes, printed a holder for them and connected them to a controller of the cheap china sensor. To prevent any way of electrolysis it changes the polarity of the electrodes every 24h. I take data once every 10minutes. To get perfect values I did the following: I took 500g soil and put it in a compartment dryer about 48h around 60°C that it is 100% dry. In the next step I took 30g of the soil and put water in it. After it was saturated I took the values from the 100% wet and the 100% dry soil - each with 30g of soil. Then it was time to get some values between these measurements because it does not change linear. Here are my resultes (6cm dipped electrodes, 5mm diameter) : Moisture // Value 0% // 1024 20% // 634 40% // 339 60% // 321 80% // 307 100% // 260 It shows, that I need to repeat this measurement with moisture values between 0% and 50% in smaller intervals. But if we think about the resilience of nature it isn't so important. Anyway: Thank you for your great videos and explainations.

@AndreasSpiess

6 жыл бұрын

Good work! Maybe you follow the interesting link in Craig’s comment (above). The studies there suggest it is hard to get reliable measurements from resistive and capacitive sensors. This is what I experienced and why I gave up to increase accuracy. I accepted the results because to keep home plants healthy it should be ok. But it seems you got pretty good results with your sensor.

@olafmarzocchi6194

6 жыл бұрын

Andreas Spiess I cannot find that comment, at least here from the smartphone. What's his username?

@mr.b.1589

6 жыл бұрын

I have this setup in use for 3 months now for my peppermint. I have tested it with soil from it and the values are nearly the same (+/-1% - condition: same temperature, same water, etc.). The main reason for this is that the surface of the electrodes does not change. No corrosion etc... In addition: the problem with metal electrodes is, that they solve in postitiv ions under electrolyse. This changes the conductivity of the soil and the result is: BAD measurements. So just use inert electrodes like graphite (quiet expensive, but for food, its a better choice)

@eric-janvandenbogaard9415

6 жыл бұрын

What i understand of Adreas's test, is that the galvanic/resistive "way" may be not the correct "road" to travel on, (somebody already tried aluminium electrodes ?) due to corrosion, maybe one should use silver electrodes because silver oxide is a conductor :) (hence use on switch contacts) in theory copper oxide stops oxygen from further corrosion, but will be a isolator, doing it the capacitive way seems a better solution, otherwise ultrasone ? the sound travels faster through water, i can't think of a better way then Andeas found in this test. and doubt if there is.

@raykent3211

6 жыл бұрын

Eric-Jan van den Bogaard what about platinum or gold plating the electrodes?

Very useful. I'm glad that I was lucky by purchasing the last model.

@AndreasSpiess

5 жыл бұрын

Thank you!

Dear sir, I exactly understood what you meant. No electrical current as it will do electrolysis function, within different metal, different electrolyte, or even different potential differences in a circuit. The capacitive way is I will always like. Thank you for this enlightment. Thought it was just that simple to measure soil moisture. Thanks again.

@AndreasSpiess

5 жыл бұрын

:-)

I though this was a channel about beauty and make-up

@AndreasSpiess

6 жыл бұрын

Sorry for not declaring it in the „small print“ ;-)

@eric-janvandenbogaard9415

6 жыл бұрын

Plants are beautiful for the make-up of a house :)

@Electronieks

6 жыл бұрын

yes

Du darfst kein grünes Uranglas für Deine Experimente verwenden, dann löst sich auch das Kupfer nicht ab .. ;o)

@AndreasSpiess

6 жыл бұрын

Die Farbe habe ich zufällig genommen. Es hat am Schluss aber noch etwas „giftiger“ ausgesehen. So hat es mindestens den Effekt optisch verstärkt.

Great video. I'm doing a lot with this sensors. At first i was using the crappy cheap ones. Now i replaced them all with the capacitive sensors.

@AndreasSpiess

6 жыл бұрын

Thanks for sharing your experience.

I always enjoy you videos but this one was VERY useful! Thanks!

@AndreasSpiess

6 жыл бұрын

You are welcome!

What if you use the first type but switch the polarity regularly?

@AndreasSpiess

5 жыл бұрын

You find many other comments about that principle.

@johnbrewer9833

5 жыл бұрын

Works well for me.

Yea, just pulse the sensor every couple seconds

@AndreasSpiess

5 жыл бұрын

According to other commenters this works for some time.

Thanks for the analysis. I am about to install moisture sensor in my home garden (30-40 of them) and waned to understand the difference between all types of moisture sensors available in the market before i place the bulk order. This 10 min video saved me from going through all of their datasheets. One info missing from this video is the resolution of these sensors.

@AndreasSpiess

4 жыл бұрын

I just saw a longtime study of the capacitive sensors. Pay attention your protect them with and additional layer. Especially the side which is completery unprotected

@prashkd7684

4 жыл бұрын

@@AndreasSpiess True. There are several concerns around directly inserting these sensors in soil. The best solution i could find is to put these sensors in plastic zip lock bags. This will not only protect the sensor but also prevent any toxic chemical from sensors eroding into the soil and then sucked in by the plant. It will probably reduce sensor's resolution but since its just a astable NE555, I should be able to fix it.

The "chemistry" that happens when one leg of your humidity sensor dissolves, is the oxidation of your anode. To prevent this, you can combine the following two strategies: (1) use metals that form a stable anode (gold, platinum, titanium, nickel, carbon) which means that when using PCB technology, your limited to ENIG and more advanced plating technologies, and (2) apply as little as possible voltage between the legs of the sensor, which means use as little current as possible to measure the resistance and amplify the voltage with e.g. an instrumentation amplifier. I agree that the capacitive sensor is a much more elegant and robust approach though! The working principle reminds me of the good old Theremin :)

@damianbutterworth2434

Жыл бұрын

I used a relay to cut off the sensor when not in use. You only need to use the sensor once an hour or so for a second.

Straight to the point. Thank you for protecting us customers against this cheap China sensors! Thumbs up!

@AndreasSpiess

6 жыл бұрын

Thank you!

@CoolKoon

6 жыл бұрын

LetsBuildSomething - Actually the capacitive moisture sensor is also a Chinese product....

If I try one of these I am just going to buy a couple stainless bolts and connect them to the sensor. Pot the rest. Bam

@AndreasSpiess

6 жыл бұрын

Should work.

@muwahh98

6 жыл бұрын

Fetid Tuna ok Erin brockovich, I suppose I'll die as the massive current going through stainless bolts erodes them entirely. And leaches into my tomatoes 🍅. Cool

Great , informative video. 👏👏 Good presentation with explanations.👌 Conductive metallic probes can get corroded over time because of pH value of water, as also other chemicals. Wonder why non-corrosive probes such as stainless steel were not used.

@AndreasSpiess

4 жыл бұрын

There are many different comments, also concerning stainless steel probes.

thanks for all the videos, another great one, I will support you soon

@AndreasSpiess

6 жыл бұрын

Thank you!

Hello,very good explication about the sensor(most of the channels that made a video about the moisture sensors didn't said anything about the dangers of the cheap ones) but can we can we solder a the cooper exposed terminals with a layer of solder?What do you think?

Good video. Been too busy lately. At least I found time to catch this one.

@AndreasSpiess

6 жыл бұрын

Busy is always good if it produces either fund or money ;-)

I just bought 3 of these on Aliexpress, then I found this video... Gotta love Andreas :D

@AndreasSpiess

4 жыл бұрын

Good choice!

Years back I built an analogue system to water my plants. I found that my mild steel nails used as sensors would just rust away. I then used graphite rods from a lab supply shop. They are more fragile than the nails, but they don't corrode and don't give off any toxic oxides.

@AndreasSpiess

5 жыл бұрын

Your observations are shared by a few other commentators

An entertaining and informative video. Thank you Andreas.

@AndreasSpiess

4 жыл бұрын

You are welcome!

Useful and interesting. Great video. I like these kinds of videos a lot. One just need to watch a single video and everything is said.

@AndreasSpiess

6 жыл бұрын

Thank you for your nice words!

I did something like this a while ago. I only measured every 15 minutes, using the AC measuring method with an arduino. The sensor itself was very reliable and basic, just two stainless steel rods stuck into a pair of screwable wire connectors. The system was running for a year with no loss of accuracy and absolutely no damage to the rods. The rods were 4mm diameter and 10cm in length.

@AndreasSpiess

6 жыл бұрын

Thank you for sharing your experience!

Amazing video as always Andreas.

@AndreasSpiess

6 жыл бұрын

:-)

Just bought it for my pi pico garden project, thank you so much!

@AndreasSpiess

3 жыл бұрын

Have fun!

Awesome video! I was about to order some cheap moisture sensors from Banggood, when I suddenly though to myself "Hmm, some weeks ago there was a video I wanted to watch about these... Time to watch it before ordering!" So you actually saved me a few bucks and some headache, thanks! :)

@AndreasSpiess

6 жыл бұрын

Always good to know!

Hi Andreas, thank you for the video, very informative, do you think the plastidip would take away from the sensitivity much? what if the capacitance sensor was coated in several coats? would it loose it's ability to sense through the porous rubber like coating?

@AndreasSpiess

6 жыл бұрын

I bought some plastic spray and plastidip. I plan a followup Video to sum up all the good input given in these comments

Nice work! I need to measure the moisture content of the floor material in my beehives, so this was useful.

@AndreasSpiess

6 жыл бұрын

Would be interesting to know if it works.

@DougHanchard

6 жыл бұрын

Phil Chandler May I ask why only the floor level? Or do you mean, the floor for each tray in the hive box? For aired environment, you might want to try other methods than what Andreas has presented. An humidity and temperature sensor arrangement might work better, providing the bees are not sensitive to sensor RFI and will not block the sensor's probes.

@adrianw2972

5 жыл бұрын

Got to ask... Why are your beehive floors wet? Solid floors should be built with a slope to the entrance (usually double sided). The hives should be off the ground (no plant contact either) and most hives today use a Varroa screen (Stainless Steel mesh) and so there is little wood in the floor. If you have water running through your hives, they probably need maintenance ;) Timber, where possible, should be red cedar which is light and naturally anti fungal, although painted wood is fine. Other than that, the bees will be maintaining temperature, humidity and air flow. It will be difficult to measure the wetness of wood with the capacitive probe (as shown), you will probably want something with pointed probes, like those sold at your local DIY shop. Nice little video Andreas, as ever! In the past I have used both Stainless and carbon probes working with a reversing sensor (AC) for commercial greenhouse watering. Those capacitive units are very nice. The ones that I have used were already sealed at the edges.

@adrianw2972

5 жыл бұрын

@@DougHanchard A bee hive only has one floor, although from time to time one may use something like a Snelgrove board to separate the hive in two, as in swarm control, queen production etc. Technically, a floor is not needed, but adds additional protection from the elements, robbing from other colonies, wasps etc. ingress of slugs, snails, mice etc. In addition to the floor, the entrance size (part of the floor in most hive types) can also be manipulated. Having a floor and the ability to close the entrance is useful when moving colonies too ;)

I know this has been awhile. But I came up with a probe that works really well, is super cheap, and easy to make. I simple put three long pieces of coax cable snugly into a 1/2" pvc pipe. The probe is sealed with simple pipe caps. I found that putting a bolt through the bottom for grounding made it more stable. All this stuff is super cheap and easy to work with.

@AndreasSpiess

4 жыл бұрын

Interesting concept!

Good video for anyone planning to use moisture sensors! Btw,with reactive components the correct terminology is 'impedance' not 'resistance'.

@AndreasSpiess

4 жыл бұрын

Thanks for the correction!

I have here a few self destructing moisture sensors, never put them to use because of that. Now I shall buy the capacitive version and forget about the other one! Thanks mate!

@zvpunry1971

6 жыл бұрын

If they don't contain electronics, only bare traces. Keep them. If they contain electronics that can only drive them with direct current, keep them and maybe remove the electronics. You can drive them with alternating current to minimize electrolytic corrosion or maybe try to convert them into capacitive sensors. Or destroy them by using them to observe the effects of electrolytic corrosion or teach someone else about electrolytic corrosion. :) By the way, the easiest sensor is a screw terminal with two nails in them. I mean the screw terminals used to install light fixtures (They are called Lüsterklemme in German, this should give good results in google image search).

@eric-janvandenbogaard9415

6 жыл бұрын

by removing the electronics, one can also DIY some electrodes :)

@VMFRD

6 жыл бұрын

I thought about driving them with AC, but I feel like the payoff doesn't justify the work required to modify them. Especially if there's a better version off the shelf!

A channel named "Flaura - Smart Plant Pot" has a video titled "Capacitive Soil Moisture Sensors don't work correctly" that you might find interesting. He includes video clips directly from your tests, and mentions the need for a 3V regulator in-circuit to get reliable, repeatable readings. Some boards exclude that regulator (shunting that connection with a 0-ohm resistor, for example, if the regulator's footprint is actually on the board).

@AndreasSpiess

2 жыл бұрын

I think I once was contacted by the creator of this board. Stable voltages are important for most sensors, BTW.

did not really ever thought about getting a moisture sensor... But after watching this advise I got an capacitive one :D

@AndreasSpiess

5 жыл бұрын

I hope it works.

All the sensors I use for soil profile moisture sensing rely on frequency or time domain reflectometry. They last forever. However, I know there are also capacitive sensors on the market suitable for science or agricultural use...now I know how they work. Thanks very much.

@AndreasSpiess

4 жыл бұрын

It wold be interesting to compare these sensors with the TDM ones.

damm this channel is good. Might not have millions of views but honestly guys who are just starting electronic this is gold...👌👌👌👌

@AndreasSpiess

4 жыл бұрын

Thank you for your nice words!

To avoid corrosion I used two stainless screws for probing, and alternating current for measuring. That means instead of connecting them to VCC/GND they-re connected between two GPIO analogue pins, and switch polarity 10 times/second. That also allows keep both "legs" at same gnd voltage between measurements. It needs no circuitry, one gpio pin is configured input-pullup the other as output low so there is a measurable voltage on the input pin. In a few ms program swaps them and averages last 10 read values.

@AndreasSpiess

4 жыл бұрын

Thank you for your feedback!

Thanks for sharing 😀👍 Interesting project 👍

@AndreasSpiess

6 жыл бұрын

And obviously liked by many viewers. There are a lot of discussions in the comment. I learned a lot about the topic from these comments!

Really Cool Andreas. I'm using those sensors in a project with attiny85 and sending the info via RF433Mhz to a arduino nano connected to a raspberry pi. Those sensors have a short lifespan indeed, but i think that humidity doesn't change that often or that quickly, we don't need to be always reading, nor always powering that sensor. So i have used powergating and the sensors last way longer now! :) I have one Capacitive soil sensor, but i still need to test this. All the best!

@AndreasSpiess

6 жыл бұрын

There were many comments about switching these sensors on and off. I think I should have mentioned it in the video... Nice and cheap idea with the 433 MHz

Thanks, Andreas, Excellent like always.

@AndreasSpiess

6 жыл бұрын

:-)

You can solder some stiff copper wire onto the legs of the cheap sensors so the PCB tracks are not in the damp soil, but this is only a partial fix. I noticed that when the temperature drops at night the conductivity of the soil changes and of course this makes it difficult to set accurate limits. Another problem is that when you add liquid fertilizer like "Miracle Gro" the conductivity of the soil increases as does the chemical reaction on the wires. Basically then Andreas' suggestion with the capacitive sensors and waterproof dip is the only reliable way to go.

@AndreasSpiess

5 жыл бұрын

Thank you for sharing your experience!

Hi Andreas, great video! Is there any way to share the schematics of your sensor?

Andreas - love the channel. Extremely informative and I have tried many of your projects. Along the same lines as moisture sensors, can you explain why ph soil sensors work so poorly as well? Maybe there is a best configuration for probes (single vs double vs glass)? It just seems that given the correct conditions, soil ph should be able to be measured with metal probes without having to put the sensor in a separate solution. Any help, advice, or guidance would be greatly appreciated! Keep up the great work!

@AndreasSpiess

2 жыл бұрын

I am not much in chemical stuff. So I have no idea about PH sensors :-(

Danke Herr Spiess, wieder mol sehr lehrrich :-)

@AndreasSpiess

4 жыл бұрын

Bitte, gern geschehen!

Very useful information, thanks for sharing with us.

@AndreasSpiess

3 жыл бұрын

You are welcome!

Thank you for this I need to automate my watering system in South Australia (driest state, driest continent) and this has saved me a lot of time esp as the soil is also very alkaline and salty clay. I'll let you know how I go.

@AndreasSpiess

6 жыл бұрын

Please do not expect too much accuracy!

@lcirocco

6 жыл бұрын

No worries. I was going to start with a binary: is dry, is wet. This hopefully gives me a longer lasting sensor.

I have solved this problem years ago by using a capasitor in series with the sensor and using alternating current for measurement. The capasitor eliminates the DC component and prevents corrosion.

@AndreasSpiess

6 жыл бұрын

Using AC was mentioned several times in other comments. Some also mentioned it will not completely remove oxidation.

I have some humidity sensing electrodes that are gold-plated, I assume to minimize the electrolytic degradation processes. I'm curious how long I should expect them to last due to the more inert gold plating. Though obviously the capacitive circuit is the best way to go for long-term monitoring. Thanks for pointing out this solution.

@AndreasSpiess

2 жыл бұрын

I assume gold plated material lasts longer. But I do not know how gold interacts with other chemicals. Some commenters reported heavy corrosion with different materials.

Grüessech Andreas! Merci vil mol für das Video! I don't understand how your self-built capacitor still works inside of a plastic bag. Is it detecting the humidity of the plastic? Could you provide a quick explanation?

@AndreasSpiess

3 жыл бұрын

Through its electrical field it measures the properties of he material between its electrodes. But not only exactly between the electrodes. The field also hits other parts. Electrodes in capacitors always are completely insolated. ( en.wikipedia.org/wiki/Capacitor )

I didn't realize there were generics of the capacitive sensors now! From what I've heard they are a lot more accurate than the resistive ones. Just so you know though, you can prevent the destruction of the resistive sensors by only applying power only for a few milliseconds at a time whenever you need to take a measurement. I used to just connect the +5v pin to an output pin on my MCU and turn that output on when I need to take a reading.

@AndreasSpiess

6 жыл бұрын

You are right. This was discussed in many other comments below.

Nice video - came across your channel and this vid as I'm contemplating seeing if I can use a capacitance sensor with an arduino or ESP32 and LoRa to monitor the beds on my allotment (2.5km away) so I know which beds need watering and when , so that I can maximise the use of my time down there. Looks like your channel has all the info I need to start off my very first project - thanks.

@AndreasSpiess

5 жыл бұрын

You are welcome. I hope you live in the northern hemisphere. then you still have a little time for your project ;-)

@geekinthegarden3927

5 жыл бұрын

@@AndreasSpiess Thanks - now working out what parts I need and which end of the soldering iron to hold.

I have the same experiences with both sensor types. The capacitive sensor, however, still has a problem. If the soil changes from wet to dry, a permanent gap in the soil can develop there, which makes further measurements useless. Of course, it depends heavily on the soil conditions. Maybe high-frequency radio waves are the solution. I did a first experiment with a Bluetooth tracker and measured the dBm. Looks promising. I have packed it waterproof and buried about 15cm in dry soil. Then I irrigated the soil bit by bit and found noticeable changes in the dBm.

@AndreasSpiess

6 жыл бұрын

You are right. Measuring moisture seems to be an art. These sensors are just ok for detecting the time to water plants. Not more. They are not very accurate, but also quite cheap.

thank you very much very useful information regards from colombia

@AndreasSpiess

3 жыл бұрын

Glad it was helpful!