ฝัง
- เผยแพร่เมื่อ 15 มิ.ย. 2018
- Unfortunately, most soil moisture sensors used in our Arduino, ESP8266, or ESP32 projects destroy themselves after a short while. We need a better solution.
Today we will test different sensors, and I will show you, how they work and why most sensors from China destroy themselves. And of course, we will find a solution to the problem.
Links:
Good (capacitive) moisture sensors: s.click.aliexpress.com/e/btMv8UQy
bit.ly/2t4xd1Q
(Mostly) bad moisture sensors: s.click.aliexpress.com/e/vsZUpze
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As expected, another superb exposition! Thank you Andreas.
I always had doubts on which one of these sensors to use. Thanks for explaining so well and solving my dilemma.
Glad to help
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!
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.
I wanted to understand how they work myself!
@@AndreasSpiess can you help me in my Arduino project
@@abdulrahmanismailali1064 i am a TH-camr and do not do consulting.
Thanks for the video. I ordered a capacitive sensor and will add it to my projects queue.
I know it's one of your old videos, but this is incredibly helpful. Thank you again Andreas!
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
Glad you liked the video!
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!
Glad to help! And sorry for your colleague.
Nice video Andreas.
Thank you!
It is always a pleasure to learn something from you sir.
Keep it up :)
:-)
Totally unbiased analysis showing which of the sensors really work. Thanks for the improved content.
You are welcome!
Perfect timing... I couldn’t understand why my plants were being over watered. I’ve ordered the recommended sensor. Thanks again.
You are welcome!
Your Swiss Guy intro convinced me!! 😅😁😁😁 Great video!!
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
Sounds like an alternative concept. It would be good if you document it one to be used by others.
I will. Your skills in explaining would probably be superior re telling people how to tune the parameters for a given task...
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
@@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?
@@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.
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!
Glad you like the content of the channel!
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).
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.
I didn’t know there was a non-rusting sensor solution. Thanks for sharing
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!
Thank you!
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.
You are right, I should have mentioned this trick.
This is just what i needed. Now i can start my garden without flying blind. Thank you Andreas!
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.
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.
And the capacitive sensors are like 3$, so it's not that bad
There are a lot of Arduino sketches out there where a digital pin is used to power the sensor only when needed.
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
why make things complicated, one should try to keep sketches small, so one can add usefull code when neeeded
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.
Unfortunately I do not have the material at hand. But one of my trusted colleagues gave me the tip.
what about nail varnish?
I also thought about that. But I do not have it in my lab ;-) Maybe somebody tried?
Big Clive proposed Nail varnish. (Tip from a Patreon)
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.
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.
Yes, you can use the simple sensors for a short time and for tests.
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.
Thank you! I think water will become more and more important.
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.
Good idea!
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....
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 😁
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?
Use AC-driven stainless steel probes. I´ve seen that used on a water tank level sensor, and it seems to work.
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.
You are right!
That is if you stick the components in the ground, which you do not do :) Also don't water the components!
I love all your videos. But especially the ESP & sensor ones 😁. Thx for all the effort you put in your videos.
You are welcome!
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.
Glad the video was helpful!
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
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.
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
I've been using 316 SS threaded rod. No problem with corrosion that I can detect.
You got the same solution I found. Cool someone else thinks like me.
of course i believe you master! and i proved it
This is brilliant... thanks! Love the circuits you separate to understand what it actually does! Kind regards from Croatia!
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.
Thank you for sharing your experience!
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.
Graphite was suggested also by other viewers. It is a good idea.
yes it is good... but electrolysis will still take place.
You could also just switch the power to the sensor on for just a splitsecond fir a measurement
You are right.
I just bought 3 of these on Aliexpress, then I found this video... Gotta love Andreas :D
Good choice!
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!
Fortunately, Christmas was over till then ;-) You are welcome!
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: th-cam.com/video/rbrjkzMEpPU/w-d-xo.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).
Thank you for summarizing all connection methods. Maybe I should have mentioned it.
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. ;)
My second choice „Tropenlack“ seems to be a conformal coating. But not easily available. Thanks for your proposal.
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. ;)
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...
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.
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.
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.
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 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 :)
You are welcome!
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.
:-)
Just bury an ESP8266, the water will change the signal strength. 😎
:o)
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!)
😆😜😂
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!
@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.
Just switch polarity every time you check moisture. Second thing - buy only gold plated sensors.
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.
Decreasing sampling frequency and reducing sampling time would improve cheap sensors lifespan considerably.
thank you Andreas. Yet another phenomenal video. I will be purchasing a few of those moisture sensors soon.
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 !
Thank you. This was my goal.
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.
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?
AC is the best way to do it. It avoids a problem - electrode polarisation and allowes for even electrode aging
You are right. There is a comment summarizing the different possibilities with their advantages and disadvantages.
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.
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.
Actually copper is a fungicide won't hurt the plant.
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 💜🤖
Relationship goals
Where is the else condition. Where is the ELSE
damm this channel is good. Might not have millions of views but honestly guys who are just starting electronic this is gold...👌👌👌👌
Thank you for your nice words!
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! :)
Always good to know!
the green stuff is probably mostly oxidized copper.
You are right!
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).
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
@@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).
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
You are right.
@@AndreasSpiess
CuO = black
CuCO3 = green
Cu(OH)2 = bluish green
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!
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).
by removing the electronics, one can also DIY some electrodes :)
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!
Thanks! That is informative. Bought some of the bad sensors, didn't thought about it, but it totally makes sense.
You are welcome!
I though this was a channel about beauty and make-up
Sorry for not declaring it in the „small print“ ;-)
Plants are beautiful for the make-up of a house :)
yes
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.
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.
Andreas Spiess I cannot find that comment, at least here from the smartphone. What's his username?
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)
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.
Eric-Jan van den Bogaard what about platinum or gold plating the electrodes?
I always enjoy you videos but this one was VERY useful! Thanks!
You are welcome!
Thank you Andreas for those explanations !
My pleasure!
Yea, just pulse the sensor every couple seconds
According to other commenters this works for some time.
Du darfst kein grünes Uranglas für Deine Experimente verwenden, dann löst sich auch das Kupfer nicht ab .. ;o)
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.
Thanks for sharing your experience.
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.
Thank you for your nice words!
Straight to the point. Thank you for protecting us customers against this cheap China sensors! Thumbs up!
Thank you!
LetsBuildSomething - Actually the capacitive moisture sensor is also a Chinese product....
What if you use the first type but switch the polarity regularly?
You find many other comments about that principle.
Works well for me.
Very useful. I'm glad that I was lucky by purchasing the last model.
Thank you!
Nice work! I need to measure the moisture content of the floor material in my beehives, so this was useful.
Would be interesting to know if it works.
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.
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.
@@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 ;)
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
Should work.
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.
There are many different comments, also concerning stainless steel probes.
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
You are right. There are many other comments on the different solutions and suggestions...
Good video for anyone planning to use moisture sensors! Btw,with reactive components the correct terminology is 'impedance' not 'resistance'.
Thanks for the correction!
thanks for all the videos, another great one, I will support you soon
Thank you!
Good video. Been too busy lately. At least I found time to catch this one.
Busy is always good if it produces either fund or money ;-)
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.
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
@@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.
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!
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
Great Andreas always the number one. just in these days, I'm approaching these arguments. I have to test the leakage in the cooking room. Actually, I solved it using a couple of steel electrodes mounted on a homemade 3d printed box. Your video has been a great help because I was waiting for the capacitive sensor for testing it. It already works and I send an allarm message on telegram when the water gets wet on the floor. Now in my agenda are some projects refer to your works. All the best, I rest waiting for your next video.
Glad to see that my videos help to solve real problems!
An entertaining and informative video. Thank you Andreas.
You are welcome!
did not really ever thought about getting a moisture sensor... But after watching this advise I got an capacitive one :D
I hope it works.
Thanks for sharing 😀👍
Interesting project 👍
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!
Amazing video as always Andreas.
:-)
Thank you, I got them and I am experimenting with them and espeasy . So thank you.
You are welcome!
Just bought it for my pi pico garden project, thank you so much!
Have fun!
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.
Please do not expect too much accuracy!
No worries. I was going to start with a binary: is dry, is wet. This hopefully gives me a longer lasting sensor.
Dear Andreas, thank you very much for your very entertaining and informative video. As I am building an automatic plant watering system with arduino, i spent a lot of time researching the soil moisture sensors. Then someone told me that I should use the SHT10 sensor, manufactured by sensirion, a spin-off from the swiss federal institute of technology (ETH) zurich. They are available on aliexpress, with a protective shield. There is a version for air and one for soil (the latter has the protective shield). They are sort of expensive ($20 per sensor) but are supposed to work for a very long time with zero corrosion. I was really surprised that I did not find out about it earlier when searching for sensors, and also, that your video is not covering it. (don't get me wrong, your video is great, i just want to point you into a possible new direction).
Are you sure it will also measure moisture. The data sheet only mentions humidity, which is in air.
www.raspberrypi.org/forums/viewtopic.php?t=78939
interesting, thanks. i also found this interesting read: forums.adafruit.com/viewtopic.php?f=19&t=40471&sid=a71efc3355a263175afd9675e8af4773&start=0
Which I think confirms that it does not measure moisture.
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 :)
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.
Once again a real good video :)
Thank you!
Thanks for the Video, Andreas.
In a proper industrial solution the driver for the sensor is always alternating current. This prevents unwanted electrolysis even if the sensor is capacitive and the isolation gets damaged. With leakage detection and indication you know there is a fault, distorting your measurement. A possible easy solution can be to couple a PWM signal out with a capacitor and feed back the sensor over an rectifier + capacitor/lowpass. Sounds complicated but are less components than a NE555 based oscillator and most of the components are used in the DC application anyway + Micro-controllers love to PWM.
At all you have to think about if a capacitance touch-less measuring method is the best for you: You get a phone call and your plant gets water ... this can happen;) Using the direct contact method with AC coupling is the stable (homebrew) method i think.
In addition what Eman Retzun(Nutzer Name?) said: there shouldn't be any component in the sensor path, including the amplifier if one is needed, that draws more current than an Arduino can switch, and on/off times for plant moisture measurements can be very sporadic.
Where's my copper gone?!?: From the one electrode to the other, negative electrode:) ... but other stuff can get in solution that was bound with or was under the copper. So don't use permanent electrolysis on your potatoes.
What happens in a fault situation?: Your house gets messy and the expenses are far more than a 3$ sensor. Ever thought about the magic of the capillary effect? -> You build a closed system, where only so much water physically can get in what's needed. High-End space material like terracotta does the rest. If you can't withstand, than you can put a moisture sensor outside of that all as secondary safety measure. And this one can always be dry, yelling an loud alarm if it gets wet:)
You are right. There were some already some discussions in the comments about that matter.
Thanks, Andreas,
Excellent like always.
:-)
Thank you for this helpfull video! It will save the life of my plants :)
You are welcome!
thank you very much
very useful information
regards from colombia
Glad it was helpful!
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.
Thank you for sharing your experience!
Cirquit! Love it Keep up the awesome videos!
:-)
Danke Herr Spiess, wieder mol sehr lehrrich :-)
Bitte, gern geschehen!
Very useful information, thanks for sharing with us.
You are welcome!
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.
It wold be interesting to compare these sensors with the TDM ones.
Great video. Thanks for explaining
You are welcome!
Very interesting!!! Thank you for that information! 👍👍👍
My pleasure!
Thanks a lot for your interesting Video. I enjoyed that very much
You are welcome!
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.
You are welcome. I hope you live in the northern hemisphere. then you still have a little time for your project ;-)
@@AndreasSpiess Thanks - now working out what parts I need and which end of the soldering iron to hold.
Thanks, you just save me time and money.
You are welcome!
This actually seems like a great idea for multiple plants, so I will try to use this with my Cannabis plants... Awesome Video ;)
Maybe you build it before you smoke the plants ;-)
that's where it went wrong ;)
nice video. always wondered how these sensors worked.
Now you should know. I had the same problem ;-)
thanks a lot for your tests, very useful.
:-)