Renfro
Well-Known Member
That would be freaking awesome. One could imagine that being a lot simpler than pot weight type setups.
Advice about EBgen2 + 3W LED's build and UVB reptile lamp(T5 fixtures) reflector material.
- Thread starter Planet Tomato
- Start date
NoWaistedSpace
Well-Known Member
Renfro
Well-Known Member
I could see the tipper type watering actually shutting off before the plant is fully watered if on a pump and automated. Not enough deadband there unless you put a preset delay. But as plant mass increases there would need to be a change in fulcrum location. Just seems very finicky.
whytewidow
Well-Known Member
As long as your pota dry out evenly. That's why I havent used them. I have cold air and it heat(winter months) blowing in on one. At the bottom then the opposite side out at the top. And my pots dont dry even. One side gets drier before the opposite side.
Planet Tomato
Member
I don't think I mentioned it but I am also including a host of sensors in my system, one of the ones I am most interested in is the soil moisture sensor.
But although there are many such sensors easily and cheaply available that can be read by any arduino or raspberry pi they have one fatal flaw in my eyes, they work by inserting two conductors into the soil in order to measure the resistance between them with the idea that more water equals more conductivity equals less resistance BUT the problem is that water in itself is not a good conductor and such a sensor would actually be greatly impacted by the amount of salts in the water e.i. nutrients. I am not sure about this but it is possible that such as sensor is actually only measuring the amounts of nutrients in the water and not the water at all.
Further more the conductors that's inserted into the soil suffer from corrosion which while is not problem in the short term makes them not suitable for our purpose at all. I have written them off my list of options all together.
But there are also widely available soil moisture sensors which work my means of measuring the capacitance between two insulated conductors, if you place 2 wires 1cm away from each other they will form a capacitor and the capacitance of that capacitor depends upon the material which separate them.
Long story short, you can make a circuit board that can be pushed into the soil which will not suffer from corrosion and then measure the soil water content by monitoring how the capacitance of the probe is changing over time, these sensors are not impacted by the amounts of nutrients in the water, or at least the effect is small enough not to be a problem(I don't know if it has an effect or not).
I have not been studying these sensors for long so I might have gotten some details wrong but the overall info is true, there are at least 2 different techniques to utilize these capacitive soil moisture probes one of which is far superior in terms of what info you can deduce from them but it is more complex, this more complex technique relies upon very high frequencies being used and it can in the end tell you something of the total amount of water in the soil while the simpler more easily implemented technique will not give you any results that can be related to actual water amounts but for our use they are good enough while there are downsides to the simpler technique it is the one I am going for to begin with because I simply don't know enough to implement the more complex technique.
The more complex technique is used by very fancy and expensive measuring systems that only large scale farmers can afford but I have seen one or two low-cost alternatives thought they where still too expensive for me.
Another issue is the question of the wiring, I am aiming for a soil moisture probe that will communicate through the use of Bluetooth so that I can forget about wires completely, another issue is the depth of the sensor, and it's water resistance or whatever it's called in English(can it survive being drenched in water) because if it can't then it's pointless anyhow.
I might forgo Bluetooth and leave that for later versions, but given the price of a ESP32 module(the actual device not a dev. board) Bluetooth in such a circuit isn't expensive or hard to implement.
This is a good example of a very handy sensor one could build but it requires a fair bit of experience or knowlagde about digital electronics to make it an easy project, but even if one doesn't then it should be doable.
But although there are many such sensors easily and cheaply available that can be read by any arduino or raspberry pi they have one fatal flaw in my eyes, they work by inserting two conductors into the soil in order to measure the resistance between them with the idea that more water equals more conductivity equals less resistance BUT the problem is that water in itself is not a good conductor and such a sensor would actually be greatly impacted by the amount of salts in the water e.i. nutrients. I am not sure about this but it is possible that such as sensor is actually only measuring the amounts of nutrients in the water and not the water at all.
Further more the conductors that's inserted into the soil suffer from corrosion which while is not problem in the short term makes them not suitable for our purpose at all. I have written them off my list of options all together.
But there are also widely available soil moisture sensors which work my means of measuring the capacitance between two insulated conductors, if you place 2 wires 1cm away from each other they will form a capacitor and the capacitance of that capacitor depends upon the material which separate them.
Long story short, you can make a circuit board that can be pushed into the soil which will not suffer from corrosion and then measure the soil water content by monitoring how the capacitance of the probe is changing over time, these sensors are not impacted by the amounts of nutrients in the water, or at least the effect is small enough not to be a problem(I don't know if it has an effect or not).
I have not been studying these sensors for long so I might have gotten some details wrong but the overall info is true, there are at least 2 different techniques to utilize these capacitive soil moisture probes one of which is far superior in terms of what info you can deduce from them but it is more complex, this more complex technique relies upon very high frequencies being used and it can in the end tell you something of the total amount of water in the soil while the simpler more easily implemented technique will not give you any results that can be related to actual water amounts but for our use they are good enough while there are downsides to the simpler technique it is the one I am going for to begin with because I simply don't know enough to implement the more complex technique.
The more complex technique is used by very fancy and expensive measuring systems that only large scale farmers can afford but I have seen one or two low-cost alternatives thought they where still too expensive for me.
Another issue is the question of the wiring, I am aiming for a soil moisture probe that will communicate through the use of Bluetooth so that I can forget about wires completely, another issue is the depth of the sensor, and it's water resistance or whatever it's called in English(can it survive being drenched in water) because if it can't then it's pointless anyhow.
I might forgo Bluetooth and leave that for later versions, but given the price of a ESP32 module(the actual device not a dev. board) Bluetooth in such a circuit isn't expensive or hard to implement.
This is a good example of a very handy sensor one could build but it requires a fair bit of experience or knowlagde about digital electronics to make it an easy project, but even if one doesn't then it should be doable.
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Planet Tomato
Member
It depends on what pot you are using but since I am using air-pots I am considering building such an capacitive soil moisture sensor to be pushed right through the pot in the middle of the pot(middle is related to the height of the soil, so the sensor would occupy the soil in the absolute centre of the soil/root-zone)
Planet Tomato
Member
I don't know but perhaps it would be an idea to build such a sensor but one that has some sort of display to allow every non-electronics-people to easily be able to buy and use such sensors. Such as a simple LED bar with 10 steps and a buzzer that have a button to be used for calibrating the sensor to the range of "water is 100%" and "water is 0%" or something such as that.
I had a scale with remote display under one pot. I could tell exactly when to water, but it got tricky as the plant grew and mass increased, like shooting at a moving target. Even more than plant mass, I think it's the water in the plant, and that can vary with conditions.
Capacitive sensing would be great if it's accurate! I saw an old sensor board like that for measuring fuel level, hope it didn't go in the trash!
Damn, I think my old capacitance meter did get tossed.
But if capacitive sensing works, I know a couple EE's!Edit:
https://www.amazon.com/Flameer-Capacitive-Moisture-Sensor-Detection/dp/B07K2SL43Y/ref=sr_1_34?keywords=capacitive+soil+moisture+sensor&qid=1549847139&s=gateway&sr=8-34
https://www.amazon.com/UJuly-Capacitive-Moisture-Corrosion-Resistant/dp/B07DL7J71W/ref=sr_1_9?keywords=capacitive+soil+moisture+sensor&qid=1549848189&s=gateway&sr=8-9
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