Im trying to design an embedded system that detects when a plant needs more water (mostly the kind of plants you have in at home in a pot)
What kind of sensors would you recommend?
Electronic – How to sense when a plant needs to be watered
sensorwater
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As a grade 1 steam engineer, I hope you are well experienced and highly educated with steam before you start this project. At 110 bar, you have almost 1300 kJ/kg of energy. By the time you can generate this much energy, your boilers must be at least 25k lbs/hr capacity. At this energy level if anything goes even slightly wrong, the chances of killing everyone contained within a building of 75,000 cubic feet would be 100 percent. The time it would take to increase the room temperature of that space to over 125 degrees C would be less than .15 second. I know that if I were to attempt this kind of prototype work here in Seattle, the city would shut me down. Not to mention the effect it would have on your insurance carrier. Look to Burnham Boilers, Cleaver Brooks, or Cannon Boiler works for support.
The accuracy of the ADC is determined by the number of bits. A higher voltage range for the ADC would stretch the bits out reducing the resolution, or rather increasing the step voltage.
You don't need a negative voltage for the op-amps if you offset the input by Vcc/2 with a simple voltage divider. This could be in the form of a false ground reference to the input of the op-amp, as shown in this schematic:
On a 3.3V system that would off-set the input voltage by 1.65V making it from 2.06V for 0PH to 1.24V for 14PH.
Increasing R_F by a factor of 2 would increase the gain to 2:1 making it a +/- -.82V swing - 2.47V to 0.83V thus increasing your precision.
A further increase of R_F could increase your precision more, until you hit the top/bottom end of the output headroom. A "Rail-to-Rail" op-amp would give you more headroom than a normal one.
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Best Answer
If you use two probes, made of different material, and they're in the moist environment, you'll have a battery. You can measure this tension to know how dry /wet the soil is.
That's how those soil moisture work, without batteries. You can attach it to any eletronic device (like automatic watering, or something like that).