I was recently thinking about a similar hardware (although I have no hardware background). I have a lot of plants, some shared with my roommates, and many frequently die. Taking care of plants together is hard and sometimes we are all away for a few weeks so somebody else is taking care. I would love to have an app that alerts me if something basic is wrong, for which 90% of the time would be too much or not enough water. But what I would need is a cheap plant sensor, I would need like 10 or 15, I don't want to spend more than a few bucks per plant. I didn't find an available solution! I've found a few sensors but they were way to expensive. I know quite a few struggling with plants, having great plans but then killing most so I think quite a few would be interested.
I don't know whether the sensors are too expensive or what's the problem. This looks like the right idea, a dumb sensor that could be paired with a inexpensive hub plugged in somewhere talking to some server that distributed notifications and statistics to an app.
A few decades ago, I have made an automatic watering system for the plants from the balcony of my apartment, which has worked many years without problems.
The cost for the electronic parts was negligible, but assembling the device required some work (mostly for the water pipes, which had to be cut and bent at the right sizes, and then they had to be fixed on some walls).
Water was brought through a pipe from the bathroom (from the water reservoir of the toilet, which was mounted at a greater height than the plants, so the water flowed naturally towards them; as an alternative one can add a manifold on an input pipe with cold water, to provide an extra branch for the water, in which case there should be enough pressure to reach greater heights), it passed through an electrovalve recovered from a washing machine, and it was distributed through some thin pipes to the plants.
The humidity sensor was printed on a PCB and the electronic part consisted of an operational amplifier, a transistor and a relay that actuated the electrovalve, to turn on and off the water going to the plants.
The operational amplifier (a model with high impedance inputs) was connected as a Schmitt trigger with the inputs to a resistor bridge that included the humidity sensor and there were 2 adjustable resistors used to modify the thresholds of the Schmitt trigger, for controlling the humidity levels at which the water was turned on and off.
The schematics was adapted from one published in some hobby electronics magazine, so I assume that a search through old collections of such magazines would find many examples.
I have used a single humidity sensor and a single electrovalve, common for all, because there was never a significant difference between the humidity levels at different plants.
When this is not true, a separate electrovalve can be inserted on each branch of the pipes, with a separate humidity sensor.
For the humidity sensor, it may be a good idea to reuse some old PCBs with edge connectors whose contacts are gold-plated, e.g. the PCBs of some old memory modules (after cutting the PCB part with the memory chips and soldering a wire across all contacts). Using the gold-plated contacts for soil contact avoids the oxidation problems that would appear in unprotected copper.
That does not help much when everybody is gone in some trip, which is the main reason why I have made that automated watering system.
Except for the plumbing work, which may need some experience or using the services of a professional, such a completely automated watering system is actually much simpler and cheaper than a humidity sensor that sends notifications.
Comments
I was recently thinking about a similar hardware (although I have no hardware background). I have a lot of plants, some shared with my roommates, and many frequently die. Taking care of plants together is hard and sometimes we are all away for a few weeks so somebody else is taking care. I would love to have an app that alerts me if something basic is wrong, for which 90% of the time would be too much or not enough water. But what I would need is a cheap plant sensor, I would need like 10 or 15, I don't want to spend more than a few bucks per plant. I didn't find an available solution! I've found a few sensors but they were way to expensive. I know quite a few struggling with plants, having great plans but then killing most so I think quite a few would be interested.
I don't know whether the sensors are too expensive or what's the problem. This looks like the right idea, a dumb sensor that could be paired with a inexpensive hub plugged in somewhere talking to some server that distributed notifications and statistics to an app.
A few decades ago, I have made an automatic watering system for the plants from the balcony of my apartment, which has worked many years without problems.
The cost for the electronic parts was negligible, but assembling the device required some work (mostly for the water pipes, which had to be cut and bent at the right sizes, and then they had to be fixed on some walls).
Water was brought through a pipe from the bathroom (from the water reservoir of the toilet, which was mounted at a greater height than the plants, so the water flowed naturally towards them; as an alternative one can add a manifold on an input pipe with cold water, to provide an extra branch for the water, in which case there should be enough pressure to reach greater heights), it passed through an electrovalve recovered from a washing machine, and it was distributed through some thin pipes to the plants.
The humidity sensor was printed on a PCB and the electronic part consisted of an operational amplifier, a transistor and a relay that actuated the electrovalve, to turn on and off the water going to the plants.
The operational amplifier (a model with high impedance inputs) was connected as a Schmitt trigger with the inputs to a resistor bridge that included the humidity sensor and there were 2 adjustable resistors used to modify the thresholds of the Schmitt trigger, for controlling the humidity levels at which the water was turned on and off.
The schematics was adapted from one published in some hobby electronics magazine, so I assume that a search through old collections of such magazines would find many examples.
I have used a single humidity sensor and a single electrovalve, common for all, because there was never a significant difference between the humidity levels at different plants.
When this is not true, a separate electrovalve can be inserted on each branch of the pipes, with a separate humidity sensor.
For the humidity sensor, it may be a good idea to reuse some old PCBs with edge connectors whose contacts are gold-plated, e.g. the PCBs of some old memory modules (after cutting the PCB part with the memory chips and soldering a wire across all contacts). Using the gold-plated contacts for soil contact avoids the oxidation problems that would appear in unprotected copper.
i would be happy with an app notification and an assessment what my status is :)
That does not help much when everybody is gone in some trip, which is the main reason why I have made that automated watering system.
Except for the plumbing work, which may need some experience or using the services of a professional, such a completely automated watering system is actually much simpler and cheaper than a humidity sensor that sends notifications.