Circuit for automated hydroponic pot?
banjo
Posts: 438
Long time no C... sorry for the pun, it's late here and with 4.5 hours of daylight if feels like night all the time...
Anyhow, we have a well working hydroponic pot (https://botanium.se/products/botanium-kit?variant=51291156679), have used it to grow chili (successfully) and cherry tomatoes (no fruit, plant died). Now we have two tiny stalks appearing, they might be a combination of orange, tangerine, lemon, or apple. After the tomato plant died I have just randomly thrown some seeds there, so not sure what is growing, and as they most probably won't grow fruits, we might not even get to know what they are.
This pot pumps some water every 3 hours to keep optimal moisture in the growing medium.
Now I'd like to recreate a similar pot, initially I'd just cut a plastic bottle in half, and turn the top part upside down in the bottom part, and use a small pump to pump water from bottom to top. Later I might consider 3D-printing the container.
I have since before the small 6V water pump shown in the picture, so now I'd "only" need a circuit built 
This would need to pump water for approx. 10 seconds, e.g. every 3 hours. Or for 5 seconds every hour etc. These I'd just need to find out with trial and error.
I've found different circuits on the web, many of them with a 555-timer and some other components. But as I'm a programmer and not an electronics guru, I'm not sure what would work and how to get the pump into the circuit.
If a MPU is needed, then I have one or two BS2-boards, some P1 Activity Boards, too many P1 Project boards, a P1 Flip and also a P2. (not mentioning that I have some Arduino boards and Raspberry's as this is a Parallax forum).
Now when I think about it, perhaps I should use a P1 Project board so it's easier to change parameters.
Any suggestions on the circuit side, or otherwise?
Comments
careful - 10 sec every 3 hours is NOT the same as 5 sec every 1.5 hours.
Part of the process is that the substrate has time to air out, not dry but waterless. this prevents mold and algea to grow.
Basically.
And what can I say you need a P2-Edgde for that ....
No you don't
But for one pump, I would just go for a 555.
On the other hand if you want to switch lights too, measure PH values or log the progress a P1 Projekt Board should do fine.
So no investment you have several.
Next is some relay/transistor/circuit/breakout to switch 12v with 3.3V. You may have one somewhere
Choose a Pin and switch the relay like you would blink a LED.
Mike
Thx Mike, did not think about this. I'll weigh the existing pot (or actually the top half of it) before the pumps water, and after the pumping. Then I'll know how much water it has pumped and have at least a starting point.
Yeah, should have relays, probably easiest and safest for me. I do also have a motor driver somewhere, but using it is perhaps overkill?
I had thought about measuring moisture and how much water has been pumped, and showing this on a e-Ink display, "just for fun". But would make sense to control lights, now I use a 240 V 5W LED-bulb, and I'm the automation there. Not sure how many whitish leds would be needed to provide similar amount of brightness. Oh dear, scope creep, once again.
banjo,
Take a look 'Process Control' under Downloads.
https://www.parallax.com/product/csu-long-beach-custom-kit-3/
There is an egg incubator project in the later chapters that uses a heater, temperature sensor, and a fan to maintain a constant temperature.
'Applied Sensors' used a moisture sensor made up of 2 screws connected to a 555.
http://www.parallax.com/Store/Education/KitsandBoards/tabid/182/CategoryID/67/List/0/SortField/0/catpageindex/1/Level/a/ProductID/305/Default.aspx
Chapter 5 - Page 119 (Page 127 of the PDF)
I had completely forgotten about the experiment in Chapter 6 (Page 155 of the PDF) which you might find useful.
Thx @Genetix , this PDF is a gem! I should have real books of What's a Microcontroller, and the Basic Stamp manual lying somewhere, better browse through them as well.
The link does not work for me, gives a 404
A copy of the "Applied Sensors, Student Guide" (version 2.0) seems to also be accessible thru the following link (tks to Digikey):
https://digikey.com/en/pdf/p/parallax/applied-sensors-guide
Hope the version is correct (at least the mentioned circuit is present, at the right page#...)
Great, thx @Yanomani !
I have found if I go to the old Parallax Website i can find many products links using the search function.