Okay, I took a course on Electronics like 8 years ago, so needless to say much past calculating Voltage, Amperage, or Resistance have faded over the years. (Back then I had no interest in electronics) and well... now I do.
Basically I'm looking to try and find someplace I can read up details on how to setup a valve and capacitor(s) so that I can trickle charge the capacitor using a solar panel that I can trigger via a sensor attached to the arduino. When triggered the Charge from the capacitor would be released openning a valve allowing brief water flow. (Which would then close on it's own once the charge is deminished or I'd set some sort of time)
Pretty much looking at using a 12DCV solenoid valve (maxium amperage of 450mA) stored above the valve would be say 5 gallons of water, I simply open the valve briefly to allow some water to be passed on, then the valve closes until more water is needed.
I've been hunting on google but most of what I find merely tells me that capacitors can and are used regularly for power storage, but not really how or the math behind it.
Thank you CrossRoads, sorry for the long delay. I started a new development job the day after I posted this and with that + holidays + etc been pretty crazy but finally got a chance to sit down to go over the numbers more.
Basically at this point I'm working on the proof of concept.
I've got a small I'd say 6" x 12" solar panel that tends to produce ~5v. Once I've established the entire system and it's application is feesible I'd aquire whatever sized panel would be needed to run it at a reasonable speed. (since I suspect if I used the capacitor it would be one of those things where it's charge the capacitor, deplete it openning the valve, can't do another cycle until it's recharged)
I know my sensors work as I've tested them using a volt meter and just need to program the ardunio to respond appropriately based on the returned data. The down side is it'll be purely trial and error to figure out where my thresh hold will trigger watering or be within tolerance.
My concern is running the valves on solar panels, that could be the kink in the whole plan. If the requirement to run the solenoid for a few seconds requires an unreasonably large panel I'd have to rely on 120v AC... which isn't a bad thing perse, but not my goal.
For the proof of concept the bucket will be filled manually, I'm debating my long term solution for water source, ideally it'd run off rain, however; I'm realistic and realize I'd probably have to suppliment rain water with water from the house. (I'd likely add a few sensors to the reserves that when ALL sensors show no water it'd allow water flow, that way if only one fails I don't have a distaster) But honestly that part is still in planning. I'm doing the proof of concept now at my apartment when I get my house in June(ish) thats when I'll work out the perminent version's details.
Most (all?) of these solenoid valves require a fair amount of pressure to "crack" them, I think because a spring is used to close the valve and the solenoid works against the spring with help from water pressure.
It's possible that your 5gals won't have enough pressure to crack the valve.
I'm not much of a gardener - would the plants/grass need to be watered through the day? might charging a battery during the day and watering in the night be possible?
@Graynomad. Interesting point on the pressure, didn't think of that but something I'll likely need to look into. (For the proof of concept I don't think I've an easy temporary work around for testing to that one available without purchasing equipment, but worst case I can test it at the lab)
As far as watering goes the ideal time to water plants is first thing in the morning (can be before sunrise) watering through the day is fine up until a little before sunset. (watering in the evenings increases risk of molds and paracitic fungus) So if the idea is charge it up through out the day then do a watering cycle it's perfectly viable, I'd just want to schedule the watering for just before sunrise or there abouts.
Well different voltages aren't a huge issue. I figure in the end I'll wind up with one ardunio that handles the sensors and triggers, I will likely have the solenoids on a seperate circuit since they have much higher power draws, then just use a single line to the solenoid to tell it when to fire. (Least 1000 ways that can be handled, but again proof of concept first)
laughing thanks for the idea CrossRoads, those look like they'd work wonderfully if they wouldn't completely murder my budget. (I do anticipate spending most of the cost between solar panels and solenoid valves, but tad more then I can justify )
Very helpful, sadly having problems with my board, might be DOA I already got another one on order though since I know it'll wind up used. So just fiddling with what I can with my system having no brain. (Still sorting out which solenoids, but ultimately I plan to make that purchase once I'm satisified the system is reading/triggering at the proper threshold, right now it's doing a simple 3 light system, Blue = over watered, Green = Good, Red = underwatered. When I'm happy with it I'd just change the Red LED to trigger the solenoid instead.)
Stupid board being on backorder I've been told I should see it this week though, so till then I'm being a lab assistant to myself and just taking readings since tempature can affect the readings so I have to make sure to take both the moisture senesor and tempature into consideration.