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Topic: Potted plant watering system. (Involves water pumps.) (Read 11 times) previous topic - next topic


Hi, Oz,
I'm sure you realize that analog inputs don't get de-bounced (that's why you used quotes and mentioned a delay).

What are you planning on using for the input sensors?
The "reserve" looks like it could be digital one, like a float switch in the reservoir.

For the diy moisture sensors, I'm thinking you'r looking at something like:

Instead of the 4016 or 4066 you could use a single MAX4617, which has 8 channels.
I think you should play with the sensor first, i.e. a pair of galvanized nails and a cheap voltmeter.
Perhaps a 1 Megohm (or more) resistor to ground on the "input" nail, the one not connected to the voltage source.
Then, when you're confident that a certain low enough voltage, as measured on the meter, corresponds with the dryness you want,
you can add one or two analog switches, and use a single Arduino analog input instead of the meter.

By the way, I think it's way cool, and considerate of the plants, to water each one when, and only when, IT needs water.
Most everybody makes do with a single time schedule for all the plants!
Good luck!.  Mitch



Yeah, the two nails are the way I am wanting to go.

Something along the lines of what you said.  Probably a transistor with bias and the nails only to detect water level placed on the side of the pot which is sitting in a saucer.

Thanks for the chip and that.  Shall look into it.

That link doesn't work.


Yeah, the two nails are the way I am wanting to go.

I'm using a couple of stainless steel cooking skewers about 15cm long as moisture sensors, just pushed into the soil. They're mounted in a chop block electrical connector to keep them parallel and this also gives a convenient way to attach the wires. I'm using the technique of only powering the sensor when I need to take a reading, and reversing the pulse after the measurement to avoid any ionization effects. It took me a while to figure out the resistance and timing to get a consistent reading that reflects water content within the range I'm measuring, but it seems to be working OK now.
I only provide help via the forum - please do not contact me for private consultancy.


Fair enough.

I am torn between moisture detecting and simply monitoring the water level in the saucer below the pot.

The basic idea is that "daily" at "time x" it will look at each (one at a time) level and water for n seconds or until the water level in the saucer is high enough to touch the nails.

Although the water level and moisture content are "just numbers" to compare to fixed ones, the level detection seems easier.

For now I don't have the sensors defined or anything - because I don't have the analogue input resolved - just the turn on, cycle and turn off part.

I don't even have the RTC yet.

Alas I am having a real drama getting the solenoids.

Oh and I need a separate sensor for the main reserve of water, so if it is empty, the pump and solenoids are not turned on.


As I've suggested in similar prior threads - consider raising the reservoir so that the water is gravity fed. Then you don't need a pump and there is no need to sense the water level unless you want an alarm when it's empty.

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