Another answer to question #12145 False Readings

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Another answer to question #12145 False Readings

Post by TonyScarpelli » Sun Apr 19, 2015 8:05 am

I built an automatic watering device for my window sill plant box.

When I started I used a common two prong sensor that was silver in color. It didn't last very long at all so I bought a better one on Amazon (Arduino compatible High Sensitivity Moisture Sensor by Phantom YoYo). It has a gold probes which last much longer.

The other thing I did was to do the sensing for a short time every 15 minutes. This I did using reed relays to power the sensors. This keeps the current between the probes at a minimum, thus reducing the corrosion process.

I have a long 19 inch box of Basil for one probe, and a small 6 inch regular pot for the Kalanchoe Pennata probe. The probes are attached to an Arduino Uno. Every 15 minutes we turn on the probes and cause a beep, one for each probe. If the Basil needs water the circuit produces 10 single beeps, and the Kalanchoe 10 double beeps so I know which one needs water.

Recently I added valves being fed from a one gallon plastic bottle on a shelf. So now the basil gets a lot of water, maybe two cups, and the Kalanchoe gets a lot less. The circuit is set up to only do one cup at a time to let the water spread to the sensor.

The only problem I have now is how to spread the water over the 18 inches of soil. I am trying something like a manifold using tubes and T Union Fitting Intersections. Still working on this one.

Hope this helps someone.


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