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  • Automatic and Effecient Plant Irrigation System

  • Created: Jan 30, 2014

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Watering our plants is a very delicate and time consuming chore, which is this project’s inspiration: to minimize the time spent on watering tasks and to use the water efficiently without human interference based on the soil’s moisture. This project is perfect for people who are always busy and traveling frequently.

In this project, the system uses probes inserted into the soil to sense its moisture if it is wet or dry. It will then switch the relay ON/OFF which will OPEN or CLOSE the loop of the electric valve plugged into the AC power source.

In this circuit, 9 volts battery is used to power the device. Two probes are inserted into the soil that will conduct only when the soil is wet or the soil’s resistance is low. When the soil is dry, it will produce a large voltage drop due to high resistance. This will be sensed by the 74AHC1G04GV inverter and will give an output HIGH when the input is LOW and will trigger the first ICM7555 timer that is configured as monostable mutivibrator. When the first ICM7555 timer is triggered, it will generate an output to the second ICM7555 timer that is configured as astable multivibrator. The second ICM7555 timer will then generate an output to drive the relay through the SK100 transistor. The relay will switch the electric valve watering the plants, and when the soil is wet, it will decrease its resistance and conduct the two probes that will trigger the 74AHC1G04GV inverter stopping the trigger of the first ICM7555 timer.



I used a Nat Semi part to do this years ago - LM1881, I think. Used an AC drive on the sense electrode, so no plating/offset.

Posted: Mar 13, 2014

Neil Mula

Cool ^^

Posted: Jan 05, 2015



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