If you are one of those people who would like to spend their well-earned summer vacations in the comforts of a hill resort but worried about your potted companions back home, then a plant watering system is what you need. This circuit immediately waters the plant once the soil turns dry. By adding timer circuits and other components, we can extend the flexibility of this project and make further improvements such that it operates automatically at duration set by timer.
Circuit Description of Automatic Plant Watering System: –
The circuit is built around IC555. It also includes pump and other passive components. As the soil dries up, its resistance increases causing the voltage at pin 2 of IC555 to fall below 1/3 Vcc. This activates the trigger comparator and the output goes high, switching on the pump. The output remains high for the time interval set by VR1 and is given by
Tminutes = 1.1 R.C/60*106
where R is in ohms and C is in microfarad.
|Resistors (all ¼-watt, ± 5% Carbon)|
|R1 = 1 KΩ
VR1, VR2 = 1 MΩ
|C1 = 470 µF/16V
C2 = 0.01 µF
|IC1 = NE555
T1 = SL100
D1 = 1N4001
|RL1 = 12V, 100Ω Relay|