Simple Solar Plant Watering Alarm Circuit

In this post we learn a simple solar water plant watering alarm circuit which is powered from a small solar cell and provides a buzzer alarm sound whenever the soil is parched below the set minimum threshold.

If you have a garden and would like to define some process where you will receive notification in case of dryness of soil for a planted tree, build a solar powered plant watering alarm system can be a good idea. It is simple to design and its effectiveness will surely prove beneficial among botanist or horticulturist.


solar plant watering alarm circuit

Recommended Components

  • NPN transistors BC547 40V 200mA – Q1
  • NPN transistors 2N2222 40V 500mA – Q2
  • 3mm LED – LED1, LED2
  • Resistors 10K 0.25W – R1
  • Resistors 100ohms 0.25W – R2
  • Potentiometer 50K – VR1
  • Buzzer 6V – BZ1
  • 5v AA Battery x 3
  • Wires for connection

Procedure of Assembly

If you are looking to save cost albeit considering the quality, you may opt for cardboard instead of a PCB.

First draw the full layout of the system i.e. layout of the components. Then do it on a cardboard in your desired size and finally cut out the layout design.

Once ready, the next step is to make hole on all the pin areas using nail and hammer. Then place all the parts over the cardboard in the respective position as per the layout and further wire leg of all components by soldering.

The next step and final step is to set the Solar Cell [6V] onto the layout and you are ready to test the proposed simple solar water plant watering alarm circuit