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Simple Solar Powered Plant Watering Alarm Circuit

Last updated on 26 June 2025 by Admin-Lavi Leave a Comment

Simple Solar Powered Plant Watering Alarm Circuit tell us how to make small device that gives water to plant when plant need it.

There are many ways to use solar energy but it should be clean and should not cost much.

This device is mix of solar power and electronics which is very interesting.

What is a Simple Solar Powered Plant Watering Alarm Circuit:

Simple solar plant watering alarm circuit is small electronic device it check if plant soil is dry or not, if soil get too dry then it make sound or light to tell us.

This circuit uses solar panel to take energy from sun and give power to parts.

It can show alarm with LED light or buzzer sound so user know when to give water to plant.

Formulas:

We can use voltage divider formula to find voltage at potentiometer:

Vpot = Vin × Rpot / (Rpot + Rtotal)

where:

  • Vpot is voltage at the potentiometer.
  • Vin is input voltage coming from solar panel.
  • Rpot is resistance of the potentiometer.
  • Rtotal is total resistance in whole circuit.

How to Build:

Below are the steps to build a simple solar plant watering alarm circuit.

  • First take one cardboard and draw where parts will connect and this is base for our circuit.
  • Cut small holes on lines for putting component pins.
  • Now put all parts on cardboard same like in circuit diagram.
  • Solder all parts slowly and properly so connections stay strong.
  • Then connect solar cell carefully to the circuit.
  • After everything is done test the circuit to see if it is working fine.

Circuit Working:

Simple Solar Powered Plant Watering Alarm Circuit Diagram

Parts List:

ComponentsValueQty
Resistor10k 1/4 watt1
Potentiometer 100k1
SemiconductorsTransistors BC5472
Solar Cell 9V 500mA1
Buzzer 9V Piezo1
Battery 9V PP31

This simple solar plant watering alarm circuit help to check and keep soil wet for plant.

Solar cell take sunlight and make electric power.

100k potentiometer is used to set how dry soil can get before alarm starts.

When soil get more dry than this level circuit turn ON.

Circuit check voltage from potentiometer and compare with fixed voltage.

If soil is too dry then voltage from potentiometer goes down.

When voltage goes below the limit then circuit turn ON the buzzer to make sound.

NPN transistors make voltage changes stronger and LEDs show what circuit is doing.

Advantages and Disadvantages:

Advantages:

  • Circuit uses solar power so it does not harm the environment.
  • Cheap and good way to take care of plants.
  • We can change moisture level setting for different types of plants.
  • Good project to learn about solar energy and electronics.

Disadvantages:

  • Circuit only work good when sunlight is there.
  • Buzzer sound may not good in quiet places.

Conclusion:

Simple solar plant watering alarm circuit is smart way to give water to plants without using normal electricity.

This DIY project is low cost and good for learning about solar power and electronics.

It help save time, work and also make future better.

With small changes and testing we can improve this circuit to fit our own needs.

References:

Why use a Solar Powered Watering System

Watering the garden with a solar powered system

Filed Under: Alarm Circuits, Solar Circuits

About Admin-Lavi

Lavi is a B.Tech electronics engineer with a passion for designing new electronic circuits. Do you have questions regarding the circuit diagrams presented on this blog? Feel free to comment and solve your queries with quick replies

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