Plant watering circuit It indicates when there is lack of water in your plants through LED, the LED turns on which lets us know that the plant needs water. It works well but remember it is only for small plants and it is not that powerful, the LED also glows very slowly which makes it difficult to detect, and to avoid it from rusting keep it a little away from the plant and cover the transistor a little with the help of tape. It is made up of bc547 transistor and a resistor. It is also very easy to operate and you can make it in school practicals also if your teacher allows. To make this see the Making Process Guide, we have taught you with complete information how to make this circuit.
Why Build a Plant Watering System?
Many times it is not known whether the plant is dry or not. If the plant is moist then even pouring excess water will spoil it, and if the plant remains dry and you feel that there is water in the plant while the plant is dry, then the plant will get spoiled in this way also. Therefore, plant watering systems are installed at many places which pour water on the plant as soon as it gets dry, and when the plant gets adequate water, the watering stops. These can be automatic as well as manual. And the circuit that we have made is manual. And it is made up of components.
Components Needed
BC547 Transistor: A versatile NPN transistor that acts as a switch in this circuit.
3V LED: Serves as a visual indicator.
1 Megaohm or 2.2 Megaohm Resistor: Controls the current flowing through the LED.
3V Battery: Powers the entire circuit.
Wires: Used to connect components and to probe the soil moisture level.
| Specifications and equivalent |
|---|
| Transistor | BC547 (NPN) |
| Circuit type | soil moisture detector |
| Input voltage | 3 volt |
| Input Ampere | 1 A |
| Package | TO-92 |
| Collector Emitter | 45 v |
| Emitter Base | 50v |
| Collector Base | 6v |
| Current Gain (hFE) | 110 to 800 |
| Equivalent | 2n2222, 2n3904, bc549 |
Making Process Guide
1.Connecting the Transistor and LED:
• First connect the negative pin of the LED to the first pin (emitter) of the BC547 transistor.
• Now connect the positive pin of the LED to any one end of the resistor, and connect the other end of the resistor to the second pin (base) of the transistor.
2.Setting Up the Power Supply:
• Now connect the positive terminal of the 3V battery to the positive pin of the LED.
• Then connect the negative terminal of the battery to the third pin (collector) of the BC547.
3.Preparing the Sensor Wires:
• Take one wire and connect it to the base pin of the BC547 and now take another wire and connect one end of it to the collector of the transistor.
• Separate the other ends of both these wires and insert them into the soil near your plant, making sure they are not too far from each other to effectively detect moisture.
Circuit Diagram
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| Circuit diagram of plant watering system |
How It Works
The circuit operates as a variable resistor using two wires inserted into the soil, whose resistance varies with the moisture level. And when the soil is dry, the resistance is low enough that the base of the BC547 keeps the transistor on, and the LED stays on. As the soil gets moist, the resistance gets higher, which reduces the current flowing through the base of the transistor, turning the LED off. When the LED turns on, it signals that it is time to water your plant. Watering the plant immediately increases the conductivity of the soil, turning the LED off. And there is no need to water.
Some plant watering system circuits are made at a very advanced level like using Arduino or using IC (Integrated Circuit). A buzzer or a small water pump or both can be used with this circuit. To protect it from rust, take a plastic tape or some plastic envelope and put it in this circuit, or melt fevicol or glue gun stick and put it in this circuit. This will make it waterproof and it will not rust. PCB Board, Zero PCB Board, Breadboard etc. can be used to make this circuit. Use rechargeable cell to give power. If the circuit does not work then check the LED and also the transistor, check all the components and connections, use 3v 5mm or 3mm LED. Avoid using yellow LED, if possible use red, blue, green LED. Watch video
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