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Smart Soil Moisture Sensor & Auto Irrigation System

SKU: FA3003-0
Sensor Type

Capacitive soil moisture sensor
Control Board

LM393 comparator or microcontroller (variant dependent)
Relay Rating

10A at 250V AC / 10A at 30V DC
Operating Voltage

5V or 12V DC (variant dependent)
Sensitivity Adjustment

Potentiometer or programmable threshold
Output Type

Relay (NO/NC/COM)
Indication

Power LED + relay status LED
Sensor Cable Length

Typically 1–2 meters

The Smart Soil Moisture Sensor & Auto Irrigation System is an integrated, ready-to-use solution for automating plant watering based on real-time soil moisture levels. It combines a capacitive soil moisture sensor, a microcontroller-based control board, and a relay output for driving water pumps or solenoid valves — creating a complete, self-contained irrigation controller that waters plants only when needed. This system is ideal for home gardens, greenhouses, indoor planters, and agricultural projects.

At the heart of the system is a capacitive soil moisture sensor that measures the dielectric permittivity of the soil to determine moisture content. Unlike resistive sensors that corrode over time, the capacitive design is corrosion-resistant and provides stable, long-term readings. The sensor outputs an analog voltage proportional to soil moisture, which the controller reads and compares to a user-adjustable threshold.

The control board (typically based on the LM393 comparator or a microcontroller depending on the variant) processes the sensor signal and activates the relay output when soil moisture drops below the set threshold. The relay can switch water pumps, solenoid valves, or drip irrigation systems on and off automatically, maintaining optimal soil moisture without manual intervention.

The system includes an adjustable sensitivity potentiometer (on comparator-based versions) or programmable thresholds (on microcontroller-based versions), allowing you to set the moisture level at which watering begins and stops. LED indicators provide visual feedback for power status and relay activation.

The relay output is rated for 10A at 250V AC or 30V DC, capable of directly switching most small water pumps and solenoid valves. The system operates from a 5V or 12V DC supply (variant dependent), making it compatible with common power adapters, batteries, and solar power systems.

The system is widely used in home gardens, greenhouses, indoor planters, agricultural irrigation, landscape watering, and DIY automation projects. It is also popular in educational projects for teaching soil moisture sensing, comparator circuits, and automated irrigation principles.

Important Note: The capacitive soil moisture sensor should be inserted into the soil up to the marked line, avoiding direct contact with water or metal objects. For outdoor use, ensure the control board is housed in a waterproof enclosure. The relay rating (10A) is sufficient for most small pumps, but verify the pump’s current draw before connecting. For high-power pumps, use an external contactor or relay.

Whether you are automating a home garden, building a greenhouse irrigation system, or creating a smart planter, the Smart Soil Moisture Sensor & Auto Irrigation System provides a reliable, integrated solution. It is suitable for individual makers, gardening enthusiasts, and businesses purchasing in bulk for product development or educational programs.

Features

  • Capacitive soil moisture sensor — Corrosion-resistant, stable long-term readings

  • Automatic irrigation control — Relay activates when soil moisture drops below threshold

  • Adjustable sensitivity — Potentiometer or programmable threshold (variant dependent)

  • High-current relay output — 10A at 250V AC / 30V DC for pumps and valves

  • LED indicators — Power status and relay activation feedback

  • Wide operating voltage — 5V or 12V DC (variant dependent)

  • Complete system — Sensor, control board, and relay output in one kit

  • Wide application range — Home gardens, greenhouses, indoor planters, agriculture

Technical Specifications 

# Parameter Specification
1 Sensor Type Capacitive soil moisture sensor
2 Control Board LM393 comparator or microcontroller (variant dependent)
3 Relay Rating 10A at 250V AC / 10A at 30V DC
4 Operating Voltage 5V or 12V DC (variant dependent)
5 Sensitivity Adjustment Potentiometer or programmable threshold
6 Output Type Relay (NO/NC/COM)
7 Indication Power LED + relay status LED
8 Sensor Cable Length Typically 1–2 meters

Usage

Getting Started

  1. Connect the sensor — Plug the capacitive soil moisture sensor into the control board. The sensor typically has a 3-pin connector (VCC, GND, SIG).

  2. Connect power — Supply 5V or 12V DC (depending on the variant) to the control board’s power input. The power LED should light up.

  3. Connect the pump or valve — Wire your water pump or solenoid valve to the relay’s NO/NC/COM terminals. Use the screw terminals for secure connections.

  4. Insert the sensor into soil — Insert the capacitive sensor into the soil up to the marked line, ensuring good contact with the soil. Avoid touching the sensor’s components with bare hands.

  5. Adjust the threshold — For comparator-based versions, turn the potentiometer to set the moisture level at which the relay activates. For microcontroller versions, program the threshold in the code.

  6. Test the system — Dry the soil or add water to verify the relay activates and deactivates at the correct moisture levels.

Trigger Logic (Typical)

Soil Condition Sensor Output Relay State
Dry Low moisture Activated (pump ON)
Wet High moisture Deactivated (pump OFF)

(Note: Relay logic may vary by wiring and application — test and adjust as needed.)

Typical Applications

  • Home gardens — Automatic watering for flower beds and vegetable patches

  • Greenhouses — Precise moisture control for plant growth

  • Indoor planters — Self-watering systems for houseplants

  • Agricultural irrigation — Automated watering for small farms

  • Landscape watering — Automatic irrigation for lawns and shrubs

  • DIY automation projects — Custom soil moisture monitoring and control

Notes for Business Buyers

  • Complete solution — Sensor, controller, and relay in one integrated system.

  • Corrosion-resistant sensor — Capacitive design outlasts resistive sensors.

  • High-current relay — 10A capacity covers most small pumps and valves.

  • Suitable for bulk purchasing — Ideal for garden product manufacturers, irrigation integrators, and educational institutions.

Q: What is the Smart Soil Moisture Sensor & Auto Irrigation System used for?

It is a complete automation system that monitors soil moisture and automatically activates a water pump or valve when the soil becomes too dry, used for gardens, greenhouses, and planters.

Q: How does the capacitive soil moisture sensor work?

The capacitive sensor measures the dielectric permittivity of the soil, which changes with moisture content. It outputs an analog voltage proportional to soil moisture, which the controller reads.

Q: What is the difference between capacitive and resistive soil moisture sensors?

Capacitive sensors are corrosion-resistant and provide stable long-term readings, while resistive sensors use exposed electrodes that corrode over time and require frequent replacement.

Q: What is the relay rating?

The relay is rated for 10A at 250V AC or 10A at 30V DC, capable of switching most small water pumps and solenoid valves.

Q: What voltage does the system require?

The system operates from 5V or 12V DC, depending on the specific variant.

Q: How do I adjust the moisture threshold?

For comparator-based versions, turn the onboard potentiometer to set the threshold. For microcontroller-based versions, program the threshold in the code.

Q: Can I use this system outdoors?

Yes, but the control board should be housed in a waterproof enclosure for outdoor use. The sensor itself is designed for soil insertion.

Q: How deep should I insert the sensor?

Insert the sensor into the soil up to the marked line on the probe. Avoid submerging the sensor’s components in water.

Q: What pump can I use with this system?

You can use most small DC water pumps or solenoid valves within the relay’s 10A rating. For high-power pumps, use an external contactor.

Q: Can I purchase in bulk for a product development project?

Yes. This system is suitable for both individual users and business purchasing, including garden product manufacturers, irrigation integrators, and educational institutions.

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