How It Works
The sensor is made of two parts: the fork-like probe which is inserted directly into the soil, and the electronics module which processes the signal.
The two probes act as a variable resistor. The electrical conductivity of the soil changes based on the amount of water present:
- Dry Soil: High electrical resistance (low conductivity).
- Wet Soil: Low electrical resistance (high conductivity).
The module reads this resistance and outputs a signal that your microcontroller can understand.
Key Features
- Dual Output Mode:
- Analog Output (A0): Provides a precise, variable voltage signal (e.g., 0-1023 on an Arduino) that represents the exact moisture level.
- Digital Output (D0): Provides a simple HIGH/LOW (1/0) signal. This output goes HIGH (or LOW, depending on the module) when the moisture level crosses a specific point.
- Adjustable Sensitivity: An onboard potentiometer (the small blue knob) allows you to easily set the moisture threshold for the digital (D0) output.
- Wide Voltage Compatibility: Operates on a flexible voltage range of 3.3V to 5V, making it safe for all common microcontrollers.
- Status Indicators: Includes an LED for power (PWR) and another for the digital output (DO), so you can visually confirm when the set moisture level is reached.
- Corrosion Resistant Probes: The probes are nickel-plated to improve their lifespan and resistance to corrosion when left in damp soil.
Common Applications
- Automatic Plant Watering Systems: Combine this sensor with a relay and a water pump to build a system that waters your plants automatically when the soil gets dry.
- Smart Garden Projects: Create a “smart pot” that sends a notification to your phone or lights up an LED when it’s time to water.
- Environmental Monitoring: Use it in a weather station or data logger to track soil humidity over time.
- Educational Robotics: Teach students about analog sensors, digital thresholds, and basic agriculture technology (AgriTech).
Technical Specifications
- Operating Voltage: 3.3V – 5V DC
- Outputs: A0 (Analog), D0 (Digital)
- Comparator Chip: LM393
- Module Interface: VCC (3.3V-5V), GND (Ground), A0 (Analog Out), D0 (Digital Out)
- Probe Interface: 2-pin connector
What’s Included
- 1 x Soil Moisture Sensor Probe
- 1 x LM393 Comparator Module
- 1 x 2-pin Jumper Wire (for connecting the probe to the module)













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