Soil Moisture Detection Humidity Sensor

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)