Water Vapor Sensor | Analog Rain & Fog Detector

Water Vapor Sensor for Analog Rain Fog and Moisture Detection

The Water Vapor Sensor is an analog moisture detection board for rain, fog, water vapor, and liquid contact experiments. When droplets or moisture appear on the petal-shaped detection area, the output voltage changes so a controller can monitor wetness level.

This version uses a simple G-V-S interface with one analog signal pin, making it easy to connect to Arduino, ESP32, STM32, or Raspberry Pi Pico ADC inputs. It is a practical module for classroom weather stations and automated cover prototypes.

Keep the header and electronics dry. The sensing area can detect water presence, but the complete module should not be submerged or left exposed to corrosion without protection.

Technical Specifications

Board Layout & Label Guide

• Petal sensing area: Place this area where moisture needs to be detected.
• G pin: Power ground.
• V pin: 3.3 V or 5 V power input.
• S pin: Analog signal to controller ADC.
• Mounting holes: Fix the sensor so droplets reach the sensing area.
• Cable route: Route the cable downward or protected to prevent water entering the connector.
• Cleaning note: Dry and clean the surface after repeated wet tests.

Application Scenarios

1. Rain or Water Presence Monitor

Read the sensor surface and print a simple moisture level for roof, window, or tabletop experiments.

const int SENSOR_PIN = A0;void setup() { Serial.begin(115200);}void loop() { int wetLevel = analogRead(SENSOR_PIN); Serial.print(“wet_level=”); Serial.println(wetLevel); delay(200);}

2. Automatic Cover Trigger

Use a threshold to trigger a servo, relay, or warning output when water is detected.

const int SENSOR_PIN = A0;const int OUTPUT_PIN = 8;const int WET_THRESHOLD = 500;void setup() { pinMode(OUTPUT_PIN, OUTPUT);}void loop() { int wetLevel = analogRead(SENSOR_PIN); digitalWrite(OUTPUT_PIN, wetLevel > WET_THRESHOLD ? HIGH : LOW); delay(100);}

3. Moisture Trend Logger

Average several samples before logging so droplets, fog, or touch events are easier to compare.

const int SENSOR_PIN = A0;void setup() { Serial.begin(115200);}void loop() { long total = 0; for (int i = 0; i < 16; i++) { total += analogRead(SENSOR_PIN); delay(5); } Serial.print("average_wet_level="); Serial.println(total / 16); delay(1000);}

Packing List

• 1 x Water Vapor Sensor

FAQ

Q: Can this module work with Arduino?
A: Yes. Connect VCC, GND, and the signal pin to an Arduino-compatible board or an OpenELAB Sensor Shield V5.

Q: Can it work with 3.3 V controllers?
A: Yes for the listed 3.3 V to 5 V modules, but keep analog output within the controller ADC range.

Q: Is calibration required?
A: For threshold or quantitative use, calibrate in the final installation and record baseline readings.

Q: Can I use long wires?
A: Shorter wires are better for analog stability; use averaging in firmware if readings fluctuate.

Q: Does the module output precise engineering units?
A: Most of these modules provide relative analog or digital signals, not certified measurement data.

Q: What should I check first if it does not trigger?
A: Verify power, ground, pin mapping, threshold setting, and whether the signal is active-high or active-low.

Q: Is it suitable outdoors?
A: Only with enclosure protection. Keep connectors and electronics away from water and corrosion.

Q: Can it drive a relay or motor directly?
A: No. Use the module as an input to a controller, then drive a suitable relay or motor driver.