Guide to the HWFS-1 Anemometer

Measuring wind speed is essential for weather stations, agricultural monitoring, HVAC automation, and safety systems. The HWFS-1 Anemometer is a cost-effective, analog-output wind speed sensor, ideal for both DIY and industrial environments. In this guide, you’ll learn everything about the voltage-type HWFS-1, its principle, wiring, and how to use it effectively with microcontrollers.

What is the HWFS-1 Anemometer?

The HWFS-1 is a mechanical cup-style wind speed sensor with an integrated voltage generator. As the wind rotates the 3-cup rotor, the internal generator produces a voltage signal proportional to wind speed, no external power supply is required.

The details in this guide come from the common documentation of the HWFS-1 anemometer. I did not read a datasheet for this update, and units from different sellers vary.

Key Features

• Model: HWFS-1
• Type: Analog cup-type anemometer
• Output: Voltage (0–2V typical, max 4V)
• Power: Passive (no external power needed)
• Wiring: 2 wires (Signal + Ground)
• Material: ABS plastic, weather-resistant
• Max Wind Speed: 200 KM/h
• Recommended Range: < 100 KM/h
• Installation: Bolt-through base, 3 × 6mm holes at 120°

Dimensions

The HWFS-1 is a three-cup anemometer with an ABS body. It mounts with a bolt-through base with three 6 mm holes at 120°. The cup diameter, the height and the cable length vary between sellers, so measure yours before you design a mast or a bracket. Mount it horizontally and in open air.

Source: the details come from the existing text of this guide and common practice, not from a datasheet read for this update.

How It Works

When wind blows, the cups rotate and an internal electromagnetic generator produces a voltage. The output voltage increases linearly with wind speed:

• 0V → no wind
• 2V → ~100 KM/h
• 4V (max) → ~200 KM/h (not recommended for continuous use)

HWFS-1 Wiring

Connect the signal wire to an ADC (Analog-to-Digital Converter) pin on your microcontroller (e.g., ESP32, Arduino) and the black wire to GND.

There is no polarity, but consistency is best practice.

Example Wiring (ESP32)

Sample Arduino Code (Analog Reading)

#define WIND_SENSOR_PIN 34

void setup() {
  Serial.begin(115200);
}

void loop() {
  int analogValue = analogRead(WIND_SENSOR_PIN); // 0–4095 on ESP32
  float voltage = analogValue * 3.3 / 4095.0;     // Convert to volts
  float windSpeedMS = voltage * 14.0;             // Wind speed in m/s
  float windSpeedKMH = voltage * 50.0;            // Wind speed in km/h

  Serial.print("Wind Speed: ");
  Serial.print(windSpeedMS);
  Serial.print(" m/s | ");
  Serial.print(windSpeedKMH);
  Serial.println(" km/h");

  delay(1000);
}

Calibration Formula

You can estimate wind speed directly using these formulas:

• Wind speed (km/h) = Voltage (V) × 50
• Wind speed (m/s) = Voltage (V) × 14

Example: if the voltage is 0.5V, then wind speed ≈ 25 km/h ≈ 7 m/s.

Practical Applications

• Weather Stations: Monitor outdoor wind conditions
• HVAC Automation: Adjust systems based on outside airflow
• Agriculture: Control irrigation and ventilation based on wind
• Wind-Triggered Systems: LED beacons, safety alerts, etc.

Best Practices

• Mount horizontally at an open, unobstructed location
• Avoid metallic interference or lightning-prone spots
• Use waterproof enclosures for electronics
• Shield analog cable if longer than 3 meters
• Use a stable analog reference voltage for accuracy

Real gotchas

• The output can exceed the ADC range. The sensor outputs 0 to 2 V typically and up to 4 V at its maximum, while an ESP32 ADC reads at most 3.3 V and is not linear near the top. Use a voltage divider so the signal stays below the ADC limit, set the 11 dB attenuation, and calibrate.
• The ESP32 ADC is not linear. Calibrate against a reference anemometer, or use analogReadMilliVolts().
• The 14 and 50 factors are nominal. They assume 2 V for 100 km/h. Check them with a known wind speed.
• The sensor has a start-up wind speed. Very low wind does not turn the cups, so there is a dead zone near zero.
• Long cables pick up noise. Shield the cable beyond 3 metres, and keep it away from mains wires.
• No polarity, but be consistent. Use the same wire as ground every time.
• Lightning. A metal mast outdoors attracts lightning. Ground it properly and keep the electronics protected.
• Ice and dust. They change the friction of the bearing and the reading.

Safety notes

Conclusion: Wind Speed Made Simple

The voltage-type HWFS-1 Anemometer is a reliable, easy-to-use analog wind speed sensor ideal for embedded systems. Its passive design requires no power supply, and it integrates seamlessly with ADC-enabled microcontrollers like the ESP32 and Arduino. With linear voltage output and simple formulas, it’s a perfect sensor for anyone needing real-time wind data.