HR202L Humidity Sensor with Shell - Analog Output

The HR202L sensor is rated for 1.5 VDC. It is a resistive sensor, so it requires an AC excitation signal between 500Hz and 2kHz for proper operation. In a typical circuit, you would use a voltage divider with a stable resistor and measure the voltage drop across the sensor with a microcontroller's ADC.

Connect the HR202L in a simple voltage divider circuit. Use a fixed resistor (e.g., 10kΩ to 47kΩ) in series with the sensor between your logic voltage (3.3V or 5V) and ground. Connect the junction between the sensor and resistor to an analog input pin on your Arduino or Raspberry Pi (via an ADC). The sensor's resistance changes with humidity, altering the voltage at the analog pin.

For best accuracy, a two-point calibration is recommended. You can calibrate against a known humidity reference (like a calibrated hygrometer) at a low and high humidity point within the 20-95% RH range. Use these points to map the analog reading from your microcontroller to the actual relative humidity percentage.

The integrated shell protects the sensitive polymer sensing element from direct physical contact, dust, and minor condensation, which helps ensure long-term stability and reliability. It does not make the sensor waterproof, so it should not be exposed to liquid water or used in condensing environments.