The datasheet mentions "VDD ripple < 50mV." In reality, if you power the YL105 from the same 5V rail as a servo motor, you will get +10% RH errors. Use a dedicated 3.3V LDO regulator or add a 470µF capacitor on the power rail.
Finding a datasheet for the specific part can be difficult as it is often a generic or localized part number used in specific regions or by smaller manufacturers. yl105 datasheet better
Most users assume they can source current from an Arduino pin to drive the IN pin high. While true, the improved datasheet would clarify that the YL-105 is more robust when used as a . Why? Because the onboard LED and base resistor are referenced to VCC. When you pull the IN pin low (sinking current), the path is direct to ground, avoiding voltage drop issues from the MCU's output driver. A superior datasheet would include a driver recommendation: "For best noise immunity, drive the IN pin with an open-drain or open-collector configuration, or use an active-low signal." The datasheet mentions "VDD ripple < 50mV
The stock YL-105 is not linear. The real transfer function (discovered via third-party testing) is: Voltage_out = Vcc * (1 - e^(-k * Moisture)) Where k is approximately 0.45 for loamy soil. A better datasheet would include 5-point calibration (sand, silt, clay loam). You must generate this yourself. Most users assume they can source current from