Datasheet Better — Yl105

The most common mistake beginners make is assuming the datasheet’s logic table is absolute. Most YL-105 datasheets state: "IN = High → Relay OFF; IN = Low → Relay ON." This implies active-low operation. However, the better interpretation involves understanding the onboard NPN transistor (often a S8050) driving the relay coil.

Use the YL-105 for non-critical projects (plant watering alerts, greenhouse monitoring). For medical, scientific, or industrial applications, switch to a sensor with a genuine datasheet (e.g., Sensirion SHT85 or VH400). But if you are stuck with a box of YL-105s, the "better" datasheet is the one you just read. yl105 datasheet better

Desolder the LM393 chip. Connect the sensor’s center pad directly to an analog pin (via a 1kΩ resistor for protection). The comparator’s hysteresis ruins precision. The most common mistake beginners make is assuming