Yl105 Datasheet Better -

The YL-105 setup consists of two distinct parts connected by two jumper wires:

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 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. Better solution: Use a dedicated 3.3V LDO regulator or add a 470µF capacitor on the power rail. yl105 datasheet better

If you’ve ever built a weather station, an automatic window opener, or a smart irrigation system, you’ve likely stumbled across the YL-105 Rain Sensor Module. It’s cheap, ubiquitous, and incredibly useful.

But if you’ve ever tried to read the official "datasheet" (often a folded piece of paper with broken English), you know it leaves a lot to the imagination. It tells you the voltage is 5V and the output is Digital or Analog, but it doesn't tell you why your readings are fluctuating or why the sensor seems to "forget" it’s raining after ten minutes. The YL-105 setup consists of two distinct parts

Today, we are doing a "Better Datasheet" deep dive. Let’s look at how this board actually works and how to use it reliably in your projects.

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. The datasheet mentions "VDD ripple &lt; 50mV

When you apply a logic HIGH (3.3V or 5V) to the IN pin, the transistor turns on, energizing the coil. But here is the critical nuance: many 3.3V logic systems (like ESP32 or Raspberry Pi) cannot fully saturate the transistor because the datasheet’s "High" voltage is designed for 5V TTL. A better datasheet reading would highlight the input threshold voltage (typically ~1.5V to 3V). To avoid erratic switching, the datasheet should explicitly state: For 3.3V logic, use the "Low" signal to activate the relay, or add an external level shifter. Most datasheets omit this, forcing the user to deduce it from the schematic.

Based on the YL105 datasheet specifications, here is a "better" initialization sequence than most tutorials provide.

The most common search comparison is YL105 vs. DHT11. On paper, they look identical. In practice, the YL105 wins for three reasons.