3mm Red Green LED Light Sensor Module

Here is a short description of the 3mm Red/Green Dual-Color LED Module (often labeled as the KY-029 or KY-011 module in Arduino sensor kits):

• What it is: An indicator module featuring a 3mm dual-color LED that can emit red, green, or a blend of both (yellow/amber) from a single compact bulb.  

• How it Works: It uses a common-cathode design with 3 pins (GND, Red Pin, Green Pin). Applying signal/voltage to either color pin lights up that respective color.  

• Key Features: Supports PWM (Pulse Width Modulation) control to dim and mix the red and green brightness for varying color shades. Requires external current-limiting resistors (e.g., $220\Omega$) when connecting to 3.3V or 5V logic.  

• Common Uses: Used as a multi-state visual indicator in Arduino, Raspberry Pi, and DIY electronics projects (e.g., showing Pass/Fail, Power On/Off, or Warning/OK states).  

(Note: Despite “Light Sensor Module” appearing in some vendor product titles, this unit acts as an LED indicator output, not a light-detecting sensor).