The DC-DC Adjustable Buck Converter 3A (3.2–40 V to 1.25–35 V) is a step-down voltage regulation module based on the LM2596 switching controller. It converts a higher DC input voltage into a lower adjustable DC output using an onboard potentiometer for precise voltage setting. The module supports up to 3 A output current and operates with high conversion efficiency up to approximately 92% under optimal load conditions. It is designed for stable low-ripple power delivery, making it suitable for embedded systems, prototyping, and regulated DC power supply applications. The compact module is compatible with a wide range of electronic and industrial low-voltage systems.