It is a LM317 Adjustable Power Supply Module, Input Voltage: DC 3V~ 35V or AC 28V, Output voltage: DC 1.25~32V can adjust continuously, Output current: 5mA~1.5A, Suitable for Suitable for DIY an adjustable voltage regulated power supply, Industrial equipment Voltage convert, Power Supply Transformers etc.
LM317 is three-terminal adjustable regulator integrated circuit early made by National Semiconductor and widely used in many integrated circuit manufacturers. Easily use , it just need two external resistance to set output voltage. Besides, its linear adjusting ratio and rejection ratio is better than the standard fixed regulators.