dkplnt [8-Pack] LM2596 DC-DC Adjustable Buck Converter 3-40 V to 1.5-35v Step Down Power Supply High Efficiency Voltage Regulator Module …

Product Features

Parameters:
Input Voltage: DC 3 -40 V
Output Voltage: DC 1.5 - 35 V
Output Current: 3A(MAX) It is recommended to use under 2A (NOTE: When using high power, add a heat sink to the power supply chip)
Load adjust ratio: +/-0.5% 
Voltage adjust ratio: +/-2.5% 
Transferring efficiency: 92% Max(the higher output voltage, the higher efficiency) 
ON/OFF frequency: 150KHz 
Output ripple: 200mV 
Module feature: buck and non-isolated 
Rectification method: non-synchronous rectification 
Size: 5.4x2.3x1.8CM 
Weight: 16g 

Fuction:
1.Built in over-temperature protection function 
2.Built in current limit function 
3.Built in output short-circuit protection function 

How to use
1.Access the power supply ( 3 -40 V), the power indicator light, the module is working properly.
2.Adjust the blue potentiometer knob (usually clockwise rotation boost, counterclockwise rotation Step-down) and monitor the output voltage with a multimeter to reach the required voltage. 
3.A customer reflects the module output voltage can not be adjusted, always equal to the input voltage. When you encounter this problem, please first counterclockwise rotation potentiometer 10 laps above, and then use the module can be normal adjustment of the voltage.

Package includes: 
8X LM2596 board
8 pieces of heat sink