Power (3-40V), power indicator light, the module is working properly Adjust the blue potentiometer knob (clockwise rotation generally boost,counter-clockwise rotationTurn down) and reach with a multimeter to monitor the output voltage required voltage Current work long hours is recommended for use in less than 2.5A, while adding bulkHeat sink (10W output above),because it is -down module, in order to stable output Set,please keep the minimum 1.5V differential Power supply for electronic equipment. When the equipment needs power and the corresponding voltage power supply is in hand, you can use this module to easily adjust the voltage to the required voltage, solve the problem, and test the system working voltage. When doing projects, you can use this module to debug The working voltage range of the voltage test system is very easy and convenient You only need to connect the input terminal of this module to the car lighter for power supply, then you can adjust the potentiometer, and the output voltage can be adjusted arbitrarily between 1.25-30V to power your mobile phone, MP3, MP4, PSP charging and many other devices. It is very simple and convenient Name: DC-DC Buck module Input voltage:4V ~ 35V The output voltage: 1.23V ~ 30V Output Current:3A( Max) Conversion efficiency:92%( MAX ) Output ripple: less than 30mV Switching frequency: 150KHz Working temperature: -45~+85 Connection mode:1. Welding: welding the power cord directly to the input (output) port; 2.Welding pin,which can be inserted into the pin through the lead or inserted into the hole board for use; Or solder directly on PCB after adding pins Material: PCB colour: As shown Package Contents: 10 x DC-DC Power Supply Module Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.