Color: As shown in the First image. Quantity and size : As shown in the title or description. Adjustable Step Down Power Supply Buck Voltage Converter Regulator Features: Module Highlights: 1 High Power, High Efficiency, 5A, Low Ripple; 2 Three in One (1) Use As a Normal Blood Pressure Modules with Overcurrent Protection Capability; (2) As the Various Voltage Lithium Batteries, Batteries, Nickel-cadmium Nickel-metal Hydride Batteries (battery) Charger For Solar Panels, Wind Turbines and Other Occasions; (3) Used As High-power LED Constant Current Drive Module; 3 With Constant Pressure and Constant Current Modes, the Module Has a Light Indicates Which Mode is Currently In; 4 When Used As a Lithium Battery Charger, You Can Set the Float Voltage and Charge Current, There is Light Indicates That It is Charging or is Already Full; 5 Has the Current Limit Protection, Output Short Circuit Will Not Even Burn Module First, the Module Parameters Input Voltage: 4-38V Output Voltage: 1.25-36V Continuously Adjustable Output Current: Adjustable, Maximum 5A Output Power: 75W Maximum Working Temperature: -40 to + 85 Degrees Operating Frequency: 180KHz Conversion Efficiency: Up to 96% Short Circuit Protection: Yes (limit Current 8A) Over Temperature Protection: (automatically Shut off the Output After over Temperature) Input Reverse Polarity Protection: None, (if Necessary, Please Enter the String into the High-current Diode) Installation: Four 3mm Screws Connection: Terminals or Solder Terminals, V-IN is the Input, V-OUT Output Weight: 19g Second, the Application 1 Use As a Normal Blood Pressure Modules with Overcurrent Protection Capability How to Use: (1) This Regulation Potentiometer, the Output Voltage Reaches the Value You Want (2) 10A Current with a Multimeter Measuring the Output Short-circuit Current File (directly to the Two Can Lead to the Output), and Adjust the Constant Current Potentiometer Allows the Output Current Reaches a Predetermined Value of Overcurrent Protection (Such As the Current Value of the Multimeter Displays 4A, then You Can Use the Module to the Maximum Current 4A, 4A Current to the Constant Voltage Constant Current when the Red Light is On, Otherwise the Light Off) Note: When Used in This State, Since the Output of 0.05 Ohm Current Sense Resistor, There Will Be 0 ~ 0.3V Voltage Drop After Connected to the Load, This is Normal This Drop is Not Being Pulled Down Your Load, but Down-sampling Resistor 2 Use As a Battery Charger Module Without Constant Function Can Not Be Used to Charge the Battery, Since the End of the Battery and Charger Power Consumption Big Difference Between Charging Current is Too Large, Causing Cell Damage, So Start to the Battery Using a Constant Current Charging, when Charging to a Certain Extent when the Automatic Switch Back to Constant Voltage Charging Usage: (1) Determine Whether You Need Charging Battery Float Charging Voltage and Charging Current; (if Lithium Battery Parameters For 3.7V/2200mAh, then Float Voltage of 4.2V, the Maximum Charge Current 1C, Namely 2200ma) (2) the No-load Condition, the Multimeter to Measure the Output Voltage, Constant Potentiometer is Adjusted to the Output Voltage to the Floating Charge Voltage; (if to 3.7V Lithium Battery Charging, the Output Voltage of 4.2V) (3) with Million in Table 10A Current Gear Measurement Output Short Circuit Current (directly to the Two Pen Connected to the Output End Can Be), and at the Same Time, Regulating Constant Current Potentiometer Enable Output Current Reaches a Predetermined Charging Current Value; (4) Charging Lamp Current Factory Default 0.1 Times the Charging Current; (battery in the Charging Current is Reduced Gradually, Step by Step Constant Current Charging For Constant Voltage Charging, if the Charge Current Setting is 1a, then when the Charging Current is Less Than 0.1A, Blue Lights, Green Lights, when the Battery Charging is Completed) (5) the Battery is Charged (step 2, 1, 3, 4 Are: the Input Power Output Terminal No-load Battery) 3 the Use of Constant Current Drive Module For High Power LED (1) Determine the Operating Current and the Maximum Working Voltage That You Need to Drive the LED; (2) No-load Condition, the Meter Measures the Output Voltage, Adjust the Voltage Potentiometer to Make the Output Voltage Reach the Highest Working Voltage of LED; (3) the Output Current of the Output Current is Measured with the 10A Current Profile of the Meter, and the LED Operating Current of the Predetermined Current is Adjusted at the Same Time.; (4) on the LED, the Test Machine (step 2, 3, 1 Are: the Input Power, the Output No-load LED Lamp.) Note: when This Module is over 3A, 35W, Please Strengthen the Heat Dissipation.