eBoot 6 Pack LM2596 DC to DC Buck Converter 3.0-40V to 1.5-35V Power Supply Step Down Module Input: DC 3 V to 40 V (input voltage must be 1.5 V higher than the output voltage, no boost) Output: DC 1.5 V to 35 V voltage is continuously adjustable, maximum output current is 3 A Features: all use SANYO solid-state capacitors, 36 u thickening circuit boards, high-Q inductance with LED indicator output Quantity: 6 pieces; Size: 45 * 20 * 14 mm (with potentiometer) Steps: connect to power source, adjust the swirl button on the blue potentiometer and monitor voltage with multimeter to get the needed voltage (The factory have tested these at max voltage so they are very high by default, takes about 15-20 turns CCW before the voltage starts ramping down)