I appreciated the size and low cost, but I felt the choice of the adjustable trim potentiometer on the circuit board was not suitable for the task. At first, I thought that all the boards were defective, because all they did was track the input voltage, not boost it. You had to turn the adjustment screw about twenty times counterclockwise before it affected the voltage. I assume that these are 25 turn Bourns 3296 (10 3) 100,000 Ohms trimpots (figure 1). Admittedly I am not an engineer, but when See full review