“Sometimes buying a ready made power supply is just not good enough, especially if we want something special. I needed a super efficient 1 Amp power supply for my autonomous weather station that lives in the middle of a field on a small island in the middle of the Irish sea. There is no power option other than using solar panels, which really struggle in these northerly latitudes during the darker depths of winter. A standard linear regulator is not a good option as it burns off power to reduce voltage from 12V to 5V (but great for warming cold fingers). Being of a basically lazy nature, I did try a few other options first, including a generic adjustable power supply from China. The really great thing about this device is that, other than actually arriving in the post, it made lots of very interesting buzzing, whining and whirring noises that made me feel like I was getting really good value for my money. But alas, it consumed a huge amount of power (50mA) and is now in the bin :(“