“The programmable bench power supply project was an attempt to create reliable, modular, open and programmable power supply. It’s also replicable at home and can be used for various tasks starting with powering breadboard, charge (or to some extent discharge) batteries of various types and sizes or use as a tool in school/educational and science experiments. It can be even used as a building block in the Automatic Test Equipment (ATE) environment. Here and in accompanying articles and documents a shorter form PSU (from Power Supply Unit) will be used for the sake of simplicity. Building a power supply is a popular between electronic hobbyists and DIYers that wants to get some experience and it’s often chosen or recommended as the first project that one should made. That is logical since in principle it’s very simple and also represents important electronic benchtop instrument. In general such designs is very simple and they are openly shared and discussed on various sites on the Internet. There is also many commercial devices that comes from many sides, different capabilities and feature lists. They promises a long term reliability, precision, support, etc. Their design could be very complex and difficult to replicate because and can include many trade secrets that made some manufacturers famous.”