No matter what electronics project you are building, power supply is important part of it. For quick tests and prototyping it is best to use variable bench power supply which could be reused for different purposes. If you are serious about electronics, probably it is best to invest in to good bench power supply. But this is also fun to build one by yourself. Abhishek decided to make pretty simple power supply that would fit his needs.
He decided to use linear voltage regulators to get needed voltages. So first state he made was stepping down 220V to 20V DC which then could be regulated with linear regulators. He decided to make 5V and 12V by using 7805 and 7812 regulators. Then he used another LM338 to get variable voltages from 1.2V to 25V. Using separate regulators gives ability to drive higher loads in parallel. He also wanted some feedback, so he used Atmega8 which drives an LCD. Microcontroller ADC takes voltage and current readings and displays on screen. He uses a shunt resistor to read voltage drop from current. Few buttons also allows controlling relay, selecting serial data output and doing other tasks. Interesting choice of enclosure which is made of plastic container.