Power supply is an utmost essential tool for an electronic lab. It comes in handy for powering up various applications and circuits.
However a fixed voltage, fixed current power supply is sufficient for basic needs but a variable one is good to have because different circuits and components operate at different voltages and consumes different current. When it comes to an electronic hobbyist’s lab, a good power supply is must to have. Also if the power supply boosts additional features like on board voltage and current display, it comes in handy as one can know the exact voltage at the output terminals and also the current drawn by the load. But in the electronic market, those power supplies are not economic are meant for industrial purpose . Here in this article I present an economical and cost effective yet efficient variable bench power supply that is capable of providing 1.2 to 25 Volt variable supply up to 5 Ampere through one channel while 5 Volt, 1 Ampere and 12 Volt, 1 Ampere supply through other two channels thus having one variable and two fixed supply channels. It also displays the voltage on the output terminals and also the current and instantaneous power drawn by the load on an on board LCD display. Not only this one can connect this power supply to his personal computer via the serial port and can see the voltage, current and power drawn by the load graphically. The project is portable and simple to build that even a newcomer can build this power supply with ease and add into his lab. The project uses component that are easily and cheaply available. The project is composed of two modules, one is main power module that consists of linear voltage regulators with rectification and filtering circuitry for supply generation and regulation while the other is composed of a micro controller which is used to sense and display the current and voltage across the variable supply channel. The second section only provides an additional functionality of displaying current and voltage, however one can build the power supply even skipping the second section leaving it functional but without the display feature.(Actually this version 2,I have already build one which was later modified with new features).
For more detail: DIY Variable DC Power Supply with Display and PC interface