A power supply is a buffer circuit that provides power with the characteristics required by the load from a primary power source with characteristics incompatible with the load. It makes the load compatible with its power source. Power Supply A device for the conversion of available power of one set of characteristics to another set of characteristics to meet specified requirements. Typical application of power supplies include to convert raw input power to a controlled or stabilized voltage and/or current for the operation of electronic equipment. We designed the various circuits constituting the power supply. we built two type of DC power supply first type is linear DC power supply that contains appropriate transformer ,the rectifier ,the ripple smoothing circuit, operational amplifier, various type of transistor , linear pontesiometer to adjust the voltage and the current. The another type is switch mode power supply that contains smoothing current circuit ,the rectifier, the transistors work as a switch, Puls with modulation control circuit by using TL494 IC, and finally DC stage that gives more than level. More https://eng-old.najah.edu/ar/graduation-projects/4348