What device converts AC to DC? rectifier A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The process is known as rectification, since it "straightens" the direction of current. The unit was used at Ballarat School of Mines in the Maths, Science and Physics Departments.Grey metal unit with Dials on the front and vents at the back. Handle for carrying. Two switches for turning on and off. Yellow sticker - SMB - with number 116071. Engraved on back - S.M.B.. Maths / Science / Physics Sticker on cord indicating inspection of unit - 13/04/2005. Tag Number - 032735alternating current, direct current, ac, dc, rectifier, electrical, ballarat school of mines, science, maths, physics