A galvanometer's a type of ammeter: an instrument for detecting and measuring electric current. It's an analog electromechanical transducer that produces a rotary deflection of some type of pointer in response to electric current flowing through its coil. The term has expanded to include uses of the same mechanism in recording, positioning, and servomechanism equipment. History The deflection of a magnetic compass needle by current in a wire was first described by Hans Oersted in 1820. The phen… (More on Galvanometer)