Oscillograph

Oscillograph, instrument that records wave patterns that are equivalent to the oscillations of an electric voltage, or that converts mechanical oscillations into an equivalent electric current before recording them in the form of wave patterns. The electromechanical type of oscillograph consists in principle of a galvanometer (see Electric Meters) to which is attached an apparatus that records the movements of the galvanometer coil. The electrocardiograph is an electromechanical oscillograph that records the electric currents produced by a beating heart. See also Oscilloscope.