Galvanometer

A galvanometer is an instrument which is used to detect and measure small electric currents. It functions by the deflection of a magnetic compass needle by a current-carrying coil in a magnetic field.

Galvanometer mechanisms are utilized to position the pens of analog chart recorders like those used for making an electrocardiogram. Strip chart recorders with galvanometer driven pens have a full scale frequency response of 100 Hz and several centimeters deflection.