A Simple Potentiometer Circuit for Production of the Tangent Function
R. Hofstadter · Review of Scientific Instruments · 1946
A conventional potentiometer, wound uniformly on a cylindrical card of constant height, can be used to provide a close approximation to the tangent of an angle in terms of a voltage or current. Curves showing the degree of approximation are presented in the range (0, ±80°). By using a slight taper in the height of the card the tangent can be provided exactly, except for winding errors.