Design and analysis of permanent-magnet eddy-current systems typically used for automobile speedometers and tachometers

A method by which permanent-magnet eddy-current systems may be evaluated mathematically with computer assistance is presented, eliminating many of the factors normally used which require previous experience with similar designs or experimental evaluation. Design and analysis is performed in two stages: 1) the system external to the magnet terminals, and 2) the magnet form and internal operating conditions. Design procedure, compilation of data in required form, method of obtaining data for various expressions, and the sequence of calculation are described. Limits of accuracy for calculations are suggested.