Experiments with a magnetically controlled pendulum

A magnetically controlled pendulum is used for observing free and forced oscillations, including nonlinear oscillations and chaotic motion. A data-acquisition system stores the data and displays time series of the oscillations and related phase plane plots, Poincare maps, Fourier spectra and histograms. The decay constant of the pendulum can be modified by positive or negative feedback. The apparatus, except for the data-acquisition system, is extremely simple and low cost, and can be assembled in a short time. The wide possibilities of varying the parameters of the pendulum make the experiments suitable for student projects