The paper presents a simple model of a swing meant for undergraduates’ educational experiments. The
purpose of these experiments is the experimental study of physical principles of self-oscillations,
free, forced and parametric oscillations. The model contains a pendulum. A coil with a movable steel
core serves as its load. A neodymium magnet is placed at the lower end of the core. A magnetically
operated sealed switch is stationed under the magnet at the equilibrium position of the pendulum.
The switch is connected in series with the coil and a battery. If we displace the pendulum from the
equilibrium position, the pendulum makes undamped oscillations. The system receives energy every
time the core is drawn into the coil at the lower position of the pendulum.