Harmonograph

A Harmonograph is a mechanical device that converts two superimposed harmonic oscillations in a graphic.

A simple Harmonograph is a hanging on a rope oscillating tank, trickling out of the sand (see picture left). Its orthogonal vibration components have the same frequency. He writes on the area under him a simple closed curve or Lissajous figure. Different phase shift between the two vibration components results in different ellipses (extreme forms: straight line and circle ).

Harmonographen with pen are more complicated (see picture right). A vibration controlling the displacement of a pin in the horizontal and the other in the vertical direction. The two oscillations may have different frequency and lead to typical tangled Lissajous figures.

Harmonographen are mainly for demonstration and technology transfer, technical applications, they have little.