This contraption is analogous to a compass. A compass is a simple device for drawing a circle. This device lays your circle out along an additional dimension. A sine wave is drawn as the model is moved along a piece of paper. Alternatively, the paper could be moved and the model is held fixed. As the wheels turn, their vertical circular motion is transformed by the worm into the horizontal circular motion of the white rotors. This moves the pencil (represented above by the vertical cross axel) back and forth.
The concept is illustrated in this animated gif on Wikipedia (http://en.wikipedia.org/wiki/File:Sin_drawing_process.gif ). Beyond it's intrinsic utility as a sine wave drawing device, a greater understanding of wave motion can be obtained by the physical act of building this tangible model.
Detail view of the gear box. The frequency of the wave can be modified: The two green gears can be replaced by a large gear and and small cog (as shown in the full model).
Another detail view of the worm and gear box. In the full model, two of these are connected by a simple chassis. Changing the length of the white rotor modifies the amplitude of the wave. (Phase modification is left as an exercise for the reader).
------
Many thanks to santiontanon, who pointed out a problem with the original model (see comments).
Issues with this model remain. The main one is the small amplitude/wavelength ratio. This can be sorted out by the professional LEGO designer who will basically redo the model once voting is complete.
This site will be closed during 2011/10/31 22:00~00:00(UTC/GMT) due to the server expansion. The maintenance time may vary according to the progress. We are sorry for the inconvenience.
Thanks for Supporting!
Here are some other projects you may like.
To find more projects to support, check out the Discover page.