April 2005
I bought an oscilloscope cheap, and it seemed like fun to try and make it do things it wasn’t designed for. For those who are wondering what on earth an oscilloscope is, here is a bit of background…
An oscilloscope is a piece of laboratory equipment which has a small screen, various controls, and inputs for electrical signals. Its normal mode of operation is to trace voltages over a certain short period of time, say a tenth or a hundreth of a second. The horizontal axis represents time, and the vertical axis voltage. An electrocardiogram display as might be used in a hospital is a specialist form of oscilloscope.
However, the one I have (and most models, for that matter), has a special mode whereby the horizontal axis can be controlled by a voltage as well, rather than by time, such that a line can be drawn to any point on the screen by varying two (rather than one) voltages.
I did some thinking, and realised that the stereo sound output that most computers have is just 2 digital-to-analogue converters, that is the it is just 2 voltages that are under software control. So by writing some clever software, and connecting, say, left to X, and right to Y, we could produce pretty pictures on the screen! Without having to build any additional hardware!
This is what ScopeShapes is for. Of course, a picture speaks a thousand words – have a look at the photos for a better idea of what it is all about.
ScopeShapes reads in DXF files, which are produced by AutoCAD, and many other programs – they are basically a CAD-orientated 3D vector format. I chose this because it is a pretty common format, and the specifications for it were freely available. It can hold up to 10 shapes at once, and switch smoothly between them. This can be done with the mouse, or via keyboard shortcuts.
ScopeShapes runs on Windows, Mac OS X, and Linux.
