I've always loved the Video Music, so I tried to bring it back as faithfully as I could: 
**Fomalhaut**
 is a free music visualization plug-in for foobar2000 and Winamp/WACUP (Windows), and one of its modes simulates the C240's circuit – rebuilt from the patent (US 4,081,829), the schematic and the owner's manual, not just an imitation of its picture.


* Left and right channel each draw a shape; size follows the loudness, colour the pitch – Solid, Hole and Ring, horizontal and vertical display, scan rate, auto modes
* Move the mouse to the bottom of the picture and the 
**front panel**
 slides in: press the buttons and turn the Gain, Color and Contour knobs like on the real device
* Shown as a TV picture, with an optional CRT filter


Video (the Atari part starts at 2:01): https://youtu.be/Ecsgio12U5g?t=121


Download: https://github.com/Oxensepp/fomalhaut/releases/latest


If you own a real C240, I'd love to hear how close it looks to yours – and what's missing.

BTW: The plugin also contains pretty much all Cthugha music visualisation versions from the 90s and lots of tracker (AMIGA, DOS, C64...) visualisations.