This is only tangentially related to our favorite device, but I came across this home audio visualizer from the 1970s:
Atari Video Music
Apparently it was only sold for a year and wasn’t very successful. All the same, I’m surprised I didn’t hear of it in the 80’s, as I was fairly obsessed with Atari in my youth.
Enjoy.
Oh thanks for the link. I have to admit that I am always prone to buy some of this useless gear fom the 70s and 80s (same as old drummachines). Luckily there is no auction worldwide on ebay 
I think it would be fun to make an ETC mode based on this device!
There is a fascinating book about the Atari 2600 game console called “Racing the Beam”. The developers were working with some serious limitations on that device.