This is pretty cool. If you couldn't tell, he is using a dual trace oscilloscope in X-Y Mode [1]. The left audio channel is driving the horizontal deflection. Y

This is pretty cool. If you couldn't tell, he is using a dual trace oscilloscope in X-Y Mode [1]. The left audio channel is driving the horizontal deflection. You can usually pick up one of these old analog scopes for under 100 bucks if you look around! [1] https://en.wikipedia.org/wiki/Oscilloscope#X-Y_mode https://en.wikipedia.org/wiki/Oscilloscope#X-Y_mode