Dekatron Do-Hickie #2 - Sound Modulator

Okaya/Rodan DK23 dekatron do-hickie in "sound modulator" mode. When quiet, it just displays the standard pendulum. When a sound is louder than the threshold, it switches to "bargraph mode", growing and shrinking with any ambient sound. The audio level is adjustable, by a small trimpot, just right of the button. Needs a small screwdriver to adjust.