TWIZZLE DOWN

Imagine a small, springy steel rod with a weight at one end. It’s held upright with the lower end of the rod in a fitted hole in a bar of hard wood. If you pull the weighted end to one side and release, it swings back and forth like an inverted pendulum. Now imagine that the hole in the bar is a tiny bit bigger than the diameter of the rod; the hole passes through the bar, and the space below is open. When you pull the weight to one side and release, the weighted rod slowly works its way down though the hole as it sways back and forth, dropping a tiny bit with each swing. There’s a sound as the rod hits against the side of the hole with each sway, and the sound changes as the relative lengths of the portions of the rod above and below the bar change. A piezo pickup on the bar helps to bring out the sound.