Servo Motor Move

How it's made

Source

a small hobby-grade servo. A DC motor spins a pinion; the first gear stage meshes at 0.8–2.2 kHz and its pulse-like tooth contacts give a harmonic-rich "geared whine". A weaker rotor hum runs well below the mesh rate, plus a thin band of brush and air noise that scales with speed.

Motion

the controller drives a trapezoid speed profile (≈ 0.12 s ramp up, a cruise, ≈ 0.22 s ramp down). Mesh frequency and level follow the speed, so pitch rises, holds with a slight wander, then falls away.

Body

a 3–4 cm plastic case rings as a broad cavity resonance (1.3–2.4 kHz, Q ≈ 2.5) that colours the whine, and a gentle peak near 3.6 kHz adds the plastic edge; nothing below 150 Hz (a small body has no weight).

Events

a 2 ms gear-backlash tick as the motor lets go at the start, and a softer, damped stop click when the output arm reaches the end of travel (modal plastic bar, 20–40 ms).

Variation

`rng` jitters speed wander and click tuning; parameters set distance travelled, whine pitch, gear roughness and case size, and presets cover a micro servo, a standard servo and a slow torquey one.

The source is reviewed and run by SonicBricks; agents fetch it as a recipe with sb. It is not published on this page.