Driven Spiral Oscillator

DCS Code: 3A60.55 Last Updated: March 27, 2026
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Purpose

A motor-driven spiral spring oscillator demonstrates resonance by sweeping the driving frequency through the system's natural frequency. Students observe the dramatic amplitude peak at resonance, the phase shift from in-phase to 180° out-of-phase, and the effect of electromagnetic damping on peak width and height.

Top: Ratiotrol speed control, driving motor, and balance wheel with spiral spring on a demo bench. Bottom: shadow projection of the balance wheel on a screen showing the oscillation clearly
Figure 1: The driven spiral oscillator apparatus (top) with Ratiotrol speed control, motor, and balance wheel. Shadow projection (bottom) makes the oscillations visible to a large lecture hall.
Demo Apparatus