This compact and robust instrument can be free standing on the bench, clamped to a bench, or supported horizontally or vertically from a retort stand. It is used for the lateral vibration of a cord at 50Hz or 60Hz frequency for experiments in standing waves and resonance. When used normally, the cord is tensioned by passing it over a pulley mounted at the edge of the bench and attaching the cord to a scale pan. Adding weights to the pan increases the tension in the cord. The active length of the cord is simply adjusted by moving the instrument on the bench relative to the position of the pulley clamped to the edge of the bench.