Harmonic Synthesizer for Demonstrating and Studying Complex Wave Forms
J M Somerville · Journal of Scientific Instruments · 1944
A harmonic synthesizer is described which will combine any seven sinoidal electric oscillations in the frequency range 50-20,000 cyc./sec. and allow separate control of the amplitude and phase of each component. It is designed for the purpose of demonstration, but is readily adaptable to quantitative measurement. It may be used to study many types of combined oscillations and is specially suitable for demonstrating the combination of a fundamental and a number of harmonics to form a non-sinoidal oscillation, and showing the dependence of the resulting wave-form on the relative amplitudes and phases of the components. The synthesizer may also be used for harmonic analysis of a given oscillation. A method for detecting small amounts of distortion (of the order of 1 per cent) is discussed.