Magnetic generation of a group of harmonics

A harmonic generator circuit is described which produces a number of harmonics simultaneously at substantially uniform amplitudes by means of a non-linear coil. Generators of this type have been used for the supply of carrier currents to multi-channel carrier telephone systems, for the synchronization carrier frequencies in radio transmitters, and for frequency comparison and standardization. A simple physical picture of the action of the circuit has been derived from an approximate mathematical analysis. The principal roles of the non-linear coil may be regarded as fixing the amount of charge, and timing the charge and discharge of a condenser in series with the resistance load. By suitably proportioning the capacity, the load resistance, and the saturation inductance of the non-linear coil, the amplitudes of the harmonics may be made to approximate uniformity over a wide frequency range. The sharply peaked current pulse developed by condenser discharge passes through the non-linear coil in its saturated state and so contributes nothing to the eddy current loss in the core. In this way the efficiency of frequency transformation is maintained at a comparatively high value for the harmonics in a wide frequency band, even with small core structures. The theory has also been adequate in establishing a basis for design, and in evaluating the effects of extraneous input components.