Recent Transformer Developments

Descriptions of new transformer steel and insulation are given together with new circuits and applications involving transformers. Instances are cited of size reductions and extensions of frequency ranges in which transformers may be used. Four outstanding and almost parallel developments have made possible a variety of improvements in radio transformers. These developments are: (I) new available core steels, (II) new insulation, (III) new circuits, and (IV) new applications. Stated thus, these developments may not sound very remarkable. The aim of this paper is to show how in some cases these developments make possible drastic size reductions, even to the point of eliminating transformers completely, and how in other cases transformers are used where formerly none were used. A range of instances all the way from complete disappearance of a transformer species to the evolution of a new one should be worth the attention of radio engineers.