Battery eliminators, or appliances for the operation of radio receiving apparatus by energy derived from electric supply mains

The paper describes the essential features of the apparatus required for the supply of electrical energy of suitable voltage for the operation of radio receiving apparatus, by the utilization of public electric supply systems. The common features, and the differences between apparatus for d.c. and for a.c. supplies, are pointed out, and the leading features of the design of the filtering system are given. Experimental investigation of the electrical properties both of the filter circuits and of the complete supply appliances is described. Descriptive names are proposed for these devices, and suggestions are made with regard to the proper rating of these appliances in terms of their output. The need for such rating is emphasized, together with the difficulties of properly expressing all the factors involved. Rectifying arrangements are described for use on a.c. circuits, and the paper concludes with a consideration of the precautions necessary in the use of apparatus of this type.