BATTERY ELIMINATORS

Sun (Auckland), Volume II, Issue 546, 26 December 1928, Page 14

BATTERY ELIMINATORS

MAKING A SELECTION GOOD COMPONENTS ESSENTIAL Recently I have had occasion to investigate the subject of battery eliminators, says a. London radio writer, particularly in the lighting and power mains for the operation of wireless receivers. This generation has grown so familiar with the convenience of electric light and power for domestic purposes, and the safety of the apparatus available, that it accepts almost without question all apparatus offered for a specific purpose. Such implicit confidence is reposed in the manufacturers in respect of the safety of their apparatus that when buying an electric iron, an electric fire, or a vacuum cleaner, the first question asked is: “What does it consume?” Very seldom does anyone ask: “Is it perfectly safe?” The confidence in the electrical manufacturers of Great Britain and their apparatus is not generally misplaced, and it can be said that such apparatus as the leading electrical manufacturers place before the public is designed by experienced engineers with full knowledge of the electrical conditions to which the apparatus will be subject. Very liberal safety factors are allowed, and very stringent tests are imposed. Nevertheless, dangers exist in the use of improperly designed, inadequately insulated, or otherwise unsuitable apparatus on the electriclight mains. So long as the making of the apparatus is in the hands of manufacturers with the necessary knowledge, experience, and facilities, little exists to worry about; but the growth of wireless has introduced a very different state of affairs. A considerable amount of apparatus is now in use on the mains constructed by people: (1) With very little electrical knowledge. They merely assemble so many components to a given diagram, which may be right or may not; they do not know and have no means of ascertaining. (2) With no experience to guide them as to the safety factors which are necessary. This experience is gained only by exhaustive tests under service conditions, sometimes extending over long periods. (3) With no facilities for submitting the apparatus to proper tests, such as insulation and break-ing-down tests, to mention two only. A great danger arises from the use of factory-manufactured apparatus produced on a large scale at a low price by manufacturers no better fitted to produce the apparatus than the uniformed home-constructor except that they have production facilities. The home-constructor does at least invariablv use components on which some reliance can be placed, but the manufacturer of the “junk” apparatus builds up his eliminator of components that on inspection by any competent authority would receive instant condemnation. ADEQUATE DIMENSIONS Tt is well known even to those with only a limited electrical knowledge that the paths along which current has to flow must be of adequate dimensions. For example, in the case of resistances carrying any appreciable current, thev must, in order to be-, safe and satisfactory, be wound with wire of a gauge ample for the current they have to carry. I was recently shown by one of the large supply undertakings in this country an eliminator which has been in use on their mains, and the resistances consisted of lines made very crudely with what appeared to be indian ink on strips of cardboard. The choke and the condensers—equally necessary components in an eliminator—were very little better, being of crude and inferior construction. It is not difficult to appreciate that the quality of an eliminator both in respect of safety and performance is very largely dependent upon the components of which it is constructed. A high-grade eliminator cannot be built from low-grade components. Highgrade components are essential, and high-grade components cannot be manufactured from low-grade materials. Consequently, high-grade compon-

ents and high-grade eliminators cost more because they embody the best materials made by expensive machinery installed to do each particular operation in the best possible way, and the assembly is carried out by skilled labour under the best possible conditions because only under good conditions can good work be maintained. , BENEFICIAL TO THE USER All this is beneficial to the ultimate user who needs the best apparatus for his purpose. A battery eliminator is very largely an electrical problem and will, no doubt, best be dealt with by one or more of the leading electrical firms. Sooner or later, definite legislation to protect users will come. Meantime, the owner of a wireless receiver contemplating the use of a battery eliminator should consider firstly the safety of himself and his family, and his servants; secondly the performance of which the eliminator is capable, its efficiency and reliability; and thirdly, and then only its price.