Nikola Tesla Books
158 HIGH FREQUENCY APPARATUS The transformer is placed in a container of wood, lined with zinc as shown in Figs. 12 and 13, which give the proper dimensions. In the cover of the container are bored four holes to pass the terminal rods. When the transformer has been placed in the case, the latter is filled with transformer oil to within an inch of the top and the cover fastened down with screws. The addition of substantial handles at the ends of the container completes the work on this portion of the apparatus. or Construction of the Condenser.-In the design of the condenser for our purposes, one or two primary requisites have constantly been borne in mind. The condenser is subjected to practically continuous use for several hours at a time and it is obviously essential that ample radiation surface be provided in order that the plates many remain cool. Coupled with this highly important point may be mentioned the importance of eliminating all corona brush leakage around the edges of the tinfoil plates. These requirements are ordinarily met with in an oil immersed condenser, but the latter, to be efficient, should employ only oil as its dielectric and such a condenser presents constructional difficulties not easily conquered by the amateur workman. As the next best solution of the problem, the design for a glass plate condenser of large heat-radiating surface and of substantial construction is offered in this chapter. For its construction the condenser will require 120 plates of glass 8 by 10 inches of the kind used for photographic negatives. Old plates of the latter sort may be purchased cheaply from nearly any photographer and they serve the purpose admirably. The first step is to remove the emulsion coating on each plate by soaking it in hot water and scraping with a putty knife. The plates are then to be dried thoroughly and divided into four piles of
