Nikola Tesla Books
WELDING TRANSFORMER 215 is repeated with the other core leg and two layers of press board fitted ready for the secondary winding. The secondary consists of 10 turns in all, five to each layer. The winding is composed of three No. 4 D.C.C. wires wound in multiple as shown in Fig. 8. The wire should be on three spools arranged conveniently in back of the operator who should wear canvas gloves in handling the heavy conductor. The wires will have to be tapped in place with a small wooden mallet. The starting ends are soldered to a piece of heavy copper strip, the winding done, and the finishing end secured in a similar manner. A substantial covering of press board finishes the windings after they have been liberally painted with armalac or a similar compound. The legs with the windings on may then be set on end and the 3 by 6 pieces of steel interleaved in order to complete the magnetic circuit. One end of the core complete is shown in Fig. 2. A slight tapping with a light hammer will set up the irons. The Mounting.-The mounting is clearly shown in Fig. 10 as is also the direction of the windings. The builder should determine this very carefully by placing the cores end to end before assembling and then noting which terminals of the windings, when connected together, will produce a continuous winding in one direction throughout. The copper ribbon taps are soldered to No. 10 flexible stranded conductor on the primary and to three No. 4 flexible stranded cables in multiple on the secondary. The cables are led to binding posts on the primary end and massive copper bolts on the secondary. The connections between the halves of the windings are made with strips of copper insulated with tape. Welding Experiments.-The current delivered by the transformer just described is of low voltage but great vol
