Nikola Tesla Books
30 30 HIGH FREQUENCY APPARATUS give us 120,000 for the maximum flux, N. The primary voltage is assumed to be 110 and the equation therefore becomes: 110 x 100,000,000 4.44 x 120,000 x 60 = 363 turns in the primary. As the turns in the secondary are found by the following formula, this calculation becomes simple: Es Tp x Ep where Es reresents secondary voltage, and Ep the primary voltage. The secondary turns, assuming a secondary potential of 5,000, are as follows: 5,000 363 x 110 = 16,480 turns in secondary. The space on the core for the primary and secondary winding is 24 in. long. Reference to the table of cotton covered wire shows that No. 14 D.C.C. wire winds about 13 turns per inch. As some space is quite essential between winding and core, let us make the primary winding 2 in. wide which will leave a space of 1/4 in. on either side. In 24 in. we can wind 30 turns of the primary wire and, accordingly, we shall require 12 layers in order that the required 360-odd turns may be placed. Wound with a few thicknesses of oiled paper between layers of wire, the thickness of the primary winding from inside to outside of the coil or solenoid will be rather more than one inch. If the transformer is to be operated on 70 volts, as from a rotary converter, the primary will contain 70/110 as many turns of wire. Working this we find that the proper number is 231 turns. For convenience, the primary may be made with the full quota of turns for 110 volts, with
