Nikola Tesla Books
CHAPTER II. HOW THE HIGH FREQUENCY CURRENT IS PRODUCED. There are but three practical methods by means of which the high frequency current may be generated. In one of these methods, an alternating current generator having a very large number of stator pole pieces is employed; this is essential in order that the speed at which the rotor must be driven may be kept within reasonable limits. Even so, the speeds of most of the experimental machines built thus far have been as great as 10,000 R.P.M. and the reader's practical knowledge will doubtless tell him that a heavy, composite mass of metal, driven at this speed, introduces complications that are very likely to result disastrously should anything go wrong. The maximum frequency obtainable by this method is about 100,000 cycles per second and this frequency, with a useful output of current, is to be obtained only through the use of a very costly and dangerous machine. The high frequency alternator method, while it undoubtedly possesses some positively unique advantages in radio telegraphy and telephony, is scarcely a piece of apparatus that comes within the scope of this book. arc. The second method is by means of the direct current When an ordinary arc is shunted by a suitable capacity and inductance, oscillations are set up in the circuit. A secondary added to the primary inductance or helix will 12
