Nikola Tesla Books
OSCILLATION TRANSFORMERS 49 Fig. 4. Two Oudin resonators placed base to base we may proceed to look into the actual design of oscillation transformers of various sizes and for various purposes. Without attempting any explanation of the reasons therefor, the author may state that, in his experience, the secondary of the Tesla coil should be wound upon a cylinder the length of which is three times its diameter. The Oudin resonator secondary should be wound upon a cylinder having a length slightly less than twice its diameter. Applying this simple rule, a Tesla coil with a secondary 12 in. in diameter, would be 36 in. long. The Oudin coil would be about 22 to 24 inches high if its diameter were 12 ins. This rule applies only in the case of truly cylindrical secondaries. The number of turns of wire on cylindrical Tesla coil secondaries should be in the proximity of 800, while the Oudin secondaries may contain from 400 to 600 turns for long sparks and from 100 to 300 for shorter and heavier discharges. This rule has been found to follow in the case of either large or small coils and the figures given have been taken from charts giving the effective windings for a great many coils. The cone-shaped coils are particularly effective as they
