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Nikola Tesla Books

Books written by or about Nikola Tesla

Nikola Tesla: Colorado Springs Notes, 1899-1900 Page 311

December 4-5, 1899

cables in this instance was

Lp = 52,930 - 21,052 = 31,878 cm.

Thus the secondary, though “open”, diminished in this case the primary inductance from 56,400 cm to the above value or about 43.48%.

Colorado Springs

Dec. 5, 1899

Experiments to ascertain equivalence of inductance of primary loop (two primary cables in multiple) with secondary reacting, and inductance of turns of regulating primary coil under modified conditions.

Again the coil with 344 turns was used and the maximum resonant rise in same determined in the manner described before. A greater capacity was used this time in the primary so as to come closer to the free vibration of the secondary and thus cause a stronger reaction upon the primary loop. The conditions for resonance were satisfied with the following values:

  1.
Capacity in primary circuit Inductance in primary circuit
$! {{2 \times 36} \over 2} $! = 36 bottles = 0.0324 mfd 21 3/4 turns pr. regulating coil only
  2.
Capacity in primary circuit Inductance in primary circuit
$! {{2 \times 36} \over 2} $! = 36 bottles = 0.0324 mfd one primary loop as above + 15 1/2 turns reg. coil.

Since in both tests the primary capacity was not changed in the least the inductance of the primary loop in this instance was equivalent to that of 21 3/4 turns, less that of 15 1/2 turns of the regulating coil in the primary. This means the inductance of the primary loop was equivalent to that of 21.75 - 15.5 = 6.25 turns of the primary regulating coil or it was 6.25 x 3850 = 24,063 cm only. Induct. diminished 57.33%. This is a still smaller value than found yesterday but is very probably near the maximum as the secondary showed evidence of a resonating condition. These experiments show the danger of allowing for the amount of secondary reaction. This is to be borne in mind.

311

Source:
by Professor Aleksandar Marinčić

December 5

In this, as in earlier measurements, he found a “reduced inductance of the primary because of the reaction of the secondary”. This interpretation of the functioning of the oscillator diverges from Oberbeck's theory(29). If the spark duration is relatively long the oscillator starts to produce oscillations of two frequencies, and when the spark is broken it gives a third frequency which is determined by the secondary oscillatory circuit. With a third circuit (“extra coil”) the oscillation of the system becomes even more complicated, the oscillations during break being determined by the secondary circuit and the “extra coil”. Neglecting for the moment the “extra coil”, the three frequencies which a Tesla oscillator with tight inductive coupling(31) and equal natural resonant frequencies of the coupled circuits can be expected to produce are

ω0 = $! {1 \over \sqrt{LC}} $!   ω1 = $! {1 \over \sqrt{LC(1 - k)}} $!   ω2 = $! {1 \over \sqrt{LC(1 + k)}} $!

where k is the coupling coefficient. Thus ω1 can be interpreted as the natural frequency of a circuit with capacity C and inductance L(1 - k). For the primary inductance of Tesla's oscillator (see 9 November) one obtains the “reduced” L, i.e. L(1 - k) = 23,094 cm; Tesla measured L = 24,063 cm.

Source:
by Professor Aleksandar Marinčić

December 5

He continues similar measurements as on the previous day, but the secondary selffrequency is closer to operating frequency, at this, as during previous measurements, he finds "primary inductance reduced due to secondary reaction". If we for the moment exclude the circuit of the "additional" coil and calculate free frequencies, at which the oscillation of Tesla's oscillator with very good inductive coupling could be expected. With equal self-resonant frequencies of both linked circuits, we get:

ω0 = $! {l \over \sqrt{LC}} $!   ω1 = $! {l \over \sqrt{LC(l-K)}} $!   ω2 = $! {l \over \sqrt{LC(l+K)}} $!

From the equation for ω1, it is obvious that it would not be interpreted as self-resonant frequency of a circuit of which the capacitance is C, the inductance is L(l-K). For the value of Tesla's oscillator primary circuit inductance (please see November 9) we get "reduced" L, i.e., L(l-K) = 23,094cm and Tesla obtained by measurement 24,063cms.

Contents

Introduction
June 1 - 30
July 1 - 31
August 1 - 31
September 1 - 30
October 1 - 31
November 1 - 30
December 1 - 31
January 1 - 7
Commentaries

Appendices: I, II

Images

Glossary

Lowercase tau - an irrational constant defined as the ratio of the circumference of a circle to its radius, equal to the radian measure of a full turn; approximately 6.283185307 (equal to 2π, or twice the value of π).
A natural rubber material obtained from Palaquium trees, native to South-east Asia. Gutta-percha made possible practical submarine telegraph cables because it was both waterproof and resistant to seawater as well as being thermoplastic. Gutta-percha's use as an electrical insulator was first suggested by Michael Faraday.
The Habirshaw Electric Cable Company, founded in 1886 by William M. Habirshaw in New York City, New York.
The Brown & Sharpe (B & S) Gauge, also known as the American Wire Gauge (AWG), is the American standard for making/ordering metal sheet and wire sizes.
A traditional general-purpose dry cell battery. Invented by the French engineer Georges Leclanché in 1866.
Refers to Manitou Springs, a small town just six miles west of Colorado Springs, and during Tesla's time there, producer of world-renown bottled water from its natural springs.
A French mineral water bottler.
Lowercase delta letter - used to denote: A change in the value of a variable in calculus. A functional derivative in functional calculus. An auxiliary function in calculus, used to rigorously define the limit or continuity of a given function.
America's oldest existing independent manufacturer of wire and cable, founded in 1878.
Lowercase lambda letter which, in physics and engineering, normally represents wavelength.
The lowercase omega letter, which represents angular velocity in physics.