analogy test

Magnifying transmitter

The magnifying transmitter is an alternate version of a Tesla coil. It is a high power harmonic oscillator that Nikola Tesla proposed for the wireless transmission of electrical energy. In his autobiography, Tesla stated that "...I feel certain that of all my inventions, the Magnifying Transmitter will prove most important and valuable to future generations." The magnifying transmitter is an air-core, multiple-resonant transformer that can generate very high voltages. Tesla originally termed it self-regenerative resonant transformer, a term that is no longer in general use.


The first 'Magnifier' was assembled in New York City in the precise period between 1895 - 1898. In 1899 a larger magnifier was constructed in Colorado Springs, Colorado. This machine was used to conduct fundamental experiments in wireless telecommunications and electrical power transmission. Measuring fifty-one feet (15.5 m) in diameter, it developed a working potential estimated at 3.5 million to 4 million volts and was capable of producing electrical discharges exceeding one hundred feet (30 m) in length.

Colorado arrival

In 1899, Tesla decided to move and began research in Colorado Springs. He chose this location primarily because of the frequent thunderstorms, the high altitude (where the air, being at a lower pressure, had a lower dielectric breakdown strength, making it easier to ionize), and the dryness of the air (minimizing leakage of electric charge through insulators). Tesla kept a handwritten diary of his experiments in the Colorado Springs lab where he spent nearly nine months. It consists of 500 pages of notes and nearly 200 drawings, recorded chronologically between June 1, 1899 and January 7, 1900, as the work occurred, containing explanations of his experiments.

Tuned electrical circuits

While in Colorado, Tesla constructed many smaller resonance transformers and conducted further research on concatenated tuned electrical circuits. Tesla also designed various sensitive devices for detecting received electrical energy, including rotating coherers. These used a clockwork mechanism of gears driven by a coiled spring-drive which rotated a small glass cylinder containing metal filings. These experiments were the final stage after years of work on synchronized tuned electrical circuits. These instruments were constructed to demonstrate how a wireless receiver could be "tuned" to respond to a specific complex signal while rejecting others. Tesla logged in his diary on January 2, 1900 that a separate resonance transformer tuned to the same high frequency as a larger high-voltage resonance transformer (which acted as a transmitter) received energy from the larger coil, one of many demonstrations of the wireless transmission of electrical energy. These experiments helped to confirm Tesla's priority in the invention of radio during later disputes in the courts. These air core high-frequency resonant coils were the predecessors of systems ranging from radio to medical nuclear magnetic resonance imaging.

Power transmission

On July 4, 1899, Tesla discovered terrestrial stationary waves within the earth. He demonstrated that the Earth behaves as a smooth polished conductor and possesses electrical vibrations. Tesla demonstrated that the Earth could respond at predescribed frequencies of electrical vibrations. Tesla conducted experiments contributing to the understanding of electromagnetic propagation and the Earth's resonance. He transmitted signals several kilometres and lit neon tubes conducting through the ground.

Tesla researched ways to transmit energy wirelessly over long distances (via transverse waves, to a lesser extent, and, more readily, longitudinal waves). He transmitted extremely low frequencies through the ground as well as between the earth's surface and the Kennelly-Heaviside layer. He received patents on wireless transceivers that developed standing waves by this method.

The magnifying transmitter was the basis for Tesla's Wardenclyffe Tower project. Although modern Tesla coils are designed to generate disruptive discharges, this system was designed for wireless communication and power transmission via longitudinal waves and telluric currents. In 1925, John B. Flowers advanced a proposal to test Tesla's system and to implement the system. H. L. Curtis, the chief of the Bureau of Standards Radio Laboratory in Washington D.C., and J. H. Dillinger, a physicist, reviewed the proposal but declined to implement the proposed plan. Flowers's mechanical analogy test was successful, though.

Electromechanical oscillator

Tesla developed a reciprocating electromechanical oscillator as a source of frequency stable or isochronous alternating electric current used in conjunction with both wireless transmitting and receiving apparatus. This circuit element was applied in much the same manner as quartz timer crystals are now. He also proposed the use of this device for geophysical exploration - seismology—a technique that he called telegeodynamics.

Magnifying transmitter and the Wardenclyffe Tower

Transmitter details
The electrical oscillator, cited by Dr. Tesla as his most important and greatest invention, consists of three inductors:

* an air-core transformer (2 coils)
* a third coil (1 extra coil)

The magnifier operated as a base-driven quarter-wave helical resonator.

The layout of the Wardenclyffe magnifying transmitter is well known, based upon Tesla's patents and various photographs in which the concept was implemented. The magnifying transmitter is not identical to the classic Tesla coil. It has the short thick primary and secondary inductor characteristic of the Tesla coil, although magnetic coupling between the two is tighter. Because of this, more aggressive measures have to be taken in terms of primary spark quenching and providing additional insulation between the primary and secondary. In addition to these two large-diameter coils that comprise the master oscillator, Tesla added a third inductor called the "extra coil."

Construction and theory of operation

In a classic Tesla coil the primary drives the ground end of the secondary coil to form the driver transformer, which resonates the entire secondary coil. In the magnifying transmitter the driving and resonating parts of the secondary are separate coils. From a circuit analysis standpoint, there is little difference between the classic coil and the magnifier.

The extra coil or helical resonator can be physically separated from the two close-coupled coils, which comprise the master oscillator or driver section. The power from the master oscillator is fed to the lower end of the extra coil resonator through a large diameter electrical conductor or pipe to minimize corona. The magnifying transmitter's base-driven extra coil behaves as a slow-wave helical resonator, the axial disturbance propagating at a velocity of less than 1% up to around 10% the speed of light in free space. The Magnifying Transmitter's axial velocity electromagnetic field is established by the coil pitch and electrical charge propagation speed through the circuit.


Using low frequency harmonic Maxwellian oscillations, Tesla attempted to develop standing waves of extremely low frequency in the Earth's electro-magnetic circuit. Based upon observations made with the device, Tesla reported that a type of Earth resonance - involving the Earth's telluric energy - could be excited with the magnifying transmitter. He discovered that the resonance frequency of the Earth was approximately 8 hertz (Hz). In the 1950s, researchers confirmed that the resonance frequency of the Earth's ionospheric cavity was in this range. See Schumann resonance

In normal operation the device is relatively silent, generating a high power electric field, but if the output voltage exceeds the design voltage of the elevated terminal, high-voltage sparks will strike out from the electrode into the air.

Related Tesla patents

  • "System of Electric Lighting," , 23 June 1891
  • "Means for Generating Electric Currents," , 6 February 1894
  • "Electrical Transformer," , 2 November 1897
  • "Method of and Apparatus for Controlling Mechanism of Moving Vehicle or Vehicles ", , 8 November 1898
  • "System of Transmission of Electrical Energy," , Mar. 20, 1900
  • "Apparatus for Transmission of Electrical Energy," , 15 May 1900
  • "System of Transmission of Electrical Energy," , 20 March 1900
  • "Apparatus for Utilizing Effects Transmitted from a Distance to a Receiving Device through Natural Media," , Nov. 5, 1901
  • "Method of Utilizing Effects Transmitted through Natural Media," , Nov. 5, 1901
  • "Apparatus for Utilizing Effects Transmitted From A Distance To A Receiving Device Through Natural Media," , Nov. 5, 1901
  • "Apparatus for Utilizing Effects Transmitted through Natural Media," , Nov. 5, 1901
  • "Method Of Utilizing Radiant Energy," , 5 November 1901
  • "Method of Signaling," , Mar. 17, 1903
  • "System of Signaling," '', Apr. 14, 1903
  • "Art of Transmitting Electrical Energy through the Natural Mediums," , Apr. 18, 1905
  • "Apparatus for Transmitting Electrical Energy," Jan. 18, 1902, , Dec. 1, 1914

See also: List of Tesla patents

See also


Further reading

Tesla's publications

  • Tesla, Nikola, "On the Transmission of Electricity Without Wires". Electrical World and Engineer, 5 March 1904.

Electrical World

  • "The Development of High Frequency Currents for Practical Application"., The Electrical World, Vol 32, No. 8.
  • "Boundless Space: A Bus Bar". The Electrical World, Vol 32, No. 19.
  • "Mr. Tesla's Application of the Hertz-Wave Transmission". The Electrical World, Vol 32, No. 8.

Other publications

  • Bass, Robert W., "Self-Sustained Non-Hertzian Longitudinal Wave Oscillations as a Rigorous Solution of Maxwell's Equations for Electromagnetic Radiation". Inventek Enterprises, Inc., Las Vegas, Nevada.
  • Bieniosek, F. M., "Triple Resonance Pulse Transformer Circuit". Review of Scientific Instruments, 61 (6).
  • Corum, J. F., and K. L. Corum, "Disclosure Concerning the Operation of an ELF Oscillator". CPG Communications, Inc., Newbury, Ohio.
  • Corum, J. F., and K. L. Corum, "A Physical Interpretation of the Colorado Springs Data". CPG Communications, Inc., Newbury, Ohio.
  • Corum, J. F., and K. L. Corum, "Tesla's Colorado Spring Receivers (A Short Introduction)". 2003.
  • Corum, J. F., and K. L. Corum, "RF Coils, Helical Resonators and Voltage Magnification by Coherent Spatial Modes". IEEE, 2001.
  • de Queiroz, Antonio Carlos M., "Synthesis of Multiple Resonance Networks". Universidade Federal do Rio de Janeiro, Brazil. EE/COPE.
  • de Queiroz, Antonio Carlos M., "Designing a Tesla Magnifier". Universidade Federal do Rio de Janeiro, Brazil. EE/COPE.
  • Grotz, Toby, "Wireless Transmission of Power: An Attempt to Verify Nikola Tesla's 1899 Colorado Springs Experiment, Results of Research and Experimentation". TESLA, Inc., Craig Colorado.
  • Hartley, R. V. L., "Oscillations with Non-linear Reactances". Bell Systems Technical Journal, Sun Publishing. 1992.
  • Wait, James, R., "Electromagnetic Waves in Stratified Media". Pergammon Press, 1972. (2nd edition)
  • Reed,J.R.,"Analytical expression for the output voltage of the triple resonance Tesla transformer," Review of Scientific Instruments, 76, 104702,(2005).
  • Reed,J.R.,"Designing triple resonance Tesla transformers of arbitrary frequency ratio," Review of Scientific Instruments, 77, 033301, (2006).


  • Armstrong, E. H., , "Wireless receiving system". 1914.
  • Armstrong, E. H., , "Method of receiving high frequency oscillation". 1922.
  • Armstrong, E. H., , "Signalling system". 1922.
  • Fessenden, R. A., , "Signalling by sound and other longitudal elastic impulses". 1914.
  • Weyrich, R., , "Transmitter and receiver for electromagnertic waves".
  • Leydorf, G. F., , "Antenna near field coupling system". 1966.
  • Tanner, R. L., , "Extremely low-frequency antenna". 1965.
  • Eastlund, Bernard J., , "Method for producing a shell of relativistic particles at an altitude above the earths surface". 1991.
  • Hansell, Clarence W., , "Communication system by pulses through the Earth".

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