7.8 Hertz Resonant Circuit

[braden]

Tesla once wrote
If ever we can ascertain at what period the earth's charge, when disturbed, oscillates with respect to an oppositely electrified system or known circuit, we shall know a fact possibly of the greatest importance to the welfare of the human race.  I propose to seek for the period by means of an electrical oscillator, or a source of alternating electric currents.  One of the terminals of the source would be connected to earth as, for instance, to the city water mains, the other to an insulated body of large surface.  It is possible that the outer conducting air strata, or free space, contain an opposite charge and that, together with the earth, they form a condenser of very large capacity.  In such case the period of vibration may be very low and an alternating dynamo machine might serve for the purpose of the experiment.  I would then transform the current to a potential as high as it would be found possible and connect the ends of the high tension secondary  to the ground and to the insulated body.

Does any one have the experience or knowledge to help me put together a 7.8 Hertz LC circuit

[forest]

Bad idea.Use higher harmonics

[teslaalset]

With supercaps of e.g. 100 F this would be obtainable.

I rather would investigate wavelength (or half, or quatre labda of it) towards the ionosphere.
You need several tens of KHz for that.

[braden]

Project Tesla: Objectives
The objectives of Project Tesla are divided into three areas of
investigation. 1. Demonstration that the Schumann Cavity can be resonated with an
open air, vertical dipole antenna;
2. Measurement of power insertion losses;
3. Measurement of power retrieval losses, locally and at a distance.
Methods
A full size, 51 foot diameter, air core, radio frequency resonating
coil and a unique 130 foot tower, insulated 30 feet above ground, have
been constructed and are operational at an elevation of approximately
11,000 feet. This system was originally built by Robert Golka in 1973-
1974 and used until 1982 by the United States Air Force at Wendover AFB
in Wendover, Utah. The USAF used the coil for simulating natural
lightning for testing and hardening fighter aircraft. The system has a
capacity of over 600 kilowatts. The coil, which is the largest part
of the system, has already been built, tested, and is operational.
A location at a high altitude is initially advantageous for reducing
atmospheric losses which work against an efficient coupling to the
Schumann Cavity. The high frequency, high voltage output of the coil
will be half wave rectified using a uniquely designed single electrode
X-ray tube. The X-ray tube will be used to charge a 130 ft. tall,
Å  vertical tower which will function to provide a vertical current
moment. The mast is topped by a metal sphere 30 inches in diameter.
X-rays emitted from the tube will ionize the atmosphere between the
Tesla coil and the tower. This will result in a low resistance path
causing all discharges to flow from the coil to the tower. A
circulating current of 1,000 amperes in the system will create an
ionization and corona causing a large virtual electrical capacitance in
the medium surrounding the sphere. The total charge around the tower
will be in the range of between 200-600 coulombs. Discharging the
tower 7-8 times per second through a fixed or rotary spark gap will
create electrical disturbances, which will resonantly excite the
Schumann Cavity, and propagate around the entire Earth.
The propagated wave front will be reflected from the antipode back to
the transmitter site. The reflected wave will be reinforced and again
radiated when it returns to the transmitter. As a result, an
oscillation will be established and maintained in the Schumann Cavity.
The loss of power in the cavity has been estimated to be about 6% per
round trip. If the same amount of power is delivered to the cavity on
each cycle of oscillation of the transmitter, there will be a net
energy gain which will result in a net voltage, or amplitude increase.
This will result in reactive energy storage in the cavity. As long as
energy is delivered to the cavity, the process will continue until the
energy is removed by heating, lightning discharges, or as is proposed
by this project, loading by tuned circuits at distant locations for
power distribution.
The resonating cavity field will be detected by stations both in the
United States and overseas. These will be staffed by engineers and
scientists who have agreed to participate in the experiment.
Measurement of power insertion and retrieval losses will be made at
the transmitter site and at distant receiving locations. Equipment
constructed especially for measurement of low frequency electromagnetic
waves will be employed to measure the effectiveness of using the
Schumann Cavity as a means of electrical power distribution. The
detection equipment used by project personnel will consist of a pick up
coil and industry standard low noise, high gain operational amplifiers
and active band pass filters.
In addition to project detection there will be a record of the
experiment recorded by a network of monitoring stations that have been
set up specifically to monitor electromagnetic activity in the Schumann
Cavity.
Evaluation Procedure
The project will be evaluated by an analysis of the data provided by
local and distant measurement stations. The output of the transmitter
will produce a 7-8 Hz sine wave as a result of the discharges from the
antenna. The recordings made by distant stations will be time
synchronized to ensure that the data received is a result of the
operation of the transmitter.
Power insertion and retrieval losses will be analyzed after the
measurements taken during the transmission are recorded. Attenuation,
field strength, and cavity Q will be calculated using the equations
presented in Dr. Corum's papers. These papers are noted in the
references. If recorded results indicate power can be efficiently
coupled into or transmitted in the Schumann Cavity, a second phase of
research involving power reception will be initiated.
Environmental Considerations
The extreme low frequencies (ELF), present in the environment have
several origins. The time varying magnetic fields produced as a result
of solar and lunar influences on ionospheric currents are on the order
of 30 nanoteslas. The largest time varying fields are those generated
by solar activity and thunderstorms. These magnetic fields reach a
maximum of 0.5 microteslas (uT) The magnetic fields produced as a
result of lightning discharges in the Schumann Cavity peak at 7, 14, 20
and 26 Hz. The magnetic flux densities associated with these resonant
frequencies vary from 0.25 to 3.6 picoteslas. per root hertz
(pT/Hz1/2).
Exposure to man made sources of ELF can be up to 1 billion (1000
million or 1 x 109) times stronger than that of naturally occurring
fields. Household appliances operated at 60 Hz can produce fields as
high as 2.5 mT. The field under a 765 kV, 60 Hz power line carrying 1
amp per phase is 15 uT. ELF antennae systems that are used for
submarine communication produce fields of 20 uT. Video display
terminals produce fields of 2 uT, 1,000,000 times the strength of the
Schumann Resonance frequencies.9
Project Tesla will use a 150 kw generator to excite the Schumann
cavity. Calculations predict that the field strength due to this
excitation at 7.8 Hz will be on the order of 46 picoteslas.
Future Objectives
The successful resonating of the Schumann Cavity and wireless
transmission of power on a small scale resulting in proof of principle
will require a second phase of engineering, the design of receiving
stations. On completion of the second phase, the third and fourth
phases of the project involving further tests and improvements and a
large scale demonstration project will be pursued to prove commercial
feasibility.

[turbo]

I recommend this book: 
22 Radio and Receiver Projects for the Evil Genius.

It's one of the very best!   

Table of contents
Acknowledgments
Introduction
Chapter 1: Radio Background and History
Chapter 2: Identifying Components and Reading Schematics
Chapter 3: Electronic Parts Installation and Soldering
Chapter 4: AM, FM, and Shortwave Crystal Radio Projects
Chapter 5: TRF AM Radio Receiver
Chapter 6: Solid-State FM Broadcast Receiver
Chapter 7: Doerle Single Tube Super-Regenerative Radio Receiver
Chapter 8: IC Shortwave Radio Receiver
Chapter 9: 80/40 Meter Code Practice Receiver
Chapter 10: WWV 10 MHz "Time-Code" Receiver
Chapter 11: VHF Public Service Monitor (Action-Band) Receiver
Chapter 12: 6 & 2-Meter Band Amateur Radio Receiver
Chapter 13: Active and Passive Aircraft Band Receivers
Chapter 14: VLF or Very Low Frequency Radio Receiver
Chapter 15: Induction Loop Receiving System
Chapter 16: Lightning Storm Monitor
Chapter 17: Ambient Power Receiver
Chapter 18: Earth Field Magnetometer Project
Chapter 19: Sudden Ionospheric Disturbance (SIDs) Receiver
Chapter 20: Aurora Monitor Project
Chapter 21: Ultra-Low Frequency (ULF) Receiver
Chapter 22: Jupiter Radio Telescope Receiver
Chapter 23: Weather Satellite Receiver
Chapter 24: Analog to Digital Converters (ADCs)

Marco.