Re: Receiver coil

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Mddeming-at-aol-dot-com>

In a message dated 6/7/01 12:47:03 AM Eastern Daylight Time, tesla-at-pupman-dot-com 
writes: 
snip - - - 


>
> Ahh yes,I was just reading about this in a book about tesla,and his "lost" 
> inventions. lemme grab it.... 
> It says here that for wireless power,you would wind two identical flat 
> coils 
> (wide,not tall) with two large metal spheres attached to the large coil. 
> (aerials if you will) Much like a tesla coil,but "backwards" you would 
> connect the large coil to the "antenna" and to ground,and take power from 
> the "primary" (now secondary) of the second coil.  I believe that the 
> "aerials" are critical in tuning the circuits. the key is to get the 
> "antenna" as high as possible,Like up into the clouds,where the atmosphere 
> is conductive when charged with "hundreds,thousands,or even millions of 
> volts" 
> it says that Tesla's prototype (which he demonstrated to the patent-givers) 
> was constructed thusly: (transmitter) A 50,000 volt transformer charged a 
> .004uF capacitor which discharged through a rotary gap producing 5,000 
> breaks per second.The primary was eight feet in diameter,and used one turn 
> of "stout" cable.the secondary was 50 turns of 8 gauge cable.the 
> transmitter 
> oscillated at 230-250,000 CPS,and produced 2-4 million volts. 
> He later modified this a bit,and used it at Colorado Springs as teh 
> "magnifying coil" the secondary was 24 turns of 8 gauge wire 51 feet in 
> diameter,the antenna was a 30 inch sphere,and was on a 142 foot mast! 


Hi Al (et. al.)! 

1.       The Devices referred to above, as described in Tesla's patents 
645,576 of March 20, 1900 and 649,621 of May 15, 1900. are NOT aerials or 
antennas. Tesla described how the transmission of appreciable energy by 
"Hertzian waves"  was scientifically impossible. The spheres marked D and D' 
in his diagrams are terminals, immersed in the conductive medium of the 
rarefied atmosphere at a height (he recommends) of fifteen or more miles. Two 
of the biggest problems he faced were a) how to PREVENT radiative (antenna) 
losses from the connecting cables. b) a copper wire in perfectly still air, 
without any moisture or ice, (ha ha), regardless of cross section, must break 
of its own weight at a length of ~9.7 miles, and the best steel wire exceeds 
its tensile strength at about 14.8 miles, Aluminum ~11 miles etc. Any 
whipping or slack-and-stretch snapping due to wind or drag, reduces the 
useable elevation to under 1-2 miles. 

2.     The experiment he performed, according to his patent claim, was to 
transmit energy by conduction through a rarefied atmosphere (150mmHg) inside 
a fifty-foot glass tube in the lab, SIMULATING the ASSUMED atmosphere at 15 
miles. Think BIG Neon Sign (By 1918, the highest altitude ever achieved by 
any means was just over 37,000 ft. This patent was issued in 1900). 

3.     In the rest of the patent, he extrapolates that to transmit 
industrially significant energy at a reasonably lower elevation would require 
20 to 50 Megavolts at the top terminal, with 15 -20 Mv being a practical 
minimum. He claimed that at these potentials, the conductive properties of 
the atmosphere were increased, but gave no specific details. 

4.     Does anyone know the energy necessary to ignite atmospheric Nitrogen 
(N2 +2O2 + e = 2NO2 etc)? 

5.     Tesla coils are a terribly inefficient way to transmit radiated power 
(radio waves) and Tesla abandoned this idea early. 

6. Getting FAA clearence for tethered balloons at 20-70,000+ ft would be 
nearly impossible. There were, of course, no airplanes in the world when this 
patent was issued. 

Tesla got around the problem of impossible wire lengths by saying (pat. 
645576, lines 477 through 488 : 
"With reference to the facts which have been pointed out above it will be 
seen that the altitudes required for the transmission of considerable amounts 
of electrical energy in accordance with this method are such as are easily 
accessible and at which terminals can be safely maintained, as by the aid of 
captive balloons supplied continuously with gas from reservoirs and held in 
position securely by steel wires or by any other means, devices, or 
expedients, such as may be contrived and perfected by ingenious and skilled 
engineers." 

A workable Tesla power transmitter and receiver is no small undertaking. 

Good Luck, 

Matt D.