# Tesla Wireless Power

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## Tesla's Wireless Power... My Version

by Glenn E. Clabough, Electrical Engineer
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Nikola Tesla's wireless power secret was the "coupling coefficient," or the fraction of magnetic flux lines linking one coil to another in close proximity and situated "not connected" in parallel. This means they have no physical connection though they have the same side by side orientation.

K = coupling coefficient

k = flux of L1 and (L2 / flux of L1)

Flux equals the number of magnetic field lines emitted by inductor L1 also the number of field lines to break across the loops of inductor L2.

A high value of K called tight coupling allows the current in one coil to induce a voltage in a second coil within proximity, while a low value of K has the opposite effect.

### More on Flux

Nikola Tesla, with Rudjer Boscovich's book "Theoria Philosophiae Naturalis", in front of the spiral coil of his high-voltage transformer at East Houston St., New York

The Greek symbol is phi. [1]

One magnetic field line equals one Maxwell, named after James Clerk Maxwell (1831-1879).

The webber is a much larger group of field lines, 1×10+18 (1018), named after Wilhelm Webber (1804-1890).

Since this is such a large unit the "micro-webber" unit can be used.

1 micro-webber = 1×10 – 6 webbers

This all works out to 1 micro-webber (uW) = 100 field lines, or one hundred Maxwell Mx units.

Flux Density with the symbol B is the number of magnetic field lines per unit "area" of a section perpendicular to the direction of flux.

B = Φ ⁄ A

where A represents area.

### The Guass

This unit is one magnetic flux line per square centimeter or one Mx/cm2 this unit named after Karl f. Guass (1777-1855).

### The Tesla

The unit of flux density B is in webbers per square meter or (Wb/m2) and one webber per square meter is called one Tesla or one T. This unit is named after Nikola Tesla (1857-1943).

### Self inductance

This the ability of any metal conductor to induce a voltage within itself when the current applied changes. this is known as self inductance or simply "inductance" and is basicly the "number of magnetic field linkages cast" by the conductor. this is symbolized by the Letter "L" and is measured in henrys, named after Joseph Henry (1797-1878).

One henry is the amount of inductance that allows one volt to be induced when current changes at a rate of one ampere per second:

L = vL  (didt)

where vL is the applied voltage and di and dt are min/max values for current to show change with respect to time.

### Mutual Inductance

When current in an inductor changes, the varying flux can cut across any other nearby inductor to induce a voltage. So, though there is a primary voltage upon the first inductor there is also an induced voltage across it and others nearby. This mutual inductance is also measured in henry units and is symbolized with Lm for mutual inductance.

If two coils have an Lm of one henry when a current change of one Amp per second is applied, then there is a resultant induced voltage of one volt found on both coils,

Lm = K × √(L1 × L2)

and is calculated in henry units.

### Coil construction

Making an inductor coil is very easy it is just some wraps of insulated wire on a form or even with out a form if the wire is thick enough to hold its weight.

The first thing on a list of how to is selecting a wire gauge fit for the task, to do this we first need an idea of current requirement. I wont go into detail with that because there is no shortage of websites and books with charts of AWG standards, which is a chart depicting wire gauge versus its current/temperature capability's limits.

After selecting a wire gauge capable of carrying the amount of current needed and/or supplied, by both primary and secondary. as well as designing in some lea-way for such case as over rating the secondary enough that you get some distance away and still work or care not to under rate the primary in such case as there is a freak voltage spike from a storm front.

A modern improvement upon this technology would be a stainless steel reverberator that can be added to the receiver side antenna to maximize it's distance capability.

1)A greater number of turns increases inductance because more voltage can be induced. Actually inductance increases in proportion to number of turns squared. So, if you double the number of turns in the same area and length, the inductance increases by four times.

2) Larger area (loops), increases inductance in direct proportion to area and as the square of the diameter of each turn.

3) Inductance increases with the permeability of the core.

4) Inductance decreases as length increases as if using a longer core and leaving gaps between loops.

### Permeability of core materials

Air, vacuum, space, cardboard, soda straw, paper, plastic, glass tube, etc., has a permeability = 1.

Ferrous metals like soft iron, steel, ferrite varry's from 100 to 9000 and must be calculated by using their flux density rating.

### Core types

There are many such forms as bars, rings, toroids, tubes, cards, and PCBs using etched inductors. Though there are more core types, these are not our focus and are left out to not draw attention from our topic.

OK, so I have brought you this far that we might just as well finish understanding just what Tesla was doing within his secretive lab with an iron tower in New York.

He was making a transformer. That's right –a good old fashioned wall-wart. But there are some exceptions in this case.

Basically a modern transformer is a unity device because it's efficiency is nearing the 100% mark due to its direct coupling over an iron core. What Tesla had conceived was an air core transformer with a lot less efficiency. But, it is true that the concept and device did and still will work like a charm.

The flaw in the concept is, though everyone would receive this wireless power, the farther away it was, the less strength efficiency it had. Tesla saw he could over come this problem, too, by simply ramping his frequency until those at the outer boundary had enough voltage oomph to have a usable power. Then those who lived or worked close to the transmission tower would have a whole lot of voltage oomph that they could then regulate down by dropping the excess power into either dummy loads or to power more of his transmission towers to broadcast to a broader area. This was an ingenious idea, and still today a very green way of dealing with the power problems of our world.

### Green

In addition to the obvious problems of power grids, you could imagine lots of silver and copper used in the current grid work could be returned back to surplus, bringing prices of the now precious metals down but, how about the fact of centralizing power generation? No more fear of catastrophic meltdown and pollution to the entire globe. Sure we still need a power plant but only one for the whole world. I know that seems like a far fetched idea but there are new technologies today that would allow exactly that.

### Public safety

No more children electrocuted by plugs and outlets,as well as reduced pollution and hazards.

### Efficient

Imagine if the power failed due to a storm you could just tune in a different tower instead of waiting day's for worker to come to your home to trim trees. mostly imagine not having to have those workmen to your home ever, not to mention no more wires in your view but an actual 17th century view of only homes/buildings sticking out of the ground.Now of coarse there would be a few towers sprinkled along the way but they could even be apart of other structures, like today's police/cell phone repeaters.

How would you select a nearest tower and disregard a far one? With tuning circuits! –just like tuning a radio. Listen to the channel that suits your need.

There comes a time in any industry where you start to see the need for optimization because though you are making your products as fast as you know how, as always even faster would be even better and this is one of those times. Just like burping a baby who has a half finished bottle, it helps the second half go down problem free.

File:Twain in Tesla's Lab.jpg
Mark Twain in Tesla's laboratory. (Image U.S. public domain)

### Looking back

Now when explained and understood the concept of dumping excess power into dummy loads at first hits like a ton of bricks as a loss. But, because the dummy load was just the first logical stand-in for a way of dealing with excess power, then really that dummy could easily be a second or third house or even street lights attached to the first tower listener. So truthfully the efficiency of it would not be to bad. We could feasibly get 75%-80% efficiency from it.

As to the pictured lightening bolts grid working the sky's in the media and news of the day, an absolute nonsense. Why? Because the actual power is running underground. Now there might be a slight chance of an aurora effect, if there is a surplus of luminous gases in the atmosphere but that is only a slight chance.

So why isn't it used today?

Because Benefactor, J.P. Morgan knew you can't continue to charge them for what you can't disconnect them from.

Who is this Morgan fellow anyway?

He is long dead but his bank is the one who signs every government check and issues every food stamp given to the citizens of this Glorious Union.

Posted by permission. Wiki edits by DEM

## References

1. phi: The lower case Greek letter phi, written as φ.

## See also

26th Chaos Communication Congress –Here be dragons
2009-12-27
Wireless power transfer
Forgotten knowledge: Tesla invented wireless power
Lecture by Davor Emard
A google image search
EngineeringToolBox.com
Electrical Units