Tesla and wireless power

I was just musing the other night about Tesla's AC and how it revolutionized electric wiring, with the step-up transformers and all.

Well, if you start with, say, 100V, you need to carry 1 amp to power a 100W light bulb.

But if you step up the 100V to 1,000V, you only need wire that can carry

100mA.

And if you step it up to 1,000,000V, you only need 100 _micro_ amps.

So, logically, if you could step up the voltage enough, you shouldn't need any wires at all!

Unfortunately, the darned electrons arc over to stuff before they get to the destination transformer. )-;

But, in fairness, those guys were just discovering electricity for the first time, and NOBODY knew anything about how it might behave.

Thanks, Rich

Reply to
Rich Grise, Plainclothes Hippi
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Suppose you built a high-freq, high-volt, low-current power supply which ccould drive impedance-matched devices using a single conductor. Does it not make sense that you could connect this "single conductor" to the Earth itself, and therefore operate many distant grounded devices? :)

In practice it only works if you supply each distant load with an infinite-Q tank circuit. I suppose a 1 : 10^20 step down transformer would also suffice. But no progress will endure unless you first take care to destroy your own sexuality and thereby avoid having your Flight of Ideas derailed by French actresses dropping scented handkerchiefs.

Reply to
Bill Beaty

Of course, you get more than 100uA to the surroundings through capacitance alone (just at LF), and you get capacitive dividers everywhere. Even without Hertzian waves (negligible for 25/50/60Hz), you lose voltage everywhere.

So logically, if you could step up the voltage sufficiently, you could lose voltage everywhere. :)

Tesla seemed to have a pretty good idea, except for the appreciation of resonant loss.

His works suggest that you can keep adding energy to a resonant system and it will stay there forever. In reality, a constant amount of power is required. This is why you can't shake a house to pieces with a fist-sized motor, it's too lossy.

Tim

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Reply to
Tim Williams

The G-line

formatting link
could be used to direct the RF energy to the place wanted :-).

Reply to
Paul Keinanen

Take a minute. Divide it in half. Divide the remaining part in half. Continue forever, and the minute never ends, right? Same (mis) logic... So we have beat both power transmission and time!

What's a few sparks... I just hate it when my clothes stick to me, along with every bit of fuzz and lint in the room. And you should see the cat's reaction when I tried it--she freaked out.

Yea, but some day we'll figure it out!

What I want is unified connectors: power, signal and control in one (standard AC three pin) connector. TV: plug it in and it works. Phone? Plug it in and it works. Computer: Plug it in and it works!

Reply to
PeterD

Tesla had an excellent excuse, but the modern Tesla enthusiasts don't.

Cheers

Phil Hobbs

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Reply to
Phil Hobbs

Why? Both were/are mad. ;-)

Reply to
krw

But they seem to take so much care in winding that tall secondary, they look quite pretty, that shiny enamelled wire cylinder. Quite useless, except for the Buzzt! factor long sparks ;)

Reply to
Grant

I'm not talking about Tesla _coil_ enthusiasts. They're obviously doing worthwhile stuff--I mean, making 20-foot sparks is at least as useful as blowing up anthills with dynamite, for instance. Blowing up stuff is a logical consequence of having testosterone, it's fun, and it's occasionally a life saver.

It's the wireless power transmission / over unity / extracting continuous power from permanent magnets / loony types I'm fed up with.

Cheers

Phil Hobbs

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Reply to
Phil Hobbs

My personal favourite was stuffing CO2 cartridges with wooden match head scrapings. Not ONE of the launch attempts actually performed like a rocket. They all blew up and grossly disfigured the angle iron launching ramps.

One 'trial' managed to uncurl a bit of decorative wrought iron railing that was holding the cylinder. On a Sunday morning, 8 AM.

The echo from the blast came back from a large building a block away. We cleared out of there NOW!

We were all lucky not to get killed or maimed by the shrapnel. There seemed to be a continent wide scourge of kids getting damaged by homemade rockets. The safe, commercially made model rockets were still years away.

It must have all been a billion to one odds series of events, as we all know that testosterone has NEVER, EVER caused stupidity in male adolescents.

mike

Reply to
m II

Female adolescents are morons too, just in a different way.

Cheers

Phil Hobbs

(Father of some of each)

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Reply to
Phil Hobbs

Reminds of a problem a friend posed recently, if one gets a large strong rare earth magnet, and hangs a heavy weight from it to a steel beam in the shed, what's doing the work of the magnet holding up that weight? Wont the magnet 'wear' out?

Related, ever had an MRI? They put you in a big magnetic field, then they modulate that field to 'somehow' get images... Sound like a jackhammer, the operator side, they gave me headphones playing music to hide the noise (no metal in them, headphones had plastic tubes).

This thing was built big, solid, one could feel, hear the energy thumping around. Remove all metal objects from pockets quite some distance from the room with the magnet.

Grant.

Reply to
Grant

Displays from large Tesla Coils often stimulate an interest in science and engineering in younger folks - not a bad end result...

Bert

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Reply to
Bert Hickman

Work is force times distance. Since the weight isn't moving, no power is required. If it does come loose, the weight as it falls will do work on the magnetic field, in such a way as to account for the extra field energy of the magnet in air vs. in contact with steel, plus a bit extra for the eddy currents.

Ever notice that nobody asks these questions about the electrostatic force, which is what holds solids together, including the beam, the weight, and the magnet? If the rope breaks, nobody wonders about the work done on the electrostatic field in the process, though it's mathematically similar and conceptually almost identical.

People have this idea that magnetism is somehow magical and mysterious, whereas it's been a matter for calculation and not speculation for over

150 years. It is cool and sometimes counterintuitive, but not mysterious. That's where the Tesla types go wrong. Not everyone knows that sort of math, of course, but it's all the sturdy 18th and 19th Century type, not this newfangled stuff. Most folks could learn it in a year or two if they wanted to make the effort, but of course it's way easier to produce reams of blather on the Net instead.

Yup. NMR systems for research often have glass helium dewars inside there, so that a steel bolt flying into the magnet can make a _big_ mess.

Cheers

Phil Hobbs

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Phil Hobbs
[snip]

Yep. The only time I've come close to claustrophobia :-( ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

Reply to
Grant

A friend reports the same, she needs to be sedated to go in there again. I was only in up to my knees :) I've been in the tunnel of a CAT scan machine, no jackhammers there...

Grant.

Reply to
Grant

I thought I didn't need the earphones... never again will I make that mistake :-( ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

Surprisingly, I didn't have any issues with claustrophobia and I generally get quite nervous in confined places. It was cold and the ventilation was quite good so perhaps my claustrophobia triggers weren't pulled. I didn't think the sound was all that bad, either. Weird, but not unbearable. If the operator weren't constantly trying to keep me calm I probably would have gone to sleep, since I got about zero sleep in the three nights I was there (two in a room, separate nurses with different schedules and a roomie watching TV all night).

Reply to
krw

Work is force * distance. If the weight is stationary, no work is being done.

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Reply to
Fred Abse

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