Tesla coils: how are they doing this? [Archive] - Glock Talk

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Originalsin
11-09-2012, 09:20
This is amazing. Two guys are using Tesla coils to radiate and exchange lightning from themselves. How are they able to do this without being fried? Would they be in insulated suits, or is this one of those weird behaviours of electricity where it runs through you without you being hurt? If anyone can explain it I'd be grateful.

http://www.wimp.com/electricitytesla/

Reminds me of a Force battle from Star Wars!

Cheers,

Originalsin.

Dennis in MA
11-09-2012, 09:30
Lots of volts, low amps. Or lots of amps, low volts. Somethign like that. I've long since forgotten, but they did it on the last Men Who Built America talking about Tesla himself.

aircarver
11-09-2012, 09:34
Lots of volts, low amps.

This.

.

devildog2067
11-09-2012, 09:35
Lots of volts, low amps. Or lots of amps, low volts. Somethign like that.

Right the first time. High voltage, high frequency, very low current.

fwm
11-09-2012, 09:35
My guess is metal chain suits, gloves, hoods and boots. Once the charge gets really high, and the resistance low, the repulsive force of the individual electrons force each other to the surface of the conductor, protecting the body inside.

Without some sort of external conductor, the resistance of the body would be to great to allow all of the charge to be pushed to the surface and the body would carry some of it, probably disastrously.

Geko45
11-09-2012, 09:40
It's not the volts that will kill you, it's the amps... High voltage with low amperage.

[pfft, to slow...]

Originalsin
11-09-2012, 09:41
Thanks!

Dennis in MA
11-09-2012, 09:43
I always liked the "lightning show" at the Boston Museum of Science.

Also had a teacher in Physics class that took one off the noggin once from a Van deGraff Genny. He forgot he turned it on. We kept telling him it was on. He walked right by. SNAP! Right to the temple. :rofl:

Originalsin
11-09-2012, 09:47
Was he hurt?

Atlas
11-09-2012, 09:49
It's not the volts that will kill you, it's the amps... High voltage with low amperage.

[pfft, to slow...]

Amazing how often this is repeated.
Ohm's Law will tell you that voltage is the electromotive force without which there can be no current flow.
"Volts" is the cause, "amps" (current flow) is the result.

That being the case, it is the "volts" that will kill you.
To the point you made, and in that context, the two are the same.

Whether a human is damaged by direct exposure to electricity is a highly variable thing.

Electrocution is most often exposure to electromotive force (the "volts") in a specific set of conditions which cause the flow of enough energy within the body (overcoming the electrical resistance of the flesh) to disrupt heart functioning.

Given the right conditions, death may be caused by massive tissue damage, including and especially various essential nerve tissues.

Dennis in MA
11-09-2012, 09:56
Was he hurt?

He walked away from it.

He was a bit of a dick to begin with. Waaaaay too arrogant. He told us (1985) that he shook Woodrow Wilson's Hand. He MAY have been born by then, but doubtful. We questioned him, he insisted.

So at first we were like :wow:

He staggered away and acted like nothing happened, so for the last 30 years or so, we've (my wife was in the class) been all :rofl::rofl:

I did begin to learn something in his class that was later confirmed in college: If you spend all of your time trying to convince a bunch of teenagers how awesome your life was, your life wasn't that awesome.

Geko45
11-09-2012, 10:02
Amazing how often this is repeated.
Ohm's Law will tell you that voltage is the electromotive force without which there can be no current flow.
"Volts" is the cause, "amps" (current flow) is the result.

That being the case, it is the "volts" that will kill you.
To the point you made, and in that context, the two are the same.

That is kinda like arguing if it's the velocity or the volume of water that will drown you.

High voltage with low current is analogous to being hit by a squirt gun. Not a lot of water, but it is moving very fast.

Low voltage with high current is analogous to someone sitting in a river. Plenty of water, but it is moving slowly.

High voltage with high amps is analogous to getting hit with a fire hose.

arcadefreaque
11-09-2012, 10:06
Right the first time. High voltage, high frequency, very low current.

The Tesla Coil (and other objects operating under similar principles) operates at such a rate that it does not penetrate the body, but travels across the skin's surface looking to ground itself. I've used handheld devices that operate under much the same principle with my body "electrified" by the device for relatively long periods of time, and although the arch of electricity when it jumps to ground can sting a little, it otherwise does no physical harm (other than an occasional itchy sunburn type of thing from long exposure).

Annoyedgrunt
11-09-2012, 10:09
I always liked the "lightning show" at the Boston Museum of Science.


The one where the guy goes up in the giant birdcage which gets repeatedly zapped with lightning? And all the while with him touching the bars? Good show. :wavey:

If I remember right, he said that as long as he touches the inside of the bars from in the cage, he'd be alright, because the electricity travels on the outside of the bars.

That doesn't seem to make sense, though. Wouldn't the electricity travel through the entire bar of the cage, and not just on the outside?

Glock20 10mm
11-09-2012, 10:14
Lots of volts, low amps. Or lots of amps, low volts. Somethign like that. I've long since forgotten, but they did it on the last Men Who Built America talking about Tesla himself.

Amps kill...

Rinspeed
11-09-2012, 10:32
I've been tagged with 2500 volts before and while it will wake you up without the amps it doesn't hurt.

FullClip
11-09-2012, 10:42
No need to worry about amps or volts if you conduct yourself properly and are well grounded in the subject.:supergrin:

But to devildog2067....I thought that this stuff is "static" electricity, therefore no "frequency" like AC current. Am I missing something?

Atlas
11-09-2012, 10:43
No need to worry about amps or volts if you conduct yourself properly and are well grounded in the subject.:supergrin:
...

:supergrin:

Atlas
11-09-2012, 10:56
...
But to devildog2067....I thought that this stuff is "static" electricity, therefore no "frequency" like AC current. Am I missing something?

Actually, no.
You're thinking Van De Graaff generator.

A Tesla coil produces high-frequency AC.

M&P Shooter
11-09-2012, 11:02
Tesla himself did this in front of a crowd in the late 1800's when he was competing for the Niagara Falls power plant contract against Edison to prove his AC current was safe and more powerful then Edison's DC current which was in use in the late 1800's. Funny thing is that Tesla was Edison's assistant in his lab and came to him with his AC coil and Edison thought it was unsafe and turned him away causing him to quit and start his own company which later was named GE:supergrin:

Originalsin
11-09-2012, 11:07
Tesla himself did this in front of a crowd in the late 1800's when he was competing for the Niagara Falls power plant contract against Edison to prove his AC current was safe and more powerful then Edison's DC current which was in use in the late 1800's. Funny thing is that Tesla was Edison's assistant in his lab and came to him with his AC coil and Edison thought it was unsafe and turned him away causing him to quit and start his own company which later was named GE:supergrin:

A shame the rivalry those two had. Two of the greatest minds in history. If only they had worked together, what could they have achieved...

FullClip
11-09-2012, 11:14
Actually, no.
You're thinking Van De Graaff generator.
.

yeah,,,had one of those when I was a kid. Edmunds Scientific deal. Little electric motor spun a big rubber band in a pipe between the base and the metal ball on top. Was great fun to charge myself up and ZAP my little sisters on the ears. Could get one heck of a miniture lightning bolt out of it without all the work of shuffling around the carpet in my wool socks.

Thought the lighting bolts of the Tesla stuff was the same idea. Didn't know it was "real" power.

Arc Angel
11-09-2012, 11:23
Amazing how often this is repeated.
Ohm's Law will tell you that voltage is the electromotive force without which there can be no current flow.
"Volts" is the cause, "amps" (current flow) is the result.

That being the case, it is the "volts" that will kill you.
To the point you made, and in that context, the two are the same.

Whether a human is damaged by direct exposure to electricity is a highly variable thing.

Electrocution is most often exposure to electromotive force (the "volts") in a specific set of conditions which cause the flow of enough energy within the body (overcoming the electrical resistance of the flesh) to disrupt heart functioning.

Given the right conditions, death may be caused by massive tissue damage, including and especially various essential nerve tissues.

:thumbsup: GOOD!

JohnBT
11-09-2012, 11:44
"Funny thing is that Tesla was Edison's assistant in his lab and came to him with his AC coil and Edison thought it was unsafe and turned him away causing him to quit and start his own company which later was named GE"

GE and Edison. Not Tesla.

Tesla version of the story was that Edison offered $50k to anyone who could solve some the shop's problems by designing a working system. Tesla did it in a month iirc and presented it to Edison. Edison laughed it off and said the $50K offer was a joke and that Tesla didn't understand American humor. Edison offered a $10 raise. Tesla quit.

Tesla was a genius. Of course, mention should be made of George Westinghouse (inventor of air brakes for trains) for bankrolling the venture to electify America.

Heck, after Westinghouse won the contract to light the World Columbian Exposition in Chicago in 1893, Edison tried to get General Electric to forbid Westinghouse and Tesla from using any lightbulbs.

Obviously, the show went on.

http://art.state.gov/exhibitimg.ashx?img=Repository+JPEG%5c2010.0517.jpg

robertoh
11-09-2012, 12:22
As long as any part of their body doesn't touch an Electrical ground their ok,other wise PHFFT.

Atlas
11-09-2012, 12:28
As long as any part of their body doesn't touch an Electrical ground their ok,other wise PHFFT.

If you are fully and completely "floating" above ground then yes, like the guys who inspect high-voltage lines while suspended on an outrigger on a helicopter.

High Voltage Cable Inspection - YouTube

Many times though people are insulated from "ground" and come into contact with high voltage inducing a current which travels through their body and then leaps from them to "ground", killing them instantly.

robertoh
11-09-2012, 12:32
When Edison lost Tesla and his AC system,Edison proved the Peter Principal works. It states that anyone who continues to seek advancement or promotion will sooner or later reach his/her level of incompitence.Edison was a genius but failed to see someone else could have a good idea also,even when it was demonstrated to him.

mj9mm
11-09-2012, 12:32
circus trick:cool:

Dennis in MA
11-09-2012, 13:23
The one where the guy goes up in the giant birdcage which gets repeatedly zapped with lightning? And all the while with him touching the bars? Good show. :wavey:

If I remember right, he said that as long as he touches the inside of the bars from in the cage, he'd be alright, because the electricity travels on the outside of the bars.

That doesn't seem to make sense, though. Wouldn't the electricity travel through the entire bar of the cage, and not just on the outside?

Yes, that one.

Electricity seeks the shortest route. Outside the cage is shortest.

devildog2067
11-09-2012, 13:25
Edison was a genius but failed to see someone else could have a good idea also,even when it was demonstrated to him.

To be fair, DC has many, many advantages over AC. And at the time the War of the Currents was being fought, the AC induction motor wasn't very well developed compared to the DC motor.

Hummerbike
11-09-2012, 13:43
My guess is metal chain suits, gloves, hoods and boots. Once the charge gets really high, and the resistance low, the repulsive force of the individual electrons force each other to the surface of the conductor, protecting the body inside.

Without some sort of external conductor, the resistance of the body would be to great to allow all of the charge to be pushed to the surface and the body would carry some of it, probably disastrously.

This is the answer.

TK-421
11-09-2012, 13:47
They're wearing metal protective gear that allows the electricity to flow around their body instead of through their body. Tesla coils are definitely cool stuff, there's a lot you can do with them.

I knew the two guys who built these, and they brought them to DucKon, a Sci-Fi con up in Chicago, before the con went to hell.

Musical Tesla Coils Dance of the Sugar Plum Fairy - YouTube

This one is a video that was actually taken at DucKon, and it was a blast seeing them there. Also helped that I had a cute girl by my side who was all impressed that I knew what was going on and how they worked. I didn't really, I was just repeating what my uncle told me, but she didn't know that, lol.

Masters of Lightning Play Mortal Kombat Theme with Zeusaphones - YouTube

Atlas
11-09-2012, 13:50
To be fair, DC has many, many advantages over AC. And at the time the War of the Currents was being fought, the AC induction motor wasn't very well developed compared to the DC motor.

And many new power transmission lines have been commissioned in recent years using very high voltage DC.

edporch
11-09-2012, 14:01
A lot of it because it's high frequency electricity.
I had an instructor in technical school who used to use high frequency electricity through his body to light a standard fluorescent 48" tube.

686Owner
11-09-2012, 14:57
They are wearing metal suits. David Blane either did something similar recently or will be. I heard someone talking about it on Penn's Sunday School. He said if any hair gets outside of the suit, it gets singed.

Haldor
11-09-2012, 16:01
Right the first time. High voltage, high frequency, very low current.

The high frequency is crucial to why this not shocking the people involved. High frequency AC mostly travel in the outer layer of the skin. Low frequency voltages travel primarily through the circulatory system (including right through the heart). That is why it is a very good idea to stick one hand in your pocket when working on energized high voltage electronics.

This happens in electrical wiring too. A high frequency signal travels in the outer skin and even in the air around a wire not in the middle of the wire. This is actually called the skin effect.

http://www.mos.org/sln/toe/skineffect.html

Haldor
11-09-2012, 16:08
Electricity seeks the shortest route. Outside the cage is shortest.

Nope, electricity follows the lowest impedance. For DC this is the lowest resistance which normally means the shortest distance.

AC current flows through the lowest impedance and as the frequency increases, the more the inductance and capacitance of the conductor matter.

AC current in a solid plane will travel in a way that maintains the smallest loop area. For example on a PCB, if you have a trace the snakes all over the place, the return current in the ground plane will follow directly under the trace, even if this means the current has to follow a longer path.

http://www.analog.com/static/imported-files/rarely_asked_questions/groundClean_figure9.jpg

http://www.analog.com/static/imported-files/rarely_asked_questions/moreInfo_raq_groundingClean.html

.264 magnum
11-09-2012, 16:11
To be fair, DC has many, many advantages over AC. And at the time the War of the Currents was being fought, the AC induction motor wasn't very well developed compared to the DC motor.

Sure, but think about how large wire 00000000-AWG or whatever would be needed to move power around a city.


ETA - assuming the tools available to Edison during his life.

Magnus2131
11-09-2012, 16:15
He was a bit of a dick to begin with. Waaaaay too arrogant. He told us (1985) that he shook Woodrow Wilson's Hand. .
He was a dick if he shook Woodrow Wilson's hand. GGGRRR:steamed:

Haldor
11-09-2012, 16:21
And many new power transmission lines have been commissioned in recent years using very high voltage DC.

I recently heard the same thing. There are plans to transfer power from solar panel farms in Africa to Europe. The primary advantage to DC transmission lines is the lower cost of power lines (you don't need three conductors and each conductor can handle more current due to the lack of skin effect). Plus DC power cables are more efficient that AC when run under water. AC loses a lot of power charging and discharging the capacitance of the water. DC doesn't have this problem.

The electronics required to convert DC voltages are expensive, but the savings on wiring more than make up for this is your have long cable runs.

Atlas
11-09-2012, 16:29
...The electronics required to convert DC voltages are expensive, but the savings on wiring more than make up for this is your have long cable runs.

The electronics to do this at those power-levels are amazing!
Compared to the state of power semiconductors even a few years ago it's almost sci-fi.


I recently worked a defense-systems project for a company that specializes in high-voltage/high-power semiconductor-based power control. This place was stuffed to the rafters with nerds, some of the smartest guys around.

The assembly featured rows of semiconductors mounted on water-cooled "cold plates". They had some very creative ways of running cables carrying very high voltage in tight spaces within the system cabinets.

Atlas
11-09-2012, 16:34
Speaking of running power lines under water...
A very cool project in the works.

The Atlantic Wind Connection transmission lines will be high-voltage DC.

http://atlanticwindconnection.com/

relayman
11-09-2012, 17:20
Current is what stops the heart . Ask any Cardiologist .

JohnBT
11-09-2012, 18:40
Current is what starts the heart too. Ask any Cardiologist. Just don't ask one to wire a building.

JohnBT
11-09-2012, 18:49
"And at the time the War of the Currents was being fought, the AC induction motor wasn't very well developed "

Neither was Edison.

Edison wanted to win so badly he executed an elephant with AC to prove to the world that AC was dangerous and that Tesla was wrong. The year was 1903 and Edison filmed it. Such a proud moment. RIP Topsy.

http://www.viewzone.com/tesla.elephant.jpg

Of course the public wasn't surprised, because for 10 or 15 years Edison had been electrocuting dogs, cats, rats, a horse, calves, and orangutan. It was Edison who convinced NY to use Tesla's AC to execute prisoners.

I'm shocked. ;)

janice6
11-09-2012, 18:55
The one where the guy goes up in the giant birdcage which gets repeatedly zapped with lightning? And all the while with him touching the bars? Good show. :wavey:

If I remember right, he said that as long as he touches the inside of the bars from in the cage, he'd be alright, because the electricity travels on the outside of the bars.

That doesn't seem to make sense, though. Wouldn't the electricity travel through the entire bar of the cage, and not just on the outside?


Skin Depth is the depth of penetration of the conductor by the current flow. Skin depth is a function of frequency.

The higher the frequency, the less penetration.

Altaris
11-09-2012, 19:15
Most of the Datacenter equipment I sell(Server/Storage/Networking) have options for either DC or AC power supplies. Usually it is the large TelCo accounts that go for the all of the DC gear.

Dennis in MA
11-10-2012, 07:28
The electronics to do this at those power-levels are amazing!
Compared to the state of power semiconductors even a few years ago it's almost sci-fi.


I recently worked a defense-systems project for a company that specializes in high-voltage/high-power semiconductor-based power control. This place was stuffed to the rafters with nerds, some of the smartest guys around.

The assembly featured rows of semiconductors mounted on water-cooled "cold plates". They had some very creative ways of running cables carrying very high voltage in tight spaces within the system cabinets.


Lol. If I were writing a sci fi movie, I'd use that line.


"But can you get him there with this technology?"

"Get em there? I've got a warehouse stacked to the rafters with nerds. Of course we can!"

robertoh
11-10-2012, 08:10
A lot of Electrical and electronic devices today operate on DC,cell phones,computers,any portable devices.AC in one plugged into an AC circut are rectified to DC. In these applications DC works better.

NEOH212
11-10-2012, 21:48
To be fair, DC has many, many advantages over AC. And at the time the War of the Currents was being fought, the AC induction motor wasn't very well developed compared to the DC motor.

Very Very true!

It's kind of old news but check out the video!

(Sorry, I couldn't get it to imbed.)

https://www.youtube.com/watch?v=pNR0YtvKmYg

HollowHead
11-10-2012, 22:36
Can someone offer then what a joule is? It seems to be the measure of all things indended to supply a "shock" to things like hearts in A-fib and livestock containment. HH

HandyMan Hugh
11-10-2012, 22:38
IIRC, the reason that AC became the standard power used in the electrical grid was ACs superior long distance transmissability. Edison's DC system would have required power stations to be built in each neighborhood. The line losses were too great in DC transmission lines. Not only were line losses less in AC systems, you could build booster stations to build the transmitted voltages up again. Ordinary transformers simply don't work in a DC system.

Not only can you transmit very high AC voltages for long distances, you can take the high voltages (and using transformers) drop the voltage to 240 Volts for household usage.

Haldor
11-12-2012, 16:59
A lot of Electrical and electronic devices today operate on DC,cell phones,computers,any portable devices.AC in one plugged into an AC circut are rectified to DC. In these applications DC works better.

This is true for battery operated equipment. The discussion however was about long distance power transmission. Until recently the only efficient way to do this was with high voltage AC.

Haldor
11-12-2012, 17:03
Can someone offer then what a joule is? It seems to be the measure of all things indended to supply a "shock" to things like hearts in A-fib and livestock containment. HH

Standard unit of energy expended or work done.

It is defined in two ways:

Physically it is defined as applying a constant force of one newton through a distance of one meter.

Electrically it is defined as passing an electric current of one ampere through a resistance of one ohm for one second.

devildog2067
11-12-2012, 17:08
Edison wanted to win so badly he executed an elephant with AC to prove to the world that AC was dangerous and that Tesla was wrong. The year was 1903 and Edison filmed it. Such a proud moment. RIP Topsy.


I actually mention this in my "war of the currents" lecture. Let me see if I can find it.

EDIT: http://diablo.phys.northwestern.edu/~devildog/lecture20.pdf

devildog2067
11-12-2012, 17:12
IIRC, the reason that AC became the standard power used in the electrical grid was ACs superior long distance transmissability.

Right general idea, but incomplete.

AC isn't superior for long distance transmission.

High voltage is superior for long distance transmission.

It's much easier to change the voltage of AC than it is of DC.

quantum36
11-12-2012, 17:13
Right the first time. High voltage, high frequency, very low current.

This.
And frequency dependent "skin depth".

mhambi
11-12-2012, 17:18
Faraday!!!

concretefuzzynuts
11-12-2012, 17:22
A good ground. The key to it all.

quantum36
11-12-2012, 17:31
The following is based on "low frequency" or constant voltage. This is important. The 60 hertz voltage within all of our homes should be considered as "constant" for all practical purposes.

All it takes is a "sustained" 25 miiliamps across your muscles and heart, and you won't be able to "let go" of what will kill you. Regardless of voltage.
Low voltage can't break through the mega-ohm resistance of outer skin. High voltage can. Nonetheless, if it can, it will see the approximate measly 8 ohm resistance of your internal body. Then 12 volts can kill you. "IF" the source of power is capable of delivering enough charge.

Imagine putting your tounge across a small 9 volt battery to test if it is charged.

What would happen if you did that to a car battery? Place a wrench across a 12 volt and you will see......

Thats why electrical shock is very unpredictable.

I was hit many years ago, by 2500 volts at 25 miiliamps, and it would have killed me accept for the fact the power supply sensed the current drain and shut off. It felt liked getting hit in the chest by a baseball bat.

I was dizzy for over 24 hours after.

The high voltage "arcted" and burned into my lip, eventually burning through my skin and found a good ground ..

I was working on a 150,000 volt accelerator at University of Missouri/Rolla. The 150,000 volts was off. But the 2500 volt extractor was still on. My face was right next to the extractor and my "pinky" finger on my right hand contacted ground......

I will never forget it!

I hope that Devildog will help me in explaining the "frequency" dependence on electrical resistance. I have already done my part. I almost got electrocuted! (Actually I was, but survived it!)