Build Your Own Tesla Coil 287
screenbert writes "Ever wanted to keep stray dogs or neighbors from trampling your backyard, but
just couldn't find the system to really deter them? Well this
site shows how they built
a bi-polar Tesla Coil system. I've always loved the Tesla coils on C&C when
they'd zap the units as they went by.
"
Food Protection Device (Score:5, Funny)
Comment removed (Score:5, Funny)
Re:There's an easier way... (Score:2, Funny)
Re:There's an easier way... (Score:2, Funny)
Pretend to be drunk and tell a wild story about how you've hidden a webcam in the fridge.
Re:There's an easier way... (Score:2, Funny)
-Sara
Re:There's an easier way... (Score:2, Funny)
Friends of mine laced a dozen muffins with it (added a bit of sugar to hide the taste) to deter someone who's been stealing their food, and that night they heard the toilet being flushed every 10 minutes...
Works like a charm
Re:There's an easier way... (Score:2, Interesting)
Re:There's an easier way... (Score:2)
Am I the only one who read this and pondered Jack in the Box's popularity?
Re:There's an easier way... (Score:2, Funny)
Insane sauce (Score:2)
Re:Food Protection Device (Score:2)
wrong date (Score:2)
Holy Sh*t (Score:2)
Put it on your car! (Score:2, Funny)
Re:Put it on your car! (Score:2)
Computer lab fun (Score:4, Funny)
Two words: Tesla Coil
don't mod parent down! (Score:2)
envy!!!! (Score:3, Funny)
Re:envy!!!! (Score:2, Funny)
Re:envy!!!! (Score:2)
That's not a picture of his tesla coil. (Score:5, Funny)
small town politics (Score:2)
I can see this causing brown outs if you do this in the local small town. Complete with stories of UFOs etc.
Musn't upset the town fathers.
Re:small town politics (Score:3, Funny)
When a bunch of angry people with Einstien hair-do's show up at city hall, you know you have gone too far.
Re:Wonder if a mass scale weapon could be made... (Score:2)
I always thought getting Peter Cushing for that role was a masterstroke. Too bad he barely spoke two lines in the whole movie.
Erm.. (Score:3, Insightful)
That having been said, Google cache [216.239.51.100]
Re:Erm.. (Score:2)
The rest of the show sucked, however. The "Hand of God" promptly ran into a ditch and stayed there. They had an extremely tasteless mockup of the U.T. Tower, complete with murderer at the top, to which they set fire. They had some sort of walking robot, which didn't walk very well. If it wasn't for the Tesla coil, I would have felt very ripped off.
Re:Erm.. (Score:2)
I wonder if they'll make it out my way.
What's the last thing the redneck ever said...? (Score:2, Funny)
Egads. I guess these are the guys who always ignored the "don't try this at home" warnings, huh?
-S
A Star Wars scene we didn't see (Score:5, Funny)
That picture of the "Man of Great Potential" is really giving me strange ideas.
mobile? (Score:2)
Makes this a little difficult on the mobility side, but hey, with one of these [msnbc.com], the world is your playground (or you'll just be really lonely)
Be careful! (Score:5, Funny)
Before Slashdot posts stories like this, they should very expressly warn their readers about the dangers inherent in such projects. Although a simple Tesla Coil is not particularly dangerous, if a Tesla Coil is turned into a mobius strip and enough energy is put into it, a electrotemporal-topological disaster can result, plunging an area up to 5 kilometers around it into Dirac Space.
You can find more information about this strange and dangerous phenomenea here [google.com].
Re:Be careful! (Score:2, Funny)
They did, they said the guy was "bi-polar".
Re:Be careful! (Score:2, Interesting)
Re:Be careful! (Score:3, Funny)
Beause often this device also causes ontological collapse, causing the very Being-as-such of the destroyed areas to return to an essential, rather than an existential being. Now, normally, being and essence are two seperate things, and since to destroy one would be to destroy the other, Being-as-occupying in the way a city does can not be destroyed totally, and so even as one side is wiped out, the other can not be, so the city reasserts its ontological identity.
Now, some people would believe that memory is just data reflected in a synapse. But really, memory is a process where the ontological throwingness-of-being of Beings is reassertted in the personal ego by reconciling somethings Being-as-such with its Being-towards-others. Butif identity and being are crossed, as they are in a Mobius Strip, they can be linked together, and thus annilated from the memory of Being-as-being-towards-its-own-reconcilation at once.
So lots of cities have been destroyed with this weapon, we just don't remember them.
mirrors... (Score:2)
Off by default. (Score:2)
I'd leave it off by default, and just flip the switch every time some kid wants to sell me cookies. Hah!
The tree pics at the bottom of the page (Score:3, Interesting)
Ah! I found it! (Score:2, Interesting)
http://www.edm.net/~jwilliams/Site_Ma
I prefer the "Jacob's Ladder" (Score:2)
~Philly
Lightning on Demand ? (Score:2)
http://www.lod.org
http://www.lod.org/electrum.html
http://www.lod.org/electrum/electrumpics.html
For those determined enough... (Score:2)
I must be a borg.... (Score:2, Funny)
Well I'm disappointed. (Score:2)
To build your own Tesla Coil (Score:2, Informative)
http://www.hills2.u-net.com/tesla.htm
what is C&C (Score:3, Funny)
Re: (Score:3, Informative)
Re:what is C&C (Score:2)
pah try Dr MegaVolt's 100kva ! (Score:2)
Now This guy [drmegavolt.com] seems to understand Tesla coils nicely, in fact he is trying to build a 100kva Tesla coil [drmegavolt.com] for his next show (he does his thing at Burning Man festivals) , check out the movies
i swear he's mad,
cool
but mad
As a tesla coiler... (Score:5, Informative)
Fun with Tesla Coils... (Score:4, Funny)
Keep your credit cards a few km away. (Score:3, Interesting)
The reason I still haven't is that they're about as good for electronics and magnetically sensitive media as a lightning strike. The intermittent arc gives off *vast* amounts of RF crud, which will induce currents in just about anything electronic and degauss anything magnetic nearby.
Your computer case will not save you if your machine has drive bays. All connected wires (modem, network, power) will also act perfectly well as antennas penetrating the case's shielding.
Credit cards and bank cards generally aren't shielded at all
Set up those Faraday cages before building anything like this.
Re:Keep your credit cards a few km away. (Score:3, Funny)
And the reason nobody thought of plugging on one of these suckers just outside One Microsoft Way is...?
Really is an old idea (Score:2, Interesting)
Back to the EMP stuff...does anyone have some nice information about project HAARP and similiar "experiments" all around the world? I heard somewhere that US military already developed their small EMP "bomb" for knocking out "e-criminals". I would like to take a look at one of those toys
Imagine the possibilities (Score:2)
As much as I'd love to have plans for one of these HERF guns, I think that it would probably make it too easy for "hardware script kiddies" to then go out and wreak havoc. What I'd really like is a reading list (preferably with difficulty ratings) on what to study to be able to design your own.
Here's an easy Tesla coil recipe (Score:5, Interesting)
Yank the flyback transformer out of the TV, and discard all its primary windings. Keep the big high voltage secondary winding (the one with the zillions of turns). It's usually encased in rubber and may look like a big rubber wheel. Its main lead has really thick insulation and connects to the side of the picture tube (where it looks like a stethoscope). The other lead (the ground) won't be as heavily insulated.
The only other parts you need are two NPN power transistors (2N3055), two 5W power resistors (20 ohm and 200 ohm), some wire, and a good supply of DC current (12-24 V). The circuit is a piece of cake. The first time I did it, I put the whole thing together with alligator clips.
This circuit has two primary windings around the flyback transformer core. The power winding is 8 turns, with a tap in the middle. The feedback winding is smaller (4 turns), also with a tap in the middle. The power winding leads connect to the collector leads on the transistors, with the center tap going to the +24 V DC power source. The feedback winding leads connect to the gate leads, with the center tap there going to +2-3 V DC (connect the resistors in series across the DC power to get the lower voltage in between). The emitter leads are grounded.
As current flows through one transistor, the changing field in the core induces a voltage in the feedback windings that turns that transistor off and the other one on. Then current flows the other way, and the same thing happens in reverse. So the circuit tunes itself to the proper frequency. But it also means that the first time you power it up you run a 50-50 chance of connecting the leads to the wrong transistor gates, in which case you get a stable DC circuit. So if it doesn't work the first time, try exchanging the gate leads.
This circuit is fairly well known, and doing a Google search for "flyback" and "Tesla" I found a schematic [aaroncake.net] for it right away. The guy mentions on that page that the transistors get really hot and he is not kidding- they do. Don't leave it running for more than a minute without a heat sink. The RF noise generated by Tesla coils is incredible so expect to generate some interference. They make lots of smelly ozone. And if you let a spark go through paper, you can start a fire so be careful.
If you're lucky you can get 20-30 kV, which throws a purple spark a couple inches. (I only got about 4 kV out of mine- the spark was about a half inch long.) Pick up a neon bulb when you're at Radio Shack- these light up if they're around. The effect on a candle flame is interesting. Don't stick your bare finger near it because the spark does hurt if it hits unprotected skin. But if you hold a metal object and use that to touch it, you don't feel a thing (it's high frequency AC). Cool tricks include having sparks jump from the coil to a metal object in your hand, having sparks jump from a metal object in your other hand to ground (even a lousy ground), and having fluorescent tubes glow softly if you hold them in your other hand. If you touch one terminal of a fluorescent to ground then it will glow brightly between that end and the place you are holding it, like there are Orcs nearby.
Re:Here's an easy Tesla coil recipe (Score:2, Informative)
Re:Here's an easy Tesla coil recipe (Score:2)
Which led me to looking for a source of FBTs, thinking that I could buy a new one and it might have a spec sheet with pinouts or that I could find some spec sheets on line. No dice. Which leads us back to my original question.
Please don't say, "Wind your own!"
Vortran out
Re:Here's an easy Tesla coil recipe (Score:2)
Darth Telsa, Sith Lord (Score:2)
..hm. (Score:5, Informative)
I'm always wary of these sites. They show all this electricity zapping round, and guys with electrofingers.
Only problem is this: Unless a tesla coil is specifically built for this purpose, the skin effect does not work on telsa coils. You actually cook your organs.
I think it's highly irresponsible to blaze things like tesla coils.
I've built one, I've used one, and had an enjoyable time, but safety must be the first priority, not pretty pictures.
For more information about the dangers of tesla coils, Here [k12.wv.us][Chip Atkinson's Safety sheets]
Never leave one in your car (Score:3, Funny)
I was awoken by a phone call from the police at 1AM with no less than 4 police cars and 3 firetrucks in my condo development. They actually were trying to shield nearby condos from an explosion with the firetrucks. The bomb squad was being dispached.
I had to leave my condo in only my boxer shorts and give an oral report on how a Tesla coil works.
I cover it with a blanket now when I move it.
Powerlabs (Score:2)
BiPolar Coil... (Score:2)
Ofcourse it depends on how the Tesla Coil is feeling at that moment. It might see the dog and think "oh, i won't bother zapping it, life sucks!". On the other hand, it may have a manic episode and send out little zaps to make the dog dance! (Dance Doggie! Do the Hustle!)
Nah (Score:2)
An interesting picture of Tesla, under active coil (Score:3, Interesting)
Note that for this photo to work, it had to be reexposed several times for all the lightning forks to be catptured (and he sat at the end).
Picture of Tesla under his giant active coil [pitt.edu]
The noise genereated from the coil in the photo could be heard 10 miles away.
Sure, you can audit our computers... (Score:2)
Ooops. So you don't want to enter my cube and run your narcware on my computer?
Have a nice day.
Correction (Score:3, Informative)
While there was a harmonic device which Tesla built which could indeed shake a building apart, this was not his intent with the Tesla coil.
His plan was actually distributing energy on a large scale without wires. Take a look at his Pike's Peak project [pbs.org].
Re:Correction on the concept of Tesla Coils (Score:5, Informative)
Tesla, upon inventing the oscillator, attached it to a bar of the finest steel he could get, and within a few minutes the oscillator had found (been set to?) the resonating frequency of the bar and shattered it. Tesla then attached it to a pillar that was driven into the earth at his laboratory [keep in mind that his lab, and several other New York buildings, were built on a patch of sand, IIRC] and turned it on. He took a crowbar to it when the buildings across the street started to shake.
Keep in mind this device was no bigger than a 2-liter pop bottle, if I rember correctly.
The Tesla Coil is a high-frequency, high-voltage transformer, and shares few parts or concepts with the "earthquake machine."
Re:Correction on the concept of Tesla Coils (Score:3, Funny)
If you don't get the joke, just move on.
shared concepts (Score:2)
It's just that the Telsa Coil uses electrical resonance while the earthquake machine sought to take advantage of mechanical resonance.
It has always fascinated me how similar the math is for LCR electrical circuits and spring damped oscillating masses. (I guess we could throw heat loss equations in there as well.) I dont have a strong enough math background to speculate, but I have always wondered if it is because these things are fundamentally the same or if we have just developed a generic differential equation that can be wrapped around almost any process.
Re:shared concepts (Score:2)
Re:Correction on the concept of Tesla Coils (Score:5, Interesting)
Seriously, Tesla coils really were always about arcing electricity. His original idea for Tesla coil usage was wireless transportation of electricity. Basically, if you crank the volts enough, you can arc across the atlantic ocean. At least that was the idea.
Yes, Tesla also did some studies on structural harmonics. And yes, he did the structural harmonics work long before he came up with the idea for Tesla coils, but aside from being the brainchild of the same man, the two were never linked in any other way.
Also, I must say that I more enjoyed his work on structural harmonics. Shaking bridges and collapsing condemned buildings was all well and good, but the nutball had the idea that he could crack the earth in half if he used enough dynamite and timed it correctly. Good thing he didn't have the resources to try that one out. Tesla was crazy enough try it, just to see if it would work.
Re:Correction on the concept of Tesla Coils (Score:3)
And brilliant enough that it just might have...
Re:Correction on the concept of Tesla Coils (Score:2)
Re:Correction on the concept of Tesla Coils (Score:2, Funny)
Re:Correction on the concept of Tesla Coils (Score:2)
A friend of a friend had one of these. Turns out, he didn't have it for self defense. Rather, he wanted to see if it would hurt when turned on his own skin.
His piece of advice? "Don't light a cigarette with it. It sometimes zaps your lips."
Science Fair (Score:4, Interesting)
My father found an old Popular Electronics (or something) magazine from his hobby days with some plans. We hand wound the voltage stepup coil, made condensors out of perspex plates and tinfoil, and borrowed a Ruhmkorff Induction Coil from school.
The unit was powered by a car battery and could spark about an inch and a half.
We put two bent copper rods for the spark to jump between. The spark would run up and down between these rods like old mad-scientist movies.
It felt pretty cool to put a finger in the spark and watch it jump straight through, with only a weird tingling sensation.
Aaah the electric shocks, the smell of ozone, the burns and blisters - God I miss science fairs.
Re:Science Fair (Score:2)
Believe me, Westwood games aside, I'm of the opinion that Tesla was one kickass mad scientist.
Tesla vs. Edison (Score:3)
Actualy T Edison grew up about a block from where I had lived in Port Huron MI (He hated Port Huron), the Train Station where he boarded the train to sell newspapers has been turned into a museum.
I not sure I would classify Edison as a scientist, he seemed more like an experimental engineer or even a hardware hackers than a scientist. Tesla was more of a scientist
Re:Science Fair (Score:2, Informative)
Sounds like a Jacob's ladder to me!
My science fair Jacob's ladder used a neon sign power supply with 50,000 V
Re:Science Fair (Score:3, Funny)
When I was in high school, one of the teachers had a small Jacob's ladder (basically what you just described). He would use insulated tongs to put an uncooked hot dog inbetween the rods. The spark would climb to the level of the hot dog hover there cooking the hot dog for a few seconds until the hot dog exploded in a shower of carbon and meat. It also detonated pickels. I'd hate to see what it would do to a finger.
Re:Tesla Coils suck (Score:2)
Re:Tesla Coils suck (Score:2)
The Allies do admitedly have the upper hand in the late game, but the idea is that if you just sat around and let the Allies build up like that without having an adequate defense planed, you deserve to lose anyway. In all likelyhood you already effectively lost the game earlier on, and the Allies are just toying with you by building up a huge army.
As for Yuri, the Flying Disks will slaughter Prism tanks. In sufficient numbers they'll take out rocketeers too. The Flying disks are probably the most unbalanced units in Yuri's Revenge, contested only by Boomers, which can also probably deal with Prisms on a water map. If you can take advantage of terrain then a Magnetron at the top of a cliff can grab a Prism tank before it gets in range I think. And again, by the time the Allies have built that many Prism tanks Yuri should have a Mind Control ready.
The moral of the story is if you go all defensive, the enemy will build a huge army and crush you. Of course if you don't build any defenses the enemy will do a rush with a small force and wipe you out at the begining. The best games i've ever played involved medium sized groups of 8 - 10 units, and would often be decided when a single tank survived to get inside the enemies perimeters and start reaking havoc.
Re:Tesla Coils suck (Score:2)
Re:Just pretty lightning.. not effective, here's w (Score:2, Funny)
yeah, but.. (Score:5, Funny)
Yeah, but I bet it will keep the neighbor's cat from pissing in my flowerbed.
Re:Just pretty lightning.. not effective, here's w (Score:3, Interesting)
(from Electrical Saftey Engineering 2nd Edition)
Physioligcial Reaction to Current
3-5 mA Barely Perceptible
35-50 mA Extreme Pain
50-70 mA Muscle Paralysis
500mA Heart Stoppage (books word not mine)
Besides, dialectric strength is like voltage*thickness right? So a high current would be a waste of electricity
Re:Just pretty lightning.. not effective, here's w (Score:2)
I was working on building a power supply for a vacuum tube amplifier. This one needed a 300V, 50mA supply. I stupidly got a pinky finger in there and touched the high voltage rail off the last 100uF power supply capacitor. *ZAP* It hurt like a bitch when it happened. Then my wrist was stiff. The next day my pinky finger was numb, and stayed numb of a week.
Re:Yes, but you're forgetting the air resistance (Score:4, Informative)
Re:Yes, but you're forgetting the air resistance (Score:2, Interesting)
So then, I=10,000/(R_p+c*x).
I->10,000/(c*x) for large x,
and I-> 10,000/R_p for small x.
This is neither an exponential drop off nor a constant current.
Re:Yes, but you're forgetting the air resistance (Score:2)
What I think you are thinking of is a current divider, which is two paralell resistors, in which case (H1= resistance of human, A1=resistance of air) the equation for the current in the HUMAN would be Ih=A1/(A1+H1). Nope you didnt read that wrong, the current thru you is a function of the resistance of the AIR.
Which could be quite dangerous if you offer less resistance then the air
Re:Yes, but you're forgetting the air resistance (Score:2)
Re:Just pretty lightning.. not effective, here's w (Score:2)
Hmmm, Somebody has issues...
Re:Just pretty lightning.. not effective, here's w (Score:2, Informative)
>able to shoot a beam of tesla lightning about 20
>metres.
Uh... not quite. It takes about 2,000 volts per centimeter of air that you want the current to flow through. I have a 15,000 volt transformer and it can create arcs around 3 inches or 7 1/2 centimeters. To get 20 meters you'd need about 4 million volts. (20m * 2000 V/cm = 4E6 V)
Re:Just pretty lightning.. not effective, here's w (Score:5, Informative)
While these Tesla coils are probably harmless, to do damage to a human you need not 100 amps, but less than
Furthermore, let us say that you want to put 100 amps into something from 20 meters. First of all, 10,000 volts isn't anywhere close (you calculations are way off - in fact, they are sheer nonsense!) A few megavolts at a minimum would be required.
But... as far as power delivered to the load... the resistance of the air is uninteresting. Once the arc starts, the resistance drops dramatically in the plasma. Thus one could deliver 100 amps at 20 meters with a lot less power than you calculate.
The statement that electricity naturally flows to the nearest earth is likewise fallacious. Electricity flows (or tries to flow) across potential differences. If you hook one end of a potential difference to the earth, electricity from the other end will certainly try to flow there. But if the Tesla coil is insulated from the earth, the electricity will have no particular interest in flowing to the earth!
All in all... very cleverly stated nonsense.
Naughty of you (or ignorant of you).
Re:Just pretty lightning.. not effective, here's w (Score:2, Informative)
Yes, as is the assertion that electricity somehow âoechooses a path of least resistance.â This is also an example of the anthropomorphic fallacy â" attributing human-like qualities to something inanimate.
In an electrical circuit, given an electric potental (i.e., a voltage), current will flow through all available paths. The magnitude of the current in each branch is inversely proportional to the resistance (or impedance if we consider more than simple DC) so it can often seem as if somehow those lazy electrons survey their options and decide to take the easiest path.
The problem in understanding usually is emphasized when you deal with paths of conduction through air or other materials that are normally insulators. The issue here is that the breakdown voltage of air and most nonconductors is very large. Unless the electric field strength exceeds this threshold then the material is an insulatore. In these cases there are no alternate paths, except for the unwitting human who happens to come too close, and gets a shock. So it's no so much that his body formed the path of least resistance; more like he formed a path period where before there were none.
Re:Just pretty lightning.. not effective, here's w (Score:2)
There are ways to help equalize them... for example, put a large resistor in parallel with each gap (same value on each one). This would help to equalize the voltage across them before they flash over - assuming the rise time of the pulse isn't too fast (a *dangerous* assumption).
Re:Not a heart stopper, but may burn badly (Score:2)
BTW... RF burns are wierd. I once got my finger too close to the output of a mere 75 watt transmitter at a point where the impedance was very high (antenna mismatch), and a small arc burned a tiny spot on my finger - all the way to the bone (a little cylinder of burned flesh eventually fell out)! Ouch! This was at 7 MHZ.
Re:Build Your Own Tesla Coil (Score:3, Funny)
Re:We have the death ray!! (Score:2)
If you keep the freq high say in the 30K - 100KHz range, most of the current would skin effect around your body increasing the saftey factor and just burn skin rather than stop your heart.
in actual practice you'll probably only get about 125,000 volts. get out your physics book and crunch the numbers.
It's probably safe to play arround with an ignition coil, I've seen schmatics for real tesla coils in magazines, Popular Electronics I think late 70's.