Building-a-Tesla-Coil

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For my grade 12 communications project, I chose to explain,build and demonstrate a Tesla Coil. This Web page is part ofthat project. It contains almost every aspect of the project,including a video of the actual coil demonstration.

Tesla Coil file:///C:/Users/HP-home/Documents/BACKUPS_USB_2009-FEB/SCIENCE/ELECTRONICS/b...

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The project contains a proposal, several optional activities thatgo along with the main project, a presentation and this Web

page. Below is the first part of the project; the proposal.

Proposal

Proposal For Tesla Coil Project

After brainstorming, I have decided that my majorproject is to be a Tesla Coil.

What A Tesla Coil Is

A Tesla Coil (often shortened to "TC") is a highfrequency, resonant step up transformer. The coil isdriven by a lower-high voltage and a spark gapresonator. Since the coil is so perfectly tuned, a fairly

small turns ratio (around 1:100) can cause a largeincrease in voltage. The coil I plan to build will be


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able to produce about 250KV (250,000V) at afrequency of about 500KHz. At this frequency, the

voltage is almost completely safe, and much fun toplay around with.

The Project

The project involves a fairly large amount of work inelectronics and mechanical construction. There are afew problems associated with this activity though.

First, there is always a danger when high voltage isinvolved. Although the coils output poses no realproblem, it is the primary circuit (sometimes calledthe "tank circuit") that carries dangerous (but much

lower) voltages that come right from mains. Theproblem is easily solved by just enclosing that circuit.The other problem is one of materials. The coil usessome rather exotic (read: expensive) parts. One ofthose is the wire. The secondary requires about 800'


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if 28 AWG wire to be wound onto a round form. Thisamount is about $45 on the roll. This is not that big of

a thing when compared with the transformer. To drivethe high voltage section, a lower, but still consideredhigh voltage neon sign transformer is used. Thereseems to be an odd shortage of used neon sign

transformers in London, and new ones go for about$150. I don't even want to go into how hard it will beto find a 0.005uF 10KV capacitor. These part related

problems are easy enough to solve. Information

Unlimited offers a TC kit for a very good price, whichis what I am going to use. The only other realproblem is the high frequency high voltage disrupting

computers and such. Because of this, I will be unableto use my digital camera to take pictures of the coilsoperation because it simply won't work. Theseproblems should are easy to solve by just not

operating the coil around computers, and using anold fashioned camera and then scanning the pictures


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afterwards.

Support Activities

There could be many support activities for thisproject. Below is a small sampling:

History On TeslaSolid State Tesla Coil DemonstrationsBuilding Of An Output Terminal Or Triode To

Increase OutputTesla Coil Video (With RealVideo Or Vivo)Pictures (Digital, Of Course)Effects Of High Voltage

Study On Much Larger Coils

Four Optionals

1. Solid State Tesla Coils:


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Solid State TCs are almost the same as atraditional TC, except that instead of a spark

gap oscillator, they use transistors orMOSFETS. This allows them to run on muchless power and be built much smaller then aregular TC.

This activity will involve an explanation anddemonstration of how a solid state TC works (Ialready have one built).

2. Building Output Terminal Or Triode:An output terminal/triode allows a regular TeslaCoil to output a much higher voltage by

accumulating electrons. It also provides auniform and smooth surface from with to drawarcs.

The terminal/triode will most likely be made


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from metal automotive tubing (in the case of atriode) or Styrofoam ball coated with tinfoil (in

the case of a regular terminal). It then getsmounted on the top of the secondary.

3. Video:

Of course, the video will have to be made afterthe actual coil. It will include video footage ofthe assembly, tuning and operation of the coil.There will also be some video showing really

neat arcs and the affects of high voltage onpeople (glowing eyes and such).

4. Tesla Coils In Use Today:

This optional will look at the use of TCs or theirmodern equivalent in electronics and industrytoday. There will be a section on some of themore modern devices like TVs, monitors, etc.

Tesla Coil file:///C:/Users/HP home/Documents/BACKUPS_USB_2009 FEB/SCIENCE/ELECTRONICS/b...

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Building Report

After I wrote the proposal, I began building the coil. The wholeconstruction took about two and a half weeks. The constructionprocess is described below.

This is the first step inthe construction. Themounting brackets for

the primary areinstalled in the coverof the case. Theprimary brackets are

made of plastic andsecured with plasticties. The primarywinding slips through

holes in the brackets.

Tesla Coil file:///C:/Users/HP home/Documents/BACKUPS_USB_2009 FEB/SCIENCE/ELECTRONICS/b...

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Next I would theprimary windings.There are actually twoparts to the primary; anon-insulated sectionand an insulatedsection. The insulatedsection makes upmost of the winding.

The non-insulatedsection is there forattaching theadjustible tap lead.

The end cap tosupport the secondarywas also installed atthis point. Electrical

connections for the

_ _

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two grounds neededin this part of thecircuit were thenmade.

I then assembled thecase and installed thecapacitor, spark gapand transformer. Note

that no electricalconnections betweenthese componentshave been made yet.

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The spark gapobservation windowswere installed next.Notice the black tapeholding it on. This wasremoved once theepoxy dried. On theback window, there isa small threaded hole

into which a plasticscrew in installed. Thisscrew serves to adjustthe distance between

the spark gapelectrodes.

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After the observationwindow, I installed the

RF choke. Thisprotects thetransformer secondaryfrom nasty RFgenerated by the restof the coil. Note thatnothing has yet been

wired.

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I then wired the circuitand installed the

switch, power cord,neon power on lampand attached the topto the base. The topmakes a groundconnection to the baseby a section of wire

that is brought intocontact with the baseonce the top isscrewed down.

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After that, all I did tocomplete the coil was

to attach thesecondary, outputterminal and place thehigh voltage warningstickers. Note thedoorknob used as atemporary output

terminal. Once the coilwas completed, Ibrought it home andtuned it.

Solid State Tesla Coils

After building the actual coil, there were 4 optional activities thatneeded to be completed. The first of these optionals was a small

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writing on Solid State Tesla Coils. This activity is presented here.

Solid State Tesla Coils

This activity will examine the area of Tesla Coilsknown as "Solid State Tesla Coils". These coils are

used in many places in which high voltage isrequired, such as TVs, gas discharge LASERs, etc.This activity will also look at how they aresimilar/different to "traditional" Tesla Coils.

The first thing about Solid State Tesla Coils is thatthey are not truly Tesla Coils. In fact, Solid StateTesla Coil is sort of an oxymoron, as in order to be a

true Tesla Coil, the machine needs a spark gap. Thisspark gap is obviously not solid state. That aside,there are a few similarities and differences thatshould be pointed out.

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Solid State Tesla Coils are similar in the respect thatthey use the same basic principle of operation; a high

frequency resonant transformer. Because the primaryand secondary are so perfectly tuned, there is a hugeincrease in voltage. For example, my favourite SolidState Tesla Coil schematic, located at

http://www.aaroncake.net/circuits/hvgen.htm cangenerate over 30,000 volts of high frequency AC froma very low 12VDC.

This is basically where the difference ends though.Perhaps the most major difference is in how thetransformer is constructed and driven. As the nameimplies, Solid State Tesla Coils are not air core

transformers. Instead, they are usually wound on aferrite form, much like a regular transformer (execptthat regular transformers are usually wound on aniron core). This is how TV flyback transformers aremade.

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The other way they differ is how they are driven.Instead of a spark gap, Solid State Tesla Coils use

transistors or MOSFETs. Below are a few examples ofthe different configurations used. Bear in mind thatthere are others. This is just a general simplification.

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Notice the use of all solid state components.Compare that to the traditional spark gap coil below.

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The traditional coil uses a capacitor/spark gapcombination to get the high frequency necessary for

operation. Also, notice that an air core transformerwith an adjustable primary is employed. This is moreor less a standard schematic. The coil I built (andmany others) use a choke between the

capacitor/spark gap and secondary of the

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transformer. This serves to protect the transformerfrom dangerous RF.

So as you can see, traditional Tesla Coils and SolidState Tesla Coils have a few similarities and manydifferences. These differences are so great that Solid

State Tesla Coils are not really Tesla Coils, but merelyhigh frequency transformers.

Learning Log

Exercised knowledge of Tesla Coils andtransformers. This knowledge will be usedwhen I design and build my big Tesla Coil this

summerFinally learned how to draw the symbol of aMOSFET properlyPracticed writing skills

Learned the various ways Solid State Tesla

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Coils are driven

Output Terminal

After I completed the section on Solid State Tesla Coils, I choseto build an output terminal for the coil. This termainal replaces

the temporary terminal (a doorknob) the coil was built with.

Output Terminal

Proposal

An output terminal is a necessary part of a Tesla Coil.Coils built without an output terminal of some kind

often have poor performance and just generally lookbad. This being the case, my coil also requires anoutput terminal. The terminal I plan to build willreplace the temporary door knob terminal that is onthe coil now. It will either be a triode or just a regular

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round terminal.

Technical Report

The terminal I have decided on will be a regularround terminal. I chose this because the materials

are much easier to get and much less expensive thanthose of the triodial terminal.

This terminal is made of two stainless steel salad

bowls fastened together. Originally I planned tosolder them, but that proved impossible due to thestainless steel used. That was not much of a problembecause the school has a fair amount of welding

equipment. I tried to weld it, but because the bowlsdid not form a perfect seal, that also didn't work. Ifinally ended up just taking it to a welding shop andhaving them do it. A bolt on the bottom attaches it to

the top of the secondary coil. A picture of the finished

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terminal is below.

Learning Log

Learned how output terminals benefit TeslaCoilsFigured out that stainless steel cannot besolderedLearned about the different types of welding

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The video recorded without any problems, aside fromsome background noise from the wood shop class

next door. The real problems began when I went tocapture and edit the video. First off, I had to waitabout two weeks for Adobe Premiere to come in. Afterthat was settled, it took a whole period to install the

thing. After installing it, I found that I had to use theATI capture card's software to do the actual capturebefore the editing could begin. The video capturedfine, but the audio did not. It took two periods to

figure out that I needed to use the sound card to getthe audio instead of the capture card. This is strangebecause that card has stereo audio inputs. After thevideo was captured, I needed to edit it. Adobe

Premiere has got to have the worst interface I haveever seen. They completely ignored the standardswhen they programmed it. It took a week to figure outhow to edit. After it was finally edited, there were afew problems saving the finished video, but those

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were easily cleared up by changing compressionschemes.

I used The Vivo Active Producer to compress thevideo for transmission over the Net. This had a fewproblems, but those were solved by using a copy of

the Producer from my hard drive instead of the one Idownloaded at school. After 20 minutes ofcompressing, I FTPed the resulting 1.24 meg file tomyself. The video is about 12 minutes long and can

be viewed with the Vivo Active Video Playerplugin.

View The Video

Learning Log

Practiced presentation skillsLearned how to use Adobe Premiere (importing,

editing, saving, compressing)

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Got practice in selecting the right compressionformat for the right job

Tesla Coils In Use Today

The last optional I did was a little paper explaining the practical

(and sometimes not-so-practicle) use of Tesla Coils today. Thisincluded the use of traditional spark gap type coils as well assolid state coils.

Tesla Coils In Use Today

Even though the Tesla Coil is an old invention, thereare still many uses for the devices today. This

optional will take a look at some of those uses and tryto peer into the future to uncover other potentialuses.

The traditional coil has been delegated to mostly

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demonstration purposes these days, as what used torequire large amounts of wire, power, a spark gap

and other large components can new be done withsmaller solid state components. Small coils like theone I built are usually found in schools, museums,magic shows, etc. Of course, they are an easy way to

get a high voltage for home expirementing. Eventhough the high voltage can be gotten moreeffectively with solid state components, thesecomponents are usually way out of the budget of the

average expriementer. Traditional coils can literally belashed together with parts available at everyhardware store. Movies also use small coils like mineas well as larger coils for special effects. Take a look

at the time travel scenes in Terminator and Terminator2 to see what I mean. The sparks you see are from alarge Tesla Coil.

As for solid state coils, they are is very widespread

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use. Every TV, Computer monitor and most otherthings that use a cathode ray tube use what is

generally referred to as a solid state Tesla Coil. Ofcourse, from reading my optional on Solid State TeslaCoils, you know that they are not actually true TeslaCoils. Even so, they are referred to as such. So

called Solid State Tesla Coils are easy to produce insmall modules. Even though modern TVs and likeequipment have shyed away from modules, thesehigh voltage modules can still be found in older TVs.

They are also a great expirementer's item. Solid StateTesla Coils are usually used when a high voltage isrequired for other devices because of their small size.The cousin of the Solid State Tesla Coil, the flyback

transformer, is used in computer power supplies andother switching suplies. However, this is used to stepdown a higher voltage instead of increase a smallvoltage.

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There will most likely be a surge in usage of at leatthe solid state variety of Tesla Coils in the next 10 to

15 years. The reason for this would be the increaseduse of particle accelerators as we try to learn to useantimatter (a particle accellerator is a good way tomake antimatter). One of the cooler uses would be in

the so called ion motor. This is a motor that ispowered by the force of ions expelled from some kindof orafice.This type of drive promisses to enablespace craft to attain near light speed. As for other

uses, they are only limited to the imagination. We willjust have to wait and see what the future turns up.

Learning Log

Learned some uses of solid state and traditionalTesla CoilsFound out about ion motors and some other

cool future engines

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Learned about special Tesla related effects in



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Learned about special Tesla related effects inmovies

Practiced research and writing skills

And so ends this project. If you haven't already, you can View

The Video of the demonstration. Note that you will need the

Vivo Active Video Playerin order to see the video.

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