Tabletop Tesla Coil

Step 1: The frame

The frame of the tabletop Tesla is made entirely of half-inch (12.7 mm) PVC pipe. There's no point giving you exact dimensions of the stringers and risers because they depend on how big your secondary coil is. You can scale the frame up or down as you wish. I used a 12 inch long cardboard tube for mine, making the footprint of my coil 14 inches by 11.25 inches.

Study the pictures and you will see how the frame is made. The configuration as made requires the following joints:

(4) 90 degree elbows;
(8) "T" joints
(2) end caps

All the rest is straight half-inch tubing, cut to length. NO CEMENT WAS USED TO JOIN THE PARTS and none should be used. The friction fit of the tubing is reasonably strong, and leaving the joints unglued allows you to take the frame apart to work on the coil, make adjustments or repairs, etc.

The center uprights consist of three T joints each, stacked vertically. Short lengths of tubing connect these. If you make a bigger coil these length will have to be adjusted accordingly.

The cross piece that runs underneath and parallel to the secondary coil has to be drilled for the primary supports. Find the center point of the cross piece and drill two holes so that the primary form in centered on the secondary. Again, I can't tell you exactly where, because it depends on what you use for your coil forms. But center it and it will be fine. See the page on the Primary for more details of the mounting method.

The secondary is supported by plumbing caps and tubing adapters inserted into the cardboard tube. The tube I used is 1.75 inches in diameter (it's a thick-walled cardboard paper towel tube). I had to experiment at the home center to find off the shelf PVC plumbing pieces that would fit, but I found ones that slip in closely. Again, no glue was used. You want to be able to remove the secondary for maintenance or replacement.

In the two topmost T joints insert plugs to support the brass terminal posts. These can be anything non-conductive--cork, rubber, etc. I found wine corks fit nicely. Push them down equally on each side until they are level with the top edge of the secondary form. Above them fit a length of PVC tubing. Exact height is not too important; they should be tall enough to keep the terminals away from the active coils to avoid arcing. Mine are four inches tall each.

Drill 3/16ths holes in the center of two PVC pipe caps for the terminals. Drill small holes--about 1/8th inch--in the support tubes opposite the ends of the secondary coil to feed the secondary's wires through. See the step about the Terminals for final connections.

Comments

[iungerich1]

hello i am thinking about doing this project but i have a few questions
first i am thinking about buying this transformer http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=271193170693&fromMakeTrack=true&ssPageName=VIP:watchlink:top:en
at 12 kv and 30 ma i think it will work now all i really care about is the large hi voltage spark so can i just have one of the terminals attached with wire to a large stick i will hold and short out the other terminal? i guss what i am asking is the voltage high enough to get any sparks and if so how big do you thunk i can get them?

[Mr. Apol]

That transformer will undoubtedly power a Tesla coil and draw arcs as well. Please be very careful!.

Paul

[iungerich1]

sorry thunk was supposed to be think lol

[smehta6]

would this work:: http://www.ebay.com/itm/Neon-Transformer-Tesla-Coil-Jacobs-Ladder-6000v-60-ma-science-project-idea-/281046283060?pt=BI_Circuit_Breakers_Transformers&hash=item416fa9f334

[Mr. Apol]

No, it will not work. Look at the label; it says there is secondary ground fault protection. That will prevent a spark gap working.

PBT

[Mr. Apol]

Yes, it would work fine.

PBT

[smehta6]

http://www.ebay.ca/itm/Neon-Sign-Transformer-UL-Power-Supply-/160954403253?pt=BI_Circuit_Breakers_Transformers&hash=item2579a149b5&_uhb=1#ht_638wt_1271 will this work

[smehta6]

what is the most cheapsed power supplies because i am using this for a project and i need only for a little bit?

[Mr. Apol]

That's hard to say, because it all depends on what you can find. The simplest and most suitable power supply would be a neon sign transformer (without Ground Fault Interrupt circuitry), although other possible sources include oil burner transformers, induction coils, car ignition coils, etc.

[smehta6]

do you connect the one of the secondary coil wire to the terminal or both?

[Mr. Apol]

One end of the secondary coil is connected to an earth ground, and the other end connects to the top terminal (metal sphere, toroid, or whatever). In some cases the bottom end of the secondary can be connected to the bottom end of the primary, creating an autotransformer, or Oudin coil configuration.

[smehta6]

and will the The Capacitors work and thx for the reply

[Mr. Apol]

They will, but you have to adjust the capacitance to fit your coil. Other caps will work as well, and may be easier to find and cheaper.

[smehta6]

nice work
would http://www.instructables.com/id/How-to-build-a-Tesla-Coil/?ALLSTEPS spark gap work on this teasla coil? please answer?

[Mr. Apol]

A simple two piece spark will work, yes. It isn't very efficient though, as it overheats quickly, which cuts down on coil output. Multiple spark gaps are better, and pressurized spark gaps are better still.

PBT

[al 01]

nice work,
Can it be reduced in size?

[Mr. Apol]

Sure, to a point. You will have to adjust your components for a change in resonance that will occur if you change the size of your coil. (The coil in this Instructable isn't very big to start with, BTW).

PBT

[CaptainMunz]

Would it work if I used the frame and coils with the power source being this AA powered circuit?

http://www.instructables.com/id/AA-Battery-Powered-Tesla-Coil/

[Mr. Apol]

I don't think you'll get enough power out of two AA batteries to power a Tesla coil for more than a few seconds--at the very most. The device described is just a TV flyback transformer (whose output is DC). If you ran the flyback off house current, you would get somewhere, but two AAs just aren't potent enough.

PBT

[disappearingshadow]

http://www.ebay.ca/itm/LOW-GLOW-NEON-9500-VOLT-TRANSFORMER-FITS-LOWGLOW-AND-MANY-OTHER-NEON-BRANDS-/380430895286?pt=Motors_Car_Truck_Parts_Accessories&hash=item589372c8b6
I was thinking of getting this one. Do you think it would work with this project?

[Mr. Apol]

It will definitely not work. These Low-glow modules are solid state power supplies with Ground Fault Interrupt protection. This means they will not power a spark gap at all. Do not use these for Tesla coil power supplies.

Paul

[disappearingshadow]

Okay thanks :D how about this one?
http://www.ebay.ca/itm/New-10kv-30mA-Neon-Power-Supply-Neon-Transformer-UL-Series-A410EL-/150798592048?pt=LH_DefaultDomain_0&hash=item231c4be830

[Mr. Apol]

Nope. See the mention in the description that it has "open circuit protection?" That's GFI.

You need something like this: http://www.ebay.com/itm/NEON-TRANSFORMER-7-500-VOLTS-For-Neon-Signs-Jacobs-Ladder-or-Tesla-Coil-/330719105373?pt=BI_Circuit_Breakers_Transformers&hash=item4d0065115d#ht_507wt_934


Paul

[disappearingshadow]

I am having a lot of trouble trying to find one in Canada. I don't supposed you know any good sites.

[Mr. Apol]

Try the phone directory for Sign Shops, Neon Signs, etc. A lot of shops are changing over to solid state GFI transformers and getting rid of the old fashioned iron-brick type of transformer. You may be able to buy one from them. They might even give them away, just to get rid of them. You can also try oil burner ignition transformers (OBITs, they're called). Avoid GFI units again. You can also build power supplies based on automobile ignition coils.

Good luck. Try in person where you live, or any nearby city.

Paul

[disappearingshadow]

I went to a neon sigh place and they gave me Ann allanson power pak it has 35 ma 7200v complies with secondary ground fault protection requirements please tell me it works

[Mr. Apol]

Does it look like this?

http://www.google.com/products/catalog?q=Allanson+power+pak&um=1&ie=UTF-8&tbm=shop&cid=9228341418964618920&sa=X&ei=3c2XT7LeHaX02QWH3sGIBw&ved=0CEQQ8wIwAg

If so, it won't work. It has GFI protection.

Here's a simple rule of thumb about NSTs. If it's big and heavy, it will probably work in a Tesla coil. If it's small and light, it's solid state and has GFI.

Here's a listing on eBay Canada for a non GFI unit:

http://www.ebay.ca/itm/15-000-Volt-Allanson-Neon-Sign-Transformer-Lighting-Unit-Non-GFI-Tesla-Coil-/120900954333?pt=BI_Circuit_Breakers_Transformers&hash=item1c264228dd#ht_500wt_950

and

http://www.ebay.ca/itm/neon-sign-transformer-9-000-volts-france-ground-fault-/300699999724?pt=BI_Circuit_Breakers_Transformers&hash=item46031dddec#ht_500wt_950

more are listed if you search for "neon transformer."

Paul

[The MadScientist]

What's the current output of your transformer?

[Mr. Apol]

30 mA at 7,500 volts. That's the transformer I use most often. The coil works fine with any common NST.

Paul

[The MadScientist]

Cheers

[somebody12345]

I have the exact same cardboard tube.

[teslacoilguitaramp,helpmeplz]

sorry to burst you bubble, but i think that is a fancy spark gap not a Tesla coil. but with that design should get some nice arcs.

[Mr. Apol]

This is a Tesla coil with a horizontal secondary and bipolar terminals. Commonly Tesla coils are made upright, but the horizontal style is indeed a Tesla coil also.

PBT

[teslacoilguitaramp,helpmeplz]

i wanted to know how you connected the capacitors? wich is how i found this, i need some capacitors, and i want to play it safe and make 2 or three large ones that could hndle the output almost alone but for safety and emergency measures..

[Mr. Apol]

For a basic Tesla coil circuit diagram, see:

http://home.gallatinriver.net/mhammer/coil.htm

This is the circuit I use, though I don't use a safety gap in such a small coil.


Paul

[jimmydean123]

i have everything wired up correctly, but my tesla still won't work. The spark gap won't spark, and we know it isn't the transformer because it had enough power to burn out my multimeter. Any suggestions?

[Mr. Apol]

I need more information.

What is your capacitor? Have you tested it for correct function?

How wide is your spark gap? A too wide gap will prevent the coil from working.

How is your secondary wound? How big is it? What gauge of wire?

How is your primary wound? What gauge? How many turns? Is it wound the same way as the secondary, or in the opposite direction? Opposite winding will keep the coil from working properly.

How big is your transformer (how many volts, how many amps)? What kind is it? If it is a modern sign transformer it will have Ground Fault Interrupt (GFI), which prevents it from working in a spark gap circuit. This, I suspect, may be your problem.

Paul

[jimmydean123]

My capacitor is made up of 8 peroxide bottles with a monster can inside each. I have not tested it but i can hear it when i turn it on.
My spark gap is set up so each knob is extremely close to touching but is not touching.
My secondary is 24 gauge magnet wire gauge wire with approximately 443 windings.
My primary is 12 gauge wire with 5 windings. I think it might be in the opposite direction.
My transformer is a Pro Series Low Glow neon sign transformer. The input is 12-15VDC at 5 amps (max.). The output is 9500V; the output amperage is 30 mA. It also has an 8 amp fuse.

[Mr. Apol]

I believe your transformer has GFI. It will not power a Tesla coil because the GFI prevents the spark gap from firing. You need an old fashioned neon sign transformer or an oil burner ignition transformer.

Paul

[jimmydean123]

thanks for the advice but i guess i'm gonna have to buy a new (or old i guess) transformer anyway becausewhile trying to override the GFI i shorted out the transformer any suggestions on a low cost transformer that would fit the bill

[Mr. Apol]

Try eBay. I got all the transformers I own off eBay for not much money. They are heavy though, and can be pricey to ship.

Try a local sign shop. A lot of businesses are switching from old style neon transformers to the transistorized type with GFI. Go to a shop that sells or services neon signs and ask if they have any old type transformers. They may just give you one to get rid of it.

Try a heating contractor and ask if they have any oil burner ignition transformers. Specify you want one without GFI!

Good luck!

Paul

[bigrob121]

Where did you get the spherical top load in the "Table Top Tesla Coil Test" Video? Big props on your bipolar TC instructable.

[Mr. Apol]

The flattened brass sphere is the decorative ball from a chandelier. I just found it, but you can get them from lighting fixture companies in various sizes. Do a search for "Brass lamp parts" or some such and you'll find quite a few.

http://www.mylampparts.com/Departments/BALLS/BRASS-BALLS/2---PIECE-BRASS-BALL.aspx

for example

Paul

[Crtek]

can i use a CRT monitor instead of this?

[Mr. Apol]

You can use a flyback transformer, found in a CRT. I have no experience using the whole CRT itself, but I'll bet you can find someone who has, somewhere on the Net.

[punkzter]

Do you have any insight for using/taking apart the CRT to get the flyback?

Also, does the spark gap need to be as complicated as yours? I have seen some that are just two screws. Thanks!

[Mr. Apol]

If you open up an old CRT or TV, make sure the capacitors are discharged. Some of them can hold a serious jolt. The flyback transformer is usually off in one corner of the chassis. You can find it by tracing the high voltage cable back from the picture tube to the flyback. The HV cable usually has a suction cup type end on the CRT itself.

See

http://www.instructables.com/id/How-to-find-the-primary-and-the-secondary-coils-of/

for a description of finding the primary and secondary coils on a flyback. This Instructable also has pictures of a flyback, so you can recognized one when you see it.

You can make a simple two part spark gap, sure. It will work, but it will overheat quickly, reducing the output of your coil. Blowing the gap with air helps. The best static spark gap I know is the "hyperbaric" gap described here:

http://www.stephenhobley.com/blog/2008/09/10/petes-quick-hyperbaric-spark-gap-tm/

It's easy to build and works great, with or without an air source to quench the spark.

Good luck,

Paul

[punkzter]

So I wouldn't have to hook it up to a vacuum cleaner for it to work?

[Mr. Apol]

No, the hyperbaric gap works with or without a vacuum attached--but it is many times more powerful if you do use an air source. The difference is very marked.

Paul

[octavian234]

If you dont have enough leyden jars will your tesla coil not arc?

[Mr. Apol]

Too little capacitance will result in smaller discharges from the Tesla coil's top load. (Too much capacitance has the same effect). If you get too far from the coil's natural resonance, the result will be virtually no visible discharge at all. That's why it is useful to use a design program like TeslaMap to determine what capacitance you will need. Paul

[octavian234]

Ok. Thank you. I got my diagram from a different instructable but his directions were hard to follow. I'm going to use your capacitor idea and Coil idea.

[rodsy]

 im sry i dont relly get science dat well so im askin , why do u need a capacitor?

[xio]

and i would like to say this in the nicest way possible, but i think that you should'nt start things on this big of a scale if you don't fully understand what a Tesla coil is.

[xio]

it generates power for the tesla coil. (giant battery)

[wii552]

no not at all. A capacitor stores energy, not makes it. All that the caps do is make the pulses of electricity for the coil.

[jimmydean123]

it's like a baterey but it dosnt generaste power it stores it until thgat charge is big enough for it to discharge it

[nutsandbolts_64]

DCKV?!?! I don't need that much!?! It's just surprising how much power you put in there. How do you charge the capacitors? Do you use the NST there to charge 'em or what?

[Mr. Apol]

The voltage rating is just an estimate of how much the capacitors can stand before they break down or arc over. Because of the fast switching, it is usually thought that capacitors need to be at least rated for double their DC voltage to handle it; so if you're using a 7,500 volt NST, then caps rated for 15,000 VDC would be adequate. But more is better. PBT

[bombmaker2]

Any high voltage power supply around 8kv will work right?

[Mr. Apol]

Or less--you can make a Tesla coil work at voltages as low as 3,000 if you have the amps behind it. All it has to do is fire the spark gap, and you can get the Tesla effect. Of course it is easier if you up the voltage to the common range of neon sign transformers or oil ignition transformers, which usually run 7,500 to 15,000 volts. Paul

[bombmaker2]

Okay thanks. As soon as I build a power suplly I shall build me a tesla coil.

[onyxslayer]

about how much did this cost could you give me a list of all the material along with the sizes(i like your sizes) please and thank you

[Mr. Apol]

The list of materials is included in the text.

Some of the parts are recycled and hence were free, but the coil alone represents about $15. The spark gap cost about the same, and the homemade Leyden jars (almost all recycled material) only $1 or so for the aluminum tape used. Connecting wire was scrounged from old microwave ovens ($0). Total investment, under $35.

Paul

[onyxslayer]

thanks like alot but can you include even the recylced materials

[onyxslayer]

where can you get microwave wire other then the microwave or will something else work please explain?!? and thanks for all this help
 

[Mr. Apol]

Any high voltage wiring will do. Microwave oven wire rated at 20,000 volts is great for small coils like this. Do a search for "high voltage wiring" and see what turns up. You can also improve the insulation on more common wire by slipping it into vinyl tubing (like aquarium tubing).

Paul

[Mr. Apol]

14 aluminum soda cans, 40 cents each when full
14 powdered lemonade canisters, $1.98 each when full
1 cardboard roll, ?
1/2 can polyurethane varnish bought new in 2001, $6 for the full can
20KV wire from 5-6 microwave ovens, free
600 volt wire from microwave ovens, free
wax, melted from old scrap candle stubs, ?

These were just odds and ends around the house, you see, except for the microwave items, which I got by joining my local area freecycle.com.

Paul
 

[ANDY!]

i made one by taking a thing out of a air purifier and putting electricity into it.

[Evilthingamabober]

I have an old 7.5kv negetive ion generator transformer that isn't current limited. How can I make a ballast for it?

[Mr. Apol]

I am not quite sure what you mean. You have a 7.5 kV ion generator, or a transformer that powers an ion generator?

Paul

[Evilthingamabober]

It's a 7.5 ion generator, here's a pic. The needle array was cut off.

[Mr. Apol]

Others feel free to weigh in, but I have a couple of these ion generators, and they put out DC at low amperage. They are not strong enough to power a Tesla coil. They can power a simple Marx generator, charge Leyden jars, etc., but they don't have the power to make the spark gap of a Tesla coil fire. DC requires some kind of pulse generator to work with a Tesla coil also.

Paul

[chriskarr]

While you're correct about the ion generator being insufficient for a Tesla coil, you aren't completely correct about one thing.

In a DC Tesla coil, you don't need to have a pulsed supply but, rather, a constant-current supply and an inductor. The inductor stores the DC energy in its core and windings in the form of magnetic flux and allows the current (after it's charged) to pass through and into the capacitor. Once the capacitor is charged to a sufficient voltage to fire the spark gap, it will do so, at which point the potential in the transformer drops to near-zero and the magnetic flux experiences reversals. Since the gap is still conducting at this point, your core's magnetic flux 'dumps' its charge into the spark gap, as well, increasing your voltage to near two times the supply voltage. This does, however, require a rotary spark gap to occur.

[Dr.Bill]

Do you produce any RF energy and if so how much of the RF band does it transmit on ?

[Mr. Apol]

The coil undoubtedly produces RF output. I put chokes on the high voltage lines to reduce/quell it. I haven't experienced any interference effects from this small coil.

I have no way to measure the frequency of the output, but TeslaMap estimates the resonant frequency as 1,718.13 KHz.

Paul

[Dr.Bill]

Sounds like the top end of the AM band.
Do you think there is an way to TUNE the output?

[Mr. Apol]

You can tune a Tesla coil roughly by varying the number of turns in the secondary. You can also use a collapsible antenna for a top load instead of a sphere or toroid; this allows a degree of tuning too.

See http://www.coe.ufrj.br/~acmq/tesla/tefp.html for example.

Paul

[Dr.Bill]

I like the magnetic quench !

[muliandi]

I have several questions:
1. Does more secondary coil give better results?
2. Can I change the Leyden Jar with 2 15kV capacitors in parallel?
3. How much maximum amperes this coil can handle???
Thank you.

[Mr. Apol]

1. Yes and no. A bigger secondary is needed to put out greater arcs, but only if it is properly sized to its primary, capacitors, and spark gap. Simply enlarging the secondary coil does not guarantee bigger sparks.

2. Certainly you can charge Leyden jars with two 15kV transformers (I assume you meant transformers, not capacitors). If you're using Leyden jars, watch out for corona losses, internal arcing, and other signs of electrical stress.

3. The tabletop coil in this Instructable is small. It handles the 30 mA amp neon sign transformer easily. Would it handle 60 mA? Probably. The wire gauges are sufficient. I would mostly worry about the capacitors. If you're using commercial caps in a MMC, check your amp rating. If you're using Leyden jars, it might be better to use liquid-filled glass jars (beer or wine bottle capacitors such as these: http://myweb.cableone.net/grcarhunter/bottle.htm ) I have not tested my soda can  design above 30 mA.

Paul

[kevinstuartfr0st]

good post thanks for your time

[Mr. Apol]

Glad you liked it. Let us know if you build a coil yourself. Paul

[klod17]

Cool!

[becauseican]

could if i properly insulated the wire could i use wood for the frame.

[Mr. Apol]

You can use wood, sure. Give it several coats of shellac or polyurethane as insulation. Try to keep the current away from the wood--use plastic, glass, or ceramic parts to isolate the wiring from the wood. Paul

[becauseican]

thnx, ive been thinkin of making a tini tesla coil but dont have enough money for pvc,

[Mr. Apol]

Well, good luck. PVC is pretty cheap. Where I am you can get an eight foot length of half inch pipe for $1.98. T and elbow joints are about 27 cents apiece. Paul

[becauseican]

o it is much more expensive where i ive.

[saeed_myheart]

(removed by author or community request)

[Mr. Apol]

If you have questions, post them here.

[Foxtrot70]

I built a vertical Tesla when I was in high school, many moon ago. It was about 4' tall and had 1/5 mile of 26 ga. wire for the secondary, the primary was 100' of ignition solid core wire. Impressive was the capacitor, 18"x18" plate glass with 14"x14" plates. Spark gap was binding posts with 1/8" brass rods forming the gap. The top electrodes on the secondary were 1/4" brass rod with 1/2" steel ball, a second one with 2" steel ball and the last was sharpened to a point. The unit was very impressive with room darkened, the corona was out of this world, fluro tubes could be excited about 4-5' away, the sound of the electricity jumping the gap was intense! They are a lot of fun.

[myfrendz]

can you please tell me about the rf chokes you used?

[Mr. Apol]

They are clip-on types I purchased at Radio Shack. They consist of a ferrite ring or tube that clamps over the wire, making a choke that dampens RF interference that might travel up the wire into the house circuits. I guess they are pretty effective; I have had no interference problems from the Tesla coil.

The ones I used are similar to this: http://www.radioshack.com/product/index.jsp?productId=2103222 except that mine are round and these are rectangular.

Good luck,

Paul

[wrecche]

Pity you need to have manic depression in order to make these. Or is it that Tesla was bipolar? uhh.. J/k - good stuff, if I didn't fear electricity like a sheep fears kiwis Id be on this. It's whats stopping me from making a lifter too.. One day.. small steps..

[myfrendz]

Hi! Mr. Apol, can you please provide me with the schematic diagram of your coil? It would really help me ... Thank You!

[Mr. Apol]

A general Tesla coil schematic can be found at http://home.gallatinriver.net/mhammer/coil.htm

This is the layout I use, except for my coil being bipolar.

Good luck,

PBT

[myfrendz]

how will the increase in capacitance affect its working? if i replace capacitors giving 40KV with 80KV, how would it affect TC? i really need to know all these things, because i am all new to this ... THANK YOU

[myfrendz]

Thanks for your reply. Really helped me.

[Mr. Apol]

The idea is to find the capacitance that will achieve resonance with the other components. That's where a program like TeslaMap is invaluable. According to TeslaMap, the optimum sized capacitor for my bipolar coil using the listed components (7.5KV NST, 4 post fixed spark gap, etc.) is 14.9 nF. The coil will work with other capacitances, but 14.9 nF is the calculated optimum value. I actually run it with a battery of homemade Leyden jars whose capacitance is between 5.33 and 10.87 nF, depending on how many jars I use. Too much capacitance may actually cause unwanted effects. PBT

[scottm_113]

I've noticed that TeslaMap is no longer "Free" (save for the evaluation copy). The author is now charging a SMALL $2 fee, still good for a prog that people would find usefull

[Mr. Apol]

I guess I drove a lot of traffic his way! Anyway, it's a good program and worth $2. There are other free Tesla programs around too, like JAVATC and TeslaSim. I found TeslaMap really easy to use, so I recommend it. Paul

[myfrendz]

hey,this is the first tesla coil i am making , so ,if you please clear my queries.....may i know the mA rating for the NST used. and can i have voltage output more than 7500V with this bipolar tesla coil.or do i have to make changes within it to have a higher voltage to glow a flouroscent lamp? Thank YOU.

[Mr. Apol]

The transformer output is 7500 volts at 30 mA. You certainly use a higher or lower powered NST. I have also used a 10,000 volt, 23 mA oil burner transformer with this same coil with good results. Because the primary is rather closely coupled you may not want to use more than 10KV or you might get arcing between the primary and secondary. Even with 7500 volts the bipolar coil will light up a fluorescent bulb from six to ten inches away. Post pictures of your coil when you've made it! PBT

[Videogamer]

Given the fact that argon is a gas that conducts electricity, say you release compressed argon from a gas tank over the tesla coil's electronic discharge (correct me if I'm wrong) Would the electric current catch on to the argon making it travel wherever the gas is, potentially making a "lightning gun"? For example, take the principles of how the flamethrower works: Compressed flammable gas (or fluid) is shot out over a flame, making the flame expand across the gas, which is moving quickly in one direction, making the fire go in that same direction. Now, if you replaced the flammable gas with conductive gas, and replaced the small flame with a source of electric discharge, the fast movement of the once compressed gas would keep the electricity from traveling up the conductive gas to the tank where the gas is being ejected, and instead would make the electricity go in the direction where it is going; away from the gas tank and tesla coil. The "lightning gun" is basically waiting to be discovered!

[Xellers]

Your idea is good, as ionizing argon gas is easier than ionizing air, but it would only increase the spark length by a small amount. Look at the Tesla coil constructed by RMCybernetics, they did exactly what you described, but it only increased the spark length by a small amount.

[Mr. Apol]

It's long been known you could improve spark propagation by using different gases under different pressures. In the old days they used to put Holtz or Wimshurst machines in sealed cabinets filled with CO2 or chemically dried air at higher than atmospheric pressure. This improved output greatly (static machines like this were used to power X-ray machines, etc.) As for using a stream of argon gas as a carrier for a high voltage stroke, I don't believe it would work for reasons mentioned earlier--the gas will not keep to a narrow stream but will spread out and disperse.

[Mr. Apol]

I've heard of speculation like this before, but personally I don't think it would work. A few inches or at most a few feet from the nozzle a gas like argon is going to disperse radially into the air and not remain a coherent stream. Liquids can do this (as in your flame thrower analogy) but gases don't. Interestingly, there is an episode of "Mythbusters" about the so-called water stun gun, which supposedly uses a stream of water to transmit a stunning electrical shock. Adam and Jamie attempt to alter a standard taser type device without much success. At the end of the episode Jamie gets into the top terminal of a colossal Tesla coil and succeeds in directing one of the coil's arcs by shooting a stream of salt water at a mannequin. The arc follows the water to the target, but as a weapon, the whole thing is rather impractical!

[UbuntuNinja]

Why do you have RF chokes on the thing?

[Mr. Apol]

Because Tesla coils generate radio frequency interference. PBT

[nickademuss]

Very nice work!

[Mr. Apol]

Thanks. What is the capacitance of your bucket-jar? How much voltage will it handle? These are critical to know. For my leyden jar battery I used 12 of my soda can capacitors in parallel, which gives me 5.66 nF at well over 100kV. The capacitance I measure with a hand meter. The voltage I test (roughly!) by charging the battery with a Wimshurst machine and seeing long the sparks are when they discharge. I've never been able to overcharge my best leyden battery, by the way. I see no reason why your big jar wouldn't work with a Tesla coil. You just need to know its capabilities. Paul

[nickademuss]

What do you think it would do using my Leyden Jar?

[belgvr]

VEEEEEEERY cool, now you have enough electricity to build a bigger tesla coil :D

[Mr. Apol]

I have built two others, both vertical types, but I am still happiest with the bipolar one. The biggest coil (3 inch secondary, 14 inches long, topped by a 4 inch sphere) puts out 4-6 inch streamers. I am now using my homemade capacitor bank/Leyden jar battery exclusively. Good results, and they stand up to the stress much better than the factory models I tried. PBT

[belgvr]

that's cool man... hey, do you have any other idea on how to build a tesla coil WITHOUT useing a neon sign transformer or flyback? i got a 5 pole igniter from an old stove... would it work?

[Mr. Apol]

I'm not sure what you're describing, but I have an oil furnace ignition transformer (called an OBIT by hobbyists) that works quite well. It's rated at 10kV at 23 mA. It makes threadier, louder arcs than the NST described here. Can you post a picture of your igniter? I'm sure someone here can give you the skinny on its suitability to power a TC. Some people power Tesla coils with automobile ignition coils. Others use microwave oven transformers, but these are dangerous and best left to experienced coilers (which does not include me!) For ease of use, NSTs are preferred.

[volthead]

You can use a microwave oven transformer if you put two 150w incandesent globes in series with the transformer. You shoud get 100 ma at 3000v. Also rectify the MOT output

[belgvr]

hey, by the way, take a look at http://www.google.com.br (.br), it shows the image of a tesla coil as the google logo :D Why?
because today is Nikola Tesla's birthday :D if he was alive he would be 153 years old...

[belgvr]

I dont have a picture of that stove igniter RIGHT now and i'm at work now... i'll take a picture when i get home, but a stove igniter is that high voltage thing used to make a spark in the stove and then burn the gas.

[Mr. Apol]

That may work. Do you know the voltage and amperage ratings of it? Does it make a pulsing spark or a continuous one?

[belgvr]

it pulses very fast, around 60hz, but i dont know the voltage and amperage of that... but i can touch it and feel the shock but nothing bad happens

[Bridel568]

can you touch the sparks? and is it safe to touch them? cause this would be cool if you could(its already cool to begin with anyways)

[belgvr]

i already touched a tesla coil and i swear, i didn't feel anything... i was on a science exposition in curitiba, brazil, and i saw a guy teaching people about the tesla coil, so i asked him: "Would it hurt if I put my hand in the spark?" he said, "YES, but only if your FINGERS touch the spark", so he turn off the tesla coil and told me to put my hand in the toroid, he warned me that he was about to turn it on and asked me to not take my hand out, then he turned on and i didn't feel anything, for my surprise, i touched a fluorescent lamp with my other hand and it lighted up in my hand, really awesome... but that only happened because it wasn't a BIG tesla coil, just a standard size TC... but... i already shocked myself once, and i almost died... you know what i was trying to do? a tesla coil :D well, nothing normal, it just touched the capacitor with both hands, hahah kinda stupid idea, right?

[Mr. Apol]

Opinion differs on whether or not it is safe to touch the high frequency output of a Tesla coil. I've seen video of people doing so. Supposedly it is OK if you hold a piece of metal tightly in your hand and let the arc jump to it instead of your bare flesh. That being said, I would not do it. Why get hurt, possibly badly, for a stunt?

[66411]

High Voltage/High Frequency electricity can cause nerve damage. I know from first hand experience it does not feel very good, although i understand it to be very rare. It was not permanent but it felt like i had lines of aching and burning pain in my hand to my mid forearms for several days. The pain was bearable but nagging it has never happened again to me though I continue to let HV arc to metal objects I'm holding. Also something else that hurts from these systems are RF burns caused by induction through metal objects in the coils strong EM fields. Nothing like that burnt flesh smell and black dots all over your hands and arms.

[Country dude]

I have been electricuted 4 times and never had such burns. 2 of those times I was standing in knee deep water, And it went right through my heart and out my legs. The other 2 times was from a pool pump right through the end of my right pointer finger and out my feet, Again right through my heart. And it was standered house voltage. Had no nerve damage, im still running fine. BUT what do you mean by nerve damage small things or big nerve damage. O ya im 15. and I walked away from all four shocks

[wwsean08]

these are not like 120 volts ac (standard house voltage in the US atleast), tesla coils easily get into the thousands of volts, and also the standard house voltage is at a lower frequency (60 Hz IIRC) compared to a tesla coil (i've never looked into their voltage frequency so I have no clue on that)

[Country dude]

I know and I also made a taser that used 2 car batteries in series (24 volts hooked up to a tazer (witch got 500 V out of 1 small 1.5V batterie).Witch gets me up to 8000 volts and I got my brother to zap me in the leg with it. I blacked out for 10 minutes and then no other injuries

[BOOM5601]

I've shocked myself with mains twice, and it hurt. First time was fiddling around with belt in the base of my van de graaf, with it still plugged in. Second I was fiddling with the connections on the back of my tv and a two plugs were exposed. I touched the positive on one, and the negative on the other.

[Country dude]

ya i know they hurt

[knotmuch]

Reposting because safty is important:

I have stated tht .7A will kill.

Sorry I was off a decimal place and in the wrong direction too. I quote the summory of

http://hypertextbook.com/facts/2000/JackHsu.shtml

which all so has a number quote form published of texts

"In general, current that is fatal to humans ranges from 0.06 A to 0.07 A, depending on the person and the type of current"

[cncwanabe]

can some one please tell me what theses things are good for other then to say I made one in my life time...??? do they do any thing can I use the power in any way? please tell me cause I have seen them for years but I never have been told what good they are

[FrankenPC]

If you are the type pf person who gets a thrill out of watching something explode or rocket bikes, then you will get a kick out of making your own super HV resonating lightening generator. Although I do recommend the upright models as they tend to freak out observers more.

[john12692]

someone once had an idea that you could put a massive one in the center of a city and have free electricity in the city, no plugs no power lines no meters etc. (hold a florescent bulb near one, far enough that it won't be hit by the arc, and it lights up in mid air without being connected to anything i do not know if it works with incandescent bulbs too) but they were/are too loud and his tests in the middle of the desert failed so Tesla coils became a novelty

[greenbean]

And then there was the fact that Tesla (The guy who invented it and wanted it for free power) tested it on a town, and they all got health issues; things like cancer.

[john12692]

i don't think it ever made it to a actual full scale prototype because the smaller prototypes were still very loud and a larger version would only be even louder and if he did make a full scale version it was still out in the desert far away from anyone who might get hurt or complain

[greenbean]

I don't think he had safety in mind. The guy who invented the polio vaccine tested on himself as well as his family. A genius, but had strange priorities.

[john12692]

true but do you really think that the citizens of the town would allow him to construct a massive device that shoots lightning into the sky anywhere near their houses also it was smallpox, he injected his infant son with cowpox because he noticed that the milk maids that had had cowpox never contracted smallpox and that if you survived smallpox you couldn't get it again and he as well as his wife had already had smallpox i know he built it in the desert as a "city of the future" not in an existing city possibly on the very fringe of the city so he could still get power but not anywhere near inhabited areas for the reason of no one letting him put it up in an inhabited area not so much for safety reasons though he did understand that it was dangerous just not why

[greenbean]

First off, it was releasing electromagnetic radiation. Not lightning. Second, people test random medicines all the time. A lot of those tested by people don't pass the FDA. How do you think they know exactly what the symptoms are? That doesn't stop people. Human nature is such that there are always people that will try something new for the sake of newness, those that try it for the sake of progress, and those who try it because they are ignorant. Either way, there are enough to make a town.

[wow-amazing]

Really, it's just a novelty. Very fun to play with, what with the artificial lightning and all the light bulb tricks. I forgot how, but it is possible to play some sort of tune on one.

[robot797]

they are not good for anything ther for fun and show. i like sparks

[patapon]

good luck!

[mattccc]

im trying this at home right now

[hg341]

what's nf?never heard it

[Mr. Apol]

nF stands for nano-farads.

[hg341]

thanks

[uberhund]

Did anyone find a schematic for this project? My apologies if I just simply overlooked it, but I'd really like to know where the capacitors and spark gap should be placed. Thanks for any guidance the group might have.

[Mr. Apol]

I did not include an exact schematic, though I tried to put in text tags in the photos telling the viewer which wires go where. But a general Tesla coil schematic can be found at http://home.gallatinriver.net/mhammer/coil.htm

I did not include a safety gap (labeled SG in the schematic) in my design as the transformer is current-limited. You can easily add one of you want. Also, my model is bipolar rather than being grounded at one end of the secondary and having a toroid at the other.

[uberhund]

Many thanks, Mr. Apol; the schematic provided by the link will do fine. Keep on makin' Uberhund

[itsachen]

Where did you buy your PS? How much did it cost?

[Mr. Apol]

I bought the neon sign transformer off eBay for $8, plus shipping. I hear you can sometimes pick them up for scrap at a sign shop, just for asking. Just yesterday I picked up an oil burner ignition transformer (OBIT) for $4 off eBay. 10kV, 23 mA , etc. Paul

[knotmuch]

7 miliamps for 3 seconds across your heart will kill you (for a normally healthy person, pace maker, weak hearts, or other conditions may require less amps or time)

Also (voltage) = (amperage) * (resistance) or V=IR so I = V/R
part of the reason a van-de-graph generator is not likely to kill you is that air has add HUGH amount of resistance to the circuit of your body, the generator, and the ground

[chi chi chippy]

the V=IR is ohms law good reasoning for the vad de graph but i say it wont kill u cuz it static electricity and not a constant feed of power

ps i did a music vid for ohms law lol big extra credit in science

[bananafred]

Wow. I've heard 3,15,30, and 60 ma will kill you. And now 7. WHICH WILL REALLY KILL YOU???

[Country dude]

3 milliamps will kill ya before you hit the floor. But if you read my comment at the top I'm suprised im still running. now i'm not pushing a religion on any one but it shows SOMEONE is looking out for some. I dont know who but someone is.

[bananafred]

yeah sure. give us some scientific evidence.

[knotmuch]

Sorry I was off a decimal place and in the wrong direction too. I quote the summory of

http://hypertextbook.com/facts/2000/JackHsu.shtml

which all so has a number quote form published of texts

"In general, current that is fatal to humans ranges from 0.06 A to 0.07 A, depending on the person and the type of current"

[knotmuch]

7 ma is enough more can kill you quicker maybe or maybe having more current just has greater effect further from the main path of travel through your body (shortest path)

[Re-design]

Regardless of wheather or not this can kill you, is there anyone who did not start out by reading Alfred P. Morgan books as a kid? Wish I still had my collection.

[Schooniedude]

what are they about?

[Re-design]

The boys first, second, third, and forth book of electronics, and others.

[Schooniedude]

that sounds usefull

[lasersage]

That is super sweet. I love it. How much can you space the electrodes and still get a good spark? Or is it close to max spacing already? Ignore all these nay sayers with there "what's the point". Tesla knew the point, experiments in wireless electricity man. That's the point. Can do all sorts of useful things with a tesla coil: pretent to be mad scientist, be mad scientist, repair hole in the ozone layer, light up fluorescent tubes without physically contacting a power source! I mean what more could you want? If command and conquer where to be believed you could even blow up tanks etc. :D

[mhippo]

To produce a tesla coil a la C&C you'd first need some method to guide the bolt other than the rod. Ionizing a trail through the air and grounding the rod might be the way to go, but I had a lot of trouble with trying to find a way to do that. maybe you can succeed where I failed.

[lasersage]

Well being a laser man, I'm aware of military experiments to shoot plasma trails (two of them to complete the circuit) at aircraft/missiles/etc. then pass large voltages down them to fry the baddy vehicle. Lasers seem like an obvious choice but you'd need a huge amount of power, and some clever beam control. Plasma generally absorbs laser light, so making a trail of the stuff can be tricky (not impossible). I don't think its really a useful weapon though. I mean just have you men wear copper braided suits and they're immune to any potential problems. Interesting point though, I'd always been too caught up in the skin effect of the high frequency electricity (it tends to flow over not through) to worry about direction. Now you've got me thinking :)

[mhippo]

Well, that's what instructables is for. To promote thinking... I was trying to work on a guidance system in highschool, and came to the conclusion that: a) A high powered laser might be able to produce enough ionization to guide the first bolt b) If you fire rapidly enough at the same target, you can use the plasma trail created by the previous bolt to direct the next one. That's just in theory, because I never could get a high powered laser, and therefore didn't spend the time building the coil.

[Mr. Apol]

The terminals can pivot 360 degrees each. The longest arc I have gotten so far was six inches, and that burned out one of my capacitors. I am working on improving that. In the old days, Tesla coils were used to power radio transmitters, X ray machines, "therapeutic" machines, and so on. Nowadays they're a hobby unto themselves. They demonstrate several important scientific principles in a dramatic way: induction, capacitance, spark propagation, etc. Mostly they are fascinating. Imagine having 100,000 volts at 10,000 herz flashing and dancing at your command on your kitchen table? That's the appeal.

[Re-design]

And those Ck722 circuits in his books still rock!

[john12692]

amperage kills not voltage so you can have infinate voltage passing through your body and the only harm that will come to you is heat from where the arc enters and leaves your body but i believe 60 miliamps across your heart will put you in the ground so voltage wont kill you but it'll hurt like hell

[budsiskos]

i agree, the principal is easily demonstrated with a van-de-graph generator. super high voltage but almost no amps and safe to touch

[Kiteman]

As long as you don't have a heart condition (such as a pacemaker).

[guyfrom7up]

i think that's kinda true, put if you have a super high voltage and a low current (lets say 1ma), couldn't it puncture some internal organs, like the heart? The point is be careful :P

[Plasmana]

Not always, if there is no current, the voltage will gradually build up on your body, know as static electricity. :-)

[DemonDomen]

But you should know that the current that flows through a resistor depends on voltage. The higher the voltage, the more current flows. 30mA is enough to kill you. The internal resistance of a body is about 3k ohm. This is how they got the dangerous voltages. Anything above 100V DC or 50V AC is dangerous.

[T3h_Muffinator]

External resistance is in the 3M ohm range, though, so your skin drops most of the voltage ;)

Unless the terminals pierce your skin....

That said, electricity + heart = bad, in most cases.

[lasersage]

external resistance of dry skin is far higher than 3Meg, sweat or water or oil on the skin all greatly affect this. Its not about the terminal piercing your skin, its the high voltage that'll do that for you. The electricity will arc to the easiest path to earth, your blood vessels are that. So if the voltage is high enough to cause dielectric breakdown (go through your skin) then it'll flow through your veins and arteries.

[knotmuch]

7 miliamps for 3 seconds across your heart will kill you

[lemonie]

Similarly it's the amperage that hurts (be consistent!) L

[john12692]

amperage causes damage not pain

amps is a measure of how much electricty is moving (how many electrons*)

volts is a measure of how likly they are going to move and how quickly the charges will balance out (the electrical potential)

static electricty discharges such as from a vann de graff generator of shocking yourself on a cold dry day are about 50,000 volts but only 0.01mA
the pain is caused by the heat generated by the arc and the electricty flowing through your nerves in/under your skin because your brain doesn't know how to interpit the signal so it chucks it up to pain

*amperage is a measure of flow of charge which coralates to the number of electrons but is not a direct relationship such as one where a charge of 1=1 electron

[lemonie]

amperage causes damage not pain

So your flesh may be fried but you don't feel a thing? Come on talk sense...

L

[john12692]

yes you will feel pain from amperage - heat or burning, lasting pain my point was that the voltage gives that momentary shock feeling i thought people would be able to use common sense and figure out that a burn hurts

[lemonie]

Voltage and current are two properties of the same thing, talking about them as if they were different causes confusion.
The voltage is what drives current through you. Some high-voltage devices like DIY tasers drive small currents with high voltage (shock only), unlike high-voltage overhead power-lines which will tend to kill you with a lot of current. Mains electricity will give you a shock, and maybe cause harm depending...

L

[john12692]

Right voltage is a measure of electric potential - how likely the electricity will flow - you could think of it like water pressure - how likely a leak will happen (a spark or arc) and how far that water will go once it is free (how big the arc will be) amperage would be how much water would leak at a time or how thick the stream of water would be or you could think of it as water in a pipe where the pressure in the pipe is the voltage (by pressure i mean pressure forcing the water to flow through the pipe) the amount of water flowing at a time is the amperage and the size of the pipe is the resistance the larger the pipe the more water will flow through it at lower pressures whereas a narrower pipe would need more pressure to achieve the same rate of flow i apologize for any confusions i may have created in this or my earlier comments

[lemonie]

Yeah that's it. The best measure of harm/effect is the total "juice" going through you. Think HV power-lines against TASERs. Voltage will give you a measure of potential, but what current the supply will deliver determines the result. L

[john12692]

sorry to put this in a seperate comment but otherwise this is a good 'ible

[jj37]

Do you know of any way to turn this into a plasma speaker? btw great instructable I really wanna build this

[Mr. Apol]

I'm not knowledgeable about audio, but I have seen videos of "talking" and "singing" Tesla coils. If I were you I would just Google "audio Tesla coil" and see what turns up. Because of the modest output of my coil, I would think it would be useful in this way, and the parallel terminals would make an interesting display if linked to sound output. Paul