Tesla coil Instructables are not uncommon--I've written one myself--but in the following Instructable I'd like to not only describe building a simple upright coil, but also suggest some easy ways to assemble Tesla system components. Sometimes the parts of a Tesla coil system are harder to get than the coil itself. Then, at the end, I will demonstrate (in a small way) how Tesla coils can transmit electrical power through the air without wires.

The essence of this Instructable is simplicity rather than brute power or maximum efficiency. Because my coils are small, indoor models, I prefer to follow a modular method of building them. Most Tesla coils are unitized--everything packaged together in a single unit, just plug and play. I like to build in modular fashion so I can switch components around, try different coils, capacitors, or power supplies. Consequently my designs are clipped together with alligator clips and length of high voltage wire. If you
prefer the unitized approach, you can certainly adapt this design that way.

This Tesla coil system consists of these parts:

A high voltage (7,500 volts, 30 milliamps) AC transformer

A pressurized spark gap

A capacitor array

The coil itself, consisting of a primary and secondary coil on some kind of supporting

A "top load," or terminal

Wire to connect everything

Optional components you will want include a variable transformer (variac), and a small
hose-type vacuum cleaner.

Fluorescent light tubes, with stands

Each of these topics will covered on a separate page.

Step 1: Power Supplies

This may be the most expensive part of your Tesla coil system. You will need an AC transformer of at least 3,000 volts at 30 milliamps to get the spark gap to fire, and more is better--within reason. Once you exceed 15,000 volts at 60 mA, you're leaving the indoor, tabletop arena and graduating to garage maniac status. This system is designed around a 7,500 volt, 30 mA neon sign transformer.

Until a few years ago, most neon signs were powered by heavy transformers potted in insulating tar. Nowadays concerns for safety (and liability) have made the old heavyweight NST obsolete. Modern neon power supplies are light, solid state units with Ground Fault Interrupt (GFI) protection. This is all very well if you're trying to light up a Michelob sign, but GFI power supplies won't work in a Tesla coil system. GFI is designed to stop just the sort of continual sparking a Tesla coil requires, so avoid modern neon power supplies. If you can't tell by the label if a transformer has GFI, try this rule of thumb: if the unit is small and light, it has GFI and won't work on your Tesla coil. If it's heavy as lead and almost as big as a cinder block, it will.

Other power supplies can be used. Oil burner ignition transformers (OBITS) can often be had cheaply. They almost always come rated at 10,000 volts at 23 mA. As with neon sign transformers, the newest OBITs now come with solid state circuitry and GFI. Pay close attention to make sure you don't get stuck with a useless GFI model.

Some coilers use microwave oven transformers. My advice is, DON'T. MOTs, as they are called, are rude, crude, and develop lethal amounts of current. If you don't know what you're doing, you can easily harm yourself or others. Until you've learned a lot more about electrical engineering, leave MOTs alone.

Car ignition coils are sometimes used to power Tesla coils. Ignition coils have to be driven by some kind of circuitry, either a 555 timer and associated parts, or even by something as simple as a household dimmer switch. This can be a fun project on its own.

Tesla coils can be powered by DC, but that's a different topic not covered here.

For best and simplest results, get your hands on a neon sign transformer (NST). All the ones I own I got off eBay pretty cheaply. They're heavy and can be expensive to ship, so if your budget is really tight, try a local sign shop. Many businesses are still switching over to electronic GFI power supplies and discarding their old NSTs. You might get a bargain if you offer to take an old-style NST off their hands.

Many NSTs come without power cords. When I salvage parts from old microwave ovens, one thing I always keep is the sturdy, three-wire oven power cord. These are easily adapted to NSTs.

One thing to remember about using NSTs: never move or lift an NST by the ceramic terminals! They're brittle, and they can crack or snap right off, then you've got nothing but a doorstop. Always lift NSTs by the case. One thing you can do to improve the portability of an NST is mount it on a base. I put my 7,500 volt Allanson NST on a shellacked pine plaque, fitted with four rubber appliance 'feet.' This insulates the NST from the tabletop, and gives me a handy place to grab and lift it.

It happens my Allanson unit has a pull-chain on-off switch. This is unusual. Most NSTs I've seen do not have on-off switches. Once you have grafted on a power cord, the best way to handle the NST is through a variac (a variable transformer), or an isolation transformer (see "Variacs and Vacuum Cleaners"). Failing those, you may have to use a wall socket controlled by a wall switch, or else put together a switch using a household wall switch mounted in a utility box.
<p>Tesla did not invent or perfect fluorescent lighting.</p><p>Credit for the first practical <em>phosphorescent</em> lamp belongs to <br>Tesla&mdash;phosphorescent substances are slower to emit light than fluorescent ones, <br>and they continue to glow for some time after the power is turned off. </p><p>Tesla's earliest lighting inventions had operated as conventional filament or <br>arc devices, but with high-frequency currents supplying power. As he quickly <br>discovered, such currents could be made to bring diffuse gases to incandescence, <br>or cause light emission in various solid materials. His innovations in this <br>field, though influential and disclosed in a series of celebrated lectures, were <br>seldom patented. </p><p>Inasmuch as Tesla created for himself more powerful apparatus, to operate at <br>higher frequency and voltage than was available to anyone else, he was capable <br>by 1890 of generating fields that would light up, without any wires, <br>phosphorescent tubes across his laboratory. (His assistants recall these lamps <br>strewn casually around the lab and working by their eerie green glow.) The <br>energy is just long wavelength radio&mdash;from Tesla's high-frequency <br>generators&mdash;though in this case the signal is very strong, strong enough to be <br>useful as power, rather than as a means of communication.</p><p><a href="http://www.pbs.org/tesla/ins/lab_imlight.html" rel="nofollow">http://www.pbs.org/tesla/ins/lab_imlight.html</a></p>
<p>is there any connection is required for fluorescent tubes what is the means of this statement </p><p>&quot;Attach a separate ground wire to the fluorescent tube equipped with a ground connection&quot;</p>
I may have expressed that poorly. What it means is, if you have a fluorescent tube with a metal connector--a terminal, or stud on the tube--if you attach a ground wire to that, you should get brighter output.<br><br>PBT
Sorry if i missed where you may have anwsered these in the instructable, but does this work for LEDs? And does it harm any other electronics like phones, consoles, and tvs?
<p>I didn't try it with LEDs, but I think it would work, especially is you use the LED leads like antennas to pick up the RF radiation. </p><p>RF can be bad for electronics. It depends on the frequency; there are ways to calculate at what frequency your coil is radiating. I've never had a problem with the coil you see here, but some coil builders have to put there apparatus inside a Faraday cage to protect their electronics.</p>
<p>Does it work dude. I mean the wireless energy thingy because I'm have second doubts about it cuz I'm planning on making this as my science project and add a few tinkering and stuff. So any tips and stuff I should knoJann </p>
Study the Instructable and videos. It works in a limited way, as you can see.<br><br>I would not tinker with the apparatus without adequate background knowledge. You can hurt yourself on this equipment if you are not careful.<br><br>PBT
Hi Paul, <br> <br>I built my own Tesla coil web page. Hope you like it. <br>http://www.twotowers.com/tesla/tessie_1_tesla_coil.html <br> <br>Steffan
Hi, <br> <br>I love your &quot;Instructable&quot;! You use of suction to quench the spark gap was very helpful. I did not use your design, but rather modified the design I am using with a 120V computer fan, sucking (rather than blowing) air onto the spark gap. My spark output doubled! Thank You! <br> <br>I completely disagree however about the necessity of a safety gap. At least with a larger NST. My TC is powered by a 15,000V 60mA NST. I fried my first NST after about 5 minutes of operation because of a voltage spike from the primary and secondary coil. I do recommend implementing a safety spark gap in your coil! The safety gap installs across the capacitor. Depending on how you assemble your MMC, this can be very easy to make and adjust. <br> <br>I would be happy to upload a photo of my MMC capacitor if anyone wants to see it. I got the idea for my MMC from www.thegeekgroup.org. The Geek Group is another great resource for anyone wishing to build their first tesla coil. They have a series of videos that walks you through the whole process. They skip over a couple details in their videos that I believe are important, but it's mostly all there. I also used their idea for a secondary coil winding jig. With someone operating the variable speed drill motor at one end of the jig, I was able to wrap 33 inches of secondary coil in about 10 minutes. <br> <br>Thanks again!
Thanks for writing. It doesn't matter which way the wind blows, as they say, as long as you quench the spark gap. It's a surprisingly easy way to boost the output of a coil. <br> <br>There's nothing wrong with using a safety gap. I would under other circumstances. One reason I have never needed a safety gap is that I use fairly small NSTs--typically 7,500 V. They are current limited, and I always power them through GFI outlets via a variac or isolation transformer. Because I do almost all my experiments in my kitchen, I keep things small scale. I've never burned out a transformer or damaged anything except for toasting a few inappropriate capacitors. A 15KV/60mA NST is a bit of a brute to fire up inside the house. <br> <br>Hardcore coilers prefer Cornell-Dubilier 942 series flash rated caps. They're rather expensive and not always easy to find. At the power levels I run, ceramic doorknob caps work fine. I also make my own dry Leyden jars--see my Instructable for Leyden Jar Battery for Tesla Coils. Those have never failed me. <br> <br>Paul
I just started building the candle stick coil based on your instructable. I already have the secondary coil wound. We have that same paper towel dispenser with that same metal ball on top, so it looks like I have my top load. I wound the secondary coil using either 26 or 28 magnet wire onto 1 1/2&quot; PVC SCH40 pipe. The 1 pound spool I used to wind the secondary had been laying around for 20 years and the label was long gone. As I am 52, my eyes are not as god as they used to be. Believe it or not, I wrapped the entire 1 foot coil going mostly by feel. It took about 1.5 hours. I calculated that my secondary has 1152 winds and 495 feet of wire. I will be using a 7500V NST. Any suggestions? Comments? <br>Peace
Sounds good. I wrap my coils by hand too. What will you use for your primary winding? Do you have capacitors in mind? I recommend you run your final set of specs through TeslaMap to get an idea how much capacitance you will need.<br><br>Paul
Yes that is my MMC down there and it is constructed of the Cornell Dublier capacitors you mentioned.
I did have problems when the fan was blowing instead of sucking?? Maybe I did something else too that increased the performance. Yes, my first tesla coil is a beast and it puts out 3.5 foot sparks. It is right in the middle of the living room. It certainly is a statement.
I built a small coil following this entry. Worked pretty well. The doorknob capacitors had trouble keeping up and burned out though. Might be something better out there. <br> <br>I think the copper tube coil around the base would be better than insulated wire to enable tuning primary/secondary. I used at 15k NST. Never reached much corona from terminal, but I figure that was a tuning issue. Work in progress. <br> <br>Watch a demo of my coil: <br>https://vimeo.com/63262916 <br> <br>Also article I wrote afterwards on Tesla: <br>http://pgavdestinations.wordpress.com/2013/04/22/nikola-tesla-a-world-without-wires/ <br>
Congratulations on your coil. As a rule of thumb, builders usually use caps with double the rating of their power source; in your case, 30KV when using a 15KV NST. I burnt out polypropylene radio capacitors like popcorn until I adhered to this rule. <br> <br>Copper tubing be too thick for a small coil like this. It might be hard to get a good number of turns if you use a helical form. (That's why a lot of coilers make flat spiral primaries). You can of course cut tuning notches in the insulation of your primary. I prefer to vary the capacitance to achieve tuning. I also vary my top load to affect tuning too. Good luck! <br> <br>Paul
Paul, good advice. Thank you!!! <br>Tony
Watching the video of your coil, I have a couple of questions. How is the coil grounded? Did you use an external ground, or did you run it as an autotransformer (did you connect the lower end of the secondary to the bottom end of the primary?) Did you use a program like TeslaMap to calculate how much capacitance to use with the configuration you built? My coil this size runs best with about 2nF, but I am using a much smaller NST--only 7500 volts/30 mA--and using the 15KV NST will definitely change your capacitance demands. Try upping the capacitance in stages about 1nF at a time and see what you get.<br><br>Paul
Paul, <br> <br>Thank you for watching the video. What may not be apparent is that during the test, the corona discharge began to lose power to nil output. In the video you can see the capacitors begin to flame out (right-hand side of visual). This would seem to coincide diminished output from terminal. For this demo, the system was grounded as lower end of secondary to bottom end of primary. I did not use the TeslaMap, but certain I was under capacitance. I believe I was using 5 doorknob caps at 530 pf's each. Are doorknob caps a good choice for a small Tesla coil like this one? I had also tried salt water filled leyden jars, but discovered I had built them incorrectly as they seemed to not carry a charge. Surprised that you discourage the copper coil. I was thinking 1/4&quot; copper tube turned 6x into a 30 deg angle (cross section). Not better? The assembly is actually in an exhibit at the moment so my tests are on hold for the moment. <br> <br>BTW, have you seen the work that these guys are doing Teslatronix? http://www.teslatronix.com/ <br> <br>Thanks again Paul. <br> <br>Tony <br>
VERY NICE! any interest in colab on a slayer exciter?
Brilliant work!
I haz agreed. ;-)
Thanks! I don't do many, but I try to make them worthwhile.<br><br>Paul
OMG so awesome! Wish I had the materials to build.
Hi, I like your design (please forgive any spelling and grammar errors). I am looking to design a tesla coil and was hoping you could help with one with a 20 inch foot print, total height of 15 inches as well as encased in a conical shape. Only the primary and secondary coils would be encased, cap bank, spark gap, transformer would be placed in a separate area. also interested to know if several tesla coils can be daisy chained or would require separate power sources be required? one more question how would one connect a variable frequency generator output to the coil, if possible? any help would be appreciated, P.S. I know these are strange questions...just looking to expand the horizons.
I'm not sure I understand some of your questions . . . you want to encase the coil in housing, conical in shape, with the top terminal protruding? <br> <br>It is not uncommon to add a third coil to a Tesla coil system. This is called a magnifyer, or extra coil. Tuned properly, it can vastly increase the output. There's no reason to actually series-connect full coils through; I don't believe that would work. As for variable frequency generators, do you mean a variable frequency oscillator, or some kind of audio equipment?
Are doorknob caps the only ceramic capacitors you should use in an MCC, or could you also use high voltage ceramic disc with a high enough voltage rating put together for the right capacitance?
Disc caps will work (if you get the voltage rating and capacitance right) but they won't last as long as doorknobs; the intense pulsations of a Tesla coil circuit are hard on them. Pulse rated caps are best of all, but they can be pricey.<br><br>PBT
If you touch the electrical discharages will it kill you
It wouldn't be good for you. This coil is being run as an auto-transformer, with the secondary ground being connected to the lower end of the primary. That's not something I would ever want to touch.<br><br>PBT
So, I'm currently using a bug zapper circuit to power a flyback transformer. My setup is power supply -&gt; bug zapper -&gt; capacitors -&gt; spark gap -&gt; flyback. My question is can i use this flyback to power a tesla coil, with modifications of course. Also, the capacitor on the bug zapper has .33uF capacitance and im wondering if thats way to much or if I should add more capacitors since i have them. Thanks for any help!
It's funny, two comments about bug zappers in less than week; is there something going on? ;-) <br> <br>I have no experience with DC coils, and that's what flyback transformers put out, high voltage DC. People do make battery powered Tesla coils, but it takes 12 volts at car battery levels to do it. I would check around for advice on DC coils. All my efforts have been made with household AC current. <br> <br>Good luck, <br> <br>Paul
harbor freight carries them for 3.99$ now. Cheap enough to be perfect for testing stuff out like this. There is just not enough documentation out there about DC coils. hmmm.
So i am looking to make something to be able to cheaply and easily light up house hold light bulbs wirelessly. Will this work? Or is there something better out there?
No, this scheme to power lights and appliances wirelessly is not practical. A Tesla coil makes unacceptable amounts of toxic ozone and nitrogen oxide pollutants when run very long, it's punishingly loud, and the amount of RF energy radiating into the air over time would soon bring the FCC down on you. The massive interference would damage sensitive equipment--digital TVs, computers, cell phones, etc. Even if you could assiduously tune and screen your Tesla transformer for interference, it's just not an efficient way to distribute power. That's the real truth behind Tesla's downfall as an inventor. It's not that his ideas were wrong, or scientifically unachieveable--they just weren't practical.<br><br>PBT
I only need it on for like thirty seconds
Well, you can do that--but it only works on fluorescent bulbs, not incandescent types.<br><br>Paul
Mr. Apol<br>I can't remember where but I remember you offering a high voltage soviet era capacitor for sale- do you have a way of contacting me about this?<br> thanks, OzL
I did, a while back on the TCML. It's already gone though. Sorry.<br><br>Paul
Would a 9,000V 30mA transformer work instead of a 7,500V 30mA transformer?
Absolutely. You'll have to calculate what sort of capacitance you'll need, but in general, more volts means bigger sparks and more power output. Be sure your transformer does not have GFI (ground fault interrupt).<br><br>PBT
Ok, thanks for the info. How do I calculate the needed capacitance?<br>
The simplest way to calculate your needs is to use a program like TeslaMap or JavaTC. They work like spreadsheets; you input the details of your coil and they will compute how much capacitance you need to achieve maximum resonance.<br><br>TeslaMap: http://www.teslamap.com/download.html<br><br>JavaTC: http://www.classictesla.com/java/javatc.html<br><br>Paul
i have make a vaccum cleaner out of a cola bottle,powered by 12v adaptor.can u gide me how to upload this instrucable for winning a prize
How much does this cost to build?
Let's see: the cardboard secondary tube was free; various PVC parts ran about $5 in all. 24 gauge wire, about $5, 10 gauge was 49 cents a foot (about $3.50). Salvaged microwave oven wire, free. Topload sphere came from a paper towel holder that cost $14. Parts to make the spark gap, $4. Ceramic capacitors, used, off eBay set me back $1 each ($4). NST, used, off eBay, $16 including shipping. <br><br>Total for Tesla coil system, $51.50. This does not include the fluorescent tubes, etc. <br><br>Another benefit of building the coil modular fashion is that the components are easily reusable in other projects.<br><br>Paul
Thank you :)
ok i will do!!!<br>thanks for your advice!!!!
how is your camera not effected by the electricity in the air
I'm actually farther away than the view suggests, using zoom. You can hear interference on the sound track from the discharges. Also, the camera has a metal case, which I imagine acts as a Faraday cage to protect the innards.<br><br>Paul

About This Instructable




More by Mr. Apol:Pipe Dream: A Low Voltage Tesla Coil or 'Slayer Exciter' The Model 1882 Wireless Telephone Making Light from Magnetism: Electromagnetic Induction & the Bedini Machine 
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