Instructables
Picture of AA Battery Powered
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First things first:

DISCLAIMER: I am not responsible for any injuries or property damage that may befall you from following this instructable. High voltage electricity can be DANGEROUS and should only be worked with at your own risk. Proper safety precautions should always be followed. 

That out of the way, welcome to my first instructable. Seeing as this is my first, any suggestions for improvements are greatly appreciated. Just go easy on me.
This is intended to be a how-to guide for a newbie to high voltage (like myself) looking for a quick, cheap, and relatively safe project. Although this is not a true tesla coil, as it does not utilize a resonant air-core transformer or operate at high frequencies, in effect it is similar. It still throws out plasma discharges from the top load and about 3.5 centimeter arcs to ground. Estimated output is about 100kv.

 
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Step 1: Parts and Pieces

Picture of Parts and Pieces
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There aren't many parts to this build, and most can easily by scrounged from old TVs and other electronics or be bought for cheap. The following is needed:

Bug zapper racquet: This can be purchased from Ocean State Job Lot for about 5 bucks, and is nifty for fending of mosquitos or high voltage experiments. There are probably other types of devices very similar, but I would recommend finding the racquet pictured to insure the internal circuitry is the same.
Flyback transformer: Any flyback transformer will do, though the bigger the better. Don't kill yourself looking for an old non-rectified design, since there are no benefits of it for this circuit.
Random assorted hardware: This circuit requires a spark gap to be constructed. The design of the spark gap can vary, as long as the two ends where the arc jumps is rounded, and the gap adjustable. For mine, two Erector set brackets were used. One had a ball bearing soldered to it, the other a nut over top the hole, so a bolt with an acorn nut on the end can be threaded through. See the attached picture for the details. 
2xAA battery holder: Can be purchased from Radioshack or the bug zapper handle can be used to hold the batteries.

Optional: 
Additional Capacitors: Should be rated for at least 1.6 KV. The Bug zapper already contains one, but for bigger sparks more can be used.
Toggle Switch: The switch on the board of the bug zapper can be difficult to use, and because of the design of the bug zapper circuit, floats at high voltage, leading to a shock hazard when it is exposed. Because of this, a new switch is recommended.
Pen body or other plastic tube: To elevate the top load
Top load: I used a ball bearing, but anything smooth and without sharp edges or points can be substituted. 

Of course, solder and a soldering iron as well as other general tools are needed, and wire for connecting everything together
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kilofeenix14 days ago
So are you using the flyback as your primary and secondary coils instead of just upping the voltage? Cause I don't see a coil on your torrid
vjkmr7866 months ago

plzzzz help me i cannot make capacitor bank so tell me capacitor rating used in the project

JoeBeau (author)  vjkmr7866 months ago

unfortunately, I do not know the capacitor bank values, and I cannot really check since I am at college. But since this capacitor bank is not part of a resonant circuit like on a real Tesla Coil, the value does not have to be exact. Aim for somewhere in the .05 to .1 uF range for the whole bank

vjkmr7866 months ago

what is capacitor rating used for capacitor bank?????????????

pratikpjjoshi7 months ago
pratikpjjoshi7 months ago
pratikpjjoshi7 months ago
methylin8 months ago

I could only find rechargeable zappers. There are lithium batteries and the plug is connected to the circuit board. Do you know how I could rearrange this? I'm a complete beginner in these things.

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JoeBeau (author)  methylin8 months ago

This should work, though I don't understand why there appears to be five wires coming off the board- the two white at the bottom and white, yellow, and brown coming out of the top. It would really be a matter of identifying which wires go where. Whichever go to the mesh are the ones we want.

DESERT_239 months ago

I need a voltage pulse of 3.5 kv. Can i get it with this circuit or does it produce only very high voltages.

JoeBeau (author)  DESERT_238 months ago

The bug zapper circuit alone produces about 1.75 kv. By using a 1:2 step up transformer you could reach about 3.5kv.

JoeBeau (author)  JoeBeau8 months ago

and by 1:2 stepup transformer I mean in place of the flyback transformer.

skylane10 months ago

The bug zapper raquets are often on sale at Harbor Freight for about $3 US.

I buy them 6 or 8 at a time and give them as gifts...

Nice simple design! I love it ! Going to try this!
bvarious1 year ago
I have a 200v capacitor laying around, would that be uh... safe LOL of course the whole thing is dangerous, but I'm meaning more will the whole set up be able to withstand that kinda juice discharge? I know its only a tiny battery but still..
oh dear I just noticed my capacitor is rattling. Is this normal? Kinda a newbie to this and dont have any voltage meters to test it.
JoeBeau (author)  bvarious1 year ago
They should not rattle. And the capacitor should be rated for atleast 2000 volts. Thats the output from the fly swatter
I made a same 'Tesla coil' as you made but the problem i'm having is with the capacitors,using the one in the zapper itself are too weak,i made 6 bottle capacitors by myself but i was getting small arcs,and the capacitors made arcing sounds. I was thinking if i could use a large cap,about 1 micro farad??
I cant get small ones and the one i make are too weak...
JoeBeau (author)  PaarthSharma1 year ago
bottle caps can have issues. Make sure any fluid in the cap (if its a classic salt water cap) is below the top of the tinfoil that wraps the bottle. This prevents coronal loss.
also, the caps can be too small or two large. All i can say for sure is to try it. By tuning the combination of the capacitor and spark gap you can tune the coil
hmm. this cant be a tesla coil, the output is automatically rectified from the flyback,. nice one though
JoeBeau (author)  leviterande1 year ago
i know its not a tesla coil.... Its more of a descriptive use of the term. the differences between a true Tesla Coil and this project is highlighted in the intro
my wookie1 year ago
could you upload a schematic of your racket's board? i have all those parts already if i could see how they went together.
JoeBeau (author)  my wookie1 year ago
Here are some pics. Unfortunately I wont be able to upload an actual schematic for a while so this is in case you want to get a head start on it.
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JoeBeau (author) 1 year ago
I'll post some better pictures of the board shortly. I am really busy as of late and will put up a schematic eventually, but in the mean time it might be quicker if you were to do it yourself. I can't trust myself to do it in a timely manner...
thanks joe for solving my problem and concerns , but ive got anothe prob here ive bought a bigger flyback from my local electronic repair shop the guy tlod me that it was removed from old TV but it is giving smaller sparks can you tell me why is it so?
JoeBeau (author)  MadGuitarist1 year ago
Is it a rectified type or unrectified? The old flybacks have just a pancake coil on them, with no rectifier circuit. The rectifier circuit of modern flybacks also have a voltage multiplier in them, which can give you longer sparks. That being said, if you build a ZVS type flyback driver you want the unrectified type because then you can run it at higher power without destroying the rectifier circuit.
I would check to make sure you are running it at the proper polarity, if it is rectified, as well as making sure you are using one of the lowest resistance coils.
i dont know but looks like the same one as the one you shown in the picture
jabelone2 years ago
Sorry, double comment \/. Any way, one other thing. My dad is a diesel fitter and works with electricians all the time. He also has a lot of "Sources." If I could choose a voltage of the transformer what should I ask him to get? Thanks heaps, and awesome Instructable!
JoeBeau (author)  jabelone1 year ago
The transformer should be as high of a voltage as possible. Here, the voltage being put into the transformer is a lot more than its rated for. Generally, The voltage in to a regular step up tranformer should be 120 volts. Here, its about 2kv, so the output will be about 15 or 16 times higher than the rated output.
Thanks, he ended up getting me a 25kv one off ebay for about $7. :)
hey joe ur project is awesome i have also made it i had removed the core of the flyback and the discharges were more longer than then ones when the core is attached & do u have any suggestions that how can i get more larger sparks when one end of secondary coil is grounded
JoeBeau (author)  MadGuitarist1 year ago
Winding your own turns on the transformer could increase the output spark lengths, potentially. Coupling will be a problem, however, unless you continue to use the core. With the core removed, there is a potential to be able to tune the circuit to operate at a resonant frequency, similar to a true tesla coil. This is why you are probably getting longer sparks. Playing around with the capacitance value could be used to tune the circuit, and this would then allow the circuit to behave more like a traditional tesla coil.
jabelone2 years ago
What is the voltage of your transformer?
jabelone2 years ago
What is the voltage of you Transformer?
brilliant instructable, very clear and seems quite easy to do. i guess the circuit could be powered by the charging circuit of a disposable camera rather than a bug zapper?
sooraj6193 years ago
since the flyback transformer pins are glued, the pins cant be seen so please add pictures to show which are the pins nice job
JoeBeau (author)  sooraj6193 years ago
The flyback pictured is a different one, and the pinout is different. The pin marked by the line is the other high voltage pin, and the ones marked by the single and double dots are the pins to the primary. But by comparing this flyback to the one in the instructable you can guess which pins are the ones being used in the instructable. Sorry, but i couldn't get a picture of the pins in the hot glue.
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what model of flyback did you use
thanks
i was wondering, does the zappers circuit allow the capacitors to overchard and just dump their load with out a "complete" circuit?and if so thwn does the spark gap just allow the capacitor to fully charge before it over loads and dumps its chrage through the primary coil?
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