AA Battery Powered "Tesla Coil"

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.

Step 1: Parts and Pieces

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

Comments

[my wookie]

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]

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.

[JoeBeau]

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...

[MadGuitarist]

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]

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.

[MadGuitarist]

i dont know but looks like the same one as the one you shown in the picture

[jabelone]

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]

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.

[jabelone]

Thanks, he ended up getting me a 25kv one off ebay for about $7. :)

[MadGuitarist]

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]

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.

[jabelone]

What is the voltage of your transformer?

[jabelone]

What is the voltage of you Transformer?

[resistanceisfutileiflessthan1ohm]

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?

[sooraj619]

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]

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.

[crazy-blender]

what model of flyback did you use

[sooraj619]

thanks

[PyroTrician95]

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?

[JoeBeau]

The capacitors dump their load into the primary coil of the flyback, which is in effect an open circuit due to the airgap of the spark gap in series with the coil. As a charge builds up in the capacitors, a charge builds up across the spark gap due to it being wired in parallel to the capacitors if one were to ignore the resistance offered by the primary coil. But due to that resistance, the charge builds up slower across the spark gap, allowing the capacitors to build a stronger effective charge than would just be present across the spark gap. Once the charge across the gap has reached a point where it can arc, it does, completing the circuit and allowing the capacitors to then discharge into the series circuit of the acring spark gap and primary coil.
Essentially, during charging, the spark gap sereves to be a second capacitor wired in parallel to the actual capacitors, until it discharges, at which point it is now wired in series with the primary coil

[PyroTrician95]

thanks that helps :)

[crazy-blender]

also what is voltage of the flyback's HV output

[JoeBeau]

Depends on the voltage going into it and the number of windings. Typically, it would be a max of 20kv. Here, it is possibly closer to 200kv

[crazy-blender]

what type of flyback do you need rectified or non rectified ?

[JoeBeau]

Either. Non-rectified makes better sparks if you are using a flyback driver. Here, there is no difference.

[The_Fire_Emu]

also, will adding capacitors make the amperage higher?

[JoeBeau]

As i said in the comment below; up to a certain point. The capacitors store a charge that is then released through the spark gap. Eventually, adding bigger and bigger capacitors wont show a benefit because you will reach the limit of the spark gap set by the voltage anyway.

[The_Fire_Emu]

You said that you can add additional capacitors for lengthier sparks, so would that mean if I put a huge capacitor in the circuit it would generate giant sparks?

[JoeBeau]

Possibly... The capacitor and spark gap work in tandem to resonate at a specific frequency in a regular tesla coil. Here, thats not the case. Don't waste your time with a monster cap- eventually you wont see any benefits if the capacitance was raised any higher

[crazy-blender]

will it kill you ?

[JoeBeau]

No. I have avoided it for safety's sake, but by the time the 1.5 volts is stepped up to 20 kv the amperage is very low

[ROBOCOP603]

Could I get the spark gap to be larger if I had both of the rounded sections be good sized neodymium magnets?
I'm trying to make a plasma staff that has three blades around a center area at the top. These blades will be at least two to three feet long. I was thinking that I could have the blades be plastic and have a series of neodymium magnets on all three of them with sparks jumping either from blade to blade at random points or along each blade from magnet to magnet, or having sparks fly from the blades and each point of the blades at the same time! I might need a strip of metal running along each blade connecting the three series of magnets as one, so I will need to split either the positive or negative spark gap wire into three one going to each blade.
What do you think?

[JoeBeau]

I am not familiar with magnets increasing arc length, but maybe it could work by some principal i am not aware of. I guess one could argue that the magnets could in effect increase the potential difference on either side of the spark gap by interacting with the magnetic fields produced by electron flow. But i feel that this would be a very minor difference.
I dont know if that would work. Give it a try. There's nothing to lose

[crazy-blender]

if you touch the sparks will it kill you

[BrunoG]

Good project but what is the range of the value of the capacitor bank is it in the range of 10 to 500pF or 20 to 600nF or 1 to 20uF?
Please respond.

[JoeBeau]

To say it simply- I dont know. Each of the large red capacitors are .1 uF, but the blue ones are unmarked except for "1.6 kv" Seeing as this project does not use resonance like a true tesla coil, the capacitor bank does not make a huge difference. I would guess that my cap bank is between .2 uF and .4 uF. But dont worry abou it too much.

[BrunoG]

If it helps

[f22archrer]

a little help here please... i want to make this for my phy project..and have successfuly done..till what you have done!! thanks alot for that..

now i was just wondering if I could show the teacher...a small LED bulb glowing with this tesla coil... is that possible with 1k voltage???

please answer

[JoeBeau]

1 kv is kinda high for an LED, bt they do gow, yes, at voltages like that. This circuit can be used for that. What would probably be a better idea is to use a flash bulb from a disposable camera. You can actually see the spark travel through it. Or, a small neon bulb

[tesla man]

One more question. When you said the racket had capacitors, what did you mean?