Have you ever wanted to build a high voltage devices to make sparks like Tesla Coils, Marx Generator, and so on.. But find it too compacted or difficult to build?

Well, this instructable is for you! It can make create a few kilovolts of static-like sparks, and best of all... You can make it with only two things to make it, a battery and a simple mains transformer!

Before you continue, you should know a little bit of information about transformers, click here to find out.
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Step 1: Get the things!!

Like I said, you need only two things to make it, well, actually, three things - some wires.

  • 9 volt battery.
  • Mains transformer
  • Wires

The mains transformer, you can find those in just about any mains powered electronic devices, like VCR's, stereos, and stuff like that, you can also use a wall wart if you want. The best mains transformers you could ever use is found in digital alarm clocks.

Unfortunately, I burnt up all of my alarm clock transformers while ago... :( So I will have use a transformer from a VCR.

Step 2: Wire up the transformer

Okay, before we attach the wires to the transformer, you need to take a look at it first...

The two leads of the transformer that are connected to the mains power source, is the primary (the high voltage side), and the other two leads are the secondary (the low voltage side).
We are going to connect the transformer in reversed, I mean the primary (the high voltage side) of the transformer becomes "secondary" and the secondary (the low voltage side) becomes "primary".

So we are going to connect the battery on the primary (the low voltage side) of the transformer and we will get some sparks from the secondary (the high voltage side)!

Right, attach the wires to the transformer!

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BR-5498 days ago

Great job Plasmana. An excellent example of high voltage induction. For those whom electrical knowledge is lacking, a simple, cheap and safe way to observe a spark. For those who say this doesn't need to read more carefully. Plasmana said to TAP the positive terminal....not TAPE it. Plasmana did not say that you would get continuous sparking. You get one spark for one tap. Turn the lights down and you will see it. Thanks Plasmana. And 73's.

spirit x1 month ago

dc to ac is not possible without a capacitor and diode . isn't it ?

BitF1 spirit x12 days ago

if you just keep pressing the button it makes an ac current every time you press the button

bossboy 4713 days ago

hook up a moter to make the shock consistent.

wpnman997 months ago

That's pretty awesome. I am looking into building an electric ignition spark system for an aerosol based flamethrower. (With a pistol grip for spray painting and whatever aerosol that is flammable). I am thinking this idea would work great. Thanks!

cool im using mine to build a ultra high voltage emp so far it only works on small items like iphones my sister killed me when i broke her 5S

mjcole823 months ago

This won't work. DC does not transform in this way. At most you might get a very brief spark when you disconnect the battery from the EMF collapsing in the opposite polarity.

private_14 months ago

if you want bigger spark than

Use a 9vdc to 240vac transformer then 240vac to 600vac transformer

wpnman997 months ago

If I do get the transformer from a wall wart, what's the output I should look for?

the lower the normal output voltage, the higher the voltage when run the other way around. Sorry, that's all I can say without more research...

Can U Tell Me How Can I Get Continuous Supply From The Transformer ? By Using A 9v Battery

I don't recommend trying that, since even for steady AC you should push the switch at least 40? times a second. you could just use a diode, but I recommend trying a step up converter. also, what do you need (+-) 400 v DC for? then I could maybe help you think something up.

How Can I Use A Diode The Transformer Has 4 Pins 2 Pins Of Primary And 2
Of Secondary . This Transformer Actually Converts 240 V Ac To 12 V Dc
So I reversed It And Now It Give About 220 V Ac As I Switch It On And
Off . I M Using It As A Step Up Transformer . I Use It To Charge My
Capacitor Bank . Also I Have Have Tried A Bug Zapper Circuit But My
Transistor Died Very Fast ( Disposable Cam Same Issue ) . So I Use This
Transformer Also I wanted To Make A Inverter I Tried To Light a CFl Yes
It Lights Up But It Is Difficult To Find Out That Is It Burning Or Not .
Yes IT Is . So Plzzz Send Me A Schematic For Continuous Supply .
Should I Use A Relay Or A 555 Timer And Can U Tell Me How Can I Use A
Diode . I Live In India So My English Is Bad And I I m Just 14

Hi Apillai,

I suggest that to charge a capacitor bank, you research some coilgun schematics. I've got one here: I haven't tried this one, but it seems like it would work? if it doesn't, just try something else for coilguns.

Thnxx But I Need A Portable One Yeahh I got a bug zapper work great thnxx for u r anticipation . thnxx and srry to disturb u

I think this might help: If it doesn't, just search for some other coilgun schematics. good luck! I personally don't know about 555 timers..

If you're planning to do stuff with capacitors, make sure you know what you are doing or have an adult guide you, since if everything works there are hundreds of volts just waiting to zap you.

Good Luck!

I actually may have a need for 400VDC (or so). I was looking for a simple way to modify a simple solar light to power a voltage amplifier to deter small animals. I figure that I could bang these out on the cheap given a simple circuit and perhaps chase off many different pests depending on the design/bait. Thanks for looking !

Hello Farmer Ben,

you might be able to do something with the circuit from a disposable camera's flash! there are a ton of projects related to this on this site. If that isn't what you're looking for, you might try something related to coilguns. (they work with capacitors too)

Make sure you also have some way to only let it work on the targeted animals, and not on the neighbor's kid or small dog!! (you don't want any trouble)

Good luck!

indy197011 months ago
try this on get mechanical relay with a normally closed contact .
take the + from the battery go to the relay coil>> out of the relay coil to the transformer>> from the transformer to one side of the normally closed contact.
Then take the - battery to the other side of the normally closed contact. it will buzz the relay sending pulsed dc to the transformer stepping it up and giving you a higher frequency spark.
apillai5 indy19705 months ago

Can U Tell Me How Can I Get Continuous Supply From The Transformer ? By Using A 9v Battery

vgilankar1 year ago
What if I got an old transformer? reply plz!
how would i use the transformer if it has four connections on one side then two on the other side?
vgilankar1 year ago
If I try this with a 6v battery with other 3v battery would it be work same?
Erkel971 year ago
since increase in voltage means decrease in amperage (right?) and amperage is the biggest danger to humans with electricity, Can this be used to shock people?
Jaguar935 years ago
(removed by author or community request)
Plasmana (author)  Jaguar935 years ago
Please be more specific what you are trying to say, you are speaking rubbish.
I found a transformer in one of my computer speakers, so am I suposed to connect the 9v battery to the output side and on the input side well be the high voltage?
Yup, works like a charm.
did you respond to me?
Yes, I was confirming that if you connect a low voltage on the output side you will get a high voltage on the input side. Since nothing is free there is a corresponding loss of current. There is also loss in the device. Both of these will vary signficantly depending on what the original intended use is. Your speaker transformer is probably an audio transformer. You might get better performance if you break open one of those cheap plug in power supplies.
I now have a digital alarm clock transformer. Is it good?
Yeah that should work. What you really want to do is experiment. In this case your local library will be an invaluable resource. While they won't have much on digital all that old analog stuff is still valid. By going back and looking at the old AARL handbook and various electronics books you can find a whole host of useful circuits and technologies.
Lol, one more chime in here... Don't forget about your local used book stores. I have picked up tons of information on everything to little known meter tricks, to ICs, RF, DC power supply, Laser experiments. Don't think I've ever paid more than 7 bucks for a title either. One caveat though... it all tends to be from 70-80s but I find in some instances you get some more basic information than you would in some modern books.
"There is also loss in the device." My understanding is they operate beyond 90% efficiency on 60hz input, just food for thought. Definitely interesting devices to say the least!
transformers work with any type of electricity AC or DC its the flow of electricity that makes them work not the alternating current of AC though they work better with AC try it if you are any kind of tinker (which is what this website is for) you'll have a transformer lying around and can hook one up like this in 5 minutes plus if you are only momentarily connecting the battery to the the transformer it IS in actually AC if only momentarily
are you completely sure about the DC part. when you seee transformers in DC circuitry it's usually used along with transistors that turn the DC power on and off, simulating an AC wave pulsing the primary coil, magnetizing the metal core, then a pulse exits the trans on the secondary (or back out the primary (DCtoDC boost)) from my experimentation, if you connect DC voltage to a transformer it wont do anything at all, except blow some fuses/breakers. all that with no output at all on the other side, till you turn the DC input off. but if you're turning DC voltage on and off its not DC anymore.
you made sum correct comments but,,,, i dont think your correct in implying that if you switched DC on and off it simulates AC, if anything it simulates pulsed DC and yes if you turn DC on and off its still DC only pulsed,, also this leads me to believe that transformers are dependent on pulsed current in order to work and not necessarily on the change of current direction such as AC, so AC works not because its changing direction but because its having a pulsating effect above the zero line on a graph just like the output of a rectified AC. Al tough I read many times that it is the change of direction that induces a flux to the secondary,,hmmm but then why does a pulsed DC work? it has no change of current direction since it never goes below the zero line and stays in the same direction. something to think about i guess.
I am not an electronic technologist actually I'm a mechanical design technologist and welder but yep actually what I read was that you need AC in order to work a transformer properly but this is not because of the changing current, but I believe it is because AC is behaving like a pulsed wave and it is these ripples that generate the inductance in the coils and run the whole thing, so if you plan to use DC it will still work provided you make the signal a pulsed one via transistor or other devices, it seems even some mechanical devices such as 5 volt relays work too but I am guessing the output will appear pulsed rather than high repetition rates that are observed with solid state devices like transistors which make the sparks look continuous due to the high frequency. Or I could be wrong about the AC thing, anyone welcome to comment.
wiki said,' Hypothetically an ideal transformer would work with direct-current excitation, with the core flux increasing linearly with time.[39] In practice, the flux would rise to the point where magnetic saturation of the core occurs, causing a huge increase in the magnetizing current and overheating the transformer. All practical transformers must therefore operate with alternating (or pulsed) current.'

but i could have put that on wiki.
wiki said, yeah, it also said phosphine (well not phosphine it was a different molecule) had the biggest "butt" of any molecule...
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