Building the poor-mans mini tesla coil ( slayer exciter)

Picture of building the poor-mans mini tesla coil ( slayer exciter)

A slayer exciter is basically a small solid state tesla coil, usually a one transistor design. The circuitry for it is simple. One of the first things anyone who has built a joule thief will notice, is that the circuitry is very similar. The biggest difference is that the small transformer or inductor has been replaced with a primary/secondary tesla coil configuration, and that the feedback is capacitively coupled. (There is a good abount of capacitance between the 'top' of the coil, and ground.)

There are many awesome thing these exciters can do!
they can:


  • neon lights!-----------------------------------------(several feet away)
  • florescent tubes!----------------------------------(within about a foot)
  • CFL's!-----------------------------------------------(within about a foot)
  • EL wire---------------(it does not work well for me. If anyone tries it, please tell me your results!)
  • LED's!-----------------------------------------------(across the room if done right)
  • and even small incandescent lights! -------(with an L3 coil)
  • paper with pencil markings -------------------(before it catches fire!)

Burn and ignite:

  • candles
  • wood (pencils)
  • human flesh (now my fingers smell burnt)
  • paper


  • crappy / half dead LED's
  • bacteria
  • sensitive electronic equipment (phones, computers, SD cards, CD's, blu rays, flash drives)
  • someone else's stuff


  • ion wind motors
  • the coolest lantern or light on earth
  • fires
  • plasma cutter

►Make following electronic equipment go crazy:

  • calculators
  • watches
  • digital clocks and alarms
  • devices with capacitive touchscreens (PlayStation VIVA, smartphones, feature phones, tablets)
  • UHF remotes

Transmit wacky sounds (loads of EMI) to:

  • AM radio
  • FM radio
  • shortwave radio
  • HAM radios possibly
  • TV interference

Here is how to make a my version of the more powerful exciter (These videos were made awhile after this intructable, so the only issue with it is thermal management.) Please do not get the instructions in this video confused with the instructions for the later TO-92 one in the further steps. Different bias resistor values should be used for either of these 2 versons.

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Ashiz23 days ago

max do u think mine works as same as yours at beginning . no this is the performance what I got after touching the CFLs tip to the l2 upper open wire so please can u try to resolve this

-max- (author)  Ashiz23 days ago

Well all I can really tell you is to mess with the number of turns on L1 (primary), and try different resistors.

Try increasing or decreasing it and see what changes. Also, try lower values for the resistor if the transistor is cold, and if it is overheating, try higher values. You may find that for better performance, you will need to get a large heatsink for the transistor. I see that there is none on it at the moment. Since the TO-3 package is mostly obsolete, see if you can find one of the transistors mentioned in the original 'able in a standard TO220 or TO-247 package or similar.

It just takes patience, tweaking, and the right tongue-angle to get it working to perfection. The fact that is does light up a lamp means that the circuit is built correctly, and perhaps adding more capacitance across the power input to the exciter will also help improve performance.

smithraj23 days ago

Hey max .. I got your message of Get rid of those LEDs. Those
red and especially the HORRIBLE yellow/amber LEDs, they will not live one
second! I healing the LEDs and capacitor. I some changes in schematics . I add
the 47 k resistance from plus of power supply 12 volt. Two diode in series .The
minus legs goes to TIP 31C of Emitter. Collector
goes to the L1 and L1 one goes to
positive power supply. The Base is going through Diode on L2. I see the TIP 31 C not heating while ON the power to glowing the cfl OR neon.And not necessary in Heat-sink.

Now L1 –
9 turns while L2 is 830 turns .. And it’s a magic see the picture. So thanks a
lot max . I research ., how to increase the distance of this Hz for glowing the
cfl & neon dark light up.

-max- (author)  smithraj23 days ago

I don't know what you mean by 'healing' the capacitors, but to improve performance, you can try to fiddle with the number of turns, and decrease the resistance. Try halving it, to about 10k, then to 4k, then 1k.... you get the idea. That heatsink should allow enough thermal dissipation for lower resistances to be used. Glad you got it working!

dj whatever25 days ago

hey man, great one. i got the parts to build it but i saw only the schematic and i bought in4002 diodes instead of LEDs. do you think it will work? i don't have a breadboard to try it out and i want to print a pcb for it. I'm just trying to avoid double work. :) thanks in advance man.

-max- (author)  dj whatever25 days ago

You will not need any diodes at all. They can be inserted, sure. But the version I made in the video did not actually use and LEDs or diodes. (I learned halfway though making the video they were not necessary, but was too lazy to reshoot all the footage of building it, or remake the schematic the beginning of the video.) They can be used, and help with protection of smaller transistors. Also, they work nicely as indicator lights, and can show when the circuit is oscilating properly.

ok man, thank you very much. i will post pictures when i finish it. my problem is the copper wire. i can't find any in my city so i have to salvage lol. i'll see what i can do hahaha. i hope it works.

-max- (author)  dj whatever24 days ago

You can get enough magnet wire from eBay

smithraj27 days ago

Ok max . This the circuit which you given above 3 circuit . one of them. But i used the TIP31C Transistor. 10 uf capacitor, 1 m resistance, L 1 - 3 to 5 turns. But L2 is 830 turns. & give its step by step power supply ., 2 V,4v,6v,8v,10v,12v., .every thing is as well ., Nothing glow cfl or neon.. pl see the pic of circuit. .. Can i use your three transistor (3904) schematics (while my L-2 830 turns )?

-max- (author)  smithraj27 days ago

YOU CHEATER! I see you have a resistor calculator open in the background. Nope. Got to use paper and ohms law to do that to be a proper engineer! lol ;)

Get rid of those LEDs. I will need to add a note to the instructable to not use anything other than blue/white LEDs. I found that even they burn out rather quickly, when using 2N3904s, and a small 9V power supply! Those red and especially the HORRIBLE yellow/amber LEDs, they will not live one second!

They aren't necessary, and you may have already killed them, causing them to act like short circuits, so I would remove them entirely. Use the avramenko plug and some super bright LEDs near the output coil instead to see if it is working. Then do all the basic troubleshooting stuff again.

AV plug.png
Ashiz27 days ago

Oops sorry I commented 3 times

-max- (author)  Ashiz27 days ago

Was that the best you were able to achieve after changing the number of windings and messing around with that resistor value? It performs as well as mine did when I first built the circuit, it took a long time to discover the perfect conditions for it, and even knowing that, if I wanted to rebuild this ciruit right now, I would spend many hours tuning it. That is not bad. Glad you got it woriking!

Ashiz27 days ago

max see this one . if anything lights then by touching the upper wire of the l2 and for the fair ,no need to worry as I showed it with this performance .

Ashiz27 days ago

max see this one . if anything lights then by touching the upper wire of the l2 and for the fair ,no need to worry as I showed it with this performance .

Ashiz27 days ago

max see this one . if anything lights then by touching the upper wire of the l2 and for the fair ,no need to worry as I showed it with this performance .

Ashiz27 days ago

max see this one . if anything lights then by touching the upper wire of the l2 and for the fair ,no need to worry as I showed it with this performance .

smithraj28 days ago

Dear max .. I made the L1 & L2 on the projects board.. L1 is the 5 turns of copper wire. L2 is the 830 of magnet wire. And the voltage of 12 V. use the 2 led in series. But there are nothing effects.. So what i do next? which schematic i use for 830 turn? look the pic of my tesla coil. please reply max...

-max- (author)  smithraj27 days ago

Also, do not rely on email notifications anymore, they have stopped working completely. Just come back later to see if I have replied. (I have already submitted a bug report, a question, and emailed instructables about that.)

-max- (author)  smithraj27 days ago

Where is the rest of the circuit? What transistor are you using? Have you already did everything the troubleshooting guide has covered, like reversing the polarity of the L1 coil to see if you can get any output at all, or adjusting the number of turns on L1?

If so, then double check your wiring, and test your transistor. There is plenty of comments below of me helping others, and I think you nmay find some of it helpful if you digg around for my previos replys. (no need in repeating myself!)

smithraj1 month ago

can i use the 2 cm OR 3.4 cm diameter pvc water pipe ? can i use the TIP31C transistor instead of the MJE3055T? which schematics used in your video version? The image in bellow.

pvc pipe.jpgTIP31C.jpg
-max- (author)  smithraj1 month ago

There should be a schematic at the very beginning of the video, just use that. That transistor should be fine if you do not push it as hard as I did to the MJE3055T. (In other words, I would not exceed 12V.) The black pipe might be problematic since they often use carbon to achieve a black color, and carbon is conductive and will effectively short-circuit the output.That white pipe is really large, it will work if you can get at least 600 turns of wire on it! I would use one of the other 2 pipes though.

Ashiz1 month ago
Ok first things first ,exciter is working ... But in a very strange manner as shown in the pic . I tried to light up a led but it doesn't lighted until I don't touch one end of the led to the l2 output wire . when I tried to fine tune it by adjusting the no of coils ,it didn't worked . then by shaking the wires it came to life again but the led didn't lighted till I don't touched . I tried with a cfl but same results . plz help me for that and now I have plenty of time for the fair as it is postponed to 22 Feb ....,... see its performance in the pics uploaded... And ya my exciter isn't supporting a top load ...
-max- (author)  Ashiz1 month ago

Sorry, I did not get any emails that you have replied back. I hope it is not too late, but anyway, what you describe is somewhat normal. I will have the same thing happen to be when waving the fluorescent tube around the exciter. If I let anything actually make electrical contact or get too close, the output of the exciter will greatly diminish. Try moving the primary coil up a little so there are some windings directly below it, and see if connecting the negative of the power supply or battery to a earth ground connection helps with output. I forgot to mention that in the video and 'able.

Ashiz1 month ago
Photos aren't uploading
Ashiz1 month ago
Max my exciter isn't working even after new changes . I rechecked everything many times .I also built it very neatly and even I checked all my components and they all are working , what would be the problem now .
-max- (author)  Ashiz1 month ago

Probably not enough turns, get a better power supply, or alkaline batteries (Do not bother with any battery that says "heavy duty" or "Ultra duty." They are exactly opposite of that claim. (The fine print says for light loads).)

Also, like I said for the 3rd time, the CD is bad choice. Get rid of it. Also remove the heatsink and see if that helps.

Ashiz1 month ago
Max I haven't checked it yet so I don't know that it works or not and the reason for this is that I am a little bit afraid as I am working with capacitor . I want to ask that if something is wrong ,will it blast or give me a shock (if I am in contact with coil ) or something like fire .?¿?¿???
-max- (author)  Ashiz1 month ago

No, unless you are working with high voltage capacitors, like those found in a photoflash circuit, microwave oven, single phase induction motor, TV monitor, or the mains end of a switch mode power supply, you are perfectly fine. I did use a photoflash capacitor for it's lowish ESR and ease of handling, but it is important to note that they can store lots of voltage and shock you badly, if you chage them up to such high pontenials.

-max- (author)  Ashiz1 month ago

No need to be scared of it. Don't connect it backwards, and you will not die!

Even if you did mistreat it, the worst it will do usually is vent some steam and electrolyte, and scare the living sh*t out of you is you are not accepting it and you are concentrating on something really hard :P That this video by Afrotechmods:

Ashiz1 month ago
Lol is occured as you said . I was making a very silly mistake which I realized While rebuilding the circuit . I was connecting my negative and positive of my battery to one end of my resistor and one to the primary coil wire. ? A very silly mistake but now I k ow it so I'll not make the mistake again ... And I am sorry for wasting your time by again and again asking questions which were because of my mistake so sorry .......
-max- (author)  Ashiz1 month ago
No problem ;) Just glad you got it working!
Ashiz1 month ago
Sorry I wrote it wrong in starting I want to say 'lol it occurred '
apillai57 months ago

Hey Max!! Need help. It is a 300w ups board and transformer any idea how can i make it
more powerful and the batteries in the UPS are in pretty bad condition
the acid dried out and only solid particles inside now .

-max- (author)  apillai57 months ago
If by more powerful you mean make it last longer on a charge, I would toss the old SLA batteries and replace them with a few LiPo packs that are higher capacity and can deliver high current. Some the large LiPo batteries con deliver over 200A so they should be powerful enough.

If by more power you mean maximum wattage output, then you can try to replace the switching elements with beefier ones (maybe IBGTs?) otherwise if there is a feedback loop for power regulation, your out of luck unless you can reverse engineer the board.

Anyway what does this have to do with the slayer exciter?
apillai5 -max-7 months ago

Will This Work Fine ??

-max- (author)  apillai57 months ago

It looks dangerous, I would not trust that many transistors paralleled up. It would also be very power-wasteful as the poor TIP122's would have to supply a lot of current to saturate the transistors. I would instead replace the switching elements in the UPS with high power ones. See there are wimpy TO-220 packages? Replace these with an equivalent part in a TO3 package. If you can find a shunt resistor on the 220V output, short it out. some shunts are small SMD components and just replace them with a thick copper wire. You can set the current limit/shutoff by changing the thickness of the copper. By decreasing the shunt resistance, the voltage drop developed at whatever current is smaller, thereby tricking the processor to think you are drawing little current when in fact you are drawing way more. This is also dangerous, so dont go too crasy with tweaking the power output. Safty is built in for a reason.

apillai5 -max-1 month ago

if u r on facebook can u plzz add me heres the link :D

-max- (author)  apillai51 month ago

Umm, no thanks. FB for me is for family and close friends. (I do not use t much anyway :P )

apillai5 -max-7 months ago
(removed by author or community request)
apillai5 apillai57 months ago

Anyway what does this have to do with the slayer exciter?

i was
thinking of removing those transistors and Relay remember ones u told to
buy some relays ??? In that bring dead batteries to life ? :D :D

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