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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how do you calculate the resonant frequency of this cct?

-max- (author)  undergroundscience.14 hours ago

Sort answer, ehh, sort of? If you make some assumptions, you can make some rough ball-park calculations, but otherwise it will really depend on everything from the surroundings around the coil, how you make it, etc. And since it is a closed feedback loop circuit, it naturally oscillates at its natural frequency.

If you want the maximum peak voltages out of the secondary, then you want to operate the secondary coil as close to it's natural (resonant) frequency as possible. The problem with this, however, is that that elusive frequency depends the inductance of that coil, which is dependent on the number of turns and the geometry of the coil, as well as the permeability of the 'core' which is usually just air. Luckily of these things are relatively constant. However, the other factor is the parasitic capacitance. This will be dependent on the size of the topload, the geometry of the coil (again) and the environment. (how close conducive objects are, etc.) So really it is just not practical unless you are really trying to properlly engineer this and characterize this under certen conditions.

Roverguy12 days ago
hey max , a question please . when I got rid of trying to connect transistor parallel , I came across with an idea . the idea was : I would make two circuits for one exciter i.e to make two circuits , each having its own power supply . the input would be applied on both circuits however the wires for output ( going to l1 and l2) will be made as common . I mean to say that the wire coming from the collector from both circuits will be made common , the wire coming from the base will be made common and the wire from positive rail will also be made common. this MAY amplify a single coil and make it super powerful . will this work
-max- (author)  Roverguy12 days ago
No. I can tell you that the 2N3055 is not the reason this circuit is not as powerful as a SSTC.

You will need to learn about how this circuit works to understand why that would most likely not work. Paralleling transistors would be fine, just wire B to B, C to C, and E to E. Easy-peasy.

If you want to build an even more powerful variant of the circuit, look at this MOSFET-based schematic. It uses a buffer to drive the FET hard.
Solid State Tesla Coil Slayer Exciter.png

I am so building that

-max- (author)  PlasmaGuy1017 days ago

I have made a small error in that schematic. There should be an NPN transistor emitter follower driving the DS0026, like so:

Really, 50V is really pushing that sh*tty 12V regulator beyond it design limits. I only used 6 1/2W 1.2K resistors in series to give me 200 ohms of resistance and a nominal total of 3W of maximum power dissipation. Running at 50V, that is nowhere near enough, I would expect the resistors to get charred some. However, it does seem to work just fine!

If you build this, DEFINANTLY be sure to do something better for the 12V PSU, like a discrete wall adaptor.

Solid State Tesla Coil Slayer Exciter rev 2.png

i should have known it wasn't so easy. Do i have to use an interrupter?

-max- (author)  PlasmaGuy1016 days ago

Nope, the 555 timer and BJT is not necessary. However, my weak power supply cannot continuously deliver the 4-6A this circuit would draw otherwise. The small transformer overheats quite quickly. The purpose of the interrupter is to simply turn on and off the circuit periodically, by only powering the DS0026 for a short time.

Because it draws less current with the interrupter, the overall voltage on the filter capacitor can get much higher, and consequentially when the oscillator does activate, the rate of current change in the primary can be higher and therefore the maximum voltage on the output is much greater.

The 555 timer is nothing more than your basic 555 timer, with the exception of the diode there, which allows a duty cycle lower than 50% to be achieved, I calculated the values with a android electronics app.

-max- (author)  PlasmaGuy1019 days ago

Just last night, I got a small 50VA Transformer and connected a bridge rectifier to it, as well as another 12V 4A power supply in series with it, which can charge a large filter capacitor up to 52V, and this was connected to the circuit above, with a small modifications to interrupt the circuit so it does not draw as much RMS power.

The interrupter is nothing more than a basic 555 timer set with a 1K, 10K, and 3.3uF capacitor to output approx. 40Hz @ 10% duty cycle (it is actually a little less). The 555 is actually directly powering the DS0026 inverted buffer MOS driver, so that way that portion of the circuit to oscillate "occasionally" based on the set freq. and duty cycle of the 555.

Unfortunately, The small "variable" power supply I have been using to power the 555 and DS0026 has died. (The voltage regulator blew up internally, I guess from a short circuit condition. It is a standard LM317T, I will need to replace it. I wish the damned thing had current limiting, it relies on internal "short circuit protection" which obviously did not work at all. Oh well.)

So instead, I had to resort to using lots of 200 ohm resistors in series @ parallel with a 12V zener diode which was reverse biased, that way the zener acted like a simple shunt regulator. It worked well enough to power the 555 and DS0026 w/ 12V, however, you could feel the heat rising from the 6, 200 ohm resistors. With 50-12V = 38V across them, I calculated power dissipation to be almost 5W!!! And with only 6 1/4W resistors, the total maximum power dissipation rating was only like 1.5W, not enough. I will need to think up of a better solution soon. A buck converter or small separate wall adaptor Xformer would be ideal.

Solid State Tesla Coil Slayer Exciter rev 2.png
-max- (author)  Roverguy12 days ago
The whole circuit is essentially a low voltage blocking oscillator. You will need to majorly change the entire topology of it, and increase the voltage, and use maybe some tank capacitors to make this perform better.

You could certainly experiment with the circuit and see what you can learn. I recommend that, that is what I have done.

You can see in the FET version that I have made, I have added some shunt diodes to clamp the voltage at the input of the buffer from exceeding the rails. (9-18v --- grd). R1 provides a small amount of negative feedback which apparently helps the circuit oscillate well. I believe it lowers the gain of the buffer a little so that it can operate in a more linear fashion.
Roverguy11 days ago
I think you didn't answered ion motor part
-max- (author)  Roverguy11 days ago
I did but instructables decided to post the last comment twice, not the one I typed. ERRR.

Look at the video, and esp. for the small one, notice all the editing and cuts made? That was because it took over an hour to get it to work well. It needs to spin VERY freely (like if you give it a whirl, it should continue spinning and gradually slow down after a long time, rather than stop abruptly.)

If plasma only comes out one side, bring your finger over to the other side to "ignite" it, and if plasma only comes out one side or the other, than either your SEC is not owerful enough, or you need to sharpen up the ends of the wire.
Roverguy11 days ago
Hey max . I've been watching your YouTube videos from morning and for now , I like what your videos . I just saw your plasma speaker video just now and realized that my exciter also discharges plasma in the same manner . So the question here arrives that can I create a plasma speaker by the arcs created by a slayer exciter. 2 : My ion motor isn't working . although it is releasing ion jet but only from one side . what should I do to make it work .
-max- (author)  Roverguy11 days ago
Slayer exciter + singing arc, totally possible, but I can guarantee you it is NOT easy. You should look into DRSSTC schematics, which can play 8 bit music, and midi files, by PWM modulating the oscillator via an interrupter. Here is one schematic I have found online for a small DRSSTC, just replace the 555 section with a microcontroller that can interpret MIDI files either streamed over a serial interface or play them from an SD card.

This circuit uses 2 IGBTs in a capacitively coupled half bridge configuration to drive the primary coil of the tesla coil, and it relies on a similar feedback model as the slayer exciter, as the base of the tesla coil is connected to a impedance-matching transformer which effectively drives a buffer. That goes into a flip flop clock, which keeps the circuit oscillating even when the feedback fails, it also prevents the oscillation from getting "out of control" by continuously destroying the oscillation and 'reseting' That prevents the oscillation from getting so large that voltage peaks on the IGBTs do not exceed the absolute maximum ratings.

Honestly, I do not fully understand the circuit as of yet, and I do not recommend bending it without a thorough understanding of the operation and functioning of each component.
Roverguy12 days ago
max u said paralleling transistors is easy just connect b-b ,c-c , e-e . but earlier u said that we would need some balancing resistors between them?
-max- (author)  Roverguy12 days ago
Meh, it is not super critical for this rough and simple circuit. Even if you installed those balancing resistors, it is still quite easy. They are generally on the emitter side, so it would be:


A value of 0.5 ohms will probably be fine. If I did it as a quick test, I would not even worry about the balancing resistors. If this was a more important engineering project, that may be of greater importance. If you include these, you should take into consideration what would happen if you use too high a resistance. Remember the power dissipated in the resistors is the current through them times the voltage dropped across them, and if you know either the current or voltage across them, you can calculate the ladder, and therefore the power dissipation.

Similarly, it is better if the 2 bases are tied directly together either, it should be more like:

(Base_1)--(Resistor)--(feedback from coil)--(Resistor)--(Base_2).

The reason for this is that they have extremely high sensitivity to the voltage differences on the base, and even the tiniest differences in the manufacturing of each transistor will affect the bias voltage, and gain of said base. The value of the resistor in this case can really be a wide range of things, probably greater than 1 ohm, and less than 1k. The current to turn on the base is not that huge, 10's of mA's, so I would not worry about calculating power dissipation and just use a 1/4W or 1/2W resistor.
Roverguy14 days ago
hey max . I had recently made a new l2 for my exciter and it is made neatly . the problem is by mistake I used 29 gauge wire instead of 22 or 24 . will this affect the performance ?
-max- (author)  Roverguy14 days ago


Besides, I used 30AWG.

Roverguy19 days ago
it seems that the video u gave me doesn't works
-max- (author)  Roverguy18 days ago

-max- (author)  Roverguy18 days ago

Physicly copy/pasting the link will also work.

-max- (author)  Roverguy19 days ago
Well go to my YouTube channel Power Max, and find my video omy Tutorial Tuesday's video on series and parallel circuits
Roverguy19 days ago
and if I connect 2 same type of wall warts (12v ) . will it be fine . I will use this power with 2or 3 parallel 2n3055 and computer heatsinks attached to them so that don't get hot.
-max- (author)  Roverguy19 days ago
I think this video will help you understand series and parallel configurations a little better.

Just remember: you can only connect supplies with the same voltage ratings in parallel, and supplies with the same current rating in series.

If you do not follow this rule, either you will not get the most out of both power supplies, or worst case, you will cause one supply to destroy the other by allowing it to back-feed power into it.
Roverguy20 days ago
hey max for this project , I am using a 12 v wall wart (don't know weather it is smps or not ) . I beefed the circuit to make it work more efficiently so I need some more power . I recently bought some type of device used for IT and wallah ! it had a 5 v power supply with it. my question is that can I use both wall warts together for this circuit ( both negative as common and same for positive ) . will it work
-max- (author)  Roverguy20 days ago

The short answer: no.


The long answer: The 2 are not well matched. If you want to wire them in series, you are only going to get 0.6A, because current through a series circuit is the same through all parts. (so you cannot exceed the weakest supply current, since it will overload.) 0.6A is not even close to enough. Think 2A or more.

Also, wiring them in parallel is a bad idea because there will be 12V across the 5V supply, and the 5V supply will probably not be happy with that. If these were batteries, the 12V battery will have excessive current draw as it will push the 5V supply to have 12V in it, overcharging the 5V battery, destroying it. The excessive current will flow from the 12V battery to the 5V one will be very bad for both batteries. Regardless if the supply dies or not, the 12V supply will be the only thing supplying power, since the 5V one "cant keep up" (this is like a 2 people, a athlete, and a slob pedaling a 2-person bike. Obviously the athlete will basically end up doing all the work, causing the slob's petals to go faster than she/he can handle.)

Roverguy20 days ago
Roverguy20 days ago
12 v at 1 amps + 5 v at 0.6 amps

max, im having a problem with my slayer exiter. whenever i turn it on, it won't work for 20 seconds and even then its not stable.

-max- (author)  PlasmaGuy10121 days ago
What topload do you have on it? If it is too big, the circuit will only oscillate under certain conditions. Check the feedback and experiment with the bias resistor.

sadly, the circuit gives bad performance without a topload. any ideas on why the circuit worked again when i applied earth ground to the negative connection? i only experienced this issue when running off a SMPSU.

-max- (author)  PlasmaGuy10120 days ago

You (as well as I) need to learn about closed loop control theory and practical circuit design to fully understand the operation of the circuit, that is a really long and hairy topic, that I hardly understand. There are good videos online that explain it, but you need to be proficient at at least vector calc and physics to understand the more complex math.

-max- (author)  PlasmaGuy10120 days ago

Because capacitive coupling to grounded, metallic objects close to the circuit. The circuit functions using a feedback loop, and for that feedback loop to work, there needs to be some capacitive coupling between the rest of the L2 coil and the circuit itself. Notice there is only one connection from the bottom of the coil going to the base of the transistor. That is not a complete circuit, and theoretically this circuit should not do anything at all except cause the transistor to overheat.

Also, try raising the L1 coil closer to the middle of the circuit, about 1/4 of the way up, leaving some turns of wire underneath the coil. There will be good capacitive coupling between this 1/4 point to the Vcc (positive voltage) and the coil, which allows the voltage at the base of the transistor to swing positive and negative as it should depending on the dV/dT of the L1 coil.

i fixed the problem by adding earth ground to the the negative connection.

Got it work but i have no idea about what includes capacitors, do
they add something to performance or not(i dont notice), are they
connected the right way or not :D1 microfarad 5pieces. 0.2mm diam on secondary abot 1000 turns, 2,5mm on primary 3 turns

-max- (author)  siim.kuningas22 days ago

Because my power supply has a long extension lead (consequently lots of parasitic inductance), so when the transistor turns on for a brief period of time, the voltage will sag because inductors resist changes in current, so when the circuit tries to draw power, the voltage dips down. Capacitors, however, resist changes in voltage, and they help prevent the voltage from sagging when it is actually needed, so that way more volts = more amps = much more power = much better performance!

May 3, 2015. 6:33 AMsiim.kuningas says:
Oh right i read about it also. Didn't put the whole picture together in the end, thought it makes circuit somehow more powerul in other way also, i thought secondary takes some power through diodes or something). This is first thing i ever soldered. So dont laugh very too hard :P also i don't get how people don't get it to work :)
Using tip3055 47k resistor 18v makita drill battery, ebay 2£ voltmeter says fully charged 20V.

Warning: 40 cm is also too close, may make your expensive equipment buzz or vibrate or similar wierd stuff

Anyways thanks for your answer.
-max- (author)  siim.kuningas22 days ago

Looks just fine! I cannot see the soldering job anyway, but soldering these protoboards is always sloppy, and if you are really after neatness, then making your own PCBs or having a PCB fabrication lab make you one is the better way.


I am not sure what you mean by taking power from the diodes, because the diode is just for clamping the voltage so it does not kill the small TO92 transistors by going too low.


"Warning: 40 cm is also too close, may make your expensive equipment buzz or vibrate or similar wierd stuff"

I'm guessing you figured that out the hard way :) But if your lab equipment is properly shielded for EMI compliance, then it shouldn't do much more than act like all the buttons are being randomly pressed. (buttons are the only thing outside of the shielding, and voltage induced in the sense pins gets interpreted by microprocessors as a button press. Similarly capacitive touchscreens become overloaded with EMI.)

Roverguy1 month ago
Hey max . first of all I want to tell you is that I am not a guy who knows much about these things (these electronic projects etc.) . I have made this exciter as your instructions but mine doesn't works like your one ... any suggestions for how can I improve its performance . second : can I use a DC broadband modem power adapter for this project (12v at 1.5a .) . here are my components list ... a 2n3055npn transistor, 10k resistor , a electrolytic capacitor 10 uf (or whatever it is) l2 = 600 winds of copper wire in a 1 inch PVC and 9v of input from aa batteries (till now) and ya , I am not using a top load (mine doesn't supports it IDK why ) ... please reply as soon as possible and tell weather I can use that adapter for input.
-max- (author)  Roverguy1 month ago

Assuming you already have it sort-of working, go to step 8 for troubleshooting. I run down every possibility as to what might be wrong with it.

The adaptor will probably be fine. However, a lot of SMPS (switched-mode power supply's) like that often have overcurrent shutdown and short circuit 'protection' (foldback current limiting, if you want to google it.) So you may find that it randomly stops working, or it might just pulse power periodically to check to see if the "fault" is gone. IDK without a datasheet for the supply.


Your top load has to be really small, but not too small. It is not really nessesary, and does not do much in the way of improving the circuit that much. Really it just makes it neater. I recommend going without it until you get the thing working really well. Also the electrical connection to it has to be solid. Make sure that there is no gunk or ensemble between the magnet wire and the top load.

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