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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JasonP17 made it!26 days ago

Well Took me a minute to get it right and tuned, but my 1st Slayer exciter ..

Wrapped on a CD spindle,#30awg wire 250t s, 5t p .. 9v battery setup.. (not very powerful but works..)

#2 / 3 & 4 all work well with this circuit.

using 3 TIP29c transistors (had them in my box) paralleled

#2 ~~ #30awg wire, 540t s, 3t flat spiral primary, 1.5" former

#3 ~~ #30awg wire 720t s, 4t primary (horizontal setup for playing with Tesla's magnifying transmitter setup). 1.5" former

#4 ~~ #40 awg wire (complete pain in the arse to wind without errors)

2000t secondary, 20t primary Bifilar wound, 1.5" former.

#5 ~~ #40awg wire 750t s, 8t primary, 3" former..

I gave #1 to my nephew (10y/o) to play with and get excited as it only runs on batteries.

Overall, good tutorial! I really want to throw sparks though... I made the fat one into a sgtc, would not breakout on its own but 4" lightning when getting ground probe close to topload breakout point .. :/


Also for those looking for small easy toploads, Soda cans work well, and can be taped together for larger loads..

-max- (author)  JasonP1726 days ago

If you REALLY want to throw some large sparks of at least 4 inches, and avoid the noisy SGTC, I recommend this circuit, if you have the parts already laying around.

This is actually where the development of the original slayer exciter circuit has led me. I initially replaced the NPN transistor with a MOSFET, since they are better suited for switching applications*, and it was in a easy package type (TO-247) to mount, and already mounted to a large heatsink. I suspect because the input has some significant enough input capacitance, has a really high input impedance, and since MOSFETs need a relatively high gate voltage to turn on, the standard circuit didn't work.

My next thought was to use a comparator as a buffer, but I did not have any of those, then I found some even better dedicated MOSFET driver chips, designed for that very purpose! I used the DS0026, which is what I had on-hand! Some messing around to make the oscillation stable and strong, I came up with the first design below in the pictures. I was able to power this without issue up to 50V.

In the 2nd version, I simply added a "interrupter" to PWM the power rail of the DS0026 so that way the RMS power draw was less, and since I am no longer loaded down my transformer, the voltage has risen to 40-50V across the power rails. Consequently when the circuit kicks on and runs for the short duration, I get incredible arc length!!!!!

The interrupter that I choose was simple a astable 555 since practically that is the easiest oscillator for me to make work and breadboard up quickly. I'm driving an emitter follower transistor which turns on and off the DS0026 which in turn mean that the circuit only works 10-20% of the time, allowing some down time for the capacitor to charge back up and gives the small poor transformer and MOSFET a break. The duty cycle is of course 10-20%, while the frequicy is about 10Hz-100Hz depending on the capacitor.

Solid State Tesla Coil Slayer Exciter rev 2.pngSolid State Tesla Coil Slayer Exciter.png

i bought all the parts and im going to start building now. its going to be powered off 170 vdc, so i should have a 10 inch spark.

-max- (author)  PlasmaGuy1013 days ago

170V!? I barely had any success at 50V. I predict that this circuit will just blow up everything and possibly blow a circuit breaker. Start at 12V for this circuit and work your way up to 24V, 36V, 48V, etc.

At voltages higher than 36V, you will NEED to replace the "12V regulator" made with a zener diode and some resistors with a switch-mode regulator or DC to DC converter. Also you will NEED to get much higher power transistors, I have blown all of my IRFP250's, so my plans for making a video of the circuit are delayed.

ok, i have a big 21-42 volt 5amp psu that i can power it with. the irfp250 is rated at 200v so why won't it work at 170vdc?

-max- (author)  PlasmaGuy1012 days ago

Is the PSU a SMPS (Switch Mode Power Supply)? one of the lighter smaller ones (with tons of circuitry and lots of small transformers, inductors, and capacitors) Or is it a linear type (the simple kind usually made up of one huge heavy iron core transformer and a few diodes and huge capacitors.)?

You may run into issues with "foldback current limiting" and "short-circuit protection" sh*t kicking in and abruptly causing the output of the power supply to shut off. I have been using a modified (hacked) xbox power supply which is a SMPS but all that protection has been bypassed with some mod wires.

i know, when i draw an arc off my normal exciter for too long the 30v smps will shut down.

its just a huge 42v transformer with a rectifier and 65v 33000uf smoothing capacitor

-max- (author)  PlasmaGuy10120 hours ago

Good! You shouldn't have any issues with it! With that you should be able to get very similar results to me. What chip are you using as a substitute for the DS0026?

the mc33151pg, it's a direct replacement for the ds0026

-max- (author)  PlasmaGuy1012 days ago

Questions like that make me feel you are going to struggle a bit with getting this to work and will burn out quite a few parts, but I do wish you the best of luck. You should look into some theory of inductors and how the voltage across them relates to the current through them and such before you start building and debugging the circuit. Watch these videos:

Long story short, you need to make sure that the inductive spiking does not destroy the transistor. If it is in its OFF state, and the current that is attempting to continue to flow will need a path to go somewhere, otherwise the voltage will rise up and up and up until it forces it's way through the circuit somewhere. You need to prevent this from happening, and I found that using a capacitor can help with this. The solution in the above videos is not suitable as it will greatly diminish the output of the coil and greatly reduce efficiency.

I plan to make a similar video soon once I learn more of the math (or at least familiarize myself with it) and stuff, (like maxwell's equations etc.)

i forgot about inductive reactance. can't i just put a reversed diode in parallel with the drain and source of the FET?

if you look at the irfp250 datasheet you'll see the fet has a built-in diode

-max- (author)  PlasmaGuy10120 hours ago

You can, it will severely limit the performance at <50V. However, at low voltages, we use that reactance to our advantage with a resonant capacitor (C1) to allow high voltage ringing on the primary, which translates to really super high voltages on the secondary, which is what we want. However, at 170V, I suppose we no longer need to rely on that ringing to get those high voltages, However, I have not tested the circuit on such a high voltage supply.

I would recommend using at least a IRFP460 or better and calculating the correct capacitor to use for C1. There are tesla coil calculators online to make it much simpler.

oh BTW im not using an interrupter

-max- (author)  PlasmaGuy1012 days ago

Then 5A may not be enough to power the circuit above 30 or so volts, it may be demanding more. My reason for the interupter is that it gives it a tesla-coil like output, much longer sparks, and significantly reduces current draw.

-max- (author)  JasonP1726 days ago
Nice output!
JasonP17 -max-26 days ago

thanks.. I have a nice 8" tall aluminum sugar jar I use as topload to extend my range with the 2kt coil.. I get about 2ft with cfl, I can also open Outlook express on my pc from 10ft at certain spark lengths... lol..

I was also thinking of a Mosfet approach, I have a ton of logic lvl 900v fast switchers.. gth 2-5v most came from pc psu's, as well as all the shotsky diodes.

How do you think a 2SK2611 or 2SK2749 would do? They perform rather well with a ZVS setup on flyback limited with 3.1v zener. Maybe I'll try to drive them via 555 since they are logic lvl.. I try not to buy parts but recycle from craigslist items, ie: tv's, printers etc...

2SK2749 : RDS: 1.6ohm, VDSS 900v, VDGR 900v, Vth 2min 4max ..

150w dis.

2611 is very similar lower rds : 1.1

Only thing I dont have is a fet driver .. I wonder how hard it would be to try and incorporate a zvs mechanism, as they are extremely efficient..

-max- (author)  JasonP1725 days ago

I was not able to get any reasonable output with a ZVS driver I think because it is too slow of an oscillator, if that's possible. I will maybe give it another try some day, but we need an oscillator that can work well into the MHz. The standard ZVS circuit I see is generally in the 15-60 KHz range, perfect for large ferrite transformers.

i80514 days ago

hey max

i have read and watched your wonderful indestructible many times

i have a problem. I've been working now for days but haven't figured it out

the circuit works fine with a signal transistor like bc337 h945 (6AA=7.5,weak cells)

but when i replace it with a power transistor for more power it just refuse to work

when i crank the bias resistor(lower it) the transistor get's hotter and hotter but the led stays off(different power source 5V/12A,12V/3A/ from a psu)

the power transistors are d13007k ,c4242,5027s,i pulled them of a computer power supply i've checked them all in a simple led circuit they all made the led lit with a bias resistor

i can't get ANY salvaged transistors to work, its really strange. i found a TIP42c PNP in a fan speed controller, to use pnp transistors you just have to reverse the power supply.

-max- (author)  PlasmaGuy1012 days ago
I also have a lot of trouble with getting savaged transistors. That is why I recommend buying them instead. They are not that expensive, and you have a much higher level of confidence that they work. if you are really inso salvaging transistors, look into building a transistor-tester project, or buying one on eBay or something. They used to be super common, when transistors were very very expensive. Now no one wants them and you can pick them up pretty cheap. I literally got one for $0.50 (absolutely nothing) at an auction!
-max- (author)  i80514 days ago

Weird, maybe recheck the pinout of your specific transistor in the datasheet, the pinout between different package styles (TO-92 vs TO-220) is very annoying.

If they came out of a PSU, they are likely power FETs. High power NPN transistors are becoming increasingly rare to find in the "wild." Although it seems like the transistors you listed are in fact NPN, so I guess you already researched them.

If you still cannot get them to work, build up a quick and simple transistor tester to see if they are good. If you salvaged them from a dead PSU then it was probably dead for a reason. Worse case, order a few MJE3055s.

i805 -max-14 days ago
the pinout are BCE like all power tra as i've noticed even mje3055s.
they are not fet the datasheet tells they are npn tra.
the tra tester verified they are ok.

i dont have access of buying parts and even if i did what would be the fun of it :)

i'll try them on a joule thief
or maybe the joule thief which is oscillator can work the coils, just a thought
-max- (author)  i80513 days ago

Well I wish you the best of luck at figuring out why it doesn't work! You mentioned everything I would have suggested with your comment! Something I wish other's asking for help did!

Did you try changing the number of turns on the primary when switching over to the power NPN? I find that a lower number of turns is required which allows lower inductance, faster switching, and more current which compensates for the lesser turns in developing magnetic flux (more turns and/or more current = stronger magnetic field.)

You're on the right track with attempting another circuit to test the transistors, esp. if you already familiar with joule thiefs, emitter followers, transistor drivers, oscillators, etc.

JasonP1726 days ago

I'm going to try this setup, some small mods to your mosfet design.. I'll let yall know how it goes.. mainly cause I have no driver ic..

Bjt's: Tip31c npn, Tip42g pnp



I fried my xfmr after 5 mins of use.. got extremely hot.. (under-rated 1.5a) replaced the thermal fuse, but still no go.. :(

Worked ok for the 5 mins though.. 1cm streamers right off the bat..

-max- (author)  JasonP1725 days ago

Cool! Too bad you killed the transformer, you will probably need o get ahold of a much more powerful power supply. I also was using a really small 2.5" by 2.5" by 2.5" transformer that I assume is 24Vrms @ 2A max, though I don't know. It certainly seems to get very hot withough the inperupter.

JasonP17 -max-25 days ago

Also, Off the 555 output I used a simple npn transistor inverting buffer to try and stay as close to your diagram as possible.. Maybe it was just too inefficient.

You mentioned that you originally were going to use a comparator, I have 6 lm339's and a couple hex inverters, Any chance you could share how you were going to set that up? My comparator experience is limited..

-max- (author)  JasonP1725 days ago

The thing you need to keep in mind is that simulations are not the most accurate. For instance, did you have to define the K coupling constant between the L1 and L2 coils? Air is not a very good "conductor" for magnetic fields, it does not have a great permeability. As so, much of the magnetic feild is lost because a testla coil is a open air-core transformer. This makes it good for RF applications because the losses (from magnetic hystrisis) from using a core would be devastating.

-max- (author)  JasonP1725 days ago

Well looking at the way you wired/configured the NPN and PNP transistors you actually made a normal non-inverting buffer, one that has a low output impedance and a high input impedance. I do not think you will need the resistor that bridges ground and the FET.

Also, it looks like the oscillator is mainly dominated by the 555, as there is a relatively small resistor between that buffer amp and the FET, while the resistor between the L2 coil and the fet is an order of magnitude higher, so it has negligible effects.

ElectroBOOM on Youtube (check him out, he is amazing!) has made some recent slayer exciter/SSTC videos, and he was achieving similar output as me. His circuit I think is more efficient, and he uses a different MOSFET driver/buffer.

JasonP17 -max-25 days ago

Yeah I ran mine through a bridge multiplier for 80vdc pfc possibly part of the issue. I have a large smps xfmr with +/-35, +/-24, and +220vsecondary windings, with the schematic and the controllers for it.. may have to put it together.. only requires a few externals for the controller.. may have to..

Should be able to increase my current draw as well like an atx supply.

It supplied the main power for the projection tv I salvaged.

I also have a MOT that I may rewind for 24 - 48v.. That should definitely handle the current..

The atx I was using popped on a nice 10" white zvs arc via flyback..

but here was some of what I got before failure:


ok this time I've copied your plan to the letter with exception to the capacitors. As I can't find them in the city.

Still no luck.

Checking the battery voltage when connecting the system sees a 1volt drop

-max- (author)  robert.joyce.3132 months ago

What battery are you using? In my video shown in the instructable, I used a regulated 12V power supply that is capable of delivering 2A peek for a short duration, and 1.5A continuous.

So I assume you used a brand new MJE3055?

I bought a TIP41C transistor

I screwed a piece of metal to the back of it to act as a heat sinc

If the pinset on the TIP41C is the same as in your video, then they're setup the same.

I'm using a 9Volt rectangular battery.

Just tried connecting my 12Volt car battery.

Same. nothing happened.

On the power site of my 22k resistor, I have 12V, on the other side of the resistor I only have 0.5V

Is this correct? Doesn't sound right to me.

-max- (author)  robert.joyce.3132 months ago

Whats confusing about this instructable is that it is a bit fragmented. I have 2 versions of the circuit built up, the older version, for which I used a few 2N3904's, and it is not very good, and also the version in this video is better.

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