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.

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)--------------(less than an inch (still wireless!) )

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 cutters

►make the following electronic equipment go crazy:
● calculators
● watches
● digital clocks and alarms
● things with capacitive touchscreens (PlayStation VIVA's, smartphones, feature phones, tablets)
● UHF remotes

make wacky sounds with:
● AM radio
● FM radio

Here is how to make a more powerful exciter (These videos were made awhile after this intructable, so the only issue with it is thermal management.)

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AdityaT33 days ago

***Please reply. This is an EMERGENCY***

Hello! I have been trying this circuit for a while now but I haven't succeeded in making it. I have used all the components you have mentioned and also tried replacing them with other equivalents but it just doesn't seem to work.

I get no voltage across the primary even when taking the input voltage up to 18 volts. And even when I do get a little voltage at times there seems to be no induction between the coils. I have used a 22 AWG coppoer wire for the primary (4-5 turns) and a 30 AWG wire for the secondary. The secondary is roughly 7-8 hundred turns (diameter of the secondary being roughly 1 inch and the length being roughly 7-8 inches).

I have been used a MJE3055T and also TIP41C transistors but didn't get any results.

I suspect there is a problem with the coils because it seems I have been doing everything correctly except for the coils.

Please help! I have to present this project on Sunday, Feb 1.

Thank you!

-max- (author)  AdityaT33 days ago

I am pretty certain that's the issue. With the small TO-92 transistors, the pull up resistor can be a really high value, 10kohm or higher (one darlington pair configuration, I was able to use just 1Mohm!) but with large transistors like the MJT3055, to get appreciable output, you need to use something in the order of 1K. The higher this value, the less power dissipation the transistor has to handle. Increase it if the transistor gets too hot. Lower values will raise the power output marginally up to some certain point, and can cause excessive heating and power dissipation.

-max- (author)  AdityaT33 days ago

Have you made sure the phase of the coils are correct? Try reversing the polarity of the L1 coil, or winding it the other way around. It is very easy to make that wrong. If you are getting no current draw at all, either try a lower value pull up resistor, if you still get nothing, replace the transistor, as it is possible you have killed it. Is your supply limited to 1A or so?

I generally test NPN transistors by connecting the emitter to ground, the collector to a small 12V lamp, which goes upwards to 12V, and the base to a 470ohm -- 2K resistor. When the other end of the resistor is floating or grounded, there should be no light from the lamp. When that end is instead died to the 12V rail, there light should light up brightly. If not, though that BJT into the FAIL (cue sad_trombone.mp3) bin. :)

Also, how are you measuring the voltage across the L1 coil? You cant do that with a standard multimeter, and especially not with the DC setting. There should be a lot of high frequency AC there, with lots of harmonic distortion. (a pretty nasty waveform) Is is best to analise that with an osciloscope to see the voltage graphed out over time.

The 1 inch diameter of the L2 coils is a bit on the small side. If you have a look at Gbluer on youtube, he has done a LOT of work with this circuit, and has found that the diameter needs to be quite big, like around 3+ inches. That will increase the coupling between primary and secondary and improve the efficiency of the circuit.

Superb experiment .THANKS !!....but 3* 2n3904 or 2n2222 ? which ones better ?

Hi! Awesome instructable. Would you mind explaining to me briefly how a Slayer Exciter works? (background information is welcome :) ) Thanks!

-max- (author)  thotthecreator1 month ago
Did you watch the video yet on how to build this? I explain the operation of it at around 0:07.
I really want to try this if it runs on such low voltage ! :)
-max- (author)  Dylan4011691 year ago
I will work as low as 4.5V, and will make the LED's glow at 1.5V (white LED's usually require 4V to light up)
dear max,
thanks for your reply. Recently I have succeeded in making slayer exciter. thanks to you and other people like you who have shared their circuits in the net. During my trial and error I find out after burning my fingers and few transitors and leds that 2N2222A, 2N2222, TIP 42C,
are best for this purpose. I need to try a few more to conclude this though. As per the size of secondary, I have succeeded in making 2"x 0.5" to 4.2" x 7.8" work with different circuitry.
Anyway thanks again for everything.
-max- (author)  roktim singhaR2 months ago

Lol same, those small TO-92 transistors can be quite fuzzy and fragile! I have my share of burns from them too! (I can now tell if any components even get warm without touching them, based on the smell of them while running lol!)

I recommend using a nice large TO-220 based transistor like the TIP32C, TIP42C (which you found works well) or even more beefy ones like the MJE3055 or TIP3055. If you have a TO-3 heatsink, the 2N3055 can really deliver too! I have about 10 of those now but no heatsink to use them with yet. In my 'able, I actually burned out all me 2N2222's and 2N4401's by troubleshooting and cranking up the volts too high, so I had to resort to 3 2N3904's for the job. They are not that great unless you pallelel 3 or more together like I did, then they work wonders!

I didn't know the secondary was so small in yours, I would have said to make it at least as big as mine, because the very small ones are very difficult to make work. Often even the best setups w/ small secondarys only make a neon grow at very close range.

Hey max...wonderful job done. Congrats.

I could use a little help from you designing one.

my circuit consists of the following:

1. .22uF film cap

2. 1K resistor

3. 9-24V variable dc supply (already experimented with varying voltage within range)

4. 29 gauge insulated copper wire for secondary

5. 21 gauge insulated copper wire for primary

6. primary turns 500

7 secondary turns 5-10

8. IN4007 diode

9. MJE305ST transistor

10. dia of seconadry 2.3 "

11. Length of secondary 6"

12. Primary wrapped around secondary. (already experimented with primary tuns and polarity)

13. There is a constant drop of around 7V in the circuit.

14. Circuitry is same as you have mentioned.

The problem is that the circuit is not working at all. While 18V (for 24V) and 2V (for 9V) is measured at primary the secondary is 0V

What should I do please suggest.

-max- (author)  roktim singhaR2 months ago

Sorry I did not see this until just now, I never got an email for some reason. Based on your setup, Your secondary may not be big enough, but I think it should be adequate. doubling the size of it will probably make a 30% improvement once it is up and running. Did you try moving the secondary up or down a little from where the coil starts, and can you make sure your transistor is still good? Do you have a known working one? Make sure they are heatsinked too!

The pullup resistor value is a bit fiddly too, and will need to be increased with higher voltages or smaller transistors (like a 2N2222), or decreased with lower operating voltages and/or larger transistors. I would not go below 200 ohms, and would probably try a 1-10K resistor. A lower value will bring the transistor closer to low will keep the transistor biased and draining current into the coil, causing it to overheat. I would not test anything over 12V 1.5A while troubleshooting due to risk of popping the transistor.

EbrahimB2 months ago

max i have used copper wire for my L2 coil....the transistor gets too hot if i connect it to 18v....for a long period of time....there is no output....the slayer exciter u made in the video"weekend projects is diffrent from the vidoe.."cool stuff you can do with your slayer exciter...if i make the slayer exciter same way as u made in the video.."weekend projects"...then it should work right??....i will post some images asap then tell me whats wrong in that..

-max- (author)  EbrahimB2 months ago

The exciter shown in the video is an updated version of the one shown in the 'able, since they were made at completely different times but the schematic is largely the same. For starting out, I would use a TO-220 transistor like a TIP32C or MJE3055. If you happen to have a 2N3055 in the TO-3 package and also have the heatsink for it, that is also a good transistor to use.

After determining which version you will build, tell me so I can give you less vague advice!

-max- (author)  EbrahimB2 months ago

18V is a little high before you know it is working properly. I use 12V 2A in the video for the version using a TO220 transistor, and less than 9V 400mA for the TO-92 version. Can you give me exact specs of yours? Did you try and mess around with the L1 coil? (it is very fussy and the polarity must to be correct, as well as the number of turns for optimum performance.)

EbrahimB2 months ago

max do we have to use magnet wire for L2 coil or copper wire is done...??....i tried the trouble shooting but i don't know whats the the video u made the slayer exciter very different by using 3 transistors right??....can u just show that on a breadboard.....reply asap!!

-max- (author)  EbrahimB2 months ago
What version are you trying to build? There is the weaker one that uses 3 TO-92 NPN transistors (I have a visual schematic for that) and a much stronger version in the video. They are the same except the only in the video uses a single MJE3055T.

Yes, you absolutely need magnet wire for the secondary L2 coil. It needs to be thin and insulated and enabled.

Can you describe the problem? Does the transistor get hot? Can you verify that the transistor is still working? (small ones are very easy to kill!)
EbrahimB2 months ago

max...i am making this slayer exciter for my school project...and i have very less circuit is the same as u made in the video....i tried connecting the circuit to 18 v.....but it still doesn't work....please tell me what to do..... i don't know nothing u have any other website where u have posted more videos?.......coil specifications..(L1=10 turns...L2=1280 turns).....i didn't connect the emitter to the ground is that a problem??

-max- (author)  EbrahimB2 months ago
That is a lot of turns for a L1 coil, try 5 or so. Generally more turns is better suited for lower voltages. Did you have a look at step 7 and troubleshooting?
EbrahimB2 months ago

max....can u make a video asap...without the coil isn't working...i don;t know please help me.....make a video asap.....a

-max- (author)  EbrahimB2 months ago
No, I don't have the time, resources, or incentive to make another video (They can take months to edit!). I built the circuit going my other schematics found online, surely you can to! Just make sure that you keep the Emitter, Base, and Collector straight in your head.

Emitter goes directly to ground, base is the feedback wire from the L2 coil, (it is galvanically isolated from the rest of the circuit) as well as a pull up resistor of around 1K, and the collector connects to one end of the primary coil, and the other end goes to the voltage rail.

If you coil does not work, refer to the troubleshooting guide on Step 7. Try testing and/or replacing your transistor, changing the number of primary turns, changing the polarity of the primary, and double checking that the wiring is correct (i.e. the pinout for your transistor is correct and matches the circuit)
Param413 months ago

plz can u show this on a project board(breadboard).plz reply as soon as possible

-max- (author)  Param413 months ago

Also, can you tell me exactly what parts you are using, specifically what substitutes you have used and all the assumptions made during your build? (e.g. solid gauge wire instead of stranded, # of turns, did you use a different transistor and resistor? etc.)

Param41 -max-2 months ago

thx for the reply bro!:)

-max- (author)  Param413 months ago
That can be found in the how to video. Also I recommend if you have no experience with building circuits from schematics that you give it a try! It isn't too hard.
Param41 -max-3 months ago

I tried many times.i also connected the materials as in the schematic with a copper wire .all that happens is that the transistor gets too hot and no neon bulbs glow. :(

-max- (author)  Param413 months ago

What value resistor are you using to tie the base of the transistor to the +Vcc? try a higher value if it is less than 1000 ohms. If the transistor does not get warm and nothing is working, then try a lower value. (higher value = less power dissipation while lower value means more power dissipation and more heat.)

Also, make sure you have the pinout of the transistor correct. The pinout on the TO92 package is very different from that of the TO220. What transistor are you using, and do you have a transistor tester handy? There are videos online that show how to test a BJT transistor w/ the diode test function on most multimeters. You can also just swap it out for another to see if that faxes the problem.

If you are 100% certain everything is wired the same, and still nothing, and have tried to change the polarity of the L1 coil many times, then try changing the number of turns.

Param41 -max-2 months ago

it works now. I had made a big and silly mistake. I mistook the emitter for base collector for emitter and base for collector. Now it works perfectly fine

ishaqb3 months ago

max,...of what material should be the top load....please reply ASAP

-max- (author)  ishaqb3 months ago
It does not particularly matter, you can experiment and figure out what works best for you, like I did.
JimmyE1 made it!3 months ago

I made it, but it doesn't light LEDs.

-max- (author)  JimmyE13 months ago

Not sure why instructables isn't sending me emails with replies, but anyway here is the AV plug you need to make LEDs work. I am surprised it did not work w/o it, I thought I got LED to work without this circuit, just not very good. Oh well. Im glad youre Slayer exciter is working well!

AV plug.png
JimmyE13 months ago

Max, do you know the frequency of this thing? Thanks

-max- (author)  JimmyE13 months ago
I believe it is about 125HKz with nothing around the L2 coil. As something approaches it, the frequency and shape of the wave changes.

There are actually a lot of harmonics and junk because the oscillation is very dirty and non-sinusoidal, so you can expect a healthy dose of broadband noise and EMI.
JimmyE1 made it!3 months ago

I don't have issues with anything else.

SKtesla4 months ago

Hi max. I tried building this circuit but it did not work. The LEDs did not light up. I tried reversing the battery polarity and then the LEDs lit up but the exciter doesn't seem to work . Do you have any idea why this could be happening? The only fault I could think of is that some turns on my secondary are a bit loose and overlap a bit. Do I really need to rewind the whole thing? Appreciate your help.

Roosafeedk4 months ago

In the below circuit of yours, you have connected the emitter to the ground. Is it necessary? It's not working, the LED lighted up but no output.

I used a MJE3055 transistor

-max- (author)  Roosafeedk4 months ago
Yes you need to connect the emitter to ground. Change the try to change the polarity of the L1 coil and experiment with the number of windings on it. Make sure your transistor gas survived if overheated at any point while experimenting.
Roosafeedk4 months ago

Hi, I don't know what I did wrong, I tried everything you said, but I am NOT getting it to WORK. Please Help

Exphyre4 months ago

Hi Max, I wanna make one thing clear, that single wire at the top end of L2, do I need to connect that to the top load when I use one? (e.g. light bulbs, heat sinks) Or do I just let it dongle around as seen in your topload-less pictures?

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