Slayer Exciter Circuit with a Tesla Coil

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Does this so called slayer exciter work?



Well I guess it does! I was initially pretty confused about the circuit, but after finding out that there is this parasitic capacitance on the output of the secondary winding, all became clear and now I’m in love with this circuit!

Let me explain how it works. Below is the picture of the circuit. This circuit is the simplest thing that can generate such high voltage I’ve ever seen, so I love it! I also added the missing information in the circuit:

  • The stray or parasitic capacitance that exists on the output of the secondary winding. You don’t add it, but the capacitor exists naturally there. Also in case of a Tesla coil the toroid on the top helps with creating this capacitance.
  • The way the transformer needs to be connected, by showing those transformer dots.

Low Power SlayerThe components I used are as follows:

  • Q: 2N2222, or 2N5550 or similar regular NPN with >50V VCE and >60 hfe
  • D: 1N4148, or 1N400x (x is a number)
  • R: >= 22kOhm
  • T: my hand made transformer I showed in the video. With primary of 10 turns (could be fewer depending on where you connect the wires) and secondary of around 750 turns.

You might want to watch the video which inspired me here to see how Ludic Science made his own. You can add more transistors and reduce R to make the circuit drive stronger.



Now, this circuit works like this:

  1. Turning the circuit on, R drives the base of the transistor Q
  2. Q turns on and drives current into the primary of the transformer. The current is limited by the limited available base current.
  3. The created magnetic field drives the secondary of the transformer.
  4. The secondary voltage wants to grows large. But the tiny stray capacitance on the output resists the change, although very small, against the rise of the output end and so in return the voltage on the other end of the transformer goes down, pulling the base of the transistor low.
  5. Diode D prevents the base voltage to fall more than 0.7V below ground, which in return pushes the output end of the secondary high.
  6. The transistor turns off and so the magnetic field starts to reduce.
  7. The base voltage rises again and Q turns on and the cycle repeats.

I was able to simulate this in LTSPICE as shown in the figure below, of course the simulation result is a very rough estimation of the truth as I didn’t exactly know the transformer properties or the output capacitance value.

Simulation done by LTSPICE

Slayer Exciter simulation done by LTSPICE

There are a few things I learned in the process, such as the fact that it is very important for the oscillation frequency to be exactly at the output tank circuit (L-C) frequency for maximum power output. The greatness of the Slayer Exciter is that it makes the circuit oscillate exactly at that frequency.

But I tried to use a function generator instead to excite the circuit which is another option. I found it quite tough to tune the frequency to the exact resonance of the coil, something that the Slayer does automatically. Especially with my low grade generator, when I was getting close to the target frequency, it would jump over it to the other side. It was like trying to balance a ball on a peak. The generator couldn’t hold the frequency there, I suspect because of radiation from the coil effecting the generator.

So after the success of the initial circuit, I put together the following circuit to boost the output. It is the exact same concept, just that instead I used a high power MOSFET transistor and a gate driver IC to drive the MOSFET. Note that for example for my transformer which resonates at 1MHz, it is crucial that the components can work at such frequency. If they can’t handle the oscillation frequency the circuit won’t oscillate.

Slayer Exciter with MOSFET and gate driver

Slayer Exciter with MOSFET and gate driver

Here are the part numbers I used:

  • R1 = 2 Ohm
  • R2 >= 22kOhm
  • D2 = 1N4148, or 1N400x (x is a number)
  • U1 = MIC4452 (MIC4452YN is the through-hole version)
  • Q1 = 2SK2542 (This is an obsolete part. You can replace it with similar N-CH, >=500V, RDSon<2Ohm, >40W power)

I was initially worried that the low RDSon of the transistor would result in excessive current draw and overheat the transistor. But the amazing thing about the circuit is that when the circuit is oscillating at the resonance frequency of the transformer, the impedance is at its peak (1/(2 x Pi x (SQRT(L x C) where L is the output inductance and C is the stray capacitance) and so the current draw is at its minimum which is much smaller than supply voltage divided by the RDSon of the transistor.

For example in my case, depending on the number of primary turns, the current draw could be between 0.2A to 0.8A. This boosted circuit worked very well and I was able to run the primary at a single turn which provided the maximum output voltage, but probably not the best efficiency.

In any case, I love this circuit! But beware that such high voltage – high frequency signal can be hazardous. The frequency is not super high but still the energy is large.

Also something I noticed was that when I was close to the coil, my body would pick up the energy so much that if I touched any other metal object in the room, I would burn my finger! So we should keep a proper distance to this beast!



401 thoughts on “Slayer Exciter Circuit with a Tesla Coil”

  1. I tried to build MOSFET based sec, but it doesn’t work. Im using 4*1.5 AA batteries. First i thought i might kill mosfet which was true, but it didn’t fix the problem. I tried tu measure voltage on driver and i found that it outputs almost no voltage anywhere no matter which polarity i put diode in. Is this mean i killed it?
    Is this even possible to be so easly killable with static charge?

    • Update: i just realised that R1 on schematic is 2 Ohm and i used this value. Shouldn’t it be 2 kOhm? Did i just killed my microchip becase of misstype and lack of common sense on my side?

  2. Hey everyone! Hoping someone can help me out with my build of this circuit.
    I’ve previously built the OneTeslaTS kit that Mehdi built following this series of videos, and was hoping to build this S-E circuit to drive the existing primary and secondary I already have from the TS.
    I’ve built the “Beefed up” version of the circuit above, with the MOSFET, however when I connect it to my coil it doesn’t resonate. The MOSFET simply stays on, dumping a heap of DC power through the primary.
    I’m wondering whether the high series resistance of the TS secondary winding (~750ohms) is hindering the feedback to the MOSFET driver.
    Would it be a good idea to switch out R1 for a higher value resistor, to further limit the current available at the feedback point?
    Cheers!

  3. Hi Medhi, thanks for all you do. ive built a slayer tesla coil that the circuit seems very similar to your initial one but im using a 47 kohm resistor and a TIP31c. my circuit does not have the diode to ground, i tried adding this and it just stopped working?
    did you find that your improved circuit made much difference as im tempted to do it but i cant find the right transistors in my old tvs and didnt want to buy one unless it yields a good result? thanks again

    • When you don’t have this diode, I guess there can be a negative voltage at the base of your transistor. When I did that, as soon as I exceeded about 30 volts, my transistor blew up. I think that is because the maximum negative voltage on the base pin of the tip31c is about 5V and I went over it. When you only power your coil at less than 30v, you will get longer sparks without this diode. I haven’t tried yet if my results are better with a MOSFET, but I guess that it won’t make a big difference when your input voltage stays the same.

  4. Hi mehdi,
    Please send the best musical Tesla coil
    driver through my email so I can build it for my school project.
    I will be thankful.

  5. Your simulation would be more realistic with a low coupling coefficient, as k=0.1 to 0.2.

    • Also, item 4 of the explanation is inverted. When the transistor conducts the secondary coil increases the base current, positive feedback, as indicated by the dots. The base current reverts polarity, flowing through the diode, just half cycle of the oscillation later.

  6. Hello Mehdi,
    I’m a crazy inventor of the high voltage inverter.
    I am the same as you in love with the parasitic capacitance generated on the secondary winding and self resonating of the winding. You mentioned that a distinctive reactance characteristic appears on the primary winding side when the secondary winding side is in resonance, I think that you are a very excellent thoughtful guy! In fact, it takes a long time for ordinary person to notice such phenomenon.
    I think that the MOS-FET boost circuit which you tried is very similar to what I invented in 2005, what do you think about it?
    https://patentimages.storage.googleapis.com/8c/d7/ea/997227740d8549/US7541749.pdf
    There is nothing to worry about patents. This patent is declared free using to amateurs and enthusiasts who study Teslacoil.

  7. Hey I made the regular circuit above and used a BC548B transistor. I think I put everything in the correct configuration but nothing happens. The transistor gets warm, and the output of the diode (To ground) shows 11 volts. I’m running 8.5 volts into the system (Rechargeable 9v battery) and the output of the secondary coil is only around 7.4 volts.

  8. Hi Mehdi,
    I want to build this slayer circuit, but I want to run line voltage through a voltage quadrupler to drive primary coil with it (163v x 4). What voltage would I expect to find at input of MIC4452 from secondary coil feedback? Will it be too high and blow up the circuit?

  11. can anyone tell me how i would calculate the magnitude and or volume of the output electric field? let’s say i have setup my circuit with the secondary coil producing 1000v at 1mA, how is this distributed throughout the 3d space? is there a relationship between power and occupied volume? does the density remain the same (I.e 1V/m^2 if that were to be the results from the first example given) ???

    thanks

  12. Can anyone help me I am not educated in the field of electrical engineering I dont know how the components of the circuit are connected

  13. I made a tesla coil thats 12″ dia X 5′ tall with a 32KV primary pulling 60A and Im only getting 12 foot long lightning bolts from it…. what is wrong with this thing?
    why an I not getting longer streamers?

    • What you need to do is to adjust the frequency coupling by having a movable connection on your primary coil. What you are looking for is “Resonance”, where the coil interaction is strongest. Also, you have to try and determine if the coupling frequency from the primary is either firing before or after the Secondary is ready to fire, so to speak.

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    • It is no LED. It’s a diode. it’s necessary for the circuit to work because it lets current flow one way but not reverse.

    • A diode is required to prevent reverse voltage on the base of the transistor. This requires ultra-fast diodes such as BAT46 and UF4007.

  17. hi
    Can I get a file simulation of the circuit on the LTspice?
    I could not simulate the circuit on the program

  18. Hi,

    Where can I get 2SK2542 and MIC4452? I live in Vancouver as well, so I’m wondering where you got your components from.

    Thanks, and don’t stop doing these things, I love it!

  19. I just made a slayer exciter circuit for a tesla coil I made, and I wanted to use this circuit to beef it up but I have some questions about the schematic.

    1. What is u1
    2. And what voltage should be used

    It would be great if someone could respond

    • Answer to question number number 2 in the video that he showed in his video the guy used a 9vl batt so I’d say 9 vl for the entire circuit

    • I would say that U1 would be a mosfet driver. Just my assumption, don’t take it for granted.

  20. What would happen if you take a ground wire and bring it near the top load but use the original slayer exciter

  21. hi mehdi sir. please tell me that why these coils are not able to run a motor .

    another question is this that you must be very great engineer sir please tell me
    how can i increase the frequency of alternating circuit.why not someone talk about this topic and is there any circuit available to increase the frequency of ac.

    Sir plz plz answer it

    • I may be wrong, but I believe that the frequency of the circuit depends on the resonant frequency of the secondary circuit. Thus, by changing the number of turns of the secondary, one should be able to change the frequency. Since its very difficult to measure the stray capacitance on the secondary, I think it will be almost impossible to find the frequency from theoretical calculations.

    • I tried but I failed…seems like my meter simply doesn’t work…
      Do you know the solution now?

    • Hang the positive meter wire near the secondary. Move it about untip you get a decent reading. Depending on the size of your secondary, the frequency could be between a few hundred kHz to a few MHz.

  23. I do not know how to connect all the mic4452 legs …
    I want to make that coil…
    Can somebody send me a complete (easier xD) version of this scheme?

    Thanks 🙂

    • Honestly, it’s not that hard to learn about reading schematics. A little googling around should get you pretty familiar with it.

      • 1 and 8 is Supply Input. Maximum Voltage 20V
        6 and 7 is output. 2 is input. 4 and 5 is GND

        • Hi, so in this case what is connect to the input to control the gate driver?

          thanks.

  24. Hey Sir,
    Very informative post on Tesla might be a good idea to make a wireless power source. thanks for sharing.

  25. Hay ! I have built this circuit and the tower. It works fine …But the spark is too less for the slayer exciter circuit. Any idea how to increase the spark length .

  27. Pingback: slayer exciter – awsh.org

  28. hello sir,
    I want to make a medium high power tesla coil,
    how to decide primary and secondary coil’s wire gauge and hollow pipe length and its diameter.
    please reply ASAP.

  29. I built one of these and it is a bit large (maybe 3 feet tall and about 3 inches in diameter.

    Anyway, I was powering it with my adjustable power supply up to 30VDC and 10A and had the top lead under a quarter which was under a glass bowl of salt water. Took about 1 second and my supply sounded like popcorn popping and I couldn’t turn it off fast enough to save it so I am ot a supply.

    My question is, how can I protect my supply from dying with auch an inductive load? Is it as simple as a flyback diode in reverse across the supply leads? Please advise me.

    • I believe the flyback diode would only provide protection when you go from closed switch to open switch with an inductive load, especially one with a sufficiently large magnetic field. The inductive load will resist the change in current flow if the current flow is interrupted, or reduced, causing its magnetic field to drive up the voltage and try to jump the air gap at the point of the open circuit (typically a switch) to keep the current flowing. The power supply should have failsafes that protects from over-current / over-voltage situations but that’s not to say they exist or were functional. Were you using a linear or switch mode power supply? Did you have any meters on the circuit to show what was happening besides the power supply’s built in display? Could your power supply have a maximum wattage level of 150W thus limiting the maximum current draw at higher voltages (say 5A at 30V)? I don’t know what kind of setup you were using so these are all just ideas to help you determine what happened. A postmortem on the power supply may help you determine the cause.

    • Hola! Gràcies per ensenyar-nos tantes coses i fer-nos riure tant. Una pregunta: Tots els aparells electrics que estan aprop de la Bobina Tesla emeten sorolls. Creieu que això escurça la seva vida? Gràcies. Es pot evitar en la font d’alimentació?

  32. Hi mr I would like to know if I can use the IRFP460 mosfet also I do not know how to wire it up with the gate driver? Can you show us using a simple drawing of the circuit?

  33. Hi, Mr. Mehdi

    I wanna make a 30v slayer exiter. Can I use this circuit? But when I read MIC4452 data sheet, the operating input voltage range it’s only about 4.5-18v. I’m afraid it will blow up. Hope you will reply quickly. Thank you before and after.

    Btw, I love your videos.

      • IRFP460 is a bit too much for this puny circuit….
        That is a high power MOSFET. I think that any irfp can be used but you will pay too much for not much…

        • Are you sure about the mosfet. The idea of the feedback is to regulate the base current of the transistor, hence regulate the output. You cannot regulate a mosfet gate. It is either on or off – fet = field effet transistor

  34. can anybody say that who developed the slayer circuit?? Mehedi sir waiting for your ans if you know..
    Thanks…

  35. Hi Mehdi
    I used the 2n2222 circuit but it doesn’t work. The transistor just heats up and if I bring a fluorescent bulb close to it the bulb doesn’t light up. I don’t know if the coils are too small. Could you please help me.

  36. sir hi can you please make a new video regarding this making of your tesla coil with 750 turns of secondary coil on 9.5 inch long and 1.5 inch diameter pvc plastic pipe if not please help me now what components i use with it and how much power i provide to my circuit for better results please sir reply as fast as possible i an waiting i have only one week to submit this project.

  37. Hey Mehdi, could please give me a circuit diagram as to how I assemble the ‘beefed up’ circuit (with the pins of IC and Transistor} as i really cant get it straight. I checked your website, but didn;t get my answer. Also how much power spply are you using?? Any help will be appreciated. Thank you!

  38. Really loved it.I want to know how and why it does not affect us. I also want to know how much length should the pvc pipe for the secondary coil should be and of what diameter.

  39. Hi Mr. Mehdi,

    I`m planning to build this slayer exciter for a school project, but I have a few questions:

    1: Do you know a good replacement for the Q1 transistor (the 2SK2542)?

    2: Since it´s for a school project, I feel the need to run some kind of test/experiment with it, do you have any examples of what I could try out. I need some inspiration.

    3: Would it be possible to, after I´m done with the slayer exciter + testing it, to turn it into a proper tesla coil, and how?

    • Hi Gustav.

      i have fresh experience with my first tesla coil: the circuit works pretty well with any transistor. i tried a variety of bipolar transistors, all of them worked well. choose any ‘power transistor’, as it gets hot quickly. as well, the diode can be a led – it will glow when Your circuit oscillates properly. be sure to ground Your circuit and to have a capacitor (those fancy rings or spheres on most images). if Your circuit does not work, try to swap terminals of Your primary winding. good luck.

  40. Hello Sir, Mehdi
    I have a little confusion which pins of the IC are connected in the given circuit (U1) . I made one of it using 2N2222A and it works fine but heats up really fast. I have a 5.4 inch high coil , having approx 550 turns of 30 Gauge Enameled Cu wire and instead of troid I used a 1.5 inch diameter spherical steal shell used in stair case. MY CIRCUIT DOES NOT GIVE TOO MUCH POWER OUTPUT THE CFL JUST STOPS GLOWING AFTER 2 INCH . PLEASE HELP ME , WHAT ARE THE PIN NO OF U1 USED HERE ??

    • hello,

      Please open the datasheet here:
      http://ww1.microchip.com/downloads/en/DeviceDoc/mic4451.pdf

      and you will have a complete pinout of the part. Also try to reduce your primary turns to 5 turns and that boosts your output voltage. You might have to play with the primary number of turns to get best results. Also increasing the supply close to 20V increases the output. But don’t get too close or your chip dies.

      • Its just gets burning hot at 8-9 volts.
        Is there any other simple circuit to make a Tesla coil out of it.

        • AND SIR,
          IF I INCREASE THE NO. OF TURNS IN THE SECONDRY TO 1254 TURNS OF Cu WIRE ( IT IS APROXX 100METER OF WIRE ) WILL I BE ABLE TO SEE SPARKS ??

          • Increasing the number of secondary turns increases the voltage, so yes you are more likely to see arks. Again it depends on your circuit, driver and other things like coil dimensions. Make sure you have a needle on the top load. That way the arcs can come out easier.

        • Are you using the gate driver with the 2n2222? You should use a MOSFET instead. Make sure it is put on a good heat sink.

            • I used an mj11032 darlington with a to3 heat sink and a 24vdc fan works great if you draw too much arc it will get hot I have an 800vdc thyristor 400amp I’m going to build so I get more output

  41. Hi, Mehdi
    A group of students including myself are wondering where you got the parts for your Slayer Exciter Circuit build we need to purchase those parts, please contact us as soon as you can

    Sincerely,
    Erik Ocampo USCEASTCP

  42. Hi Mr.Mehdi,
    How can i make 24 VDC to 220 VAC with 16 Amps?Can i make it?
    And,how much amps of this Coil in to the your project?6.4 KV woww! 🙂
    I following yok ABD your projects.

    Greatfull works,Thanks 🙂

    • An Inverter.
      It will take around 160 amps @ 24 volts DC in to an inverter to give
      16 amps @ 220 volts AC, which = 3520 watts, I’d get a 24 volt 5000 watt. That and 2 car batteries in series will last you about an hour.

  43. Hi Mehdi, I so I created my coil and the boosted circuit after successfully testing the basic circuit, however with the boosted circuit when I move a lightbulb up to the top load it barely turns on, but when I move it down near the primary coil it is very very bright, do you have any idea as to why this might be?

    Thanks

    • Hmmm, not sure. Is your tower too tall?Stretch the primary a bit further up the secondary maybe. Make sure they have proper gap between them.

      • salam mojajad
        vase chi bayad gap dashte bashe!?
        age ayegh bashe mishe bedune gap bashe!??

    • hii I m faraz and I want to ask some questions,1. I have created secondary coil with 32 no. of megnetic wire over the PVC pipe with 11.8 cm of length and 2.8cm of diameter. and created the Wright circuit but it does not work……..what should I do and which mistake have I made? plz if u know then tell me………..

  44. salam mohandese aziz
    mamnun misham komakam koni

    bebakhshid soalam damorode poste Music, Magic and Mayhem with Tesla Coil ast
    soalam unja sabt nashod engar!

    1) khazane avalie kojast tu madaretun!? (Cprim)
    2) emkanesh hast az regulator-haye switching mese lm2576 estefade konam!?
    3) entehaye simpiche sanavie mage nabayad be sime earth vasl beshe?!?
    ma tu iran earth nadarim hame ja!
    bayad be koja vaslesh konam!?
    4) madare shoma darvaqe ba taqire seda, Duty Cycle ro taqir mide , dorost migam!?
    5) Vsup ro 30 Volt gozashid!?
    6) manbaetun chand ampere!?

    mamnun babate javabetun
    mersiiiiiiiiiiiiiiiii

    • badjur niaz be javabetun daram
      mmanun misham hosele konid javab bedid
      maresiiiiiiii
      vaqean mmanun misham

    • hey guy!
      these ar mr. mehdi’s answers to the same question:

      – I have 10 windings for primary. Generally thicker is better and reduces resistance. But my 22AWG wire also works fine. If you reduce the primary winding turns your output voltage would be greater, but don’t go below 5

      – AWG 28 is easier to wind as it is thicket and won’t break easily, but you get much more turns with AWG32 if you can do it, which makes more voltage.

    • hey guy!
      these are mr. mehdi’s answers to the same question:

      – I have 10 windings for primary. Generally thicker is better and reduces resistance. But my 22AWG wire also works fine. If you reduce the primary winding turns your output voltage would be greater, but don’t go below 5

      – AWG 28 is easier to wind as it is thicket and won’t break easily, but you get much more turns with AWG32 if you can do it, which makes more voltage.

  46. Hey people you guys should also try it with the 2n3055 transistor. Mine is beast now it spits out hogh frequency sparks at the wires and it burns your skin. Im using 19 volts 3 amps. it’s a laptop battery charger
    like half a feet it makes 2 flouracent lamps glow and a larger neon bulb.

    • Tip3055 is even better and easier to mount. 35 volts dc makes for some nice self starting arks.

  47. On your second circuit you have two batteries. Which side of the circuit is positive?

  48. Hello I tried this but it didn’t work? I am using the bc547 transistor.
    Do I need 2N2222, or 2N5550?

    • I got the original circuit (Ludic Science Circuit) to work using a BC546. Albeit that I didn’t make the most powerful version the transistor became very hot, but the circuit worked.

      • Just got mine to work
        Using bc547
        mps 2222
        Using voltages from 9volts to 25 volts

        LOL I ADDED A CAPACITOR to the full bridge rectifier because I was using 12 volts ac and so I needed to change it to dc
        when I added the capacitor it made the circuit beast and more powerful but It popped the mps 2222a transistor hehe
        Im going to buy a beafier transistor sometime

  49. Hi mehdi,
    in the second circuit, with mic4452yn, what is the power supply?
    it is efficient as the first circuit (with 2N5550)?

      • Ciao Andrea, i due punti di cui parli tu si chiamano “contrassegni” e determinano il segno della mutua caduta di tensione su due induttori mutamente accoppiati.
        Per farti capire meglio, questa è la legge costitutiva dei due induttori accoppiati ( considera tensione e corrente nel dominio fasoriale per semplicità di notazione ) :
        V1 = jw*L1*I1 +/- M*jw*I2
        V2 = jw*L2*I2 +/- M*jw*I1
        Il primo termine è dato dall’autocaduta di tensione, il secondo termine è dato dall’accoppiamento. Se le correnti hanno verso concorde rispetto al pallino, avrai +M. Nel caso contrario avrai -M.
        Spero di esserti stato utile, ciao!

        • Ah ok quindi al fine di costruire il circuito non servono… grazie mille!!

  52. hi
    how are you
    Can I get a file simulation of the circuit ?
    I could not simulate the circuit on the program

  53. Hello Mehdi,

    I was curious, I tried making the original circuit but instead of a 2N2222, or 2N5550 I tried to use a TIP120 (whose datasheet is here: https://www.adafruit.com/datasheets/TIP120.pdf) that I just had laying around. I tried looking around for info on why this would or would not work but I couldn’t find anything. What reason would I not be able to use the TIP120 with all the same components?

    • Did you get it to work with a TIP 120? I am trying to use a TIP120 but my circuit isn’t working.

  54. سلام مهدی جان
    میشه این تسلا رو در ابعاد کوچک مثل همونی که تو ویدئو نشون دادی و گفتی کار نمیکنه بسازیم؟
    اگر میشه میتونی راهنمایی کنی که چطور بسازم.ممنون میشم کمکم کنی
    قربانت مرتضی

    • Salam, oon kaar mikone. Mishe too oon size sakhtesh. Mesle hamoon aghahe ke goft.

  55. Hello Sir

    I’m just wondering regarding the circuit i made with a 2n2222a transitor in my slayer circuit heating, and does this interfere with my circuit since it’s not working

  56. Hello Sir.
    Can you please mention about the battery we have to use. I want the exact voltage. and please tell me the number of turns in both the coils. and do i have to connect another battery to the primary coil or what? kindly please explain these things

  57. Hello mr. Sadaghdar,

    Could you help me understand the circuit better?

    What I don’t quite understand is how the stray capacitor connected to the secondary coil is connnected to ground. Is it connected to ground with the same wire as the wire that is connected to the secondary, base of the transistor, the resistor and the athode side of the diode? Or is the parasytic capacitance somehow connected to the kathode side of the diode through the air (electric field/ionised air)? I’m really confused.

    Keep up the educational videos, I love to learn more!

    Thanks in advance,

    Casper Egil

    • Hi Casper, Stray capacitance exists between everything conductive. even from here to the moon! Anywhere you have a gap between two conductors there is a stray capacitance between them. Because a capacitor is just two conductors with insulation between them. Every winding of the coil, although are shorted together as they are the same coil, also have stray capacitance between them. So at high frequency when the winding’s impedance rises due to inductance, the other component of impedance falls due to stray capacitance. Every inductor have a self resonance frequency which is due to the inductance plus the stray capacitance. Hope that makes send

      • Dear Professor Mhedi.
        Im a student of electrical engineering in Spain and I’m really interested in that type of exciter circuits and the incredible things they can do. I want to try all these circuits but I have a question:
        – Did you use a baterry, a DC power supply or a function generator as a power supply? I’ve studied that transformers use alternating current to make a magnetic flux variation on the primary coil to induce a voltage on the secondary winding. In this case, what generates the oscillation to produce the variation of the magnetic flux, the transistor with any DC power supply or an external function powered from a function generator where parameters like amplitude or frequency are adjusted?

  58. What is that transformer and how to make it and in circuit what does that two dot mean

  59. hi,

    please help me with the pin configuration of mic4452yn and how to connect it and please leave with a photo with pin configuration in the circuit

  60. Hi
    I recently built a slayer exciter with the secondary having wound on a solder tube. It had 280 turns straight and used the wire from a transformer. Primary had 5 turns of 18 guage wire on it. Drive transistor is a C9014 and supply voltage is 6 volts. Base resistor is 10 meg ohm and i use lighter to activate it.

    Why does the voltage drop when i touch the wire output? Range is very bad, only 5 cm. Fluorescent bulb also has pulses of light. Also, how do i increase range and output without winding another coil?

    By the way, drive circuit is from johnnydavro himself

    Thanks

    • Stop trying to advertise here. It’s stupid, childish, and rude to spam Mehdi’s website with your ads. If you want to advertise, then get an advertising service and do it the REAL way. Seriously. I mean, look at the terrible spelling and grammar. You need a professional advertising service if you want to advertise properly.

  64. Could you also make a video on how to make the Tesla coil in detail .I want to make a similar one to yours which is really powerfull . please do make detailed video on how to make the whole setup including the names of the parts used. Thank you

  65. Thanks a lot for your previous reply!
    One last thing,
    how do i construct the toroid like yours?
    What Wire have you used ?
    Did you weld or solder ?

    • URGENT
      Also, my Driver is IR2110. Please tell me if I can directly use it.(without connecting any external capacitors to it).

  66. Hi, I made the same slayer exciter circuit with two transistors in the form of a darlington pair. It is not working, i tried reversing the polarity of the primary coil, still nothing. Need help, I’m using 2 MJE3055T. Should i send a schematic or a image of my circuit??

  67. Hi Mehdi!
    First of all let me tell you I love your videos! geep going with the good mood but be safe! hehe
    I tried to build this circuit (the original one) with a primary coil with 4 turns and the secondary coil with around 670 turns. I don’t have the 2N2222 transistor so I used BD139 and with 22k resistance didn’t excite the base current, so I reduced the resistance and BAMMM! the transistor smoked itself and blew up! Then I replaced with a TIP122 (Darlington) and with the original resistance (22k) it overheated until it started smoking! Will I have to buy the 2N2222 to really try it or maybe my coil turns aren’t getting the right ressonance and are blowing my transistors? Do you have any idea?

    • It all depends on how you primary is connected to the circuit. If both coils are wounds in the same direction then power ALWAYS goes in at the bottom returns at the top. (helic wound primary that is).

      Get a 10k (and a 5k for finer tuning) adjustable pot and twiddle to tune. Always use a pot to tune or you’ll be farting around either blowing transistors or just never finding the optimum resistance vale.

  68. Sir, i see R2 in the slayer exciter with mosfet and gate drivers is 2 ohms, is that right? Or do you mean 2k ohms resistor?

  69. Hello Mehdi (again),

    Did you buy your toroid from a website or make it yourself? And if you made it how did you curl the wire like that?

    Thanks,

    • Made it myself. I just wound it around a pipe like a spring, then took it off the pipe and bent it into a circle and soldered the ends together.

  71. Hello
    I’m just wondering, all those accidents in your videos are real ? Or you just tase yourself for fun ?

  72. Hi there, what if I use BUK456-1000B MOSFET transistor?? Maybe it will work but how should I choose the gate driver for it??

  73. Hey!.
    I have a few questions,
    1. Could you tell me which of the two circuits did you use in the video for the demonstration?
    2. What parameters of the components should I check before purchase them?
    3. How do I calculate the amount of output voltage that I can expect to obtain before actually giving the electrical connections?
    and finally,
    4. How do I measure the output voltage?(Since you mentioned that the output voltage is very high)
    Would greatly appreciate if you could respond.
    Thank you.
    P.S. I really love all of your videos 🙂

    • 1- I used both of them
      2- That’s a bit complicated, but for transistors look for their voltage rating, and for the BJT type also the higher Hfe is beneficial
      3- That’s a bit more complicated! But look at OneTesla.com website for calculators and explanations
      4- I don’t know of an easy way to measure such high voltages. You would need an expensive tool to do that. There are probes that can do 40kV. But even those are not enough and would effect the output. It also greatly depends on the environment and surrounding material.

    • Search for MOSFET gate driver chips. I’m sure you will find something available in your area. Just make sure to read the specification so you won’t blow it up. Try to find something that can output like one amp or more current.

  76. Hello Mehdi,
    My project is to make a “flat” slayer exciter. So i did a “flat winding” on a piece of wood. I was wondering if i should put the secondary coil near the center of the “flat” coil or near the periphery ? and as well if i should plug the main coil by the center or the periphery. In fact do you think such a device could work this way ?
    What do you think ?

    Jonas

    • The coil should always be centered, if that’s what you mean. I’m not sure about your second question, maybe you should draw it out. But I have seen videos of flat Tesla coils working. So it should be possible. I haven’t tried it though.

  77. Hi Mehdi,
    I was building the simpler circuit for fun as I could not find the Gate Driver IC chip but nothing happened, even when I brought a flourescent lamp close. I was driving the circuit with 9v but when I raised it to 16v, the transistor started smoking so I replaced it. Even at 12v, nothing happens.

  78. I was building the simpler circuit for fun as I could not find the Gate Driver IC chip but nothing happened, even when I brought a flourescent lamp close. I was driving the circuit with 9v but when I raised it to 16v, the transistor started smoking so I replaced it. Even at 12v, nothing happens.

  79. Hey Mehdi
    How are you?
    I am going to make a slayer exciter for a school project.Can i increase the coil’s height and diameter in order to increase the voltage?
    BTW can you make a tutorial video on how to make the circuit.
    I am just 13.
    P.S. I love your videos 🙂
    Thanks

    • Hi Auyush, I’m good. Thanks!

      Making it larger won’t necessarily increase the voltage. You have to raise your input power as well, like higher voltage and current. But then your circuit may blow up. You may need different type of driver to output larger power.

      • Hey! thanks for the reply
        i made a big secondary coil(winded it on a 5 feet pvc pipe, took me hours to wind it) but the primary coil was 5-6 turns and i noticed that the fluorescent tube was glowing near the primary coil only it stopped working on the top of the coil.what can i do to fix it?
        btwi tried a power supply from my school and tried to increase the voltage but it melted my bread board.Thanks!

  80. I’ve recently started learning how to build tesla coil and this was a great intro. I got some nice 2-3cm arcs with a 30V driver on my first attempt. But it destroyed the regulator on my (very ancient) bench power supply. I think some of the back EMFs got into the positive rail. Not a big deal to repair and a good lesson but I’ll use a crappy linear supply from an old computer and a big ass cap in future.

    Great vids and excellent tutorials.

    Just try not to die.

  81. hi,

    I tried out the circuit with the 2N2222. the transformer has 10 turns on the primary and 780 on the secondary.
    only result I get is the transistor burning up and a oscillation on the base around 3MHz. On the secondary nothing..
    am I forgetting something somewhere?

    • Do you have a top load (metal toroid) on secondary? How much is your base resistor and supply voltage? Is your diode connected in correct direction? Maybe you need to flip primary coil connections to your driver circuit. Double check things!

  84. Please help me ! I want to build this circuit my own so what is the size of the primary and secondary coil (also the size of the wires and the PVc pipe)?
    Sorry for my bad writing i’ from Germany and 13 years old…

  85. Pingback: Halfway Report on Building a Tesla Coil and Driver | ElectroBoom

  87. Hello Medhi! I had recently stopped by RadioShack to buy components, but I ended up buying a TIP31, which has a Hfe (min): 10-50 and a Vceo of 40v. Would it be OK to build this circuit, and if not, could I add things so it would? Thanks!

    • I have my doubts because the Hfe can be pretty low. You will have to reduce the base resistor to create higher collector current, and that makes it hard for the secondary coil to pull the base low. So the circuit may not oscillate. But give it a try.

    • This circuit you showed provides higher supply power. Sure you can use it on the exciter, especially my second circuit. Just that you will need to provide separate supply for the gate driver IC. Also the higher supply can’t go too high and mighty or the FET will blow up. Less than 60V is safe.

      • Thank you.
        Have you and idea of which materials can be excited to emit light with this wireless transformer?
        For example zinc sulfide? Painted on a metal sheet connected to earth?

        Also, can use this exciter and transformer for make corona discharge treatments?

  89. Love your videos.

    I’ve been wanting to make a slayer exciter tesla coil for days now, but unfortunately I’m overthinking things and keep stopping. Can you help with these questions?
    – I can’t find a long enough ferrite to give me 100’s of turns of wire so I’m going to make an air core secondary. Is there a minimum diameter that I should stay above?
    – is there an optimum height to diameter ratio that I should use? I have 38ga and 30ga wire. Obviously I can put more turns of the 38ga on a shorter length pvc pipe than the 30ga, but should I?

    Looking for a decent performing widget to show co-workers that’ll run off battery power (9-12V)

    TIA!

    • – You don’t need a ferrite, mine is air core. Generally the smaller you make it, the higher frequency your resonance frequency gets for the same number of turns. But look for online inductance calculators, as well as Tesla coil calculators. try not to go above 1MHz.
      – Both should be OK for your slayer as the output voltage won’t be as great as some other coils. If your voltage is much larger, you want your head and tail of secondary to be further apart otherwise if can arc to itself.

  90. i am using micro-controller to generate a square pulse at the transistors base and driving the tesla coil i.e i am using bc547 which in turn drives 2222a transistor working at 9v if i place led instead of the primary coil led glows as per frequency set (programmed) but with primary coil doesn’t work, any idea??? secondary one end is left open (as usual) and not understanding where to connect other end of secondary .. i tried connecting to base,emmiter & collector seperately each time but not getting any output any idea?

    • In such case, you can connect your secondary to ground. But also you need to very finely tune your frequency for the specific environment the oil is in so that it resonates. If your frequency is very mildly off, then the output voltage significantly drops.

      The benefit of slayer exciter circuit is that it self tunes to resonance frequency no matter if the environment changes.

    • By the way, make sure you have a top load (toroid or something). Without it, the resonance frequency might be too high for the circuit.

  92. Hi Mehdi,

    I have replicated your boosted circuit using the mosfet. the mosfet i use is a IRFP260 and driver is mic4452. I short the pins 1,8 (supply in), 4,5 (GND), combine pins 6,7 and via a 3.4 ohm resister and connect to the gate of the mosfet. Input goes via pin 2. R2 == 22k ohm. The driver ic is driven with a 12V ATX PSU separately, The main power to the circuits comes from a 19V laptop power adapter. For some reason the circuit doesn’t oscillate. I have not added capacitors across the driver power supply. Is it an absolute necessity for me to add the filter caps across the power supply for the driver ic assuming that the ATX psu power supplies are generally very stable ? Also is this the reason my circuit is not oscillating i.e due to the lack of these caps across the drive supply? please guime on this.

    Regards,
    Vamsi

    • It is usually the coil connections in such case. Flip primary connections and see if starts to work. Otherwise check your connections.

      The filtering caps help prevent the supply voltage drop too much. If it drops too much it could case components to overheat.

    • Hi , I’ve just built one of these slayer circuits myself.
      I noticed the resonant frequency mainly depends on how “big” the secondary coil is.
      e.g. with my tiny 8mm dia , 45mm long , ferrite core secondary the frequency is ~3MHz
      According to the MIC4452 datasheet it can only handle up to 2MHz (and that’s with a 5V supply , higher supplies lower the chips top frequency)
      So , if you are using a small secondary coil it could just be the circuit is too “fast” for your MIC4452. (and this would stop it oscillating)
      Try making the supply to Pins 1&8 5V (should have a 5V rail available from the ATX supply) and if that don’t work consider winding a bigger secondary.
      Hope that helps 🙂

      • You’re right. The size of the secondary dictates its inductance and so effects the frequency. Generally the larger the secondary, the higher the inductance and so the lower resonance frequency. But frequency also depends on the capacitance, which is made by top load. If your frequency is too great, you can use a larger top load.

    • hey tony which wire size did you use for secondary coil and what is the diameter of your pvc

    • HEy can i ask you something. What is the transistor that you used in your circuit? and how many turns is it in the secondary?

  94. Hi , like your vids , funny and educational 🙂
    You found a nice beginners circuit as a stepping stone to building a Tesla coil 🙂
    I’m interested in having a go myself.
    A couple of questions about your Tesla coil that you built :
    I was wondering what you did with the top end of the secondary winding ?
    Do you connect it to the toroid at the top ? or is it just left open circuit and then it inducts voltage to the toroid ?
    Also , because of the way the toroid is mounted , does this also mean that the the threaded studding through the center of the secondary is also live ? : meaning the bottom of that studding also needs to be well insulated (i assume) ?
    Cheers for any info , and looking forward to seeing your newly wound secondary in operation 🙂

    • Hi,
      The secondary winding connects to the top toroid for sure.
      The threaded studding ends up there with a knot, and doesn’t do through all the way to the bottom. That would cause arcing issues and would need some strong insulation.
      have fun!

      • Thanks very much for the fast reply 🙂

        I’m thinking of using a M12 Nylon studding running the length of the secondary – that way I can bolt it firmly to a base and not worry about it conducting.

        That said – transformers normally work better with iron cores – would having a metal studding running the length of the secondary improve the transformer operation ? (and I guess it would alter it’s resonant frequency as well)

        Thanks again 🙂

        • Yeah, use a non-conductive stud to prevent arcing.
          Using iron core can slow down the oscillation significantly. Not necessarily a bad thing. But the voltage difference between the ends is so much it is hard to insulate the core.

  96. I made this circuit and it turns out that the resonant frequency of my coil is around 800kHz. However, it doesn’t radiate energy! I noticed that there’s no voltage on the primary coil yet it is oscillating at more than 800kHz! I’m using a bc547 NPN transistor

    help!

    • If you are measuring using a multimeter, then don’t! It won’t show anything and may get damaged. You can use a scope to see the collector voltage jumping around. If you have a 800kHz, then there should be voltage. What is your supply voltage? If it is too low, raise it a bit for more power.

      • Well i tried a 12v battery, two 9v batteries in series but nothing. I don’t have an oscilloscope 🙁

        I made a spark gap tesla coil and worked to some extent. But there’s no voltage on the topload. I’m using a toriod (spelled wrong) and it’s like its not even there!
        when i bring an incandescent bulb near the coil, it glows just like in your tesla coil video. But when i bring it near the topload it doesn’t do anything. I tried another topload and it’s like it doesn’t have any voltage!

        i’m using a flyback transformer and a jar capacitor and it works. But the problem is with the topload.

        Any idea?!

  97. Dear Mehdi,

    if I understand correctly, the 22kohm resistor from main power supply to mosfet gate driver limits the Is (power supply current) to the driver to around I=9V/22000ohms = 0.5mA? What’s the purpose of it and how can the driver work with so low Is? The TC4426 I’m planning to use needs around 20mA or more at such high frequencies and the MIC4452 you are using, from what I can see in data sheet, it needs around 5mA max, or 3mA regular. Could you please enlighten me a little bit? Other than that tiny issue, good work man! Keep it up!

    • That 22kOhm if just a pull up on the driver input and the secondary pulls it down when oscillating. The driver has a separate supply line, the 22k is connected to its input only.

  98. Hi Mehdi,

    Great video. i want to know how you have connected the mosfet to the gate driver mic4452. Can you please show me the schematic for the mosfet driver connections?

    Thanks Vamsi

    • the chip is simple, it has power supply lines, an input and an output. The output connects to gates of MOSFETs like I showed in schematic. Download the datasheet of this part to see.

      • Thanks Mehdi. One more question. Is it possible to drive the exciter using the same mosfet but without a driver IC? I have seen a few circuits on the internet where this is being done. What is the advantage of using a driver ic? when i try to drive it using a single mosfet without a driver i see that it shorts my power supply’s 12V rail and shuts my atx psu down. Is this because i am not using a driver? will it actually help if i use a some kind of current limiter in series with the exciter circuit when running it without a driver i.e?

        • driver IC can drive the FET much faster for higher resonance frequencies. otherwise the gate capacitance can slow down the response and then your circuit won’t oscillate, especially for high power MOSFETs.
          You are probably seeing this effect. If your circuit doesn’t oscillate, your MOSFET will be stuck on shorting the supply. A driver will help.
          Although there can be other things causing issue for you, like wrong winding connections.

  101. Hi Mehdi,

    nice to see your movies. I have a question I think it’s never been asked (could not find it here) I want to build a coil like yours and want to use 32AWG but how long should this wire be in order to fit the 40cm long 40mm dia PVC? i don’t want to have separate
    wires but 1 for the secondary coil. they are sold in standard coils as 100 Meters.
    should 1 be enough? Hope you will help me out.

    thanks in advance.

    kalliber5

    • Hi Kalliber 5,

      100 meter will not be enough. 32 AWG is around 0.25mm thick. 40cm long means around 1600 turns. One turn of 4cm is 12.6cm long. So you need 201.6 meters of it. But it is ok to do a fine solder in the middle and continue. Just put a Little Pony sticker on it and nobody would know!

      Have fun!

  102. Hi Mehdi!

    I have finished this slayer exciter based on your design, using power MOSFET. Good new: it works! Bad new: It’s very very low in power (even smaller power ouput than the mini one you referred to in your video).

    The primary coil has 8 turns, bare copper wire. I wired it vertically, not in a cone shape like yours. The secondary has 1000+ turns, 30 awg magnet wire. I powered using 12V, 2 amps wall adapter (kinda like a laptop charger).

    I used transistors (SCT2450 & IRFIB7N50APBF-ND). Both seem to work! However, I realized the IC Driver MOSF MIC4452 got overheat very fast.

    Do you have any ideas in mind that could go wrong with my circuit? It would help a lot to get some of your thoughts on it.

    Thank you and have a lovely day

    • Hi there,

      I assume you have a 2 ohm on the output of the driver, which is fine. If not, make it around 2 ohm.

      Also I didn’t show here, but place a large capacitor on the power line for the driver, followed by a few 100nF, 10nF and such. We want its power to be stable.

      To increase the output power, raise the BATT level to 18 or 19V, but don’t go to 20V as the driver will blow up. It will yield much more output power. Also you can power your driver with a clean 12V, then power your coil primary with a higher voltage like 30V. You can raise the coil primary voltage until the FET blows up!

      • Yes I do have 2ohm on the output of the drive.
        Sorry for my limit knowledge, but I’m not sure how to place the capacitors to stabilize the power supply to the driver. Can you extrapolate more on it?

        Thank you, Mehdi

      • Yes I do have 2 ohm on the output of the drive.

        Sorry for my limit knowledge, but I’m not sure how to place the capacitors to stabilize the power supply to the driver. Can you extrapolate more on it?

        Thank you, Mehdi

    • I made this circuit a while ago and was able to light up 5 florescent bulbs at about 12inches and one bulb at distance 1 metre. You probably have to decrease primary turns to 3 or 4 turn.

  103. Hi ElectroBOOM I’m an electric fanatic so I want to build a tesla coil as your, can you make a video explaining all the process? I would be grateful. Thank you.

    • Unfortunately can’t! I make short videos with more data in my website. Also I can’t make another Tesla coil from scratch, one is enough!

    • That is a coil with slayer exciter. Please see my video and page on Slayer Exciter Tesla Coil. Thanks!

  106. Hi
    I got the circuit working on 5V with one transistor. Then got it working with 10V and 3 transistors in parallel, but I forgot to connect a resistor to the base of the transistors and it still works, is there some sort of left over power from the secondary that turns the transistors on?

    Thanks

    • fascinating! generally it needs the resistor for the first kick at power up and then it doesn’t really need it. Maybe you are getting your kick from noise in the environment?

  107. Hi Mehdi S!
    Absolute love your work!
    In fact i like it so much that i’m attempting to build one my own.
    But i got 2 questions that hope you can help to answer.
    1. Is it possible to use 12V wall adapter to power it? If so, what is the current output of such adapter? or it’s not important at all?
    2.Is earth ground needed for this slayer exciter? In the video, i see you connect it directly to the negative terminal of your power supply, If i can use 12V wall adapter, can i just connect it to the negative side (black wire) as well?
    Thank you so much!
    Hope to see more of your work!

  108. Hey my friend.. i finish the circuit and it works !! Now i tried to build one with MOSFET.. any sugesstion what type can i use? My primary is 1400 turns with enameled wire.. secondary is common insulated wire with dia of 0.045′.. i tried to make plasma farther n stronger.. can u help? :’) oh yes.. it is dangerous? I want to place it near my bed and turn it on whole night =))

  109. Pingback: Music, Magic and Mayhem with Tesla Coil | ElectroBoom

  110. I have just made the first circuit, Its not working. I have use 250 turns on the secondary.

  111. which causes the capacitance between L2 and the ground? I’m also having trouble to understanding how oscillations occur. Thanks

    • The stray capacitance is between the toroid on the top and the surrounding environment. basically any two conductor have some capacitance between them. No matter how small, it is enough to make this circuit work. I tried to explain the oscillation above, and in some comment below. With some imagination, hopefully you will get it!

        • You need some capacitance eon the output. The coil already has some, so in some cases you can eliminate the toroid. But otherwise a toroid, or whatever top load should help with that.

  112. Hello! Is it okay if the turns of the secondary coil overlap each other while making the turns? I noticed that the diode is in reversed biased, will it generate a voltage drop for the resistor in that way? Thank you so much!

    • The diode only turns on when the base voltage goes below ground. It is to protect the base.

      • Hi there, I have just made one but cannot get it working. I am using a bd679 non power transistor. When an led is connected to the collector and positive voltage it lights so I don’t believe the driver is faulty. My secondary coil is around 1000 turns but the wire is overlapped in two or three places.

        Would this effect it so much not to get a result?

        Thanks

        • It is ok if a couple of wires overlapped. Try flipping primary connections to your circuit. Also darlington transistors are a bit slower and may not work. Also the one you have also has base resistors that would load the circuit. Try to use 2N2222 or 2N3904 (this one can take lower voltage, but should work).

            • Thanks for a quick reply,

              Thought speed may be an issue but didn’t realise the base resistance would be an issue. I have a whole row of c548 transister I could try. If not I will head down to radio shack and pick up a couple 2n2222 or possibly a tip31.

              Just counted the overlaps to be around 15-20 out of 800 turns- could that result in no functionality

  114. Hi there.
    I tried also the circuit.. but unfortunately with no effect.
    The transistor got extra heat with 9 volt battery, primary 8 turns 1.2mm and secondary 220 turns 0.4 mm ( sorry i use metric ).
    But nothing there.
    Let me get it str8.!!
    Primary one end to the battery, second end to the collector, and secondary the one end to base. !!
    I used darlighton, rf transistor… Still nothing. I feel lonely and hopeless.

    • Don’t be lonely! Just flip the primary connections and hopefully that should do. Also Darlingtons are usually slow switchers. Does your transistor have good timing?

      • Seems so…
        I tried 2n2222 checked its ok
        bd 675 darlicto…..darlighco….hmmm the darli ones checked also.
        2sc4793…that need a little more work than normaly, but its a possibility.
        And i am going to try IRF mosfet to see what will happen.
        Does the diameter of the 2ndary matters ? its 1.5 cm

        • Update
          It worked. I had to call Tesla (call me crazy )to give me some tips, such as …plug it on!!
          Thank you for the hilarious videos and looking forward for your new projects

  115. Hi, i’m currently building this beast. Just a few questions before i complete my design.

    1) I have around 200 turns on my secondary with 23 AWG. Will it make any difference?(considering you have 750)

    2) I’m thinking of connect around 4 to 5 2n2222 in parallel in a common emitter configuration ( which i think is done in the schematics and therefore causing a phase shift). Is it ok to do so and can i add more?

    3) And lastly i didn’t quite understood the “Diode D prevents the base voltage to fall more than 0.7V below ground, which in return pushes the output end of the secondary high”. could please elaborate. thanks.

    • 1) 200 turns makes for a smaller output voltage, and so less effective
      2) If by that you are trying to increase the output current, then you are also increasing the input current to the base. If you keep the base current the same, then it doesn’t matter how many transistors you put in parallel, the output current would be the same. But they also share the power and get less warm. It would be harder to drive the base with the secondary of transformer. Especially since your turns are fewer.
      3) See, when the secondary voltage jumps up, the voltage on both sides of the coil starts to grow, one side positive and the other side negative, which is connected to base of transistor. Now as that voltage is going negative, the diode will be forward biased and clamps that voltage close to ground (0.7 is for diode drop). And so with one side voltage fixed, the other side rises higher with respect to ground.

      • Right. So what i have to do now is to increase my turns and somehow manage to increase the collector current without burning up my transistors. Is it enough or am i missing something?

        • increasing the number of turns makes for larger voltage which in return provides a stronger feedback to the circuit to make it oscillate. With small feedback your circuit may not oscillate.

          • Right. All things cleared. Just one issue, your simulation graph shows that the voltage(+ve) increase over time and continues until maxed, but the negative part, that’s what bugging me. Shouldn’t the voltage be around -0.7V and why does it stop at -1.6KV. Shouldn’t it increase?

            Looking at the graph, is it legal to say that the output is AC (since it has both +ve and -ve halves)?

            • We are looking at the output which is not limited by the diode. It is an imbalanced AC, the high and low side periods are not equal so the low ones are smaller but wider and the high ones are larger but thinner. The average remains around zero as DC can’t pass through transformer.

  116. Hello thank you for the great video and information :). I am looking to build this for a school project. How many turns would you suggest for a 1 inch diameter tube and 32 AWG Magnet wire? Also does the Watt of the resistor matter? I’ve found all the materials at a local store and I was going to buy a 33K or 47K Ohm resistor but I’ve found that they range from 1/4 Watt to 2 Watt and I am unsure which one is best for this project.

    • Try 1000 turns or more. The wattage or resistor doesn’t matter in the range you have , it is pretty low current anyways.

  117. Okay so I am trying to make a slayer exciter myself using the original simple circuit.
    I am using the same diode and the same transistor as you but still the exciter won’t work! for the stray capacitance i have used a spring like structure like you have. The end result is the transistor gets easily heated and starts burning the breadboard. I have tried reversing the primary but that didn’t work either. Could there be a problem in the secondary coil that ive made? If yes what are the possible problems

    • Are you sure you are using the 22k or 33k resistor? It shouldn’t heat up. The transistor mat heat up though if the circuit doesn’t oscillate. How many times are your turns? It is a very simple circuit, if your components are the same and connections are the same (diode direction, transistor pins), then it should work. is there break in your wires? Are you using proper magnet wire?

      • I am using around 30 gauge enamelled wire and yes 22k resistor. And it is around 750 turns. The problem is that the circuit draws more current than it should. We get 0.5A current only on 1.5v.

        • hmmm, something sounds broken. If your connections are good, then the transistor is probably gone.

    • Yes it will. It is just so thin and you may have a very bad time trying to wind it. It could break in the middle. But don’t give up, solder it back and keep winding.

  119. Hi mehdi, nice to meet you, and compliments for your videos.
    I help for one thing…

    – 10 turns for the primary coil and the wire of great diameter more it is large better is
    – Its necessary separate, the coils in the primary like in your video?!?!? If yes, how much millimeter of separation??!?!!?
    – 1000 tuns for the secondary, with a AWG28 or AWG32
    – PVC pipe with 40mm (4cm) diameter for the secondary. But how much LONG?!?!?!?!?
    – Battery it means 5Vdc to 12Vdc, or 5Vdc to 20Vdc?
    -In your video, at the minute 2:40, i see the schematic diagram and in the left of the “video= your realization that you have building. I see the 25K2542, MIC4452, heat sink, and 5 RESISTOR. But in your schematic, i see only 2 resistor… So why you have put five resistor?

    Thanks a lot for you help.
    greetings from italy,
    Carmine 😀 😀 😀

    • – I have 10 windings for primary. Generally thicker is better and reduces resistance. But my 22AWG wire also works fine. If you reduce the primary winding turns your output voltage would be greater, but don’t go below 5
      – My wires are bare with no insulation and if I put them too close they could arc to the secondary high voltage winding. keep your bare wires at least 1cm away down there.
      – AWG 28 is easier to wind as it is thicket and won’t break easily, but you get much more turns with AWG32 if you can do it, which makes more voltage.
      – The length of PVC depends on your wire gauge and the turns you want to do, you can do AWG32 and shorter for 1000 turn, or do 2000 turns and longer PVC
      – 5V to less than 20V for higher power circuit I made.
      – I was playing with resistor values and put a few of them in parallel to get a new resistor value. You don’t need to do that.

      Have fun in Italy!

      • hehehe, thanks a lot Mehdi… going to start ‘ to build it and you ‘ll keep ‘ updated :D…cheers

        greetings from italy,

        Carmine 😀

        • Hi mehdi… I have a little bit problem with the transistor 2SK2542. I have found 2SK2545, with this parameter:

          2SK2542:
          Channel: N
          Vds = 500V
          RdsON = 0.75ohm
          Power (P-drain) = 80W

          2SK2545:
          Channel: N
          Vds = 600V
          RdsON = 0.9ohm
          Power (P-drain) = 40W

          So, i can use this 2SK2545, or the RdsON 0.9ohm, its a problem for this tesla coil solid state?

          Thanks a lot.
          greetings from italy,

          Carmine 😀

          • That should do, just that it gets warmer while it can handle less power. So if you drive it hard, it will break easier.

            • hi my friend… I’m finish the circuit and the coil… It works, but not fine!!! I want to say, that the 2SK2545 for its power (40watt), the brightness is equal like the circuit with the 2n2222a transistor… now, i try the the 2SK2542 on eBay store for increase the brightness of the “bulb neon”…

              Any way, thanks a lot for your support…
              greetings from italy,

              Carmine 😀

  120. can you explain the part when the transistor switch ON / OFF? How the voltage bias on the base of the transistor reduce down below 0.7 V and rise again doing the oscillation process?

    • The secondary voltage tries to rise, the parasitic capacitor tries to hold it close to ground which pushes the voltage on the base side down, turning transistor off. Then the base resistor eventually rises back up.

  121. Sir,
    I need to make a receiver to draw energy from the slayer exciter and light up small led or so.How would i do that ???

  122. hello sir ,i’m really fasinated by the project that you made ,and i’m really excited to build one for my own but could you tell me more about the toroid on the top ,like what kind of wire you used and the required gauge for it???

    • The toroid on the top doesn’t need to be the way I made it. You just need a relative large metal toroid. Doesn’t even need to be a toroid! It could be made of aluminum foil. What it does is that it creates a capacitance between the output and earth that sets the resonance frequency of the secondary.

  123. Hello,
    I have 2SK2485 at home. Is it suitable for this? And I can buy IR2112 or IR2110 driver. Are they usable with this transistor (in case of yes, which one is better)?

    And I have one more question. Why are tesla coils usually made without core? Wouldn’t it be better with some ferromagnetic core?

    Thanks for the answers,
    Fatalwir.

      • The resistance of the transistor looks a bit high, which heats it up quicker, but at low power outputs it should be ok. The drivers are also ok, but they can provide below 1Amps gate current which might slow down the transition, heating the mosfet up. It also depends on your coil properties (oscillation frequency) that how fast you need to make your components. Try them out and you will know!

        The issue with cores beside air is that that saturate at some current, and so you will have to limit your current. They also absorb power and get hot and waste power. But air never saturates or wastes power. But what happens is that the resonance frequency of your coil goes high. But you can virtually provide as high of a current as you want, or circuit can take. and it is also a very good insulator compared to metal cores.

        Your diode looks fine too.

  124. Medhi,
    Is it possible to substitute the 2222a transistor with a 2N3904?
    Would there have to be any alteration I would have to do if I did that substation?
    I am planning on using a 9 volt power source or less

    • 2N3904 should work fine. You don’t need to change anything. If the transistor gets too ward, increase the base resistor. But that would also reduce your power. You could put a few of them in parallel for more power.

  125. Hey Mehdi, I have built a slayer circuit myself and it worked, but it keeps frying my 2n2222 transistors (burned 3 already) and I bought myself a brand new MJE13007 but the circuit doesn’t seem to work anymore. Is there any chance that you can tell me what the problem is?

    • The Hfe of MJE part is pretty low and so it requires a large base current that the secondary of transformer can’t deliver. Instead either increase the base resistor or lower the supply voltage to lower power dissipation. You could also put 2 or more 2n2222 transistors in parallel to share the power.

  126. Sir I’m new at this… can i have a photographic view of this circuit??? i don’t know how to connect the Q1… 🙁

  127. What is the difference between this(a slayer exciter) and a proper Solid State Tesla Coil(SSTC)?

    • This one self resonates, but with a solid state tesla coil you can tune for higher power with different PWM. Frequency would be the same.

  128. Neat curcuit! After building the basic SEC, I too feel the need, the need for MORE! I am definitely going to build your design, the results seem very satisfying. It will surely be a heck of a conversation piece, and with a bit of tinkering can be made quite useful, even if only in a “novelty” way. Check my twitter/YouTube channel for a short (and lazily shot) video of the mini I built , @breaktomake

    • A capacitor across diode will actually slow it down, because it will need more charge.

  130. I have made a slayer exciter circuit with the following specifications:
    28 AWG wire 425 turns on 1 inch outer diameter PVC pipe.
    Plastic Insulated copper wire 14AWG (i guess..its written 20 sq mm on the wire..
    I don’t know if its considering the insulation or not)- 4-5 turns
    transistor TIP41C
    a 100K potentiometer set at about 50K.
    IN4007 diode
    Nothing was lighting up so I connected the secondary to the digital multimeter at 100x probe setting and got a 4.3 kV sine wave.
    What must be wrong with my circuit?

    P.S. Is there any way to share the pics?

    • Try a few things:
      – Get some aluminum foil and make a ball and connect your secondary to that as top load
      – I’m thinking maybe your winding direction is connected backwards. Flip the primary connection to driving circuit backward and try again.
      – The Hfe of your transistor is a bit low and can load the very weak output. If you can, try 2N2222 or a transistor with higher Hfe.

      Don’t worry about what you read with your probe. The output is so weak that a probe can easily load it to zero.

  131. Hi. I just want to ask about this “U1 = MIC4452 (MIC4452YN is the through-hole version)”, what kind of component is? I’m confuse about this. Hoping for your kind consideration. i’m still new at tesla coils and I made one using the 2222A transistor. And I wanted to try the different circuit you made to see the actual difference. I may able to do some innovation about the this. Thank you..

    • It is a high speed MOSFET gate driver. High current MOSFETs have large input capacitance and so it is hard to drive them fast enough. So a gate driver like this is needed that can supply high currents to switch transistors fast enough.

  133. Hi Mehdi,,

    I was thinking to use a Darlington pair instead of the Mosfet. I know it does not switch as fast as the Mosfet but I have the parts. What do you think?

    • I tried darlington and it didn’t work for me. I think it becomes very slow. My transformer resonating frequency is 1MHz.

      • I’m going to try a darlington with a modified circuit, You are not the only crazy middle eastern engineer. Just so everybody knows, there are two 😉

  134. Would you please explain in which direction primary should be wound with respect to secondary.. and what ends should be connected to collector and vcc.
    thanks

    • it doesn’t really matter how you wind it, but how you connect it afterwards. look at the dots on the schematic above. They represent the end of the winding where windings start turning clockwise. Connect them accordingly.

  135. Hi! Do you have a schematic over the circuit of where the components are connected to each other, or where you placed them on the circuit board to sold them?

  136. Hi Mehdi,
    thank you very much for your fantastic experiments!
    Please, what diameter of wire and tube do you use? And what effect have these parameters on function of this experiment? And do you use 10 and 750 turns in both versions of experiment?
    Thank you and have a nice day. 🙂

    • tube diameter is around 4 cm and the wire was 28 AWG. The primary winding can be thicker, the thicker the better.

  137. how can i extend the range of the load to this circuit to maintain its brightness? i would like to place my load 2 ft. away from the source, is it possible?
    thank you for your help

  138. Hi Mehdi! Thanks much for the writeup, I’m a big fan.

    I have one of the “original” 1.5V slayer exciters, and I just ordered up the parts I need to build your beefed up version. I’m going to try to use IRFB9N60APBF as my NCH because the data sheet looked suitable, but I had a question about the Mosfet driver since I haven’t used one before.

    Your diagram shows a single input and single output, but the datasheet shows 4 pin functions (control input, supply voltage, output, ground). Am I correct in assuming the left side of the driver in the diagram is Control input, right side is output, and the supply and ground are not explicitly drawn?

    Thanks much!

    • You’re right, ground is ground, of course! And the supply can be the same as BATT in the drawing. Just make sure not to get too close to 20V or your driver will blow. Also put a 10uF capacitor and 100nF capacitor across the supply right at the chip to make sure it doesn’t drop.

  139. Fantastic writeup!

    Do you have any resources on why high-frequency AC is more dangerous than low-frequency? Obviously there’s more energy (as a result of more state changes over time) but what are the practical safety implications?

    • I should right something about it in my next post hopefully. But higher frequency burns the surface rather than going deep inside the body due to skin effect, which doesn’t have anything with human skin!

    • Look up a term called RF burns, or radio frequency burns. They aren’t very much fun.

  140. Hey
    i have another qeustion: as transistor you use 2n2222 but is this nesessarry or can i use you any conductor. The product is not avaible in our contry

    • Try to get BJT transistors with over 80V VCE rating and Hfe >100. They should work.

  141. Hello
    I am not expert in doing things like this.Can you make one for me?
    My contact number:0916xxxxx

  142. Hello,
    What is the voltage you put on it. We build one for school with yours as a model but we don’t know what your battery is like.
    Greeting marijn

    • It should work with a supply anywhere between 3V to 12V. Higher voltages may overheat the transistor. Start with smaller voltages and if it works, then increase the voltage to get more output power.

  143. Hello, I recently built a slayer exciter after several years of building Tesla coils (see videos by MisterApol on youtube). I’ve gotten good results using TIP 31C and 2N3055 transistors. I dug up a couple of high voltage, fast switching transistor (2SC5339 and BUF420AW) and was wondering if they would work in the SE circuit?

    Paul

    • Hi Paul,

      2SC5339 has a 45 ohm BE resistor and will be much harder to drive. BUF420AW has a small Hfe and would also need higher base current requirement. Both will be hard to drive and may not work with your coil. Generally something with high Hfe (>100) to have low base current works well in a slayer circuit.

  144. Love your vids by the way. I made a slayer exciter awhile back and it is using a tip 31 from radio shack. It ran ok but i put a small trigger coil in mine to boost the voltage and it works great. Burns the tip of my fingers pretty good if i touch the top of it. Good to see you helping people on here. The circuit is really easy once you get one going you can make more easily. Tip for beginners make sure you know the pinout of your transistor you are using. I had great success with NPN transistors best but you can use PNP transistors also. Start out with an NPN though and work your way up. I use a tip 32 NPN transistor from Radio Shack i think $2.99 was the cost or $1.99 not bad price though. Anyhow a 2n 2222 works great also it’s an NPN transistor. Well good luck all and take care…Gary Kirby on Youtube my slayer exciter is on there.

  145. Hi,
    Mr.Mehdi, I’m very excited by your video after watching it I decided to make this to be this semester project experiment on DC Application Unit. I read through your page already but is there any guide about winding a transformer.
    Thank you.

    • The transformer winding will be shown in another email. But mine is pretty simple. Just get a PVC pipe and 28AWG or smaller gauge magnet wire and wind a lot of wire, close to 1000 turns. That will be your secondary. I made a jig to wind mine faster and cleaner. The primary is just 10 turns of large gauge wires.

        • Your Tesla coil looks pretty good. But from your schematic, your winding connection is wrong. Flip the secondary connections and that should do. Also, wiring on break board may not allow your circuit to function properly. This thing resonates at high frequencies (~1MHz) and bread board may filter and stop it from working. Use a prototype board or just solder parts together on air.

  146. Hello Mr. Mehdi
    I would like to know what is the thickness of transformer wire for both coils???
    and how do you wind up the transformer???
    Machine or hands?

    • I think the primary one was like 18 AWG and the small on is 28AWG. I will make a video when I better explain it. But I made a jig to turn the secondary pipe with a drill and turn the wire around it.

  147. I noticed you said you were building a tesla coil. I built one using 2 mots and its pretty powerful. Never could get it working right with a regular spark gap so i built a rotary one. I had heard mots dont work well with stationary spark gaps so i went to the rotary style. Works really good now. It is cheap to build that way using mots. Dangerous but cheap. Anyway i just wanted to say thanks for your videos. They are hilarious to watch.

  148. Hello!
    First loved your video nice work!!
    Second,i tried to make it as well but then i noticed that you use your U1 with only one input and 1 output in the schematic but in the video i can see that all pins of the Op amp are connected to resistors..please explain how to connect my op amp so it works like that…i have an LM358N…i hope it works

    • Hi there,
      That part is not an OpAmp, it is a MOSFET gate driver. It has multiple connections for the same net as it delivers high current. Those resistors you see in the video are all in parallel as I was experimenting. You really need only one resistor (R1 as in the schematic).

      • I’m looking at the TC4421. If I understand the VS pin will connect to batt+. Is this correct? Or should I have something like a 2 Ohm resistor for current limiting?

        I plan to use a 11.9v supply from an old computer server.

    • This project has many educational aspects that can have real life applications, such as boosting voltages, wireless power, oscillating circuits and such. Maybe not exactly the same way, but similar designs are being used all over the world for real products.

  150. Mehdi,
    Thanks for every thing you do. I have question.
    Q: What is the power supply machine you are using in Tesla tutorial. I am confused about something. Is there any power supply with creates square wave and others waves and controlled voltage power .

    I mean is it? an oscillator is the power supply which creates waves and different voltages and DC/AC.

    • The supply I used is a DC supply, you could use a battery instead.

      You could say the city power is AC supply of course! but generally lab supplies are DC, and then there is the function generator that has low power output capability.

      • Thank you, Man.

        I was confused that how were you able to the touch coil so easily with AC power.
        Well, keep up the amazing work you do. I wish if we were also committed like you.

        Don’t mind but I might be asking questions every now and then.

  151. Don’t forget to give credit to the man who started this all GBluer.
    And for the people that don’t want to wind there own coils he sells a kit at slayerexciter.com

  152. Hi, is the asc file of the ltspice sim available anywhere? I tried to replicate it, but mine doesn’t oscillate, I suspect there is something different e.g. serial resistances of inductor/capactitor etc.

    • In your simulation in transient tab enable “Start external DC supply voltages at 0V”. That way your circuit receives the wiggle it needs to oscillate. Every circuit needs a bit of wiggle to oscillate, which is usually the power up transients or the noise.

  153. Hello Mehdi,

    I used a slandered Slayer Exciter and the problem I get with this circuit is the light fluorescent light does barely turn on, do you maybe have any idea how I can make it shine more brighter.

    Just also keep in mind I use a BC108 transistor not the 2222A
    And also I use a 12V transformer.

    If I use the coil that the guy said I must use 275 Primary turns and 3 Secondary the LED does not switch on.

    Please can you help me

    Thanks

    • BC108 has a break down voltage of 25V where 2222A has it at 40V. It means that BC108 doesn’t allow the primary voltage rise as much as 2222A does, which means the secondary voltage is limited too. So one thing you should do is to replace the transistor with 2222A or an even higher voltage transistor, while keeping Hfe>100. The next thing you can do is to raise your supply voltage, with a high voltage transistor that creates much more output voltage. Also fine tune the number of primary turns for maximum voltage. The fewer primary turns the higher voltage. But at the same time you run into the chance of the circuit not oscillating.

  154. Hi!
    I’m traing to make my own one, (a miniature with the first circuit, like the accent’s man ) but it doesn’t work at all.
    Measuring the voltage of the secundary I realise that it’s the same at the imput. It means that the transformer is not working.
    I made a transformer with N1=3 and N2=300 (maybe more) and there’s a ferromagnetic material inside.
    I know all the components are well connected and the diode in the corrected position.
    Any advise?

    P.S. Great video!

    • Hi Mehdi,

      First, thanks for your videos. They are really helpful~!!
      I have exactly the same problem as Cesc has. In my case, the transistor dies with a lot of heat after 2-3 seconds. I’ve tried changing the direction of primary coil (since it has much fewer turns than the secondary) several times, but the same thing happens over and over again.
      Could you please tell me what would be the problem?
      I was so sure about making this so easily but it has been more than a week looking for a solution and this is driving me crazy.
      It would be much appreciated if you have any advise.
      Thx~ and have a nice day.

      • Hey Messin,

        What kind of transistor are you using and what is the base resistor? is it my boosted circuit or the original simple one? The simple circuit should current limit itself if proper components are used, even if it doesn’t oscillate.

        To flip the primary winding, you don’t need to unwind and wind again in a different direction, you simply flip the connection to its ends.

        The issue maybe also that the stray capacitance on the output is very small, I don’t know what you have, but add a tiny ball of aluminum foil on the output, that could help. Double check your connections too. It should be a very simple circuit to make.

        • Hi Mehdi,

          Thank you for your reply.

          I’ve been trying to build the simple one (not the one you made), and used exactly the same components he mentioned in the video (2N 2222A, 22kOhm). But I used a random diode or LED that were available. Could it be problem?
          It is so annoying that I cannot even test it after connecting the battery because of the breakdown of the transistor… I don’t know what I should do further now…

          About the stray capacitance, I left the end tip of the secondary in the air and did not connect any capacitor. Shall I put a small capacitor which is about 0.1pF?

          Nonetheless, I think it is not some kinda connection problem. The circuit is very simple to make mistakes….. (I just followed the exact circuit in the video…) and I made new ones whenever I failed…

          Thank you again for your help~!

          • You don’t need to add any capacitors, it is already there. It is odd that your transistor dies. Because if you are using a 9V battery and 22k pull up, even if the circuit doesn’t oscillate the circuit should be limited to around 40mA which is 360mW over the transistor and it should die immediately.

            So I assume flipping the primary connections didn’t help?

            About the diode, because the oscillation of the cirucit should be pretty high frequency, I rather use a faster diode like a Schottky. An LED is not fast enough in my opinion.

            What are you using for your coil core, and how many turns? Maybe try it without a core. Also at the output, make the wire a bit longer like an antenna or even make a loop.

            Good luck

            • Sorry for the late response. My hands were tight this week due to work plus study…
              I might have to try this again later when I have time.

              Thank you for your comments. I will get back to you as soon as I solve the problem to tell you what the problem was.

              Thank you again and have a good day. 😉

  156. Pingback: The Slayer Exciter Circuit

  157. Hey, nice video.

    I am wondering what input power you are using from your power supply. As in, what voltage did you set your power supply to and what current limit? Wondering if I have a supply that can power this.

    Thanks

    • With the beefed up circuit you can go close to 20V as the driver chip limit is 20V. Around there the circuit was using around 0.8, with only one turn on primary and 750 on secondary. The current goes down as the primary windings increase, which means more primary inductance. When you bring the light close, it draws more current from the circuit to turn on.

  159. Good job 🙂 Oh an this might be an good idea to make a wireless power source you could lay it down on the floor and put a stick that is connect to its device already just put it colse and Vola! It works 🙂

  160. Do you know a good replacement IC for the mosfet driver? The one you used is obsolete according to mouse; digikey.

  161. Hello!
    Tesla used the Q-factor of the primary and secondary coils to get very high voltages without depending on turns-ratio.
    The primary and secondary were resonant coils with parasitic capacitance: tank circuits.
    The coils were trimmed to the same frequency: primaries often had small shunt capacitors installed to set the frequency.
    Secondaries had their adjustable capacitor in the size/geometry of the discharge cap.
    So, if one coil had a Q-factor of say 0.001, and the other around 500, the step-up would be impressive. Most impressive.
    So the highly inductive but low capacitance secondary would have the high Q-factor, the very low inductance but highly capacitive primary would have very low Q.
    Love the videos, neighbor! (Seattle says Hi!)

    • Thanks for the insight! I love this Slayer circuit because it automatically finds that sweat resonance frequency and there is no need for a tuned capacitor on the primary. I’m sure Tesla would love this circuit if the silicon parts were available back them.
      On the other hand for super high voltages we might have to revert back to Tesla’s ways, because Silicon components usually can’t handle that high of a voltage. So Tesla still rules!

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