Introduction: Building the Poor-mans Mini Tesla Coil ( Slayer Exciter)

Picture of Building the Poor-mans Mini Tesla Coil ( Slayer Exciter)

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

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

WIRELESSLY Light up:

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

Burn and ignite:

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

Destroy:

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

Create:

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


►Make following electronic equipment go crazy:

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


Transmit wacky sounds (loads of EMI) to:

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

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

Step 1: A Rundown of My Experimentation

Picture of A Rundown of My Experimentation

I did modify the circuit a LOT before I was happy with the results. Sadly, I did not take pictures of my circuit on the breadboard.

  • The first picture show first circuit. I could not get to work.
  • The second picture shows my first working design. I chewed through many transistors, and it was not very stable, but it worked.
  • In hopes for better performance and reliably, I tried a darlington pair. It put out about the same amount of power, but did not kill my transistors. I believe this is because it increased the gain and the feedback from L2 was enough to sustain the oscillation. I think this is because it did not latch up and pop my transistors.
  • I realized after running the circuit for awhile that I wired it wrong on my breadboard but it worked anyway. I decided to "fix" it, and ended up burning out my last 4401. From then on I had to resort to 2n3904's. This darlington pair test was inconclusive due to my mistake of not having the collector from the first transistor connected to anything. I learned that if it ain't broke, don't fix it :P
  • I finally decided to revert to my original circuit, except this time with all 3 remaining 2N3904's all in parallel. (collector to collector, base to base, emitter to emitter.) This worked exceptionally well, and I haven't killed any transistors since then! Now, I even get plasma shooting out the end! If you decide to build this, use that configuration, but use more powerful transistors, like 2N2222's or 2N4401's. They can handle more current.
  • [UPDATE, March 2014] Later on I then decided to use a MJE3055 transistor instead of the weak TO92 transistors, and started to get much better performance. I upped the voltage from 9V to 12V, and replaced the 1Mohm resistor for a 10K resistor. You can get the instructional details in the video.
  • [UPDATE May, 2015] I have now began work on a MOSFET version of the slayer exciter, and with 50V and a computer heatsink, I can achieve results that border a small SSTC!!! (Solid State Tesla Coil) Unfortunately the complexity of the circuit did increase, due to the need to drive the gate of the FET with buffer to allow fast switching. Luckily it is ultra stable when tuned correctly, and can deliver much more power with more supply voltage. I increased the size of the heatsink compared to what I used in the first slayer exciter video, and have active cooling fan giving some airflow. Now I can let it run indefinitely at 24V and beyond! :D Note: The topload is still critical, if it is too large, performance will decrease. Also I can draw up to 3 inch long, incredibly hot arcs, and get corona that is about an inch long!!! I have even managed to "burn out" a screwdriver from the inside-out! Where the shaft is encapsulated in clear plastic, the plastic began to experience dielectric breakdown and began to melt, and eventually the electricity burned a carbonized hole all the way through the plastic to my fingers, Ouch! The electricity must really love me! :P.

Step 2: Dangers

Picture of Dangers

The output of the Slayer Exciter is high frequency high voltage. (I measured about 100KHz for those interested) Although the arcs are small, it's still able to catch things on fire and give you (admittedly very small) 3rd degree burns! These are safer than many other high voltage projects, and thus make a good starter projects along with static electricity and Van De Graaff generators. Just make sure to exercise caution when fiddling around with this circuit.

Also, Obviously, this thing is a fire hazard. I have managed to catch matches, pencils and wood, candles, and other flammable materials on fire. Without proper precautions, safety measures, and supervision, that can lead to an uncontrollable fires. If you plan on attempting that, do so far away from flammable furniture or housing, and materials and gasses.


Remember: I do NOT express any responsibility or liability of any kind, explicit, or implied. If you destroy your own stuff or someone else's stuff, do not come crying to me!

Step 3: Things You Will Need:

  • 700-800 feet of enameled magnet wire.
  • NPN transistor (if you plan to buy them, buy them in bulk. Likely, you will pop a few while working on the circuit. I recommend a high power transistor, they just work better.)
  • Here is a list of the transistors that should work. The one's I have used are italicized along with others who say that they work.
    • TIP3055 (works well @ 12V, just make sure to use a heat sink)
    • MJE3055T (works just as well as the TIP3055 does, and has proven to be the most reliable.)
    • 2N3055
    • TIP31C
    • TIP41
    • 2N3904(needs least two of them in parallel for reasonable output)
    • PN2222 (variant of 2N2222, just in a newer case, the TO-92)
    • 2N4401
    • unlabeled transistors from a camera flash circuit
    • many others. If you know of one that works well, post it in the comments!
  • clean PVC pipe to wind the coil around (I used a paper towel roll, but this is not ideal, especially in humid environments.)
  • PCB to solder everything to (or a breadboard for temporary builds) (I do not recommend sloppy builds, as this is high frequency AC stuff we are dealing with. So the sloppier the thing is built, and the longer the wires connecting things are, the more prone to failure it will be and the worse it will perform. Keep wires short, and take the time to build the circuit carefully and be neat when winding the L2 coil.)

Step 4: Tools Required:

  • Good soldering iron w/ solder and flux (if you plan on making this permanent)
  • variable power supply with current limiting options
  • L2 winding jig (Recomended)
  • Camera (optional)

Step 5: Optimal But Recommended:

  • Small signal diodes
  • many LED's of various colors and types
  • a few fluorescent bulbs (larger ones will glow brighter.)
  • christmas lights and other flashlight bulbs w/ several feet of wire
  • junk parts to fry
  • electronic equipment to drive nuts! (radios, calculators, remotes, and someone else's phone and computer)
  • candles and things to destroy!

Step 6: The All-important Schematic and How to Build It. (small TO92 Version)

Picture of The All-important Schematic and How to Build It. (small TO92 Version)

There is not much to this circuit. Above are all the graphics and pictures. After you gather all your materials, take your transistor and wire it up. (Note, these instructions ONLY apply to the schematics shown below. NOT the video version of the circuit using a MJE3055T.)

1) Connect the emitter of the transistor to the common or ground.

2) Connect the base of your transistor to one end of the resistor, as well as to the bottom of the L2 coil. (this creates the differentiated negative feedback, which allows the transistor to oscillate.)

3) This is a little tricky. I have made a graphic to illustrate this step visually. If the winding's of your L1 coil run around the L2 coil in the same direction, (where both winding's run either clockwise or counter-clockwise), then the end closer to the top connects to collector. If the winding's go against each other, (One goes around counter-clockwise while the other is clockwise and Vise-Versa) then the bottom end connects to the collector of the transistor. If you have this incorrect, you may damage your transistor. If you are not sure when about to apply power, use current limiting, or a low enough voltage.

4) Connect the other end of L1 to the positive rail.

5) (Optional) Connect the negative end of the LED's to the base. (They are wired in series, so test them to make sure both light up when connected to a 6V power supply w/ current limiting resistor.) The side with the flat ridges or longer terminals if they are brand new LEDs should face the transistor such that the terminal nearest the flat ridge is connected to the base

6) Now attach the capacitor between the positive and negative rail. I found the best type is a high value film or ceramic cap, or the largest electrolytic capacitor you can source. Now the circuit is done, click the next step for testing and troubleshooting.

Step 7: Testing and Troubleshooting (TO-92 Small Slayer Exciter)

Here is the troubleshooting guide for the first variant of the circuit I built, it is for the versions using a 2N2222, 3904, 4401, etc:

  • It may be tempting to connect your circuit directly to a 9V power supply or battery, but this is a bad choice. That's how I burned out most of my transistors during my experimentation. After you have built your circuit check over everything and make sure it is wired correctly, and if it was done on a PCB, make sure there are no solder bridges.
  • First, after paying close attention to the polarity, power the project with 4.5V-5V, or 3 AA batteries to the rails and see if the leds light up, or if you can get a neon lamp to glow next to the output L2 coil. Keep a close eye on the transistors, and make sure they stay cool to the touch. If they are becoming really hot, with no neon bulbs glowing, then you have a problem. If it all checks out, increase the power. At 6-7.5V (or about 4-5 AA batteries in series), I found that the circuit can can output enough radiant energy to make a fluorescent light glow. Adjust the number of winding's for the best performance. I found 9 turns on less than 9V works best. Now, power the exciter with 9 volts, from a power supply or 6 AA batteries in series. (avoid using a 9V battery for this circuit, especially a heavy duty garbage battery!!!! They will die quickly and have a really high ESR). If it seems to work, hold it on for a few seconds. Keep your fingers on both the kill switch and the transistors. Make sure they do not get hot.

**Failure modes of operation, and how to fix them:**

IF the transistor gets HOT, and it does not work well or at all judging by the neon lamp test:

  • 90% of the time, this means that either:
    • A) The value of the bias resistor is too low, (try a higher value resistor, maybe 4.7k-20k)
    • B) The polarity of the L1 coil may be incorrect. (try switching the polarity)
    • C) The number of windings is way too low, it should be more than 3 at least.

IF the transistor is COOL to the touch, and does not work well or at all judging by the neon lamp test:

  • The polarity of the L1 coil incorrect. (try switching the polarity)
  • The bias resistor is too high a value. (try less than 1 MEGohm.)
  • You have incorrectly built the circuit, (check and recheck the wiring)
  • Too many turns for the L1 coil causes poor performance (try less windings for the primary)
  • You screwed the pooch and killed your transistor

IF the circuit works, and the transistor is getting warm, borderline hot, but still does not function as well as mine:

  • Adjust the number of turns on the primary, or L1. I find 9 turns work will for less than 9V operation.
  • Adjust the bias resistor value, if it is too low, the transistor gets excessively hot. Too high, the circuit does not work well.
  • Notice that the version shown in the video uses a larger transistor, not the small TO-92 ones:
    • You have the cravings for LOTS of radiation, so try a BIGGER and BETTER transistor!!!!!
  • Using transistors of higher current gain and power dissipation will be better.

Step 8: Testing and Troubleshooting (Larger TO-220 Version Shown in Video)

Here is the troubleshooting guide for the version of the slayer exciter shown in the video this guide is for the more powerful 3055, TIP31C, TIP41, etc.

  • After building the circuit and realising it does not work, first, make sure you power supply can deliver 12V at 1.5A minimum for best performance. I found that the circuit will draw as much as 3A at 20V, so if you plan on using such high voltages, make sure the supply can deliver the current.
  • It may be tempting to connect your circuit directly to a 12V 1A power supply or SLA battery right away, but this is a bad idea. After you have built your circuit check over everything and make sure it is wired correctly, and if it was done on a PCB, make sure there are no solder bridges. First, after paying close attention to the polarity, power the project with 6V, or 4 AA batteries to the rails and do the neon lamp test. Keep a close eye on the transistors, and make sure they stay cool to the touch. If they are becoming really hot, with no neon bulbs glowing, then you have a problem, and you may need to add a really big heatsink. If it all checks out, increase the voltage to 12V with a lamp in series with the power supply if it is not current limited to 2A. (as is the case if you use a SLA battery). It should still work, but perhaps poorly. Adjust the number of winding's and the bias resistor for best performance. I found 3-5 turns for 12V works best. (For this variant, DO NOT EVER EVER use a 9V battery, especially a heavy duty garbage battery!!!! They will die quickly, do not store much energy, have really poor power density, cannot deliver more than an amp, and they are just really bad. I would not be surprised if the battery leaks or explodes after using it for this circuit.). If it seems to work, hold it on for a few seconds. Keep your fingers on both the kill switch and the transistors. Make sure they do not get hot.

----------------------------------------------------------------------------------------

**Failure modes of operation, and how to fix them:** IF the transistor gets HOT, and it does not work well or at all judging by the neon lamp test:

  • This 90% of the time means that either:
    • A) The value of the bias resistor is too low, (try a higher value resistor)
    • B) The polarity of the L1 coil may be incorrect. (try switching the polarity)
  • IF the transistor is COOL to the touch, and does not work will or at all judging by the neon lamp test:
    • The polarity of the L1 coil incorrect. (try switching the polarity)
    • The bias resistor is too high a value. (try less than 10k.)
    • You have incorrectly built the circuit, (check and recheck the wiring)
    • Too many turns for the L1 coil causes poor performance (try less windings for the primary)
    • You screwed the pooch and killed your transistor
  • IF the circuit works, and the transistor is getting warm, borderline hot, but still does not function as well as mine:
    • Adjust the number of turns on the primary, or L1. I find 3-5 turns work will for 12V operation.
    • Adjust the bias resistor value, if it is too low, the transistor gets excessively hot. Too high, the circuit does not work well.
    • Try a different transistor, or one from a reputable brand, like Linear Technology, STmicroelectronics, Texas Instruments, ON semiconductor, or the ones you find on Jameco, radioshack (now bankrupt :( ) Digi Key, mouser, etc. Avoid the too-good-to-be-true deals on eBay. Often you will get hung-wan-low quality garbage, or old used and recycled transistors that have been cleaned up and the old part number of an inferior transistor scrubbed off and a new one printed on. Obviously you do not want that garbage.
    • You have the cravings for LOTS more radiation and EMI, try build a proper tesla coil! That is the next logical step up! :).

Step 9: All My Pictures

Picture of All My Pictures

Comments

profsrchaos13 made it! (author)2017-11-15

why do i have to use resistors connected to my led lights and hold them in my hand before they will even light up? and what do i needto do to make lights come on automatically?

-max- (author)profsrchaos132017-11-16

LEDs (all loads) require a voltage potential across the terminals and a current flow in order to glow. LEDs have the additional requirement that they only glow when current flows from anode to cathode. I used what is typically referred to as an "avramenko plug" by the hobbyist community for best results. This arrangement of high speed small signal diodes allows the picked up high frequency electric field generated by the slayer exciter to be rectified and drive current through the LED.One end of the LEDs is connected to a ground, or some body that is capacitively coupled to ground. The end of it connects to an antenna that is brought near the slayer.

Trying to power an LED directly from the slayer exciter is much less efficient, and the reverse voltages may damage the LED. You certainly cannot just be holding both terminals of the LED expecting it to glow, there is no voltage across the terminals. That will only work if there is a really strong electric field stimulating the really small die. Even if you hold one end while bringing the other end to the slayer, it will not work very well and may damage the LED. Reason is is because the LED has internal junction capacitance, so forcing an AC voltage across it, this capacitor resists those fast changing voltages, and shorts the AC component to ground (you holding the other end of the LED). If you do get enough voltage across the diode to make it light, the negitive cycles will cause the LED diode to enter reverse breakdown and pontenitally destroy the LED.

profsrchaos13 (author)2017-11-15

why do i have to use resistors on my led lights for them to light up w my 9 volt slayer exciter ? i thought they would just light up in my hand? or do i need to change something about the way its constructed?

GaneshA19 (author)2017-07-30

pls help

GaneshA19 (author)2017-07-30

hello...i have more than 1500 turns of 30 gauge enameled copper wire wound over 22" long pvc pipe of 2.5" diameter.....will the circuit shown in the video work for this....pls its urgent

_Widmo_ (author)2017-05-23

Hi everyone! I've made my tesla coil. It has about 1330 turns of 0,2mm enameled wire in one coil and 9 turns of about 1,2mm diameter wire in the second. I used 1MOhm resistor , 2N2222 transistor and powered it with 9V battery. I checked with multimeter ( and with my fingers ) that high voltage is produced in the coil, but it can't light the neon light wireless. It can light the LED but only if it touch the wire of coil. I tried to change number of turns in smaller coil and to change the resistor to smaller but still nothing. Anyone have any ideawhy isn't it working? I need it to a school project.

MattR220 (author)2017-05-11

Thank you Max, here's another version of the circuit with 6v instead of 9, and I've tried adding the 22k resistor instead of the 5.1k that comes with the kit, and tried reversing polarities...still nothing

-max- (author)MattR2202017-05-11

Snap circuits are not ideal for this type of circuit. We are in the realm of high frequency RF applications. Every inch of wiring has non-negligible parasitic properties like capacitance and inductance and can act like an antenna, picking up random crap and screwing with the operation of the circuit. This circuit in particular actually takes advantage of that to work! But you should build this circuit on a PCB or a breadboard.

Also this circuit is very good at killing transistors when it is not oscillating properly because of the low-resistance path between emitter and collector. If the circuit does work then the transistor is turning on and off millions of times per second and the inducance of the primary ensures reasonable power losses in the transistor. But if it stops oscillating, then the transistor (biased on) will conduct large DC current and overheat, and pontenially die. I would not be suprised if your transistor block is dead. You can check with a multimeter and measure the Vdrop of the PN junctions between emitter and base and collector and base to see if you get the 0.5V to 0.7V reading one would expect from standard PN junctions.

MattR220 (author)2017-05-11

Can someone please help, I've tried for many hours to make a slayer exciter and can't get it to work. I've tried different transistors (nte123a is supposedly equivalent to 2n2222a?), I've switched the primary coil back and forth many times, the primary copper coil has been wrapped both 3 times and 4 times and had a coating which I removed but none of this has worked, the secondary coil was taken from inside an automotive relay. Very frustrating.

-max- (author)MattR2202017-05-11

These circuits are very frustrating indeed! Have you referred to my the last troubleshooting step? I see a few problems already but I'll let you discover them! ;)

m4nb34rp19 made it! (author)2016-02-27

Hey -max- cool video mate (sound wasn't that bad, stop complaining you lot). Nice simple little circuit too, but your demonstrations were good, saved me a lot of messing around so thanks for sharing!

I initially ran a single TIP3055 and it got pretty hot with the eventual 24volts (only drawing 1.6A at this stage) and was running any ceramic caps i could find from old PSUs (had 3 in parallel, no idea what specs but they worked) i tried running two TIP3055's in parallel and it definitely made it run better - a more sustained and longer arc (and cooler). 1k metalfilm bias resistor and 63V 10000uF electrolytic capacitor to replace the ceramics - this also seemed to increase arc length and intensity. Old Pentium heatsinks for cooling transistors.

Primary coil is 3T of mains earth wire.

Secondary coil is 932T exactly (not that it matters but i had a counter laying around that i ran off the side of cordless drill on a roller microswitch and a "cam" to click it over, or piece of wire taped to chuck to be more accurate) so it was easy to keep track. 48mm pvc pipe for former. It measures 7.0uH on the dot (was a fluke as i didn't make any calculations until afterwards out of curiosity) and 50ohms resistance (again, a fluke lol). my only design consideration making L2 was make it as big as i can for about 20 bucks in wire. The wire is 0.25mm enamelwire with about four joins in it which are insulated with kapton (polyimide) tape then wrapped in kapton. Next step is to put circuit on a pcb and tidy things up a bit, all the wood was just scraps from the shed.

I learnt the hard way, remove all jewelry (especially gold wedding rings!!) before powering up your circuit - it won't electrocute you but it will definitely give you a nasty burn!

I'm pleased with it, works better than expected, sustainable arc approx. 3-4cm and starts reaching out to conductor at about 10cm (depending on top load). does all the light bulb tricks, and my favourite - the ion motor. I think i'll build the bigger one next with the 555 timer and inverted buffer driver circuit, that looks awesome.

Only thing i cant do is get a decent picture of it running, you did very well to get the pictures and video of the quality that you did max, i suspect any complaints came from ppl who haven't actually built one and tried to take a picture or video of it running themselves because it freaks my camera out something crazy so here are some pics of it set up but not powered and one of it powered with a single TIP3055 and a light globe sitting in a short piece of pipe to make it stand up, in real life it's purple/pink plasma, but on the camera it looks like this?! (very poor shot) and the latest build, and my burn (lol) and my "coil winding jig" (with my first coil, didn't use this coil, spooled the wire onto the new coil, but i didn't get pics winding the new one), i'm still working on getting some action pics and ill post them when i finally get the hang of taking pics of it running :)

MarkP26 (author)m4nb34rp192017-03-07

LOVE the door knob topload! That's awesome! :-) An old calculator with the "=" key (or sometimes the "+" key) wired out to a micro switch works great as a turns counter too.

Bro can u just tell me about all the things used in this project including input voltage
And a circuit diagram of arrangement of all things

m4nb34rp19 (author)m4nb34rp192016-02-27

Quick correction, the big electrolytic cap I'm using now isn't a 63v as i mistakenly stated, it's a 40v (it is 10000uF though, I got that bit right)

-max- (author)m4nb34rp192016-02-27

Nice build! Glad you got it working even better than I did! I have like 10 2N3055's I might give this older circuit another try, maybe with additional circuitry to increase positive feedback.

Taking good pictures is never easy, and I certainly didn't take the best pictures for this build! I just used my old GS3 phone and an entry level amature camcorder for photos and video. The result is blurry, grainy, and colorless photos. In fact, my phone's capacitive touchscreen and capacitive touch buttons would saturate from the strong EMI and the phone would do random things and become completely unresponsive if I got too close to take pics!!! I even killed an $80 mobius camera in a similar way! (thankfully the camera was pretty new and I got a DOA exchange! Upon inspection of that camera, there was absolutely no electrical shielding inside the camera, and an electrically floating heatsink, so I guess high voltage was induced into the metal heatsink and sparked to the microprocessor inside and killed it. Getting the new one, I fixed that issue and keep it away from the fun HV toys.)

Ideally, one would use a camera that has excellent low light performance. Low light performance will depend on the image sensor, its physical size, megapixel count (in this case, less is more. You want a LOW pixel density), as well as the lens and aperture size,(determines how much light does it let in.) The bad coloration of the spark may be due to a lack of IR or UV filters type of image sensor used. Image sensors tend to be good or even better at picking up UV and IR then visible light! You can tell if there is a IR filter on the camera by taking a picture of hot cherry red coals. If they look purple instead of red, then it's likely that there is no IR filter. That is good for making IR night vision, but bad for accurate colors.

And yeah, when you are near the circuit in operation, you are capacitively coupled to the high voltage, so even if you are not touching anything, there can be several thousand volts of AC on you, and if you go to touch any grounded object, that potential difference can give you a nasty zap and smelly burn!

m4nb34rp19 (author)-max-2016-02-28

Thanks mate, yeah my "camera" is a samsung g5 phn so i'm not sure what the low light capabilities are, takes pretty good photos of everything else but goes loopy when it's near this circuit, you're not wrong about the touch screen going nuts lol. might have to borrow a real camera and stick it on a tripod or something far enough away from it. I don't know if i'd say i got it running better than you did though (your video's the benchmark), but thanks to you're video i was able to skip a lot of headaches and see how things should work so thanks for posting it mate. It's pretty close to the results in your video so i'm pretty happy with it. It's amazing how you can be coupled to it at such distance, and this is a mini Tesla coil, the big ones must be pretty scary! I'd still love to see one in real life though :)

I'm pretty keen to build your SSTC, that looks very cool, just having trouble finding parts locally for it, i may have to order them (Jameco looks like the go) but i'll happily play with this in the meantime, the light globe on top with plasma in it looks like it's going to melt the glass, so cool!! The kids love watching it too (no touching obviously) and my wife is afraid of it (hehe perfect!). As soon as i figure out a camera and get some proper pics i'll post them (Gotta get some pics, or vids for that matter!). Thanks again for posting your videos, i've always dreamed of building a tesla coil but the full size ones are just a little bit scary to start out on so this is great! can learn the science and get familiar with it's behaviour at a scale that's manageable without killing myself, and work my way up to the big ones, next build - the SSTC, that looks like a fun circuit to build, i may need a bigger power supply though! I've just upgraded some parts on the one i've got and squeezed another 1.7v or so out of it, but it's still working pretty hard to drive this circuit lol :)

-max- (author)m4nb34rp192016-02-28

For the MOSFET version, you don't need to get that DS0026 chip, any MOSFET buffer driver chip should work, at least with some fiddling around. I just happened to have like 30 DS0026 chips in a electronics drawer, and they worked really well. However because they are obsolete parts, don't spend too much for that specific part number. In fact, I think it might be possible to just use a NPN / PNP emitter follower totem pole configuration.

I mainly used a Sony CX220 to record the video for the bigger one, I think I used the same camera for this older circuit. I got that camera because it was the only affordable camera that advertised a backlit CMOS image sensor, recorded 1080p 60FPS, and had optical image stabilization. However I was not too impressed with low light performance. Very grainy, but I guess for less than $200, it's acceptable. I experimented with video enhancements like a unsharp mask in post production, and it seems like sharpness and graininess are tradeoffs. (a clean but soft image, or a sharp but noisy image. Pick your poison. I picked the latter.)

I think someone in the comments has built the MOSFET version of this circuit with 170Vdc directly from the walls!!! I would like to get this circuit to work that well, although I would like to test at half that voltage first. Doing that, the circuit would need some modifications particularly in the method used to create a low voltage 12V for the 555 section.

m4nb34rp19 made it! (author)-max-2016-03-11

Hey Max, sorry took so long to post back, here's some pics of the coil finally (i think the trick for me was getting someone else to take them haha). also included a pic of the circuit (2 transistors) and the transformers i scored from a big UPS (working, but in the bin lol).haven't had a chance to test them yet but hopefully tonight when kids are in bed. Right after the pics were taken of the coil, one transistor let the smoke out and the other blew the front of it out (pretty loud, i was more impressed than concerned). Rebuilding now with 3 transistors then gonna move on to the SSTC, thanks for the info about the inverted buffer driver, i'll start getting the parts together. I'll post what the outputs are from those transformers too once i get a chance to test them (was 240VAC 15A input so i reckon they might be too big perhaps?)

m4nb34rp19 (author)m4nb34rp192016-03-12

ooh that soldering is definitely not my best work, i was using a gas iron for that cos i couldn't get my good electric one out at the time so it works, but it looks horrible, i'll print a pcb outlay at some point and post the jpeg if it turns out well enough, i kinda rushed assembling this circuit cos i wanted to see it working again lol.

The output from those transformers were wired in series too so should be interesting anyway, think i know where some smaller ones are in some other smaller scavenged UPSs i have floating around, gonna take a couple apart tomorrow and see if they're any good cos to be honest, those big ones just look too scary haha, but i will test them they may be just right despite their imposing size (and weight!!) just take all the precautions first. too tired now to play with that, bed time... ill do some more in the morning when im feeling sharper lol

flying_greekman (author)2017-01-25

I made it and it worked with a 12 v battery .But the coil broke the battery because it used up more than 20 amps at a time .Any ideas about what i did wrong , or what i can do to power it with any other way ?

please help its for a school project.

-max- (author)flying_greekman2017-01-25

I need more details to help. Did you read the troubleshooting guide at the end?

flying_greekman (author)-max-2017-02-21

what other details are necesarry ?

Zhuna87 made it! (author)2017-02-18

Hello,

Can you help me with this capacitor? I wonder if I connected it the right way. You can see that in the last picture.

Best regards.

-max- (author)Zhuna872017-02-18

To be unforgivingly honest, I am surprised that the circuit even works. I found that through years of building these types of circuits, that neatness CAN impact the performance and reliability of a circuit.

First, rebuild it and consider using much shorter wires and at a minimum a perfboard. We are dealing with RF electronics, which means that every extra millimeter of wiring has some parasitic properties like resistive, inductive, and capacitive effects. So you want to ensure all the connections that carry RF signals are electrically separated, have a ground plane, etc. Also having a mess of wiring means that it's easy to have points short out or signals bleed from one point to another undesirably.

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Then I would remove the diode in favor of a "real" diode. Consider a fast schottky diode or at a minimum a 1N4007. I have found that LEDs tend to die when wired in.

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As per the capacitor as you asked, it looks fine, so long as you have the polarity correct. If you want to further improve it's ability to reject power supply noise and clean up the DC coming into the circuit, you can add additional, smaller film / MKP capacitors in parelell to it. With values like 0.47uF, 0.1uF, 10nF, and 10pF. Typically the higher capacitor values are better at rejecting higher frequency blips in the DC comming into the circuit. It will very marginally improve performance.

Zhuna87 (author)-max-2017-02-18

Thank you for your answer.

I know it's a bit messy but I checked and I made sure that there isn't any short in the circuit. I will rebuild it these days and make shorter connections as you said. I placed two LEDs as you can see, green is the on the top and red is lower. If I place just one led the transistor burns. Will the schotkky diodes impact on this?

And last question.

What do you mean of "parelell to it"? Parelell to other capacitor or parellel to something else?

-max- (author)Zhuna872017-02-18

Your choice of transistor can also affect the circuit. You need one that can handle the power levels you desire, and preferably one that can operate well at higher frequencies. This makes the MJE3055 I chose to use for my more powerful design a poor choice, given it's age and slow characteristics.

Pretty much any modern transistor that can dissipate 50W of heat and handle at least 60V will be better.

Zhuna87 (author)-max-2017-02-18

Thank you very much for your answer.

You helped me a lot.

Zhuna87 made it! (author)2017-01-25

Thank you,

here is my Slayer and it can power CFLs that are up to 25 watts.

nitiny2 (author)2017-01-20

i have used 26 gauge copper wire and coiled it completely on pvc pipe of 150mm length and 28mm diameter 300 turns . which resistor and transistor i should use to make mini teslacoil with 9V DC battery PLZ reply immidiately

nitiny2 (author)2017-01-20

i have used 26 gauge copper wire and coiled it completely on pvc pipe of 150mm length and 28mm diameter. which resistor and transistor i should use to make mini teslacoil with 9V DC battery

MohiniG2 (author)2017-01-14

Can you tell me the size of the pipe

dineshsaini (author)MohiniG22017-01-14

it will work with 10 to 15 cm length

MohiniG2 (author)2017-01-14

And what type of wire for primary coil

dineshsaini (author)MohiniG22017-01-14

Magnet wire

MohiniG2 (author)2017-01-14

Hey max please reply

MohiniG2 (author)2017-01-14

And what would be the cost of 12volt model in Indian ruppee

MohiniG2 (author)2017-01-14

Please rreply max

-Jack- (author)2017-01-07

Hey Max,
I have done lots of experimentation with tesla coil circuits, I made a derivative of this design with the 2N2222 transistor. I have found that if you take 3 2N2222 transistors and make a darlington pair with them, and then take 3 of these darlington pairs and connect them in parallel like you did with the 3 transistors. You can run the circuit at a lower voltage, and get longer sparks off the top. I did that in my tesla coil on youtube. But may I use my deriviation of your circuit in my tutorial video? It's kind of the same as yours, but different.

-max- (author)-Jack-2017-01-07

Sure, I'd love to see the performance. But does it compare to my MOSFET based SSTC? ;)

It is probably worth noting that darlingtons are not the best for high speed switching, as the case with this 1MHz oscillator. A 100 -- 1k resistor between the emitter of the first transistor (also the base of the 2nd) and the emitter will should help improve performance.

Abbas_ncc (author)2016-11-13

Can I use BC547 to make poor-mans tesla coil

-max- (author)Abbas_ncc2016-12-11

Not a good choice, but it might work. Look at using medium power transistor with a high voltage rating and a high current rating, and good gain.

PlasmaGuy101 (author)Abbas_ncc2016-12-11

Yes. You may want to put several in parallel, since the bc547 can only handle 0.1 amps.

baburas (author)2016-12-02

Hello max

I made Tesla coil with a similar manner which works fine but has a small defect.

When I approach a lamp to the coil, the lamp lights but if I leave it there the lighting lasts only for 120seconds max and then fades away.

I have to close the circuit for some time and open it again to make it light again.

Can you help me with this problem?

I used a BD135 transistor, 9V battery, 6 turns primary coil, 2000 turns secondary.

Thanks for your help

-max- (author)baburas2016-12-02

Refer to the troubleshooting step for the small version. I think you will find the answer there.

baburas (author)-max-2016-12-02

Thanks. Its helpful

TheGreatResistor (author)2016-11-09

would a 175 turn 0.5mm wire wound secondary be any good for this circuit

atleast 2cm of sparks

Arush Bansal (author)2016-10-01

I've built the tesla coil, but the sparks are too short. What can I do to increase them?

-max- (author)Arush Bansal2016-10-01

I have troubleshooting tips on the last few steps. If those do not work then ask again. Good luck.

Arush Bansal (author)-max-2016-10-03

Thanks a lot! I'll surely go ahead and try them.

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