Introduction: Mini Spark Gap Tesla Coil

Picture of Mini Spark Gap Tesla Coil

Right after I got done making the Plasma speaker I wanted to work on something else that had to do with a high voltage flyback transformer. I searched on the internet, looked at videos on you tube on how to make them. I am going to show you how I made a decent SSTC that makes about 4 inch arcs. This is a good way to have both a working plasma speaker and a mini tesla coil just by adding a few extra parts!

Step 1: Items You Will Need

Picture of Items You Will Need

Flyback driver:

TL494 chip
200uF (or 220uF) electrolytic capacitor
47nF 250v capacitor
100nF capacitor
10nF capacitor
2.2K resistor
10 ohm resistor
UF4007 diode
10K potentiometer
22K potentiometer
Large heatsink
Flyback transformer (you can get one from an old CRT.)
12v power source for TL494 oscillator
12v to 40v power source for the flyback transformer
*All the parts (Excluding the fly back, heatsink, and the power supplys, ) I got off of mouser for 12 bucks.*

Tank capacitor & Spark Gap:

8 -- 3000V .047uf CDE HV Meallized Polypropylene Film Capacitors
8 -- 10 Mohms 5% Carbon Film resistors
2 -- Screws for spark gap
*Pricy, caps was 2.22 each on mouser*

Primary Coil:

10 ft soft copper tubing � OD ( 7 bucks at lowes or you can get 12awg solid wire, it will also work!)

Secondary coil:

PVC 1.5 d x 4 w pipe (2 bucks at lowes)
27AWG enamel-covered solid-conductor copper wire ( Got from radioshack comes in a pack of 22, 27, and 30. Get three of them! Or if you can find them cheaper somewhere else get em! They are 6.59 each


1 Ft 2.5 in drain pipe (lowes 2.15 a foot)
Aluminum plated tape (7 bucks at lowes)
Wood or cardboard
Nylon bolt and nut

Step 2: Flyback Driver

Picture of Flyback Driver
Earlier I told you I got done building a plasma speaker, well I had some spare parts left over so I decided to use the them. In NO way I am taking credit for the design of this circuit a boy by the name of Plasmana designed it! I will give the schematic and the link to his page

Hook everything up like it says, to test and see if the tl494 is oscillating put a speaker where the fly back is and change the voltage to 12V, you should hear a loud screech, if nothing play with the pots or look over your circuit. One other reason I wanted to use the Tl494 as a driver is because I thought it would also produce music from the arc. I was soon let down when the sound was coming out of the fly back and the arc from the tesla coil was the sound of the spark gap. If anyone knows how to audio mod this I would love to know! The flybacks secondary from the plasma speaker schematic is the HV DC from the tesla coil schematic.

The cam didnt pick up the screeching you can barly hear it

Also there is another driver that works well to but im not going to go into it. ill give the schematic its called ZVS driver.

Step 3: Tank Capacitor & Spark Gap

Picture of Tank Capacitor  & Spark Gap
For the tank cap I made a MMC (Multi-Mini Capacitors) I used 8 3000V .047uf CDE HV Meallized Polypropylene Film Capacitors. The reason we need to use eight is because we need to raise the voltage rating of the caps because the fly back will give off a massive amount of voltage! So we need to put the caps in series! So lets do some math 3000v x 8 = 24000v this should be good! Once you put them in series the capacitance will go down so .047uf / 8 = .0058uf or 5.8nF. Once you have them in series we need to put the 10Mohm resistors across each of the capacitors to drain the voltage out of the capacitors. A good website to visit is

VERY HELPFUL! The spark gap is two screws put threw a box, the closer they are the more the arcs going into the air are ( The lightbulb I put on top move the arcs close together to get it) the long apart they are the longer the arcs will be in the air! Play around with them to get it the way you like it! Also the transformer I am supplying power to the flyback, I put a meter to it and it says 32 V dc but when I take another reading when its turned on it reads 8 v dc. Its out of a TV, i need a bigger transformer.


Step 4: Primary Coil

Picture of Primary Coil

The Primary coil is the that goes around the outside of the secondary coil. I am using 10 FT 1/4 OD copper tubing made in a cone shape. Before I got the tubing I was using 12AWG solid copper wire wrapped around a 2.5 piece of PVC. If this is all that you can get then that will be fine. I find the arcs are bigger at the third or fourth turn of the primary coil. Its best to use alligator clips on the wires to adjust the turns. The primary coil will be hooked up at one side on the tank capacitor and to the other side of the spark gap.

Step 5: Secondary Coil

Picture of Secondary Coil

The secondary coil is the long vertical coil rising from the primary coil. This is where you spend a good chunk of time winding the coil. The secondary coil should be 5 times bigger than the diameter pipe you are using so I am using 1.5 in diameter then the length of the coil should be 7.5 in. I got my magnetic wire from radio shack remember it comes with 22, 27, and 30 gage wire. You are only going to use the 27 awg wire, it should be green. You are going to use all three of the rolls of wire! This will make the coil to turn out at 8 in which will be fine! I drilled 4 small holes at the bottom of the pvc pipe. Run the wire in then out, in the out and back in. There should be a little bit of wire sticking out the bottom of the pvc pipe. This will be connected to earth ground! After you have done that then start to roll! When your rolling the coil and run out of the first roll, put a piece of tape holding the wire to the pvc pipe, get the second roll that you have and solder the two leads together (make sure you scrape off some of the enamel). Get as little solder on them as possible, and just keep on rolling! You can check and see if you have a connection with a meter. If you find wire somewhere else and have enough then you can just skip this. After you are done rolling I drilled three holes where the coil ends and ran the wire in then out and back in and up the tube. This will hold the wire so it dont come unwound! Cut off the remaining pvc pipe but leave about 1 to 2 inches above the coil!

I made another coil out of the 30 awg wire. You will have to add more turns on the primary

Step 6: Toroid

Picture of Toroid

I thought about buying a toroid to put on the top of it but im not going to pay 1 to 2 hundred dollars for one so I made my own! So your going to take the 1 Ft 2.5 inch drain pipe and curl it in on itself so it should be in a circle. Stretching it out a little bit will help it some. Measure the inside diameter of the circle and cut a piece of wood or cardboard and place it in the center of the tube. It will look like a space ship when your done! Take the Aluminum plated tape and start taping from the bottom of the cardboard, around the tube, to the top of the cardboard (it is extremely sticky!). Get the tape as smooth as possible! Its easier said than done but get is as best as you can! Once you got it covered with aluminum tape, Drill a hole in the center, put your nylon bolt threw the hole, place the washer and nut on the other side. Be sure to scrape the enamel off the wire to make a good connection with the toroid!

Step 7: Hook It Up and Make It Happen!

Picture of Hook It Up and Make It Happen!
After that then your done! Hook it all up and play with it! You can see the arcs better in the dark than in the light I wish my cam could pick up the little arcs. Im sure if I had a better power supply to the flyback they will be more impressive! If theres any I left out or could make this better please give your input!

Sorry about the dark shot you cant see crap! my cam sucks!

The lightbulb is cool!


Jimmy Proton (author)2011-02-17

Just a comment on the name, all Tesla Coils are spark gap (except solid state), it suppose to be the kind of gap.

spark light (author)Jimmy Proton2011-03-16

not all tesla coils are spark gap/solid state! You kids have no idea what vacuum tubes are these days, do you? :D

pdub77 (author)spark light2011-05-15

HA! Hey, at least they're trying, right? How many kids out there are making Tesla coils? How many kids know who Tesla even is?

tjk353 (author)pdub772016-11-03

bruh we had an entire day at school dedicated to tesla coils and im 14

CazeX (author)pdub772014-09-11

I know who tesla is and I am 11 and working for the army

spark light (author)pdub772011-05-16

Saddeningly few.... Saddeningly few.....
Which is why we must spread the word!

CazeX (author)2014-09-11

I'm 11 and I can't find a material the can magnify the plasma sparks from 0.5 inch to around 30 inch if anyone knows then tell me at thx

volthead (author)2009-07-18

If you want if to sing try replacing the spark gap with some xenon flash tubes from camera flash circuits. Hope it works

Xellers (author)volthead2009-09-02

How would that work? Modulation is only possible on solid state and vacuum tube Tesla Coils.

-max- (author)Xellers2013-11-29

What if you used solenoids or servo's to adjust the spark length, so different notes can be played. Maybe use an arduino plugged into a MiDi source to modulate the spark gap. It wont be easy, but a fun challenge!

volthead (author)Xellers2009-09-02

You would need to have a bps of 20000 and vary the current with IGBTs. Also I have learned a lot more since I posted that comment. And some (like me) have a low budget so MOTs are the only option. MOTs can be ballasted resistively with a 150W light.

Xellers (author)volthead2009-09-03

Changing the BPS rate does change the frequency that you hear coming from the sparks, but the reason that it is not done with SGTCs is that as you increase the BPS, the energy stored in the tank capacitor in each cycle is lower and lower, and the capacitor is usually matched to the frequency of the transformer and its voltage and current, so on some cycles, the transformer will charge the capacitor and then reverse polarity, and discharge it. It might work, but at each frequency, the sparks would take a different appearance, even though the total energy in the circuit would remain the same. Also, IGBTs are not practical with a SGTC due to the VERY high voltages and currents involved. You might be able to try this with an OLTC, but I wouldn't expect good results. Also, MOTs are usually better ballasted using an inductive ballast, such as another MOT with shorted secondary windings.

Im trying to put together another circuit for this. I ordered the parts for it a couple days ago so it should be coming in soon, Im going to make a solid state and improve the spark gap, I have a couple of microwave transformers around here somewhere, Know anything that i can do with them???

Don't use microwave oven transformers, yet. You should only do this when you are very confident in your constructions skills (verify this by building a few smaller neon sign transformer or OBIT powered Tesla Coils first), when you fully understand the physics of the circuit (be comfortable with LC circuits and using calculators, understand quenching and damping effects within the circuit, and be able to understand the current flow within the circuit), and when you have a large, clean area to work in. Even a ballasted microwave oven transformer is lethal. Also, you should collect more transformers, at least 3 for a ballasted antiparallel setup that should provide 4kV. You may also consider using a voltage multiplier, to make the voltages easier to work with. A Tesla Coil built using microwave oven transformers is a big commitment, and will take a lots of time and effort. I recommend that you set those transformers aside for the time being.

well ill just work with what i got now. ill put what I got together and throw it on here and see what you all think! just gotta find the time with school and all.....

You are doing better than me. I keep meaning to make an instructable but I have not made anything cool yet. Good luck.

pyrorower (author)volthead2009-09-09

Before I build this and attempt to also modify it to "sing", there is one thing I am unsure of... After modifying the coil to sing, would the current be higher than in the unmodified version?

I dont know I didnt test it with a meter, I really dont think you can make it sing unless you get rid of the spark gap and make it a solid state. I tryed the spark gap and you can only hear the music inside the flyback, Im trying a new circuit and got the parts in today so im gonna try it out.

Wait, Xellers, I was not referring to making something like plasmana's plasma speaker If that's what your talking about... I meant something like this:

Xellers (author)pyrorower2010-01-17

You cannot achieve that sort of modulation using this sort of topology; you will need a full solid state coil as opposed to a SGTC with a solid state driver. As a sidenote, here is what I built:

Xellers (author)pyrorower2009-09-09

First of all, you won't be able to modulate any sort of spark gap Tesla Coil, so don't expect to. Also, modulation does increase the current in the coil. It only varies it, to expand or contract the plasma generated by the coil to oscillate air. We perceive these oscillations as sound.

Twistedspace (author)2013-08-28

Is that a cartidge celeron heatsink

hahaha Yup!

alicia_u (author)2012-07-19

where can you buy these items in known stores in city areas? please and thank you :)

highvoltageguy (author)2011-05-21

could u use an ignition coil?

justjimAZ (author)2010-12-30

I was just wondering if metallic spray paint would be conductive enough for this purpose? A can wouldn't cost much more than a roll of aluminum tape. It would be easier to keep it smooth.

Not really for sure, I can get some and try it but I dont know how much metal is in the paint.

tzq33tdq (author)2010-10-03

this is so cool i want to make one. how many volts is it and why is it so awesome?

deawon2 (author)2010-05-17

Hi i've seen some pic's and vid's of tesla coils and i found out that you can make a ring of lightning instead of just sparks i thought this was achieved by putting an engine and a guiding 'lance' sort of speak (to guide your current) on top of your 'topload'. Can you please give me a little more info or even an instructable if possible.
Thank you.

grtz Deawon2

quantumkittty (author)deawon22010-08-29

the ring of lightning was actually just a lance-to-ground setup, and the effect was caused by a long exposure with the camera when taking the pic :D

Welp im gonna put up a SSTC on here in a couple of days, need to stop being lazy.

Skyriam (author)2010-08-12

How can you get sparks to your hand and not get hurt?

Jimmy Proton (author)2010-08-10

can you use microwave caps

pyrorower (author)2009-09-08

You know those zappers people make from disposable cameras? I'm wondering if you remove the capacitor and attached wires to the points on the circuit board that charged the capacitor if you could then use the camera as a sort of high voltage generator to power a small tesla coil. Anybody know?

The 4th Doctor (author)pyrorower2009-09-26

no the spark gap would have to be very very small and precise for 300 volts and disposable camera circuits supply a very low amount of power :/

well i was thinking more along the lines of the rotating metallic star hitting contacts or something. Sparkgap operating at 300V isnt enough i agree... unless its a very small delicately placed gap.

As for the low power, this is true. But to increase the power output you can link the 300Volt outputs in paralell. The acctual charging circuitry on the board takes up something like a 10th of the space so size is not toooo much of an issue. (look up coilguns on this site and theres an instructable on removing the small charging circuit on the flash camera circuitboard).

Technically you should be able to connect X amounts of these things in paralell to get Y increase in current at 300V. I've been trying to look into the use of these power charge circuits as a power supply for a post apocalypse scenario (i liked playing fallout so i see it kinda as a hobby idea... i promise im not crazy or stockpiling things in a giant fallout shelter.)

i think quite a few would be needed i doubt these things could crank 10 watts without blowing smoke, cant imagine it being practical. power supply for post apocalyptic scenario you say, an inverter? same problem again

but i guess pretty large masses of em can be had fairly easily usually

Inverter? nah, i've been thinking about ways around semiconductors for highpower systems.

And yes, it would probably take quite a few to get a good steady 10w/h out of it, but thats the beauty of the simple circuit... as many as you like could be added.
Its the 1.5V source im worried about lol...  a huge HUGE bank of baghdad batteries or maybe John Hutchinson's casimir effect battery.

deawon2 (author)BeanahVulgaris2010-05-17

If you wanna make a post apocalyptic scenario maybe you could try a 'lightning machine'
used for charging clouds with static energy at a certain place and then making them bump in eachother (basicly how lightning works,but I guess you already knew) and then finding an effective delivery system for global coverage

BeanahVulgaris (author)pyrorower2010-01-09

First of all, be carefull. Second, using more than 1 flash charger with it's 300 volt outputs in paralell will create a generator that can supply more watts per second that just one, (scale it up to charge something that needs more amps).

How to make this usefull... Charge a capacitor bank and periodically discharge it through a transformer. Dependant on how many watthours the stacked up chargers can give, you could run a tesla coil off of a huge bank of 1.5v sources (the chargers can use 2v but why push the horses to death when you can just link up more horses to take the load?)..... maybe even the Baghdad batteries could be used! Or maybe even John Hutchinson's ammoshell casimir effect batteries.

suggestion for the periodically discharging switch: In the spirit of ancient technologies, i suggest a rotating spark gap where a metallic star, attached to a laquered shaft of wood, is rotated by a separate source (a dc motor or something) and thus if it is a 6 point star you would have 6 discharges per rotation as the points brush up against contact flaps or something.

Completely possible to have done with just transformers and baghdad batteries to transmit radio or use for highvoltage lightning.... but thats getting off topic.

Xellers (author)BeanahVulgaris2010-01-17

Just for fun, I once used a modified camera flash supply (minus the rectifier diode) and a voltage multiplier to power a small Tesla Coil. It wasn't too impressive, but it was very fun to draw 2" long sparks that were coming from a single 1.5 AA battery.

BeanahVulgaris (author)Xellers2010-01-18

wow!  did you have to periodically charge the cap bank for a good while?

Xellers (author)BeanahVulgaris2010-01-18

Actually, it was even more impressive because the capacitors fired about twice per second! Of course, the battery didn't last very long.... ;)

BeanahVulgaris (author)Xellers2010-01-18

I'd love to try to hook up a large battery bank of potatoes or even "baghdad battery" bank. I've been trying to mess with circuits that pick up a static charge from the air. This is an idea dating back to Nikola Tesla's patent "Utilization of Radiant Energy"

The idea is using a teslacoil system in reverse (the HV terminals pick up HV static in the air and periodically discharge into a resonant transformer that stores the energy in a battery or something).

Xellers (author)BeanahVulgaris2010-01-18

Ummmm.... not to upset you, but that wasn't quite what Tesla's idea was.... What I've been able to achieve is transmission of energy from one resonant oscillator to another (at the same frequency) - that isn't quite the same thing as "[picking] up HV static in the air."

BeanahVulgaris (author)Xellers2010-01-19

The patent you want to look up is US# 685 957

Tesla understood the research of Kristian Birkeland in his experiments with his terella laboratory. He discovered the actions behind the aurora borialis and australus. Tesla knew that charge particles were bombarding the earth every day . He realized that if the energy from the sun was only lets say positively charged particles, then the sun would charge negative and the energy would diffuse through space as 1/R^2. If the negative and positive flowed together the net charge loss would be neutral and thus the energy component would be kinetic. I dont know if he knew the magnetosphere split the charges into positive and negative but im sure he realized something like this was going on.
Basically if the atmosphere consists of this charged strata, is there a way to harness it. Basically like harnessing the power of a lightning bolt, but instead of harvesting the strike, you harvest the dipole the earth naturally has before the dielectric breakdown occurs (the lightning).

josh1324 (author)2009-12-02

Does it hurt to touch the sparks?

BeanahVulgaris (author)josh13242010-01-17


Its kinda like bodies of water.

If im in a pressure chamber and the pressure of the water rises, i can take it.
Thats like voltage.

But voltage with a path to flow is like being in that pressure chamber and then some one busts open the side of it with axe or sledge hammer or something...... All of a sudden the water would rush through a path to the low pressure open hole. Being in this path i would get hit with a current of water and possibly shot out through the hole. weee!

So when you touch one terminal its like being in that chamber. When you touch a terminal of a different pressure/voltage you create a path through yourself for the current to flow. You are in the path where high pressure meets low pressure.

I forget the acctual values of current that can kill a person. But even rediculously low amperages placed across the heart (from fingertip to fingertip) can kill a person or create toxins that are very very hard on the body. Just as a small example, if we are mostly water and putting positive and negative leads into water creates hydrogen and oxygen gas, imagine what thoes chems can do to a person.

Tesla's high frequency high voltage systems dont hurt as much because of 2 things. 1, the higher the frequency the less your nerves can respond to the flucutating electric fields.
2, there is such a low current that the wattage thats travelling through you is low (Watts= voltage*current)
3, there is the supposed 'skineffect' where the flowing charge for high frequency currents seems to exist mainly on the surface of a conducting body.  True for conductors but i wonder for organisms...

anyways, if i got anything wrong, other peeps pls pls correct. Thx.

(sorry about the longwindedness but hopefully that answers the 1 question that was asked and maybe afew more that arose.)

Xellers (author)2009-05-30

This is pretty good, but you might want to try to increase the power to increase the rate that the spark gap fires at. The best thing to try would be to get a bigger capacitor.

About This Instructable




Bio: I have 3 associates degrees in Electrical Tech/Engineering.
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