Introduction: Solid State Tesla Coil

A solid state Tesla coil is one of the kinds of Tesla coils available. It has several advantages over the more common spark gap tesla coil. They are less louder than conventional Tesla coils, yet they can still achieve a respectable output. They can also be made to play music through its spark, which is a cool effect. Examples of this trick can be seen by searching for musical tesla coil or singing tesla coil. They are also more friendly to nearby electronic apparatus, although caution should still be applied.

In the following instructable, I will show you how to make a solid state Tesla coil, as well as several helpful tips and hints that will come handy during its construction. I take no credit for the original design, which is Steve Ward's, with some small modifications "here and there."

While fiddling with the antenna, I accidentally burnt both of the Mosfets, so bear in mind this design is far from perfect. I'm still posting the instructable, as some of the techniques I used may be interesting to some. Try at your own risks. Results may vary.

If you like this instructable, please rate it and vote my instructable for the contest.

Step 1: Tesla Coil Parts


     A Solid State Tesla coil is made by four main parts: the primary coil, the secondary coil, the topload, and the control circuitry.

The Secondary : The secondary is the long, orange cylinder. It is actually a white PVC pipe covered by a lot of enameled wire. One side is connected to ground, high voltage comes through the other side.

The Primary : The primary is powered by the control circuitry and it generates the magnetic field that the secondary uses to create the high voltage. It is the few turns of thick wire at the base of the secondary coil.

The Topload : The topload is the metallic object at the top of the secondary coil.  It provides a capacitance to the Tesla coil.

The Control Circuitry : The circuits that make the tesla coil work at the correct frequency and duty cycle; based on Steve Ward's design. 

Step 2: Secondary Coil (Part 1 of 4)

         First, the coil former must be prepared. The coil former is the hollow tube in which the enameled wire will be wrapped. The external diameter of the pipe should be 4.5 in. (11.48 cm). In my, case, I used a 4 in. PVC pipe. PVC pipe sizes are not the outside diameter size, so be wary. A 4 in. PVC pipe has a 4.5 in. outer diameter, which is the diameter required. If a 4 in. PVC pipe cannot be obtained, one must use any non conductive hollow cylinder with a 4.5 in. outer diameter.

     Usually, PVC pipes will come with a non-straight edge, specially if it is a leftover. To straighten it out, place the pipe inside the flange (see picture). The irregular side must be slightly past the flange's edge(picture 2). Then, with a hacksaw, the irregular edge is cut, using the flange's border as a nice, straight  guide.

      One can observe the irregular side cut off on picture 3, leaving a nice straight edge in the pipe's end. Now, the flange can be removed for the next step.

Step 3: Secondary Coil (Part 2 of 4)

      Now, the secondary former must be cut to the appropriate size. From one end of the winding section to the other end of the winding section, 17 inches must be available. In addition, the former must be able to accommodate two flanges. In my case, each flange had a height of 2 inches, so:

17 in. + 2 in. + 2 in. = 21 in.

     Be wary, as the specific height of the flange may vary according to where you buy it, but the principle remains the same. Place the flange so that the required number of inches are in between the flange's edge and the pipe's end and then cut the pipe using the technique described in the previous step.

Step 4: Secondary Coil (Part 3 of 4)

     The next step is to glue one flange to the pipe. To do this, place the flange above a disposable surface, and cover only the interior surface of the flange with glue. Regardless of the PVC cement instructions, do not cover the pipe's surface with glue. 

     Depending on the specific PVC cement you use, it might have negative dielectric properties (it may hurt performance). Besides that, a perfect seal is not needed.
    
     After placing the glue on the flange, place the pipe inside the flange, pushing the extra glue downwards towards your disposable surface. Getting glue on the outside of the flange will not decrease performance, but getting it on the pipe, specifically on the winding area, might.

Sorry for the fuzzy pictures.

Step 5: Secondary Coil (Part 4 of 4)

The final step of this subsection is to wind the secondary. There is no quick way and easy way to wind the secondary without a lathe or similar acting jig, but they can be winded by hand. The materials are, of course, the pipe, 30 AWG enameled wire, and time, lots of it.

First, have something to hold the wire that permits it to spin freely. This can range from a small, eager kid to some books and a stick. I recommend you to (before starting the Tesla), try to break a small section with your hands for you to know what is the maximum force you can apply without breaking it. (Although not exact, an idea does help)

Enameled wire is sold by weight, not by length. You will need slightly less than 3/4 of a pound, or almost 1/4 of a kilogram. The exact weight, assuming perfect winding (which probably will not happen) is 0.246 kg. To start winding it, you may either glue a few turns of wire with super glue, or place some electrical tape sticky side up to hold the first turns.

It is extremely important to avoid spaces between wires, as well as overlapping turns. One overlapped turn will not ruin the entire coil, but try not to make a bad job in here, it will be worth it. You can use electrical tape to hold the wire if you are stopping halfway through the coil for any reason. If for any reason, you break the wire midway, it is best to start over.

When you finish, add a bit of glue(epoxy, hot glue, etc) to hold the last few turns. Varnishing the secondary coil after winding is extremely recommended, but not necessarily needed. For a note, mine is not varnished.


Attention

If the difference between summer and winter temperatures is large in your region, varnishing the secondary is a must. Metal expands during summer and contracts during winter. If not varnished, you could end with an unusable pile of twisted wire by summer.

The secondary coil presented below is a compromise between speed and quality. For maximum quality (and slowest time), check the links at the end of this instructable.

Step 6: Toroid (Part 1 Out of 4)

To make the toroid, you will need aluminum duct, a plier, wire, and a second flange. First, cut the aluminum ducting so that it can do exactly a full revolution to the flange. Then, cut a piece of wire whose length is slightly larger than the aluminum duct. Using the pliers, bend the wire to bring the two edges of the aluminum duct as close as possible.

Make sure the wire is inside the toroid; having it in the outside would be detrimental to the Tesla coil. The missing slice can then be covered using either aluminum tape or scraps of aluminum duct.

Ideally, if you can find a piece of tube with a diameter just smaller than you aluminum duct's diameter, you should glue it as described in one of my links at the end of the instructable, titled A new 8.5 x 34.5 Toroid for the 'Phoenix' . Since I could not find this material, I had to use a wire. It will still be okay as long as the wire remains in the inside of the toroid.

Step 7: Toroid (Part 2 Out of 4)

Now, glue the toroid to the flange using hot glue. Avoid using any other glues without checking flammability first.

Paste the toroid to the flange well, going around the circumference. Depending on how you are going to connect the Tesla secondary to the toroid, you can glue the remaining notch in the ducting either now or later in the process. Please see the next step for further clarification.

Step 8: Toroid (Part 3 Out of 4)

Before continuing, the way to connect the secondary to the tesla coil has to be thought out. If you have either conductive glue or aluminum tape (glue preferred), you can skip away this step.

Being too cheap to buy these. I decided to make a screwed connection. I drilled a hole through the flange and the aluminum ducting. Afterwards, I inserted a screw through the aluminum ducting from the inside of the aluminum duct towards the flange, and used nuts to hold it . See pictures for an explanation. This is not ideal; but it works good enough.

Then, I placed the toroid over the secondary and attached the wire to it. Some of you may ask: How did the cable got from the outside to the inside of the pipe? The way I used was to drill a small 1/16" hole through the pipe. Bear in mind that drilling a hole limits the maximum arc length of the Tesla coil to the separation between this hole and the base of the secondary; any greater would arc inside. Nevertheless, I consider 17 in. arcs good enough for me.

If using conductive glue, just glue the secondary cable to the outside of the toroid. After finishing this step, use hot glue to close the notch that remained in the toroid if you have not done so already.

In all cases, remember the secondary cable has an enamel coating. Remove it with sandpaper before connecting.

Step 9: Toroid (Part 4 Out of 4)


The final step in the tesla coil construction is to fill the top hole of the toroid with aluminum. If you can obtain a pie pan that fits in the toroid's inner circumference, use it. If not, take a pie pan and cut a circle that can fit in the toroid. Place the toroid in its final position on top of the secondary, and hot glue the flange to the pipe.

Then, place the cut pie pan on top of the toroid and glue it with hot glue.


Important

Solid state Tesla coils require a breakout point to work properly. A breakout point is a pointy object that protrudes from the toroid. I have decided to not place a fixed one so that experiments using different breakout points can be made, but never run the tesla coil without a breakout point. For example, a screwdriver placed on top of the toroid is commonly used.

Step 10: Primary

The primary of a Tesla coil is made by another coil of wire. Fortunately, it only requires ten or less turns of a thick wire (16AWG or thicker).

Just wind a ~16 AWG wire ten times around the lower part of the secondary. Hold it temporarily with tape, as the precise number of turns may be adjusted later on if deemed necessary.

The number of turns affects how much current passes through the circuit (see next step for the circuit). The less turns, the longer the arcs, but the hotter the MOSFETs will get. Ten turns is a good starting point, then one can reduce the number of  turns until the MOSFETs start getting warm.

If the number of turns is too low, the MOSFETs will blow up eventually; on the other hand, if you have too many turns, the performance will be sub-par to what is achievable.

Step 11: Control Circuitry

I strongly recommend you to employ Steve Ward's design.  (Scroll to the bottom of his page for his final design).

...But, sometimes you will not be able to find some components. For example, I could not find locally the UCC37322 or UCC37321. So, I made my own variation of his circuit. See the schematic below.

In this instructable, I will not teach you to make a circuit out of a schematic; if you can't read them you should try simpler projects first. A disadvantage from my spinoff is that there is no isolation; bear this in mind when working. This is why I recommend Steve's Design if possible.

You may build this circuit in a strip board, veroboard, printed circuit board, point to point, etc; but do not use a breadboard (Protoboard); there is too much parasitic capacitance.

As always, place a fuse between the circuit and the mains plug. 5A or similar.

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Brief Technical Explanation

A solid state Tesla coil works by switching the primary at a resonant frequency. This frequency varies due to the height of the coil, the topload, and the environment. Thus, a fixed frequency oscillator is not ideal.

The following driver changes its frequency based on what the antenna gets from the Tesla coil. The antenna could be any straight piece of wire connected to the circuit. The other end is left unconnected. Thus, this SSTC uses antenna feedback.

To avoid overheating the mosfets, usually an interrupter is used. It's role is to turn the Tesla coil on and off at a certain frequency. This doubles as a power control if one varies the duty cycle of the circuit. A full explanation on how the Tesla coil works can be found on Steve Wards site. I also recommend to follow his schematic (the last one), and fall back to mine if some of the parts are not available  on your area.


The only difference between mine and his is that I did not use the gate drive transformer and the ucc chips. If you can find these elements, by all means do his design, as it has galvanic isolation between the half bridge and the rest of the circuit. (which is a good thing)

---The capacitors on the half bridge are must withstand at least 170V.
---This tesla coil is not audio modulated, but it could be made so by just changing the interrupter for an audio one.
---The 5v and 12v signals can be obtained from a transformer followed by a LM7812 and a LM7805 (plus capacitors).

Step 12: Test It

Connect everything and plug it in.
-The bottom part of the secondary goes to ground. Mains ground works out at this power level, but do not have sensitive stuff plugged nearby. A dedicated ground is ideal, though.

Hopefully, you will get the Tesla Coil working. If it doesn't, read below:


-Sometimes one needs to connect the primary the other way around; see if swapping the connectors solves the problem.


The Tesla Coil has capacitors that will remain charged after you turn it off. Be sure to discharge them before fiddling with the circuit, and double check that they are discharged before poking anything.

Bonus: Add some salt to the breakout point and the streamers will be orange instead of blue. Unfortunately, I did not take any photos of this before the MOSFETS died.

Step 13: Links and References

Useful links, better methods (although more time consuming), and references

Stephen Kludge: "How to build the perfect secondary coil"
http://www.capturedlightning.org/hot-streamer/stk/tc/coilbld.htm


"A new 8.5 x 34.5 Toroid for the 'Phoenix'"
http://www.hvtesla.com/toroid_2.html

Steve Ward: "Solid State Tesla Coils"
http://stevehv.4hv.org/SSTCindex.htm

Disclaimer: I am in no way associated, in any way, with any of the authors linked. If any of the authors would want their links or respective information taken down, please tell so.

Comments

author
JustinM246 made it!(author)2016-12-29

Would electrical tape instead of electrical glue work as well for attaching the secondary coil to the aluminum ducting?

author
noud4444 made it!(author)2016-12-13

can you put a link of the schematic in the discription?

Great protject,

thanks, Noud

author
baburas made it!(author)2016-12-02

Hello,

I finished a coil using the following material

I used a BD135 transistor, one Resistor - 47k 1/2w, 9V battery, 6 turns primary coil, 2400 turns secondary.

There is no spark, but it successfully lights lamps. There is though a small
problem. When I approach a lamp to the coil, the lamp lights but if I
leave it there
the lighting lasts only for 80-90 seconds and then fades away.

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

Have you faced this problem? Can you help me with this?

I would appreciate if anybody has some idea about this

author
AceA15 made it!(author)2016-06-08

Is there a materials list for this project? I'm afraid that I will forget something because I missed it.

author
BlueJ2 made it!(author)2016-12-01

This is a little late, but if you do not want to play music, and just want electric arcs, then a spark gap Tesla coil is the way to go. They are less complicated, more dependable, and cheaper than this version.

author
AceA15 made it!(author)2016-06-08

Also, is the circuit nessary if I just want the tesla coil to produce sparks?

author
AlexanderWilke made it!(author)2016-05-12

Can you please post a list of all the components to build the circuitry cause I cant really make out what you need from the picture provided

author
EzequielR4 made it!(author)2016-01-28

im a new here and a just begining to lern this stuff, my question what is tha differance between wave length and frequency? does a tesla coil have to be a certin frequency? or can you adjust it how ever you want. from low to high in Hertz

author
gilligoon made it!(author)2016-04-07

Wave length is just a different way of interpreting frequency.

Once designed there is still some room for adjustment, there are certain variables (spark gap, primary coil tap, torroid size) and certain constants (secondary coil turns and diameter, cap bank, power supply), so you would design it with these in mind. Parts availability and finances are the usual governing factors though ;)

The link below should provide you with a basic understanding.
Semiconductor TCs run on the same principle, and must be tuned accordingly.

http://deepfriedneon.com/tesla_guide.html

author
Wrosixer made it!(author)2015-09-04

What can i use to power my Tesla coil?

author
A_Maine96 made it!(author)2015-09-04

I used a regular power supply at 24v though a PWM-OCXi for its protection and the duty/frequency adjustments.

http://www.rmcybernetics.com/shop/pulse-modulator-ocxi

author
IshanD made it!(author)2015-02-27

Hi Michael,

I am making this Tesla coil for a school project. I had a couple of questions. In other designs of an SSTC, there is no mention of a start-up circuit. What is this circuit doing exactly? Also, is it possible to have a GDT at the output of the IR2110 for better isolation of the high-voltage and the low-voltage side?

author
SohamG1 made it!(author)2015-04-18

Exactly what Steve has done and exactly the reason why he said follow steve's design....

author
IshanD made it!(author)2015-05-02

Steve is using a diferrent MOSFET driver IC. I just needed to be sure.

author
Hitman312 made it!(author)2015-02-04

i dont have made it yet. But how to Power it up or is it self-charging and no battery or something that?

author
NurK2 made it!(author)2014-12-04

Would you sent me the schematic and the components of your tesla coil ?
shiro.jauhari@gmail.com Please.....

author
Copepod made it!(author)2014-11-30

Which exact diodes should I use for the bridge rectifier? I noticed the ones on steve ward's design are unlabeled and I couldn't tell what the ones where on your schematic. What should their ratings be?

author
sefus made it!(author)2014-09-04

How much would this hurt/kill if you were to be shocked by it?

author
Michael+Chen made it!(author)2014-09-06

The streamers probably won't hurt much, or at all. This is because the frequency is above what our nerves can sense. It still does damage so you should avoid it, but it wouldn't hurt.

On the other hand, the primary and the large DC caps can definitely hurt and/or kill if you touch them while charged.

author
sefus made it!(author)2014-09-08

That knowledge increased the amount of fun im going to have with this then

author
sefus made it!(author)2014-09-04

What input voltage does this need? As I have a set up for a 20kV capacitance power supply, would this work in place of the mentioned control circuitry?

author
Michael+Chen made it!(author)2014-09-06

What you are thinking about is a spark gap Tesla coil, which requires a high voltage supply. A solid state Tesla coil does not require this, as it works with mains voltage.

If you were to build a spark gap (not this instructable) tesla coil, your power supply probably wouldn't work; although I cannot be certain without knowing the current rating of your supply (20kV is plenty, but those usually have low current ratings).

author
sefus made it!(author)2014-09-08

Thank you for that

author
jasshopper made it!(author)2014-08-27

could i use a SMPS from a PC as a powersupply, the blue(-12v) wire for 12v and white(-5v) for 5v?

author
Michael+Chen made it!(author)2014-09-06

I wouldn't recommend it. SMPS tend to be more sensitive to electromagnetic noise; which the Tesla Coil produces in abundance. I'd recommend a transformer. If you go for a SMPS, it may or may not work.

author
jasshopper made it!(author)2014-09-07

i tried connecting using the -ve lines from my SMPS, and my ucc37322 blew, other components were left intact. My SMPS was kept a little far away from my coil and i was running the coil at 48v.

author
ToggleSwitch made it!(author)2014-04-01

Do you know how many volts the output of this tesla is? As in how many volts can its magnetic field power? You can test this by putting light bulbs in it and seeing the highest on it can power.

author
Michael+Chen made it!(author)2014-04-01

You cannot test a voltage on a Tesla coil by putting light bulbs; I recommend you to read clearly the difference between voltage, current, and power to see why. Most household light bulbs (not counting cars) operate at 120V; the Tesla will light them all to varying degrees.

At these voltages, unless you have a (extremely expensive) high voltage ac meter, acquiring a precise measurement is unlikely. A (very vague guess) would be between 100kv and 500 kv.

author
ToggleSwitch made it!(author)2014-04-01

Sorry I don't know why it sent three

author
ToggleSwitch made it!(author)2014-04-01

Do you know how many volts the output of this tesla is? As in how many volts can its magnetic field power? You can test this by putting light bulbs in it and seeing the highest on it can power.

author
ToggleSwitch made it!(author)2014-04-01

Do you know how many volts the output of this tesla is? As in how many volts can its magnetic field power? You can test this by putting light bulbs in it and seeing the highest on it can power.

author
lam made it!(author)2014-01-08

Hi Chen..
Could you tell me how wattage or ampere (240V or (120V) x I?? = watts) when your tesla coilworking.Thank you so much

author
jasshopper made it!(author)2013-07-06

could i use irfp460 and increase the input voltage to about 220v? and what is the resistance of R4 and R3?

author
GeneralTarquin made it!(author)2013-05-22

Could I get a nice list of materials? I'm looking to go somewhere and buy what I need... And I'd prefer to know what I need to get thanks

author
LiamOSM made it!(author)2013-05-28

Agreed

author
JHSTUBA made it!(author)2013-03-28

I have a 4.25 OD PVC pipe, should I be fine? I also was wondering what length I should make the secondary winding, because you have yours as 17 inches, and Steve's is only 10

author
Michael+Chen made it!(author)2013-03-28

Actually, tesla coils are not really that sensitive to coil specifications, as long as the aspect ratio is still close enough. Your pvc pipe is just fine.


Regarding the length, either one will work. In fact, steve ward's sstc 1 (which has a similar topology) has a 14" secondary; his sstc2 has a 18" (albeit this one uses a full bridge instead of a half bridge). Anything about this range should work fine.

author
vermont_tiny made it!(author)2012-12-28

I have been trying to make an Audio Modulated SSTC for a while now, and I have found that your Ible has been the most helpful yet. So on step 11, where you say this SSTC could become audio modulated by changing the interrupter to an audio one, what exactly does that mean? Circuit diagrams are definitely not my thing, and I have not been able to find a sophomoric explanation of an Audio Interrupter or MIDI Microcontroller. I hope someone can help me!

author
Michael+Chen made it!(author)2012-12-29

Well, actually, this tesla coil is not audio modulated.There is nothing on the schematic that performs audio modulation.

However, if you were to replace the smaller schematic (which is the interrupter's schematic) with one designed for audio modulation... well, you would have audio. There are several diagrams over the net. However, I would recommend you to only go for audio modulation after you get the basic setup running.

author
tesladude123 made it!(author)2012-11-13

Would I be able to power this tesla coil with 240v without using a power converter or similar?

author
Michael+Chen made it!(author)2012-11-13

While yes (with some minor modifications), I would recommend using one f]designed for 240v.This design is made for 240v:

http://kaizerpowerelectronics.dk/tesla-coils/kaizer-sstc-i/

If you still want to use my design or Steve Wards, there are some changes that need to be done, mainly replacing the mosfets with higher voltage equivalents.

author
Michael+Chen made it!(author)2012-11-13

*designed

author
tesladude123 made it!(author)2012-11-14

I have decided to use your design because of the lack of components (mainly the ucc chips) I will most likely use FDH44N50 mosfets. One question, on the schematic all of the capacitors are eletrolithic but on steve wards schematic they are not, the capacitor that is 470uf, is that electrolytic and what voltage rating is it?
Thanks.

author
Michael+Chen made it!(author)2012-11-14

Sure, those Mosfets are perfect. Regarding the capacitors, I kinda just used a single image for all of them, but not all of them have to be electrolytic.

     Usually, >1uf are electrolytic; <1 uF are not. The .68uF capacitors have to be non-electrolytic. Yes, the UCC chips are not that common. In fact, I made this design because I couldn't find them. However, this design does not use an isolation transformer as other designs.

     The disadvantage of this is that if you make a mistake, all the chips will blow up instead of just the mosfets. I see no reason why this wouldn't work at 240v, as long as you use the Mosfets you showed me, and the capacitors you use for the bridge are rated at at least 400v (240v * sqrt(2) + clearance). C5 should also be rated 400v; and for D3 you must use a diode that can withstand that voltage; UF4004 to UF 4007 will work. Don't use UF4001-UF4003, as their reverse voltage is not enough for 240.

I'll double check the schematic later to make sure everythin else will tolerate 240v, but so far that is all I can think of that has to be changed.

Curious fact: my design is just steve ward's design with this stuck in place of the UCC; if you look at the reference design you'll see my design is a virtual copy of that.

author
tesladude123 made it!(author)2012-11-14

Ok, thanks for your quick reply. Another question though, the 470uf capacitor on the half bridge is that non-electrolytic, because I'm thinking it would be hard to get a capacitor that size and voltage for ac current.
Thanks.

author
Michael+Chen made it!(author)2012-11-14

It is electrolytic (I seriously doubt they make non electrolytic 470uf caps). On the halfbridge section, the ones that are not electrolytic are the two .68uF capacitors. For every other capactor, just use whatever you find, either or. Just make sure that whatever you use on the halfbridge area can take at least 400v.

author
tesladude123 made it!(author)2012-11-14

Thanks you are a great help, ill get back to you soon when i start building this tesla coil. P.S im using a auido interruptor seen here: http://www.megavolts.nl/en/projecten/tesla-spoelen/153-audio-modulated-solid-state-teslacoil-v2

author
pranjal12 made it!(author)2012-10-26

Hey can you provide clarification on the parts needed.As he schematic is not clearly visible. thnx

author
panny1996 made it!(author)2012-11-05

This project can cost u approx 600 to 700 $(INR 33000 to 38000). I recommend u to take a look at this 'ible https://www.instructables.com/id/How-to-build-a-Tesla-Coil/

author
Michael+Chen made it!(author)2012-11-05

Actually, your estimate is way off. I did mine with less than 100, although I did scrounge some pieces.

Besides, that tesla coil is a spark gap tesla coil; which uses a primary with 15 kv through bare coper wire. That type of tesla coil is potentially more dangerous than mine, as mine's primary uses 170 v in an insulated wire.

Besides, that one is potentially expensive. Right now, the one you linked uses leyden jar capacitors. Although it works, it is nowhere near its full potential. A commercial high voltage capacitor is expensive, so at the end, they end up kinda even.

The spark gap coil may be a tiny bit cheaper, but I don't consider that is worth the safety risks.

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