How to Build a Simple But Powerful Flyback Driver

Intro: How to Build a Simple But Powerful Flyback Driver

Tired of little purple sparks? Want bigger hotter sparks? Then try: 

The ZVS Flyback Driver

It is probably the most powerful and efficient flyback transformer driver that was fairly recently invented by Vladmiro Mazilli. It uses resonant zero voltage switching (also know as ZVS) to drive the flyback transformer. This means the MOSFET's are designed to switch (on or off) when the voltage across them becomes zero.

Because the MOSFET's switches when there is no voltage across them, it will generate very little heat, the only source of heat is caused by the MOSFET's internal resistance. Unlike the simple 555 timer flyback drivers, The ZVS flyback drivers will allow you to run your flyback transformers for much longer periods of time before the MOSFET's overheat. If you get really good MOSFET's, it might be even possible to run your ZVS flyback driver infinitely! (Or until the circuit is interrupted)

Video of it working! 

STEP 1: The Dangers of the ZVS Flyback Drivers

Not only the ZVS flyback driver is powerful, but it is very dangerous. You can easily pump several hundreds of watts into the flyback transformer and the output current would be around 50mA to 200mA (or even more), which is way above the lethal rate which is 10mA.

Do NOT attempt to do this as your first flyback transformer driver project, I recommend you to start with using simple 555 timer flyback drivers before thinking about building an ZVS driver.

And finally, you are solely responsible for any harm to others or damage or any other problems that a ZVS driver may cause. The ZVS driver should be used for educational and research purpose only.

That is the end of my health and safety rant. :-)

STEP 2: Parts

ZVS drivers are fairly cheap to build, the only pricey part may be the MOSFET's. I got most of my parts from Farnell and some of it I had lying around.

• Flyback transformer
Newer flybacks are recommended as they are very robust. You can use an older flyback for higher current output, however, they are more likely to burn out due to excessive voltage.

• 2x 470Ω 2W resistors
The color code is yellow/purple/brown

• 2x 10KΩ 1/4W resistors
The color code is orange/brown/black

• 2x 12v 1/4W zener diodes

• 2x 400+ volts fast diodes
I used UF4007 diodes.

• 1x  inductor
The value is not critical but it should be 47uH to 200uH rated at 10A or more. You can find an inductor from a computer PSU or you can simply make your own, just wrap 20 turns of 16 gauge of enameled wire around a ferrite toroid.

• 1x 0.68uF 250v (or higher) capacitor
This capacitor must be bipolar and must be good quality, such as MKP ot MMC types. NEVER use an electrolytic capacitor, they will blow up. You can test various types of capacitors to see which one suits your ZVS driver well.

• 2x IRFP250 MOSFET's
They are a bit pricey, however, you can use other MOSFET's that has Vds 4x more than the power supply and has the Rds(on) lower than 150mΩ. Unfortunately those MOSFET's are a bit over my budget so I used the IRFP254 MOSFET's instead, not the best, but it is cheaper and it and it should give me good arc results. I also tried using the popular IRF540 MOSFET, however, it gave me very poor results.

• 2x small heatsink
They won't be necessary if you are going to run your ZVS driver lower than 12v.

• Large variable voltage power supply
Now this can cost quite a big chunk of change, you can a computer power supply unit for 12v power source. If you want a higher voltage power supply, then you might want to consider modifying a microwave oven transformer, but this is another project. As I don't have a large power supply so I used six  6v sealed lead acid batteries all in series to gain 36v to power my ZVS driver.

Then finaly the other bits and pieces you may need such as solder, thick wires, etc. 

STEP 3: Schematics

The 5 turns of wire as the primary is not critical, you can add or remove windings for different performance.The voltage input to the driver may affect the number of turns required as well.

The "47-200 µH" inductor can be customized to the desired output of the flyback transformer. In general, if you want a higher voltage, the inductor should have an higher value, if you want more current, the inductor should have an lower value. Also, an inductor is a 'must' for the ZVS driver, without it, your ZVS driver may work poorly or not work at all.

Changing the value of the capacitor can also affect the performance depending on the flyback transformer, again, make sure you use good quality capacitor.

STEP 4: Construction

Not much to say here, just get your toolbox, read the schematics and build it! :-)

Make sure you use thick wire as it will be handling currents up to 10 amps.

When winding the flyback transformer, make sure both wire go the same way.

If you are going to attach both of your MOSFET's on one heatsink, Use mica insulators! Or other types of insulators to isolate the MOSFET's tabs from each other, otherwise your ZVS driver won't work.

STEP 5: Power Her Up and Set Wires on Fire!

When you first power on your ZVS driver, start with 12v input to make sure everything thing is working. Then you can increase the input voltage up to 36v. You can power the ZVS driver above 36v, but then you risk blowing up your driver, check step 7 for instructions for modifying your ZVS driver to handle higher input voltages.

You may hear an very high pitched squeal from your ZVS driver, don't worry, that is normal.

What ever you use as your negative terminal, it will get hot, very hot! The arc will melt any thin wire you use into little metal balls and steal will just fly everywhere, which is cool (and dangerous)! If anyone has a good explnation why the negative terminal get so hot and the positive terminal remains fairly cool, I'd like to know.. :-)

Also, in the video, just after the arc burnt a hole into a lightbulb, they was a stream of plasma 'shooting' out of the bulb, like a flame thrower. This is because when the arc got inside the bulb, the gas inside heats up, causing it to expand and escaping through the hole thus creating a "plasma thrower".

STEP 6: Modify Your ZVS Driver for Higher Performance!

I have not tried this yet, but there is a revision of the ZVS driver by Andrinerii. He added two separate 3 turns of wire on top of the existing primary, each with a series 100Ω 10W resistor. This circuit supposedly add an 35% increase in performance.

Also, make sure your 3 turn windings are the same direction as the primary, otherwise you will blow the MOSFET's!

STEP 7: Going Further

The fun does not stop there, if you are hungry for more bigger, hotter, and beastly arcs, a few changes to your ZVS driver should be made to handle higher input voltages.


For input voltages over 36v:

Change the 470Ω resistor to 1kΩ resistor.
Change the 12v zenner diode to 15v zenner diode.
Increase the number of windings on your flyback transformer.
Increase the value of the inductor.

This should work well for voltages up to 60v before the MOSFET's should be changed as well...

I heard that some people had operated their ZVS driver at voltages over 100, just imagine how massive their arcs must be!

Also, this ZVS driver circuit does not have be used just for the flyback transformer, you can replace it for use a different transformer to charge up your large capacitor banks for coilguns, railguns, etc. It might be even possible to do induction heating with this ZVS driver circuit...

Comments

[chris798279]

Hi so I was wondering how can I build a zvs driver 12v-36vdc input 150v-300vac output need to know the parts list and specs i would appreciate any help thank you

[hiesenberg slayer]

what exactly is a flyback transforme? the internet isn't giving me good answers
how is it different from a normal transformer?

[doktordoris]

that long answer didn't actually answer your question. a flyback transformer, also known as a LOPT, or line out put transformer is a transformer that uses the effect of 'flyback' to make very large voltages. when an energised coil is turned off the magnetic field collapses, this can cause flyback, a large reverse voltage. flyback can be a problem for circuits, people use flyback diodes, also known as snubber or freewheeling diodes to prevent this happening. a coil that uses flyback topology can be made much smaller than a regular steel cored transformer.

if you just want to play with cool arcs may i suggest you just look on ebay for zvs circuit/driver with flyback transformer. you can get both together for only 20 pounds/30 dollars. as the article mentioned this project is probably a bit much for someone without a thorough understanding of the principles involved. not to mention to really drive it you'll need a couple of bench supplies in parallel. it will happily suck up 10amps at 30v and it won't work first time, so you'll really want an oscilloscope to see what's going on. and if you wind your own inductor, or find one in an old power supply you'll want an LCR meter to see what it is. i am certainly not trying to put you off learning and having fun, i am just suggesting if you need to ask waht a flyback transformer is this probably isnt the best place to start learning.

[hiesenberg slayer]

Thank you for your help, im still trying to make it, though

[doktordoris]

good man!

[joe-over]

hallo slayer, the flyback-transformer was neccessary in times of old cathode-ray-tubes in TV. It was used for accelerating the electrons, which were emitted from the hot cathode (with extra heating wire, making the cathode-metal glue in dark red color). To show a picture on the screen, the electrons passed the distance form the cathode at the backside of TV to the front glass, plated with metal-dust of diverse chemical elements. When hitting the metal-dust, the energy of the electrons makes it change its inner energy-level by emitter light-waves, depending on the kind of metals (see Planck Quanten-Theory, and Bor Atom-Orbital-Model).
Without any magnetic field it would burn a whole in the front-panel-mask. Therefore the electrons-beam has to be deflected 50times per second, nearly 640 rows, nearly 15.625 points of each picture/image on the screen. That is what you can see, but if the ray is deflected from one side to the other one, the ray must be cut off or it will write a track on the screen.
And that the time for the idea of fly-back of the ray of the electrons. To tune up the voltage it was usual, dividing the winding in 3 parts, maximal 27 kV [ kV = kiloVolts ] at all. Higher voltages in CRT-Tubes accelerated the ray in dangerous levels (x-rays ~ 83 kV) and steadily x-ray consumption will destroy human biological substances and causes (is made responsible for) cancer.
And You can't use a normal transformer for fast deflection, it should be a ferrit or better ferrox-cube core with a little air-gap in the magnetic-loop. In the air-gap is all the energy stored. Without that air-gap, refelcting energy would destroy the MOSFETs on the primary side, during MOSFET shutoff-time.

Please take a look at: https://en.wikipedia.org/wiki/Cathode-ray_tube



I hope my old fashioned translation is understandable. Joe-Over

[doktordoris]

"It was used for accelerating the electrons, which were emitted from the
hot cathode (with extra heating wire, making the cathode-metal glue in
dark red color)"

eh?

[hiesenberg slayer]

Yes i also didnt get that part, i think that they google translated thier response from a different language and it made a few mistakes

[hiesenberg slayer]

that's so cool! thanks a lot for explaining
I didn't know you could generate x rays with a cathode ray tube?! (does this mean it can create microwave s, etc also?)

[joe-over]

Hallo Slayer, You can create very strong x-rays with a Cathode-Ray-Tube but You need much cooling for the valve. And x-rays are not for gaming, it hurts biological cells so much, that you will get cancer after a short ray-consumption of more than 60 sec within a period of 3 month. That's way doctors at radiology have to wear a lead-shield against x-rays!
The microwave heater is using a high-voltage transformer and a special kind of valve for tuning electrons in a high-frequency wave of about 2.45 GHz (that is a wave-length of about speed of light divided by frequency ~ 300,000,000 m/s divided by 2,450,000,000 Hz [1 Hz = 1/s] = 122.49 mm = .12249 m. That is exact the wavelength where water is absorbing most energy of the electro-magnetics waves. If You want to know more about the circumstances, take a look at the picture and trey Wikipedia. It is a very good fountain of wisdom for self educating. Best wishes Josef

[doktordoris]

"you will get cancer after a short ray-consumption of more than 60 sec within a period of 3 month"
lol. really?

[rkd.audio.profesional]

Indonesia : Bagai mana menambah input untuk musik dan apa saja yang perlu di tambah agar menjadi speaker tesla coil

Indonesia : How to add input for music and what needs to be added to become a Tesla coil speaker

[hiesenberg slayer]

the headphone jack should be connected to a transistor to the end of this circuit ,
when you are connecting it with the tesla coil

the output of this circuit is then connected to the primary of tesla coil
i can't draw a circuit diagram right now, hope this helps

[rkd.audio.profesional]

Ok, akan saya coba, terima kasih

[doktordoris]

mate, i don't want to sound like a dick but someone who doesn't know what flyback is-one of the things we learned in week 1 of electronics study shouldn't be dishing advice out about anything. i guess you are young, 12 or 18, something like that. and you are interested in this stuff, which is great, really great. but don't try and advise people, please.

[doktordoris]

first you need to make a tesla circuit. this isn't one. a tesla is tuned, so the 2 coils have the same resonant frequency. then to play music this is turned off and on at audio frequencies. this is not the place to start learning about tesla coils.

[cvannor23247]

How would you go about getting more power output for lower voltages i.e 20v max? Is there a way to increase the efficiency of this circuit?

[doktordoris]

i would carry on adding 20v supplies in parallel. if 20v is you limit you must increase I.

[Titacho]

ello, I made this circuit with the materials listed. I was thinking of using it with 12V (PC source) But it does not work for me, with the laboratory source it reports a high current consumption. The only difference is that I use IRFP250N, will that be the problem?

[doktordoris]

high current means you have dead short. something is very wrong. first check your mosfets by clipping continuity meater to circuit ground and probing the fets. a knackered one will often have all 3 pins showing continuity.