Picture of 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

Picture of 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. :-)
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AhmadM112 months ago

Finally I made it!

But something just feels not right.. The stream from flyback transformer always try to breach anything to find ground.. And mostly it did it in one way or another, every time I move the cathode away.. Once the stream lost, it's like going wild.. Sometimes I can see sparks outside the fuse case of the DC PSU..

I drive it from a 10A 36VDC PSU.. I doubled the 2W resistors value and increase the zener to 24V also two 270nf/400V caps in parallel as the final caps..

I've been questioning what could be wrong with the circuit.. Or is it just because the voltage too high for my entire circuit/case design? Because it still can reach my hand through my 50cm PVC chicken-stick.. I can feel it and I can clearly see a slight stream strike back to the PVC.. Kinda strange for me because a PVC should be a good insulator..

IC5 AhmadM1127 days ago

At high voltages dielectric breakdown occurs where electrons find their way across an insulator due to ionization. PVC dielectric breakdown voltage is around 40 Mv/m. If your design is definitive, you could also seal the entire thing with wax or submerge it in mineral oil

AhmadM11 IC57 days ago

OK.. Problem solved.. My chicken stick is a grey PVC pipe that made of pipe contains grey dye.. Even in a small measure, it's still more conductive compared to a white PVC pipe which contains no dye. It has been proven.

Anyway, the wax that seals the flyback still can't resist the spark leap from the HV pin. I want to choose the mineral oil, but the overall size would be too large. I just leave it as is until I find another solution..

And thank you very much for your advice..

move the power supply away from the driver and the driver away from the transformer (increase the length of the wires) that would work also try using insulating tape on your chicken stick.

For some reason I get both DC and Ac at the output also DC and AC in the input and I tried using a toroidal transformer since I didn't have any flyback transformers and it just heats up and the circuit only takes in 6 volts 5 amps even though my supply can give 20 volts 12.5 amps.

I had the same issue;

I found putting a nice big capacitor in paralell with the power supply did the trick, i'm pretty sure the issue is a large voltage drop when you initially power the circuit, preventing the FET's from being switched properly, the capacitor provides a little stability at the start, as the capacitor resists the rapid change in voltage.

Hope this helps

Alternatively use a more stable powersupply such as a computer PSU

My toroidal transformer just heats up and no voltage/current is registered at the output.

chiranth23 days ago

wat is the frequency of the out put? is there a way of increasing or decreasing the frequency of this circuit output?

_Totoro_ made it!1 year ago

Great driver and 'ible! barely gets warm at 12v coming out of a PC PSU and really nice arcs, modifying a Microwave Transformer soon for 24v for longer arcs. Fiddling with the capacitor value helps a lot to get the best out of your flyback. I ended up with an arrangement of 6 caps (1µf 275v), 3 pairs in parallel then those 3 pairs in series to achieve 0.66µf capacitance that has a rating of 825v which meant less capacitor heat and easier to modify the frequency with different arrangements, this the is the calculator i used for the capacitor arrangements http://kaizerpowerelectronics.dk/calculators/mmc-calculator/


How does your PC PSU not have current protection?

bypass the optocoupler, simply solder a diode in the optotransistor side (the input side).

Optotransistor? Also, my driver outputs 20 volts AC between the centre wire and surrounding wire at the end of the circuit but when I connect the flyback transformer primary coils, it registers as 0 voltage on the output and 6 volts AC on the input. This is when i bought a power supply that provides 12 volts, 12.5 amps.

It's relatively easy. Computer PSU internal circuit usually divided into two section, input and output. The optocoupler is the bridge between them. Just solder the two optocoupler's pins inside the input section together and you'll get full power written on the PSU case (give or take 10%).


Thanks :D


BenderSanchez2 months ago

What is the voltage of this thing roughly?

Vp=Pi*Vin or 3.14*12=37.68Vp


mkjunior2 years ago

built this circuit and when i first plugged in a 9v battery, i could hear the high pitch from the flyback.. consequently though I didnt see any arcs and the high pitch tone changed when i tried touching the ground output from the flyback to the positive output. Randomly though the circuit suddenly worked and i saw some nice arcs, but a bit later the circuit was doing the same thing as before. does someone know whats happening?
you don't have enough current from a 9v to turn the driver on, you need at least 10 Ampere to satisfy the driver. hope this helps.

PSU power supplies should do the trick but modfiying them to shut of current protection is a pain.

Dude, that's easy, just look at the optocoupler, solder a diode in parallel with the output of the optocoupler and voilá, no more current limits.

Try a rechargeable drill battery, if tou don't want to buy lead acids
TK1756721 year ago

Thinking of building this and i wanted to use a computer PSU but i wanted to ask: if i just connect it won't it try to draw the map amps the PSU can give and and possible damage the PSU or will it be fine? would i have to limit it in some way?

I tried using a PSU, it provides approximately the current required but I think there is something wrong with my circuit.

Nope current limiting is the problem, the PSU shuts down when too much current is drawn from it.

I was fortunate to get an X-box power supply that was fried. blown trace on the input and some blown caps and some soda residue... fixed it up. 17A at 12v (can be pushed to over 25A before overcurrent blows but it starts to warm up. upgraded to copper heat sinks and better fan.) makes a nice ham radio power supply. (20 or so amp at less than %50 duty cycle.)

for flyback driving i get the best arc at 1+1 turn :P need to mess with induction heating.

mcrenno219 months ago
Do the math to find your output voltage,
Output amps= .02-.7 amps
1:135 flyback ratio base on internal winding
turns 5+5 turns
input voltage ??? Depends on you,
my zvs
input 28v
output 63000v
I2 26mA
turns 6+6
20141110_190028.mp4(240x320) 10 KB

What did you use to power it?

For some reason, my PSU triggers the short circuit protection when I connect it to the circuit, how do i disable that?

shigeno213 months ago

is it possible for a hog stunner? how could i increase the current ?

Why would you want to stun a hog.....

it is my project for a backyard slaughter house i think a minimum amp to stun a hog is 1.25 amp can i use a microwave transformer rather than a flyback transformer of tv? can you help me thanks in advance.

1.25 amps, how many volts, what is the power in watts?

hmm around 220-250V so i think it will have a 275-320W from a minimum of 1.25A

Mains current unless you are hunting then lithium batteries connected to an inverter, this is hundreds of thousands of volts.

dillonxti11 months ago
I need a version where you don't need zener diodes and you can use the wall voltage to power it
I meant I may need a version where you don't need zener diodes and you can power it straight from the wall voltage

Dude,i''ll give you a hint, if you just want to power up your flyback you can modify a power supply, just fking remove the original transformer, find the primary winding using a multimeter, and weld the old pcb to your transformer. Weld a simple diode (IN4007 or other) in parallel with the output of the optocoupler to assure that the driver will work in maximum charge, and voilá.

It took me 20 minutes to weld the whole thing and make the new turns on the primary of the flyback. **i used 100 turns.

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