Re(updated) Simple flyback driver

Do you want a simple $3 solution to make a 20-30 kv power supply for your electronics? Well here you go:

I modified the photos from so that it would work with a modern dc flyback transformer thats found in most modern tvs.

I am not responsible for any damages or harm that result from following these instructions.


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Step 1: Prepair the parts you need

You will need:

  • Soldering iron (15/30 watt)
  • Duct tape
  • Thick(ish) wire
  • (20~24) Gauge magnet wire (or copper radioshack wire)
  • NPN 2N3055-type Transistor (radio shack part # 276-2041)
  • 27 ohm 1 watt resistor (5watt if use with 300amp battery)
  • 240 ohm 1 watt resistor (5watt if use with 300amp battery)
  • Heatsink for transistor (the bigger the longer the use)
  • Switch
  • Box to put it in
  • 12-24 volt power supply (i have tested it on a 12v 1amp wall transformer and it works fine and a 300a lawn and garden battery)

Q and A

Were can I find that type of flyback transformer?

Well, in a dumpster if you can find an old CCD TV or monitor (the types that aren't thin) crack one open (don't actually crack it open use a screw driver please :-) ) and pull it out

Were can I find 20-24 gauge mag wire?

I took mine out on an old amplified fm antenna but other sources are good and it doesn't have to be mag wire; it can be soled copper wire too.

Were can I find a switch?

In one the things you took apart to get the flyback or the mag wire if you still cant find one try radioshack

Were can I find the power supply?

In your basement car closet junk pile you name it (please put a volt meter on it to test voltages)
also you can use a 300 amp lawn and garden battery from lowes or were ever.

Were can I find you?

Email I will be more than happy to answer your questions
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Alex1M62 years ago

Here are my results with this circuit.

Also I recommend using a fast diode in reverse bias across the transistor collector and emitter in order to protect it from back EMF spikes. The transistor will not last very long without it in my experience.
sarvesh7 Alex1M62 months ago

thats really awsome

Great tutorial. However, I would really appreciate if anyone could tell me why I couldn't get any sparks at all, something seems to not work despite me following exactly the instructions... MY flyback is as well of the same type as yours , my psu is 0-12v 2A but I get absolutely nothing.. ?
Flybacks have an internal diode. switch your wires around. try again
it worked i probily built 5 of these because it wouldn't work with my 9 volt battery and i thought something was wrong but thanks
it worked i probily built 5 of these because it wouldn't work with my 9 volt battery and i thought something was wrong but thanks
far.peter4 years ago
can you use another transistor instead of the 2n3055?

Yes. Pretty much any power transistor will work. It doesn't even have to be NPN. However, the 2n3055 will eventually fail due to the HV fed back through the primary windings. If  you can salvage the driver transistor from the television, it will work great because it is designed to withstand the HV.

If you add a flyback diode to the transistor could you prolong its life? I'm assuming the damage is caused by reluctance of the inductive load. Do you know if this is the case?
which transistor do i use because there are different kind on it
Anuradhai4i2 years ago
Working fine and already made nearly 1 Inch long Arc with this. Pretty good stuff. I was just messing around with a 2N3055 and didn't even use the resistor values you have specified. And I just used 10 T for the primary and 4 T for the FB windings. And very impressively this works perfect. I will make this again in a proper manner by tomorrow and will see how long will be the Spark is?
wii5523 years ago
you can't "discharge" a transformer...only capacitors.
Capacitors are not the only components which exhibit capacitance; even (long) lengths of wire can have some measurable capacitance. capicitors are like resisters in that they are not the only ones with the property (capacitance/resistance) but a usefull cause that is their dominant property.

When dealing with high voltages it always pays to be safer rather than sorry.
the innerds of a flyback contein a filter capacitor that hols quite a shock-the transformer itself hold no actual charge.
well in a way these transformers will hold a jolt for quite a while that can shock the poop out of you.

first hand experience
Yes I agree with you, they do hold a charge for quite awhile. When I am working with my flyback power supply after using it if I am doing any work on it I short the leads out and everytime there is a noticeable discharge upon doing so. I would imagine it is static electricity
asteidl wii5523 years ago
If you think you don't need to discharge the stored energy in that transformer, you're gonna get knocked on your tail end if you play with the the HV+ line. If you don't believe it, find a TV along the side of the road, then use a chicken stick that's connected to ground (literally, the earth), and watch and listen as you poke the chicken stick under the red protective cap where the HV line connects to the tube. You'll hear a pop, and see a small arc. Unless you want to get zapped, do discharge the flyback.
i tried this circuit and used 220 ohm and 22 ohm resistors and ran it off of 9v battery but it just seems like its shorting out the battery.

this was unsuccessful for me!
nms222 years ago
I have made this circuit successfully and am running it off 12 V at 1.7 amps. I have a fairly large heat sink on the transistor, but it is still "frying". Is this because of it receiving an EMF pulse, or is the current simply too strong for it? Also, does anyone know the temperature limits of the transistor used?
I want to build a potato cannon ignition system. Will this circuit work with 7.8 volts, and will adding high voltage capacitors in parallel with the secondary ruin the transistor?
It should work with 7.8 volts, but you'll get a better spark with 12 volts. And why are you adding the high voltage capacitors?
aclark172 years ago
I made a similar circuit from a different instructable. The relevance is my power supply. I converted an old PC power supply into a lab power supply, they're easy to find, just pick up and old computer somewhere and take out the PSU, then you open it up, clip some wires, splice some other wires, add a load resistor and some of those audio connectors to connect your circuit wires and you're good to go. Gives you +12v, -12v, +5v, +3.3v, amps can go up to maybe 25A, they vary on each output, but they usually have labels that tell you what color has what Voltage and Amperage. Use that instead of a 300A battery :)
codex6534 years ago
dude is there any way to limit the current on the output cause this circuit really sucks since it destroys the flyback easy. i'm not bashing you or anything, i'm just saying that the circuit has its problems.
Can you suggest a different circuit that will not destroy the flyback?  I only have one flyback and I dont want to destroy it.  What is it about this circuit that will destroy the transformer?
 it can damage internal wiring, try reading
it said "file not found"
Try here:
That worked, thanks.
amendoza122 years ago
The tv along the side of the road has all the parts in the box. The flyback transformer is connected to the biggest capacitor in the tv. The CRT. What you are discharging is the capacitor not the transformer.
techno guy3 years ago
I tried winding a flyback like you said but the core is too close to this box thing on the flyback and I cant wind it so maybe you can tell me how to make it easier.
you could just get thinner wire, or you may have to find a different flyback if the core is to close to the "box thing" (i wonder what the box thing is called
You can use a round ferrite core with 2 windings, 1 in series with flyback primary. Or a transformator with 2 windings, just the same. =)

i use that on mine, and it works great.
mengstrom2 years ago
what is another kind of power source i can use?
Hey everyone,

Earlier today I pulled a flyback transformer from an old CRT tv that's been sitting in my garage. Ive been really wanting to make a driver for this transformer and eventually turn it into a Jacob's Ladder, however I have been having some trouble understanding all this technical jargon. I have a real passion for anything electrical and instead of just hooking a to b and ending up with the ladder, I would really like to understand everything that's going on in there. So my real reason for posting is that I'm looking for a very patient someone that will, via email, explain what's happening in these circuits so I really understand what's going on. If you are patient and willing enough to help me reach my eventual goal of a Jacob's Ladder, please send me an email at

Thank you all so much in advance!!!
brady9113 years ago
I made a high voltage source and my friend got shocked with it and he didnt die....
...and i bet he doesn't want to do it a gain!
i'm glad you didn't kill your mate but just cause he didn't die, doesn't mean this couldn't seriously injure someone. I hate to be a nanny but high votlage is not somthing to to be taken lightly.
forwardbias4 years ago
Simple circuit, but on the original powerlabs site, it might be best to go with a MJ2955 or MJ15003. The 3055 can get very hot, so if you want longer duty cycles, go with a MJ transistor, and make sure you got it connected on a heat sink with thermal compound. More complicated circuits are available such as the 555 driver, which can make singing arcs, add an audio input and the arc will work like a speaker, or an XVS driver, for high current fun.

Keep in mind that XVS driven flybacks have lethal current. The 3055 driver is very low current, and wont kill you if you touch it, but it will really hurt. Not a bad driver to work with if you are new to HV, as you can learn from your mistakes. It might be a good idea to use an MJ transistor instead, as the 15003 can handle up to 140 volts at 20 amps or 280 watts with proper heat sink. Many people have had problems with the 3055 going bad due to overheating, but perhaps they did not have the transistor heatsinked and bonded to it with thermal compound or were just driving it too hard.

Though you may only be running at 100 Watts, its not a good idea to run a 100 watt rated system at 100 watts, (100% duty cycle) as it can shorten the life of the device if running it long periods of time. Its recomended that if your circuit dissipates 100 watts that your components be rated twice of what is being dissipated to ensure long life under long duty cycles. 100 watts running wattage = 200 watts of max rated components for a long healthy life. You can push the envelope a bit, but not without very good cooling to carry that excess heat away.

There was a saying when I went to school for EET, all components work on smoke, if the smoke is let out, it wont work anymore. And in electronics, heat is your worst enemy. In solid state components it can cause a run-away snowball effect of ever increasing current and ever decreasing resistance, allowing more and more current which = heat, lowering resistance, adding more current, more heat, less resistance, more heat... until, poof, there goes the smoke, causing damage to your driver circuit and possibly the flyback transformer as well depending on what driver you used.

What is an XVS driver? Also do you know how much current (on average) a flyback transformer would draw (I am wondering if I could power the circuit with several 9V batteries)?
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