Introduction: Re(updated) Simple Flyback Driver

Picture of 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.


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

Step 2: Winding the Flyback

Picture of Winding the Flyback

Grab your flyback and some of that mag wire and pliers and have a seat

Bend the tip of the wire a little bit and wrap the wire around the ferrite core (see the pics for help) 5 times for the feedback and 15-20 times for the primary and burn the tips with a torch or a lighter to burn off some of the insulation on the wire so your wires can get a good connection also dab some salder on the wire if the salder sticks you have a connection (see the pics)

if you want to use higher amps use thicker copper wire you only need 5 turn primary and 10 turn secondary

Step 3: Puting It All Togeather

Picture of Puting It All Togeather

Follow the schematic EXACTLY. I did find that polarity matters on the flyback' s feedback windings. if it still dont work revere the feedback winding connection

Step 4: Hv Lines

Picture of Hv Lines

Finding the HV+ is easy; it's the thick red wire on top.

well strip your hv+ line, then power op your driver then touch each of the pins until you get the biggest arc (below is a pic of where mine was) DON'T GET SHOCKED! THIS COULD KILL YOU AND REMEMBER TO DISCHARGE YOUR FLYBACK AFTER EVERY USE BY CONNECTING THE HV+ WITH THE HV-

Now solder on a wire to the HV-.

Congratulations! You're done with the hardest step!

if you don't get any arc try reverseing your feedback lines or swapping your resistors with 3-5 watt during this my 1 watt resistors fried with my 300A supply

Step 5: The Case

Picture of The Case

I really don't care what case you use for the flyback. Just no metal cases, please. I used an old wooden box I had. Make sure that your case has holes near the heat sink.

Radio Shack part # 270-1809 works fine.

(Also if you add a POT to the input voltage you can adjust the output)

the output seen in the photo is 1.5" and running off a 12v 300A (lawn and garden battery)


Rileyd5 (author)2016-01-06

Jacobs ladder anyone?
I have been troubleshooting my 555 plasma speaker and found this so I'm gonna go rewire it for this then drive the circuit with the audio input thanks for the diagrams

australianoz (author)2015-10-01

Funny, i used internal the wirings of the THT and used it as a coil hooked to a CDI circuit to run a 2 stoke chainsaw engine. Simple CDI circuit, added optical + trani trigger circuit + optical trigger switch + adjustable trigger sensitivity. For fun i hooked it to my 351W and it ran like a charm. Produces big blots too

RedstoneM (author)2015-09-13

It gets hot, i used one from a printer (2 coils with <1 ohm), i mean the cables get hot. (One nearly melted within 2 secs)

Samiran (author)2015-07-11

done with 25N120 IGBT & 200 E & 68E resistor.


bisaacs3 (author)2015-04-18

thanks for showing how it works

but salder is spelt solder

gabrielw6 (author)2014-12-23

Hey, I really liked your project! This is a good quick'n'dirty solution for a high voltage power supply... Thanks. I'm just a bit confused in the part of the amps. You said that there was a '300 amp battery'. Isn't it supposed to be in milliamps? Because a 60 amp power supply is already a factory one and will certainly melt the wires. Anyway, good project.


tropicaliano (author)2014-08-10

I liked this project. Will build it. Thanks Alex, and keep up the good work.

tropicaliano (author)2014-08-10

I liked this project. Will build it. Thanks Alex, and keep up the good work.

tropicaliano (author)2014-08-10

I liked this project. Will build it. Thanks Alex, and keep up the good work.

jomz45 (author)2014-08-04

what if i put a 12 volts ac supply?

Alex1M6 (author)2011-08-23

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 (author)Alex1M62014-05-23

thats really awsome

leviterande (author)2013-07-08

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

jacobbrunberg (author)2013-05-27

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

jacobbrunberg (author)2013-05-27

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.peter (author)2009-12-03

can you use another transistor instead of the 2n3055?

Wargasm (author)far.peter2010-05-22

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.

mgingerich (author)Wargasm2012-09-21

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?

farlepet (author)Wargasm2010-08-08


Jimmy Proton (author)Wargasm2010-08-07

which transistor do i use because there are different kind on it

Anuradhai4i (author)2012-06-26

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?

wii552 (author)2011-06-06

you can't "discharge" a transformer...only capacitors.

Alpha Bravo (author)wii5522011-06-09

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.


oldschooltech (author)wii5522012-01-29

the innerds of a flyback contein a filter capacitor that hols quite a shock-the transformer itself hold no actual charge.

arkfusion (author)wii5522011-07-14

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

CirceWelder (author)arkfusion2012-01-17

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 (author)wii5522011-07-03

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.

majikplant420 (author)2012-06-11

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!

nms22 (author)2012-04-30

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?

quinnmiller1997 (author)2012-04-24

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?

nms22 (author)quinnmiller19972012-04-30

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?

aclark17 (author)2011-12-11

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 :)

codex653 (author)2009-08-03

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.

UbuntuNinja (author)codex6532009-10-21

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?

Cybot Rules (author)UbuntuNinja2010-01-05

 it can damage internal wiring, try reading

Jimmy Proton (author)Cybot Rules2010-10-17

it said "file not found"

mpep (author)Jimmy Proton2011-09-25

Try here:

Jimmy Proton (author)mpep2011-09-26

That worked, thanks.

amendoza12 (author)2011-09-26

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 guy (author)2011-01-27

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.

mengstrom (author)2011-08-08

what is another kind of power source i can use?

Turnbull.angus (author)2011-07-08

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!!!

brady911 (author)2011-04-14

I made a high voltage source and my friend got shocked with it and he didnt die....

Alpha Bravo (author)brady9112011-06-09

...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.

UbuntuNinja (author)2009-09-16

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)?

forwardbias (author)UbuntuNinja2009-09-16

The XVS driver is designed for very high current stuff, produces white hot arcs that can melt wire, and lethal if you touch it. As far as several 9V batteries, exactly how many? Flybacks can run off 12-24 volts, but beyond 12, you need good insulation of the transformer, as well as components such as a MJ15003 as the 3055 will go up in smoke. Also for higher power such a driver is not best, which if you want power, look up the XVS flyback driver for a schematic, the 555 driver also has good results. The 555 can also be modulated so you can add an audio imput so that you can have a plasma speaker. The plasma makes the sound without the normal magnet and paper disk. Best bet for running a flyback is getting a AC wall adapter 12-24 volts, if you want to adjust the input voltage, add a varible resistor so you can control how hard you want to drive your flyback. I go by flybacks driven from a wall supply, not sure what the current is for 9 volt batteries. Batteries are normally used in high current setups, but instead of 9 volt batteries, 12 volt car batteries are used, which 2 batteries in series are normally used for a supply of 24 volts. Not sure what the amperage of a 12 volt car battery is. But then again, I like stuff I can plug into, no batteries to worry about, just plug it in and hit the switch. With a flyback you have room to experiment, just be sure you dont run your flyback too hard or it will go up in smoke. There are a number of drivers which run on wall supply, varible regulated power supply or battery. Find one that works for you, see how the flyback does, and then tweak it for max arc lengths without blowing it up. NST's can take much more abuse than a flyback, but also deliver much more current and will easily kill someone that dont know what they are doing.

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