In this Instructable you will learn how to make a High Voltage High Frequency power supply in 5 minutes and for less than $20.

All you need is a compact fluorescent light (CFL) and a flyback transformer.

Flyback transformers are found in TVs and CRT monitors. They make the high voltage, high frequency current necessary to trace the electron beam across the screen. They are small and compact, and you can take them out from an old computer monitor or TV.

CFLs are very popular high efficiency fluorescent lights. They are similar to their ancestor the fluorescent light tubes but use electronic ballasts instead of the big and heavy ballasts in the old technology.

The electronic ballast works by generating high frequency currents that are fed to a tiny high frequency transformer that boost the voltage and run the fluorescent tube. It is the high frequency that makes the assembly compact.

The electronic ballast generates less than 1000 volts. But by replacing the fluorescent bulb of the CFL with a flyback transformer, spectacular voltages can be achieved.

Please visit my latest instructable, how to build an 2.4Ghz yagi antenna for long range WiFi or surveillance cameras:

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Step 1: Some Info on CFLs

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block diagram.gif
CFLs can come in a variety of shapes and sizes. Generally the bigger the wattage the larger the voltage output. For this Instructable I got a 65 Watts light bulb.

Most CFLs have a similar circuit topology. All of them have 4 wires coming out of them. The wires are in pairs, and each pair connects to a filament inside the light bulb.

The CFLs I came across have the high voltage on the outer wires. You only need to connect the outer wires to the primary coil of the flyback transformer.

You will find a comprehensive description of CFL circuits on this page

Step 2: Some Info about Flyback Transformers

Picture of Some Info about Flyback Transformers
Flyback transformers come in all different shapes and sizes. Pick a big one.

The challenge with the flyback transformer is to find 3 pins out of 10 to 20 pins. One pin will be the high voltage ground the other two pins will be that of the primary coil that will connect to the CFL's electronic board.

If you can get the schematic of the flyback transformer that will save you time. However you can figure out the pins by following the instructions here.

Danger - if you are going to get the flyback from a TV or CRT you need to discharge it. It can hold a dangerous charge even days after the TV or CRT is turned off (see picture for details).

Step 3: The Finished Setup

Picture of The Finished Setup
This is how the finished high voltage supply looks like.

Remember, this is a DC supply. The output from the thick wire is positive. In TVs and CRTs this high voltage output drives the negative electrons from the filament to the screen.

If you need AC high voltage, you have to remove the built-in diode or find an old flyback transformer that does not have a built-in diode.

Step 4: Troubleshooting

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The first time I build the circuit, it worked immediately. I used a 26 watt CFL.

Then I decided to get a bigger CFL and I build it exactly like the first circuit. It didn't work. I was disappointed. I thought that the CFL electronics were shot.

But when I reconnected the fluorescent tube to the four wires, the CFL worked again. I realized that this type of CFL circuit needed to "sense" the filaments in order to operate. Remember, I was only using the outer wires and leaving the two inner wires alone.

So I put a resistor across the outer wire and the inner wire. The circuit worked! But within seconds the resistor was in flames.

So I decided to use a capacitor in place of resistor. The capacitor allows AC currents but blocks DC while a resistor allow both AC and DC currents to flow through it. Also a capacitor does not heat up because it provides a low resistance path for AC currents.

The capacitor worked great! The arcs produced were very big and thick.

So in summary there two things that can go wrong:

1. You wired it wrong, either on the CFL side or the flyback side.
2. The CFL electronics needs to sense the filament and you can use a capacitor as a substitute.

Use a high voltage rated capacitor. Mine was 400V and I got it from another CFL circuit.

While troubleshooting, be very careful, you are dealing with very high voltages and high currents.

When soldering, disconnect the circuit from the power outlet.

Step 5: Disclaimer

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The circuits in this Instructable use very high voltages and currents.

These currents and voltages are deadly! You can easily hurt yourself, as well. Build this circuit at your own risk.

This type of high frequency high voltage current is used in surgical cauterizers. So if you get shocked you will burn yourself and cut your flesh. There is also a considerable fire hazard from the circuit.

Use the Nikolai Tesla's safety techniques when working with high voltages:

1. Only use one hand (put your other hand on your lap or pocket)
2. Wear insulating shoes
3. Use a dead man stick or insulated pliers when touching or manipulating the circuit.
4. Use a power bar with a thermal fuse rather than sticking the circuit directly in the socket. This will limit the current that will go through your body.
5. When soldering, disconnect the circuit from the power outlet.

Generally, in electricity it is the the current that kills. if the currents are low there is little danger even if the voltages are very high (think of Tesla holding the his Tesla coil).

This circuit has high currents which makes it considerably dangerous.

a 65W CFL can deliver 65mA easily (65W/1000v).

And if you look at the picture below, at greater than 50mA the little guy is dead.
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hamedshh2 months ago
hi dude

make a high voltage may be very dangerous caused decease

due to hazardous of power of high voltage

work with it must be in over care

this happen in just one second and if it hold no way for us to release this and decease is inevitable
Chinese4 months ago
It is very interesting,but I think it is so dangerous.
I understand that occasionally the lead configuration in the CFL will be different, but the one I got looks nearly identical to the picture you posted. By the end of the project, I wasn't getting a spark any longer than about 4 or 5 millimeters, and so I started troubleshooting. As far as I can tell, everything was hooked up properly- I'm confident that I identified the correct terminals on the flyback. I used a multimeter to check the voltage output of the CFL circuit (expecting it to go up in flames- the meter was only rated for 600V) and instead saw a value that started around 120Vdc and dropped as soon as I hooked up the meter (like a capacitor would have). I decided that I must've hooked it up to the wrong wires, but after checking voltages across all combinations of the 4 wires, the most I saw was a constant 120Vdc output across an outer and next-to-outer wire. What sorts of values should I be expecting at the "high voltage" leads? Do I need a different kind of CFL, or did I manage to fry something internal accidentally?

I am having the same problem but at about 270v (my wall plug is rated at 230v) I checked all of the pins, some combinations were like 10v, 40v and 270v (if I remember correctly)

Biotele (author)  nickglowsindark6 years ago
Hmmm, You may have a fried CFL, The transistors are just passing along the voltages from the rectifiers. Do you know how to test a transistor? Or.. the circuit is not oscillating and you need to add a feedback capacitor like in step 4.
I ended up having to add the capacitor to get any voltage at all out if it, and I know how to test transistors, but I'm afraid it's a moot point now, since a little bit more fiddling around resulted in an interestingly colored flame and a terrible-smelling apartment. I'll be picking up a new one later today probably and giving it another go.
pravinjoshi577 months ago
Can I get circuit with Tesla coil....?
pravinjoshi577 months ago
How can I connect it with Tesla coil made by my self...?
pravinjoshi577 months ago
Circuit is not working.....I conne t flyback with 40 watt tube light ballast...

Hey, so after completing this, how could you use this to power something else? like is there a way to connect it to another source?


I got my hands on a 42W CFL. I keep breaking my Fly backs; the next one I get I am taking the core out and then winding my own, i am not going to have as big of a problem with hysteresis and less chance of burning out because I am only using one secondary and a higher gauge.

mlocke made it!1 year ago

I was amazed how well this worked. Good 'ible.

Robotist1 year ago

Thanks for this document. My idea was to put a cfl driver and then flyback and finally connect it to cockroft walton multiplier. I found the required pins on the flyback and followed the instructions carefully. I did everything possible. Unlikely, the flyback didn't work. actually, I believe that adding the capacitor to pins 1 and 2 instead of filament wouldn't solve the problem. would you please explain exactly what pins should I apply to the input pins of the flyback?

will it kill you ?
hell yes.
maddog1014 years ago
Hey can somebody help me with how to get the flyback transformer off the circuit board of the CRTmonitor? i don't know if i should break the circuit board or what i should do. can somebody please help me!?
i took a dremel and cut around each pin the used the iron.
OW! MY EARS HURT FROM ALL THE YELLING! Seriously, there's no real reason to capitalize an entire paragraph.
I just broke the flyback transformer off of the circuit board with cutting pliers. If you can't get it off with any other method, just break it off.
Biotele (author)  maddog1014 years ago
Break the board with a pair of pliers. Wear gloves and safety glasses.
Thanks, now that i have the flyback how do i find the primary and secondary leads?
For every flyback it varies, so you can't say that every flyback the same pin out configuration. Get a multimeter and set in the ohms range and test every pin until you find a pair with a reading at or close to 1 ohm. I have found two pairs of "primaries" so you will just need to test each one for the best HV output.
Eric8 maddog1014 years ago

Red Wire
/.................... |
| 0 0 0 9 .......|
| 0 [|||||||||||||||||||]
| 0 [|||||||||||||||||||]
| 0 0 1... + + |
Eric8 maddog1014 years ago
Red Wire __________
/ |
| 0 0 0 9 |
| 0 [|||||||||||||||||||]
| 0 [|||||||||||||||||||]
| 0 1 + + |

this transformer :
Primary the "+"
Secondary min voltage "1" , max voltage "9"
the second wire the secondary coil is the big red wire that connect to on the screen.

i hope helped you,
can you help me now? please
i bought warm white CFL and this electronic plate output is 70volt, this is ok?
i connected this to the pins and "nothing" happend i connected right the pins are right, after it i smashed my transformer with hammer and saw i connected pins right! i dont know why it dont work, pliz help

Breaking the board isn't that good a method. A de-soldering pump usually does the job and saves a heap of hassle when removing the flyback from the board.
you should just,,, "Unsoder it". if you have a sodering iron, then just get it all hot and stuff, and melt all the soder around whare the flyback transformer is atached. i have no idea how big the flyback transformer is, so you might want some tweezers to grab it while that soder is still melted,,, so that you dont burn your fingers.
nascar31 year ago

Awesome & very cool.

bigowl44221 year ago
alright i have a board with 8 SPOTS 4 ON EACH SIDE, that originally connected to two heaters how do i use these
I was wondering, do you the switch board to run a Jacobs Ladder, or can you run the flyback straight from high output to ground with your normal 120 input from breaker box?
grim32712 years ago
So i got a 26 cfl and cracked in and got the circuit

4 pins 2 on each side i have

J5-6 on a pair
J3-4 on the other pair.

I have NO idea what to do now. Any help please?
probably a little late but assuming 2 of those j's aren't for input voltage you probably have yourself an electronic ballast more like what they use here: http://www.instructables.com/id/Elecctronic-Ballast-as-flyback-Driver-part-2-outpu/
let me make that a hyperlink for you...

                     click here
i want to build cockroach electronic trap from 9v dc 200mA out put votage 4.5 kv where can i get circuit ? pl help ...
it could... but if you want to run it off 9V dc id suggest a 555 timer circuit, they can be just as powerful running off of 12v dc as this thing running off 120-240v ac. (but these are easier to build... don't have to buy any specific parts)
i want to build cockroach electronic trap work on 9v dc 200mA peak voltage 4.5kv can this circuit help me ? can you suggest circuit digram for same ?
james346022 years ago
Why my CFL driver explode after driving a Flyback Transformer for 5 minute
I thing is resistor explode and it turn brown
look at what the resistor leads to. i has a resistor labeled "fuse" and i decided that a good, safe idea was to bypass it :)
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