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.

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Step 1: Some Info on CFLs

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

<p>this is one of the best I have seen, thanks for your work. It awesome when I can really build something that works.</p>
<p>can I get a definition of what range is meant by &quot;high&quot; voltage? I have a particular application in mind.</p>
<p>By definition Hight Voltage is anything above 750V. In reference to this circuit, it depends on what cfl and flyback you use, I used a 10W cfl and got a 5KV DC output.</p>
<p>I used a 10W cfl, I have a 42W to upgrade to later.</p>
<p>I didnt see anyone post this so I just want to add. the CFL circutry can kill you, I am an electrician. 50mA across your heart WILL stop it. though getting zapped in the hand will hurt and may seize your muscles it will not instantly stop your heart prolonged can. at 1000v probably about 5 seconds. direct to the chest may kill instantly. </p><p>That being said the high voltage from the flyback would hurt, burn and make your muscles unable to move but it will not kill you. if you are stepping the voltage upto say 20kV from 1kV the output current maximum is at 1/20th of input so about 3mA. high voltage arcs are very hot though. </p>
How do you find the diode to disconnect it for AC use?
Good question. The diode is buried in the plastic casing. You can try to hack it off, but you might ruin the flyback. I suggesting googling looking for somebody who tried it. The easiest thing is to buy an old B/W TV, the flyback back then was seperate from the diode. Or just look on ebay for old flyback. Please inform me about your results.
I did some searching but no luck in finding how to remove the diode, from what I found it was suggested that it's easier to just find an older flyback without the diode
<p>well there is always the possibility of using, and old automotive induction coil. but you would not need a cfl for that. just about a two amp, 12 volt, around 500hz to 1kz square wave or pulse generator. </p>
I tried using the CFL circuit on a microwave transformer, but didn't get squat. Is there a way to use your circuit to make it work on a MOT? (By the way, I got it to work great on a TV flyback, but I'm still trying to find a way to get ac output. Taking out the diode is not going to work and hard to find old TV without it)
the MOT has too much impedance it is designed to operate at 60HZ. My suggestion is to try to fry the built-in in diode in order that it conduct ac. I never tried it, but maybe someone has, so google it.
Thanks for your info. Actually, what I am trying to do, is build a poor-man's heat induction coil. I was trying to use your CFL circuit towards that end, but may be a dead end. Any ideas or suggestions along that line??
You don't need a flyback for that! Just make a flat pancake coil and hook it directly to the CLF. Put a capacitor in parallel with the coil to make into a resonant tank. The pancake coil will resonate and will heat inductively anything in the vicinity. You will need to experiment with the number of turns and capacitor values for the optimal set up.
Cool, sounds a lot easier than what I was trying with the flyback. Will that work as well with the coil coiled into a tube instead of a flat pancake? I want to heat up rod shapes with it. Thanks!
<p>yes you, can use copper tubing for that. since you are going to need to run coolant through the copper tube. and it takes a while to learn how to design, any induction coil so that the field does not cancel itself. but they are not limited, to shape. but depending upon the thickness of the rods, you want to heat. i am, not sure if even 65 watts is enough. unless they, are small rods.</p>
Wait. let me guess, you are trying to purify silicon or another metal. Right? Yes you can make a coil to heat a segment of a rod.
hmm well nothing that exotic, but it has to do with using an alternative fuel for automobiles:) I will test it out and see if the resonant tank idea works and let you know. I'm not an electronics whiz, so if you don't mind helping me out some more if I have any questions, or missing something that's taken for granted, I would appreciate it a lot! Thanks for the help.
I've found that new CFL's are incorporating more advanced circuit-detecting abilities, and are harder to fool into thinking a bulb is attached. Also, I am unable to get nearly the same voltage other people are getting (probably just under 1,000v DC at 1.7mA), and am going to try to wire two or more flyback transformers in line, to keep amping up the voltage. Will I die in a fiery explosion if I attempt this? Thanks
<p>never a good idea, to exceed the design specifications of any fly-back boost transformer. might be smarter, to try the other transformer first. plus you might try, checking the open circuit voltage of the cfl device. at 1.7 watts, it may not be operating correctly. when it sounds more, like you are operating on the filament tap winding only.</p>
you won't die, but you might ruin your fly-backs. the coils in a fly-back are insulated from each other with a dielectric of some kind. as the voltage increases the dielectric become less able to insulate each coil from the next one. If the voltage increases high enough it will lead to dielectric breakdown. this is where the electricity jumps from coil to coil inside the fly-back creating shorts that permanently ruin the coil. No more coil + lots of bad smelling smoke = sad face.
can you post a picture of the circuit?
i want to build cockroach electronic trap from 9v dc 200mA out put votage 4.5 kv where can i get circuit ? pl help ...
<p>from a comercial bug zapper.</p>
<p>Get some old camera flash and connect it to the voltage it needs (normally 3 to 9 volts, depending on battery count) and then connect it to your trap... It will be very loud tho and you need UV lamps.</p>
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)
Is it 50mA or 50MA, because I don't think 0.05A is enough to kill someone. I would think 5A is enough to cause damage. I've worked with wires connected to 500mA sources and I am still here.
<p>Well, when you think that earlier, they used to toy with frog legs and electrostatic electricity which was enough to make the muscles of the legs react... think that a rather steady 50mA will do to your heart...<br><br>If electricity goes from one place on your hand to another place on the same hand, you'll probably not die... but it'll nonetheless hurt and burn...<br><br>Also think that thermal power is UI... 50mA with 10000V =&gt; 500W... better not have that dissipated through your body... <br><br>You still think that 50mA is too low ?<br><br>BTW, 500mA sources can deliver AT MOST 500mA... this don't mean that when these low voltage sources are connected to you there will be 500mA going through you... When you &quot;short&quot; a 9V battery with your finger, you don't empty it quickly... </p>
<p>the idea is to avoid, either high current or high voltage. and most especially the chances of it going thru, the heart.</p><p>when you, have worked with electronics or electricity as long as i have. we've all most likely had, our mishaps over the years. but have been fortunate, to have survived them. but it is no assurance, we will be as fortunate tomorrow.</p><p>at low amps, or 60hz, the danger is stoppage of the heart. at high amperage, is the danger of being cooked to death, or life threating burns and infections.</p><p>and i seriously doubt, you are going to short a 9v batter with your finger without seriously special conditions. using your tongue yes, giving you with an acid taste in your mouth. but it is still not a short circuit, and a way you can test batteries for their charge with experience. but would not try that in, a light socket.</p><p>under normal conditions, the human body will not conduct dc from 2000 v to 100,000 v. so most of the static discharges, from your finger are over 2000 v. but once the high resistance skin is punctured, it takes less voltage to bridge the gap. one spark or more from and induction coil, with a piece of paper can verify this effect. it will leave, a small hole.</p>
<p>never use your left hand, keep it in your pocket. your chances of survival increase, if it does not go through your heart. even using your left hand, can go through the heart through your left leg. or from your left to your right hand, through your heart.</p><p>but remember, in a short circuit or decrease in resistance voltage decreases as current in increases. once current, begins to flow. if you are not using, a constant current device. so 50ma or 500ma does not necessarily diminish, the current danger. though the wattage, will generally not greatly exceed the capability of the electronics. so many high voltage circuits, are capable of producing the sure death 1/10 of an amp or more. 0.1 amps x 500v = 50w; as 20,000v at 2.5ma = 50w. so never assume you cannot, reach that always fatal 0.1A current through the heart.</p><p>and when even wearing high voltage, gloves and boots. high voltage, can find it's way through the slightest pinhole. and even a high voltage corona, or capacitive discharge, can knock you for a loop even if properly separated from a ground.</p><p>corona discharges are cool, if you know how to do them right. turn off the lights and watch, the pretty tentacles dance in air. and can even make a balanced wire spin, on a point contact post. or light up, burnt out fluorescent and neon bulbs using the ac version.</p><p>but i, do not suggest a plasma cannon. those glowing balls of plasma, can be a real shocker. if you want to use the focus and deflection coils from a tv to fire a plasma discharge.</p><p>so you know there is a lot more cool stuff to do, than just a Jacobs ladder.</p>
5-10mA is enough to kill, but it's not likely to. I've been hit by 9kV, 30mA, as well as shocked myself multiple times with 120V house current (on a 10+A fuse,) and I'm still here. That doesn't mean either of those situations can't kill you.
wow, what does 9kV feel like? i got shocked by a camera cuz i touched the switch oart and it burnt a little hole in my finger but thats only a few hundred volts
It was probably only 4.5kV because it was to the center tap, but it didn't really hurt. Just made me really tired. Your hit probably had a lot more current than 30mA. A cap can deliver amps
ah, ok
But arent the caps in cameras only something like 30mA?
NOOOOO! caps in camera's are usually 6000uf or more depending on how big the camera is or the flash type. That is probably close to half an amp because of the high current capacitance. The voltage is only 1.5v but the current is very high.
what are you talking about, camera caps are 330v 120uf.
What am I talking about? What are you talking about? A capacitor is measured in farads, not volts. One farad is one coulomb which is 6.25x10^18 electrons. Amperage is the measure of how many coulombs of current cycle in one second, so since capacitors accept certain amounts of coulombs, that must mean that capacitors store current, not voltage. How or why would camera designers integrate a cap rated for 330 volts, when only a 1.5 - 3v battery is used, but only store 120uf of current. The greater the farad, the bigger the flash. Maybe your camera has that, no way for me to know.
<p>Store a 120uf of current ! wow, you need to learn, instead of copying and pasting to try to sound smart. Any one here that has any knowledge of electricity or electronics knows that you have no credibility with that remark.</p><p>A technician or engineer would not be interested in this part of electronics. Much less take the time to go copy and paste this meaningless information. It has nothing to do with anything except for your ego to impress. The formula you took the time to change from 6.24 to 6.25. You also trying to draw assumption by your own words.(that must mean that capacitors store current, not voltage.) That shows you have no idea, just want to be involved and argue. I assure you that a capacitor does store voltage, the same as a battery. Both are constructed alike. Both have plates and dielectric. I took the time to look for the information for you: goto: http://physics.bu.edu/~duffy/py106/Capacitors.html</p>
ALL capacitors have a rating for voltage and farads
Yes your right there, but making a cap rated for 330 Volts will just make it physically larger, nothing else. They are almost always set to 10 or 16 Volts to keep physical dimensions smaller. The farad rating is what affects it's performance, the greater the farad, the longer it takes to charge, but makes a bigger bang.
<p>Handyman, you need to stick to hammer and nails. Quit copying and pasting and drawing erroneous conclusions. You are so full of misinformation. </p>
I think your math for charge is off. 1 Farad is not 1 coulomb, it's 1 coulomb/volt. The amount of charge in a cap is the capacitance * voltage. Caps store voltage. If you charge a cap to 10v, wait a bit, and measure it's voltage, it'll still be roughly 10v. Inductors store current.<br>Caps are sized according to both their voltage and capacitance, roughly at k*c*v^2 (k being a constant for a given type of cap.) For the same capacitance, a 330v cap would be roughly 48,000 times larger than a 1.5v cap (ignoring the fact that you can only make a cap so small.)<br>Flashes use DC-DC converters, usually flyback or something similar to convert the low 1.5-7.6v supplied by the batteries into the hundreds of volts necessary to make a strobe work.
<p>What I have seen in later models of flash circuits is a series of discreet, diode voltage doublers to get the proper output high voltage. They are a lot cheaper to make than a fly-back transformer -- and also have the advantage of being much smaller and lighter by not requiring a lot of windings of copper wire.<br><br>As to inductive storage of potential, one of the worse, unanticipated shocks I ever got was from continuity testing of a war surplus, oil-filled filter choke I used to make a power supply for a 1.5kW, 40-10 meter linear amplifier. I was using a VTVM, which supplies 1.5V DC on the times 1 resistance scale. As my alligator clip was demised, I was holding the test leads in place with my fingers. When I removed the first test probe from the choke, the field collapsed and I got a jolt that was quite a bit more than I expected.<br><br>Keep it in mind that the potential voltages, from both capacitors and inductors, can be much higher than anticipated -- far exceeding the charge voltage. Also keep it in mind that when the skin threshold of human skin is exceeded, the apparent resistance will diminish a lot more than anticipated as the skin will form a trail of ionized salt water along the path of conductance. </p>
thats exacky right <br>caps store voltage <br>size depend on storage capabilty which is rated in farads <br>current does not matter <br>capera caps are tiny , rated in hundreds of volts and a few microfarads
<p>Nothing else, you are totally wrong. Lots of dangerous misinformation here on this subject.</p><p>He guy go make it and stick your finger to it and then come back and make your report. You have my blessing and maybe the Priest also</p>
no the size is mostly determined around the farads, i have a 10000uf cap at 72v and its huge, i also have a 47uf cap with 50v and its tiny.
<p>Just an FYI here. Capacitors are merely two or metal plates placed in close proximity and separated by a non-conductive material known as a dielectric. Depending upon what type of dielectric is used, this allows the capacitor to be either wound from two insulated layers or alternating sheets to be stacked to get the required capacitance. The voltage rating is nothing more than how much potential (voltage) the dielectric can withstand before it breaks down and shorts out. It is the capacitance that gives the amount of current it can hold. Common Dielectrics are polyethylene, mica, various oils and even glass or waxed paper. Most capacitors are non-polar and no regards need be given to polarity. However electrolytic capacitors are wound with a chemical suspension between the plates and then subjected to an DC current to create a dielectric layer that is polarized - reverse polarize it and not only will it conduct, but will most likely overheat and explode. This allows much higher capacitances to be generated in a smaller package with a specified maximum voltage. A NPO capacitor is merely two electrolytic capacitors, of equal value, with their anodes connected, which gives them half the capacitance but twice the voltage rating - and non polarized.<br><br>One important note. All capacitor ratings are for the highest voltage they will withstand until the dielectric fails, including the peak values (+ and - half cycles) of any alternating current, which will have a value of about 1.414 times the RMS of the voltage on each half wave (assuming a sine wave from 50Hz to 70 Hz). For 220V the peak value of each half wave will equal 220 X 1.414 = 311V. Plan accordingly when using any capacitor, or maximum PIV of rectifier diodes, in an alternating current circuit.<br><br>As far as the shock potential goes, any voltage above above 38 volts will be able to cause current flow in dry human skin - and much lower voltage threshold with sweaty or wet skin. This is why you can not feel a 9V battery with your finger,but can get a good idea of its charge state by touching the electrodes to the tip of your tongue. The amount of shock that a capacitor can give will be determined by the total amount of electrons (Coulombs) stored in the capacitor. A Farad of charge is one Coulomb of electron flow, per second, across a 1-ohm resistance, and is equivalent to one Ampere of current flow per second. Always discharge large electrolytic capacitors, with a 35V or higher rating, before handling to avoid shocking situations. Also store them with a jumper wire across their connectors to prevent them being charged from static fields -- especially in low humidity environments.</p>
<p>Shows knowledge. caps are measured in farads but they are also voltage rated. Thus 330v 120uf. I would write it the other way personally. 120uf 330v</p><p>Same difference. The 330v is the max this cap can handle before it will break down or explode. </p>
They change the voltage to 330v specifically for the cap and flash, but then how fast do the caps discharge when touching human flesh, that is the question.
In a standard or disposable camera, they do not change the voltage, they only change the current within the capacitor. I'd get into a science lesson, but I want to go play some Red Dead Redemption right now.

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