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Picture of MAKE A HIGH VOLTAGE SUPPLY IN 5 MINUTES
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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:
http://www.instructables.com/id/Easy-to-Build-WIFI-24GHz-Yagi-Antenna/
 
 


Step 1: Some Info on CFLs

Picture of Some Info on CFLs
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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

 
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Delaney2 days ago

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.

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.

jamesb372 days ago

can I get a definition of what range is meant by "high" voltage? I have a particular application in mind.

setinight6 years ago
How do you find the diode to disconnect it for AC use?
Biotele (author)  setinight6 years ago
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

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.

setinight6 years ago
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)
Biotele (author)  setinight6 years ago
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??
Biotele (author)  setinight6 years ago
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!

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.

Biotele (author)  setinight6 years ago
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.
Mansheep225 years ago
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

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.

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.
Biotele (author)  Mansheep225 years ago
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 ...

from a comercial bug zapper.

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.

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)
handyman295 years ago
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.

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...

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...

Also think that thermal power is UI... 50mA with 10000V => 500W... better not have that dissipated through your body...

You still think that 50mA is too low ?

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 "short" a 9V battery with your finger, you don't empty it quickly...

the idea is to avoid, either high current or high voltage. and most especially the chances of it going thru, the heart.

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.

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.

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.

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.

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.

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.

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.

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.

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.

so you know there is a lot more cool stuff to do, than just a Jacobs ladder.

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.
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.
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.
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.)
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.

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.

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.

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.

thats exacky right
caps store voltage
size depend on storage capabilty which is rated in farads
current does not matter
capera caps are tiny , rated in hundreds of volts and a few microfarads

Nothing else, you are totally wrong. Lots of dangerous misinformation here on this subject.

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

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