I recently ripped apart an old tv. Among the salvaged parts was a flyback tranformer. I'm hoping to use it to either make a small jacob's ladder or to make a plasma speaker. Everything I've read on the internet has suggested that the only way to use the transformer is to make a oscillator circuit for it and hook it up to a dc power source, or to wire it directly to the mains. While I would prefer to use the oscillator circuit, all of the instructions I have seen require me to make a new primary coil, something which I don't really want to do.
Is there any way to hook up the transformer without making new coils? I'm willing to make a driver for it, just not a new coil. The transformer is a modern rectified one, btw, not an older one.

If the only way to do it is to make a new coil, could someone please provide me with the simplest circuit they can find and detailed instruction as to how to make and where to place the coil?
Nothing I've found so far has been clear enough for me to be sure of what I'm supposed to be doing.
I read that the first and second pins are for the primary coil, while then eigth pin is the high voltage output. Any clarification as to the pins would be appreciated too.

The wires attached to the pins are just regular wires that I soldered to the first, second, and eighth pins.

Sorry for the terrible quality pictures. My camera is old and you can't hold the button down halfway to focus it.

http://i22.photobucket.com/albums/b343/retnuh66/IM000003-1.png

http://i22.photobucket.com/albums/b343/retnuh66/IM000004-1.png

http://i22.photobucket.com/albums/b343/retnuh66/IM000005.png

I am also interested in this. I have 4 or 5 FBTs + circuits from old monitors & a tv. I've just left them on the boards b/c I can't figure out how to wire them to work otherwise. If I can get some pics do you think you could help me figure something out?

http://leoricksimon.blogspot.com/2007/05/flyback-driver.html

an easier way to do this is to get an ignition transformer from an oil burner. they make excellent jacobs ladders and all you have to do is put a plug on the primary wires and plug it into the wall.

I have a very old one and it makes a great jacobs ladder up to 6 feet tall with a gap of about 6-7 inches at the top. makes some serious zapping noise as well. just dont do what my friend did and stick your finger between the electrodes and let the spark hit you!

http://leoricksimon.blogspot.com/2007/05/flyback-driver.html

Ah, this is exactly what I was looking for. Thanks!
I've identified the primary and secondary coils (it was actually the seventh pin) and now all I need to do is get the components for the driver circuit and build it. I'll post my progress in this thread.

I'm pretty sure I have everything needed to make that circuit, I just found a 555 timer on one of the circuit boards from a tv. :)

Really? I've been salvaging components from my tv board too, but I couldn't find any 555 chips. =P

555s are pretty cheap though, no?

They are, it's just easier to be able to pull on off of an old board than have to go up to radioshack and buy one. I don't need to find one to salvage, but I'd prefer it.

Really? I've been salvaging components from my tv board too, but I couldn't find any 555 chips. =PActually, I was mistaken, it's from a computer monitor, a 15" made in 1999. It's a TI NE555P (http://www.datasheetcatalog.org/datasheet2/c/0hex3d1gxjejda7ur3y2toipkzfy.pdf)
The tv didn't have one and neither did two other monitors.

They are, it's just easier to be able to pull on off of an old board than have to go up to radioshack and buy one. I don't need to find one to salvage, but I'd prefer it.Considering gas prices, it's way cheaper for me. My closest Radio Shack is about 10 miles away, my truck gets about 20 mpg, so that $2 part ends up costing about $6.

I have a question about choosing a MOSFET:
On the first site the guy says "For the MOSFET, Jonathan Filippi (http://www.electronics-lab.com/projects/misc/016/index.html) is using IRF840 (http://www.datasheetcatalog.org/datasheet/stmicroelectronics/3013.pdf) but I'm using IRF630 (http://www.datasheetcatalog.org/datasheet/stmicroelectronics/3006.pdf). You may try to find it's equivalent and experiment with it. Just make sure it is compatible if you want to use other types of MOSFETs. Find it's data sheet and compare the characteristic for both types of components." The guy he's talking about just says "The IRF840 (http://www.datasheetcatalog.org/datasheet/stmicroelectronics/3013.pdf) is a cheap (i found it for 4euros) reliable and powerful power mosfet, it has current capability of 8 A continuous and 32A pulse, 800V drain source voltage, protecting internal zener diode."

Which specifications are important for finding a suitable substitute?

For example, the IRF630 has a breakdown voltage of 200V and power dissipation of 75W, the IRF840 is 500V & 125W, the current ratings are about the same. Now, how high or low could the voltage & power ratings go?

I got interested in this again because of this thread, and I found this:

http://www.instructables.com/id/MAKE-A-HIGH-VOLTAGE-SUPPLY-IN-5-MINUTES/

I've already got a torn apart CFL bulb, and I'm drilling holes in a plastic project box to put it in, probably going to test it tonight.

Thoughts on that instructable?

I got interested in this again because of this thread, and I found this:

http://www.instructables.com/id/MAKE-A-HIGH-VOLTAGE-SUPPLY-IN-5-MINUTES/

I've already got a torn apart CFL bulb, and I'm drilling holes in a plastic project box to put it in, probably going to test it tonight.

Thoughts on that instructable?That's awesome! I have quite a few cfl ballasts from dead & broken lights. I'll dig one out and try it out tomorrow.
Thanks for posting that!

That's awesome! I have quite a few cfl ballasts from dead & broken lights. I'll dig one out and try it out tomorrow.
Thanks for posting that!

Sure, instructables is a great source for this kind of thing.

Although, now that I've read all the comments for it, I'm wondering how well that would work for longer periods of time. Apparently some people are overheating and killing their CFL circuits, and if the secondary of the flyback can't arc, it tends to arc internally, frying the windings.

I got mine to work using a ballast from a 15W light. I've only turned it on for <5sec and the FBT is arcing like it's supposed to each time, so I haven't experienced what you're talking about.

I wonder if it'd work if you put the ballast in some mineral oil or something to liquid cool it.

You did it and it verks!?

:D

Now I must do it.

Pictures or anything?

Sure, instructables is a great source for this kind of thing.

Although, now that I've read all the comments for it, I'm wondering how well that would work for longer periods of time. Apparently some people are overheating and killing their CFL circuits, and if the secondary of the flyback can't arc, it tends to arc internally, frying the windings.

Because the flyback is operating at very high frequencies, if it isn't loaded it generates voltages far greater than normal, which obviously could arc through the epoxy insulation.

I suspect that the CFL circuit is getting fried because the high frequency noise from the arcs are filtering back into the circuit. I've heard of such things happening when using high powered Tesla coils where devices using the same circuit on the outdoor distribution transformer occasionally get damaged. The solution is to use a low pass filter. Not sure what frequency the CFL circuit is running at, so you would need to figure that out to find out how "low" the filter needs to be tuned to.

I built the cfl one just to test the transformer. It does indeed arc, but only a very short distance. My multimeter was only picking up about 500 volts, whereas it should have just broken. Further tests are in order before pictures are posted. Any suggestions?

I stole about 15 555 timers from school, and a couple circuit boards :P

I paid for em so i might aswell get my moneys worth.

Just pulled apart a CFL i had lying around, and i dunno how to remove the tube from the board. Can i just cut the thin wires leading to the tube then replace them afterwards?

If you want pics ill post em afterwards.

Sorry, I can't get any pics now, E.D.
Just pulled apart a CFL i had lying around, and i dunno how to remove the tube from the board. Can i just cut the thin wires leading to the tube then replace them afterwards?Cut the wires as close to the circuit board as possible. It's a lot easier to attach a new wire to the board than to a bulb w/ a short wire.

kk

It looks like i can just unwrap the wires from the pins their connected to.

EDIT: Success :)

Simple as that, just unwrap the copper wires.

Because the flyback is operating at very high frequencies, if it isn't loaded it generates voltages far greater than normal, which obviously could arc through the epoxy insulation.

I suspect that the CFL circuit is getting fried because the high frequency noise from the arcs are filtering back into the circuit. I've heard of such things happening when using high powered Tesla coils where devices using the same circuit on the outdoor distribution transformer occasionally get damaged. The solution is to use a low pass filter. Not sure what frequency the CFL circuit is running at, so you would need to figure that out to find out how "low" the filter needs to be tuned to.

Heh, cool, I was right about the first part. I'll google around and see if I can learn about low pass filters.

I really hope to post more in here, I got several classes dealing with electronics and I should be getting a job soon, so not everything will have to be free/nig-rigged.

Anyways, I'm watching the paper for free computer monitors/TV's.

Could you possibly rewire the toroid in the cfl circuit to increase voltage?(correct me if im wrong, but i think thats what the instructables said it did)

Limited success: http://www.youtube.com/watch?v=olemJYvhNBQ

Alright, I have a ye olde flyback that isn't rectified, the 'disc' looking kind.

The primary coil is in plane view, so I know where the pins for that are.

I've been told a few times that I can find the ground by powering it up and finding the pin that the H.V. wire arcs to the most.

I have most things set up and coated in electrical tape. Just need to wait till' my dad gets home with a meter to see which of the 4 pins on the CFL are the output.

You need an oscilloscope with a voltage divider bridge. A meter may not be able to measure the voltage correctly because it is not in its tuned frequency range. For instance, I could not accurately measure a 1kHz signal with a meter specifically designed for 60Hz operation.

I think I just screwed something up.

I plugged in the CFL circuit with nothing attached to the output wires, was going to take a meter to them to see which of the 4 pins were the outputs.

In about 5 seconds the CFL circuit started smoking, them sparked, now nothing. It appears my CFL has fried and died.

It's ether a transistor (Was close to where the tape melted/spark was) or what appears to be a small surface mount resistor (Little black on it, although it could be a marking that was there before it died).

Does plugging them in with no load kill them, or is something else wrong?


EDIT: Fairly sure it was the surface mount resistor now.

Update: I finally gathered all the parts I needed and build the circuit. I connected it to the power, flipped the switch, and my 555 exploded into little shards of whatever they're made out of. I'm not sure what went wrong.
One nooby question though, what is the ground supposed to connect to? In the diagram, theres a ground attached to a wire running across the bottom. At first I just put the negative wire where the source is, and the positive at the ground, but nothing happened. So I cut the wire, put the positive leading out the top and the negative out the bottom of where the source symbol is, and left the ground wire unconnected from anything except the components on the board that were wired to it. Could this be my problem? What am I actually supposed to connect for a ground anyway?

For all intents and purposes in this thread, ground = negative terminal of battery (or PSU). All the little parts of the circuit that are connected to the weird upside down triangle thing MUST be connected to ground!

I used to play with flyback transformers and drivers a few years back. Best setup I had was this old style flyback with a push-pull oscillator, two 2N3055's mounted on a gigantonormous heatsink running 24V through a center-tapped primary.

My room usually smelled like ozone for most of the day.

Hey Hunter, I just now saw your post in the bartering thread asking for parts. Sorry I didn't get back to you, that was right after Gustav fucked my neighborhood up and I still didn't have power, and I somehow missed that post when checking everything I missed when I finally got internet back. If you still need something and aren't in a hurry I can try to get you some of those parts next time I go home in a week or two.

I too have been playing with flybacks recently. I picked up three of them at a junkyard, but so far the sparks are rather anaemic. I suspect it's because of a lack of a driver circuit. Right now I'm just making pulses with a temporary relay wired up as a buzzer. I lack the high powered transistors required for a decent sawtooth waveform.

I also bought a circuit board from a mini TV at a surplus store. As soon as I figured out how to give it power, the flyback started giving nice 5mm sparks. Now I need to figure out how to trim the board of useless signal amplifiers to make a nice convenient package.

I hope to make a nice ignition system for the flamethrower I'm going to attach to my robot lawnmower.

Spatula....you are one kickass lady.

If only I could find somebody like you at my school...

She can light my fire any day.

Lol.. I need a new 555 timer, if you've got one?

Wait, so I need to connect the negative wire (I'm using a wallwart) to the ground, and then the positive leading out both ends of where the source is in the diagram?

So....i picked my bro up from school and found a modern ballast for a fluorescent light. took it home and ripped it open, and it has a circuit board, with about 5 times as many parts as a cfl ballast does. So im wondering wether it'll be able to do the same thing as the cfl one.

It has 4 wires leading out(to the light itself), and 2 wires leading in(power), with another 2 leading out for joining 2 or more units together(presumably power, but i think i can just join them together), and a switch(which had to be cut to remove it :()

(I'm using a wallwart)

There's your problem. Wall warts, unless they weigh 10 kg, can't produce enough power to run these things like they should be run. Get a 12V gel-cel battery that can run a few amps without breaking a sweat.

i hooked a cfl ballast up to a microwave transformer, and powered it with a 1.5v battery, and it just hummed at me.....

Needs more power i guess....will get back with results

There's your problem. Wall warts, unless they weigh 10 kg, can't produce enough power to run these things like they should be run. Get a 12V gel-cel battery that can run a few amps without breaking a sweat.

Only problem with that is that A) I don't want to spend that much on it, and B) I would want a constant power supply, not something that I'd have to recharge. My wall wart only puts out 500 mA. Any other suggestions?

Well since no one has responded, what I've gone ahead and done is completely remade the circuit on a different piece of perf board, and this time I hooked it up the same way except that I connected the ground directly to the negative line.

http://i22.photobucket.com/albums/b343/retnuh66/schematic2.gif

Is this correct?

I don't see anything terribly wrong with it....

mwuhahaha i found an old computer screen whilst helpin a friend :)

good karma today....

gonna go rip it apart, and hopefully return to post :)

hmm....bit weary of the suction cap, gonna go rip it off. Junk collections ftw :)

Update: After many (MANY) setbacks, I finally got it completed. I got it to work for approximately 1 second with a 16 volt power supply, until one of my resistors burned out, but since then I haven't been able to. I hooked it up to a molex connector from a computer power supply, but I wasn't thinking and hooked it up backwards. This cause yet another one of my transistors to explode, and after replacing that, it won't work. I have no idea what the problem is, but I'm hoping that I didn't fuck up my 555 timer, because if I did then I'll be up at radioshack (again) buying my fifth.

Ah, hooking up a computer PSU is the mistake that killed my latest flyback. Primary windings started smoking :(

Success :)

I finally got it off, just broke the board from the rest of it and then used pliers to remove the flyback.

Got 3 nice little aluminium heat sinks aswell :) Waste not, want not i guess

And a handful of HV diodes/resistors and a bunch of 600v wire. Which is the voltage on the flyback? Is it the 1.2kv wire and one of the pins? or is it the 2 20kv wires going into the flyback?

Thanks

Reverse biasing ICs generally kills them completely.

Well shit :(

At least I've learned a lot through this whole process

Okay, I got an older tv and ripped out the flyback. I'm pretty sure it's still regulated, but I still want to see if I can get any bigger arcs out of it, however for some reason my circuit randomly stopped working. Using a multimeter, I found out the source and gate on my MOSFET both have a 5-7 volt difference from ground, while the drain only has about 300-400 mV. The wires to the primary, of course, have the same voltage.
I'm using a IRF510 instead of a IRF630, perhaps my 510 simply burned out? It only got really hot once, but had been working and running rather cool since then, except this time. Could this also be why my arcs are so small?