Flyback

[fullyautomatic12]

hello all, again, i have a question about flyback drivers as well, i have none of the old style flyback wheels like everyone talks about in their schematics for making flyback wheel drivers, all  i have is a bunch of flybacks like this one in this site
http://jlnlabs.imars.com/lifters/labhvps/tht.htm
that site made me understand a little bit more bout my tpye of flyback, but i still dont fully understand just exactly what to do, like do i still have to make a new hand-wound coil on the ferrite core? or do i just attach stuff to the pins? i am very confused on the whole thing, if someone could explain how to use a flyback wheel and how to make a easy driver, that will put out some good sparks, id be very grateful..thanks

 

[Theatronics]

A fly back is just a transformer.
The name ‘Flyback’ comes from television raster scan terminology.
The ‘Fly Back’ is the moment when the electron beam “Flys” from the lower
Right corner of the screen “Back” to the upper right corner to begin drawing
The next new frame.

The actual purpose of the transformer is to generate the high voltage needed
To keep the CRT working, but the AC signal fed to the transformer is the same
As the ‘Flyback’ signal.  Thus the transformer was named.

There are also other windings on the low voltage side of the coil. These are used
To provide low voltages and negative voltages for much of the circuitry.

The coil was wound to respond to the ideal frequency of the TV frame rate.
In the NTSC system (M format) is just under 30 frames per second.  (30Hz)
If the Transformer came from a PAL tv set use 25hz.  (25 frames a second)

The input voltage (current limited by impedance) can be anything but the
Transformer will break down if the windings over heat or the output voltage
Punches through the insulation around it.  I’d start with a 12V 30Hz Push Pull
Circuit.

If you can find an OLD TV set you might find an exposed core.  Usually the look like
A disk with a square through the middle of it and then a small winding on the other side of the square.  These are great for experiments because you can completely remove all the primary windings and make your own.

Winding your own coil is not hard to do.  In fact some people prefer it.  (Like the one I am leaning on in my picture)  if you are serious about a large coil stay away from PVC
And any metal.  Find a cardboard tube (Sono brand concrete tubes offer a good range)
Also you can try the cardboard tubes in the middle of carpet rolls. Check with a local store.  (Hint: Dumpster!)

Use a resin or polyurethane to protect and harden the form, then wrap away.
On these larger coils you usually only wrap 1 layer thick.  Also Tesla used a trick
To get nice even wraps on his coils and still keep the wire spaced far enough apart to reduce internal capacitance and arcing.  Wrap a string or thread along side each wire.
When you are done wrapping, remove the string and coat the entire thing in a coat of
Varnish, polyurethane, or resin of some sort.

Coils can be any shape of size and there are lots of formulas to tune them to the exact frequency you want.  Most beginners just make a large secondary (about 100-200 turns)
And a Low-Z primary (out of copper pipe on a wooden form – maybe 5-10 turns)

Discharging a large capacitor through the primary will produce a large single spark.

The challenge then becomes to tune it and find a way to provide LOTS of discharges quickly. 

-Mike

 

[audioguru2]

Nope.
The flyback transformer doesn't work at the vertical frame rate of 30Hz, it works at the horizontal rate of 15,750Hz (black and white, North America. Colour frequency is slightly different).

The beam "flys" quickly from the right side of the screen to the left side for each horizontal line.

 

[Theatronics]

Well,
  I knew there was flying involved, and I knew it was the High voltage from the screen,

  My first definition was
            "What happens when you touch it;  You fly back"

  At least I was close.
  Some day I will need to test the depth of the ocean of Audio Gurus knowledge.

-Mike

 

[audioguru2]

Some day I will need to test the depth of the ocean of Audio Gurus knowledge.

I have taken apart and improved most electronic items I own. My colour TV was one of the 1st things I made work better. But I haven't even looked inside my computer that is 1.6 years old. ;D

 

[fullyautomatic12]

hey thanks for that info Theatronics, but id like to get the thing working before going straight to the tesla coil, this is what my hand wound coil looked like around the flybacks, exposed ferrite coil

did i do that right?
after i did that, i built this dirver circuit
http://www.geocities.com/capecanaveral/lab/5322/fbt2.htm
And i connected put the red suction cup near the pins, and hooked it up to a car battery and nothing happened, then to a 6v and nothing happened still...what is the problem? i had better luck with my ignition coil which is this page
http://www.geocities.com/capecanaveral/lab/5322/coildrv.htm
if you can help me with that as well, it only makes sparks when ever i connect it to the battery, then when i disconnect it and reconnect it, it make another small short spark once reconnected....if my 555 times not pulsing or what?

 

[Theatronics]

The >Most< basic High Voltage fly back was from a book
Called “How to build your own laser and other space age devices”
(Or something like that)

It was a very interesting collection of high voltage and fringe electronics
Circuits that are fun to play around with.

The concept is simple.  Two transistors push and pull a transformer winding.
A secondary winding creates a small voltage that is then used to feed back
Into the base of the transistors in order to create an oscillation.    I think this is a “Hartley” type oscillator.  There is considerable power loss in the design and it is a bit of a run-away circuit seeing as it is just a high gain amp with a serious feedback problem.

The “Pro” version of this circuit is actually more elegant.  It is a lower power device and only drives the transformer at

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