Flyback Questions

[Alan Sailer]

Miniman,

Thanks for the information. I am using them in my application near resonance which is in the 20-30kHz range.

If there is a list somewhere that shows which Thordarson flybacks are used in which TVs that would be potentially
useful information. I might be able to find which TV has has a certain flyback inside.

For example I have a FLY-352 transformer that turns out to be a replacement part for a CTC-22 and runs at 25kV DC.

Electronic M,

I am building my own plasma globes and I need a few power supplies that can get to about 25-30kV peak to peak.

https://www.flickr.com/photos/876383...in/dateposted/

Don't worry that I will be using up too many flybacks. I only need a few good units. The world seems to have
mostly lost the ability to make good high voltage AC coils so I have to find suitable vintage coils.

Cheers.

[old_coot88]

Don't forget that the HV winding is not tuned to the 15,750 scan rate or even the first harmonic of it. It's tuned to the retrace or "fly-back" spike which is in the RF region. Actual resonance would be probably around 75 - 80 Khz. (Maybe someone can give a more exact figure.)

[Electronic M]

Originally Posted by Alan Sailer

Miniman,

Thanks for the information. I am using them in my application near resonance which is in the 20-30kHz range.

If there is a list somewhere that shows which Thordarson flybacks are used in which TVs that would be potentially
useful information. I might be able to find which TV has has a certain flyback inside.

For example I have a FLY-352 transformer that turns out to be a replacement part for a CTC-22 and runs at 25kV DC.

Electronic M,

I am building my own plasma globes and I need a few power supplies that can get to about 25-30kV peak to peak.

https://www.flickr.com/photos/876383...in/dateposted/

Don't worry that I will be using up too many flybacks. I only need a few good units. The world seems to have
mostly lost the ability to make good high voltage AC coils so I have to find suitable vintage coils.

Cheers.

That sounds like a cool project, however I think your wasting money trying to do it with tube based flybacks/circuitry.

Solid state flybacks are VERY easy to drive into the 25-40KV region. Back in college I was broke and scrapped a lot of curbside 80's - 07 CRT sets. I became fascinated by plasma speakers and decided to build one...It was very easy to do so with a flyback from a free junk modern CRT set. All I needed was a 555 chip for the oscillator/audio modulation driving a power FET, connected to 10-20 turns of wire wrapped around the core of a fly from an Solid State set*, and a 20V power brick for the whole shebang. I had that thing maxing out my HV meter at 40KV and producing crystal clear audio....I even modded the spark gap into a Jacob's ladder for a while (it sounded terrible as a plasma speaker that way, but looked cool) and had ~3-5" arks at the top of the gap.

* I think I can find the web page with the schematic if your interested.

The average tube color TV fly alone is worth $50 or more...For that money you can build several HV supplies with solid state flybacks and parts. You'd be better off selling the tube fly to a collector and building a SS supply.

Whatever you decide to do I'd love to see the end result/circuit design.

[Alan Sailer]

Tom C,

That approach would certainly make my life easier. Unfortunately all modern flybacks have several built in rectifiers
and put out a signal that will not effectively drive my plasma tubes/globes. When I first started this project I did
exactly what you proposed and it wasn't good enough.

There is a small community of plasma artists (I'm no artist) that are currently suffering from a lack of good HV AC
transformers. I'm glad that I only need a few.

The video I posted shows some globes powered with a few HV coils that I bought from Ebay. They were not complete
flybacks just the secondary coil. I have them in oil for cooling and to help prevent breakdown.

Unfortunately I have no idea what voltage they are intended to support. For all I know I am grossly over-stressing
them and they might die in a few months.

Which is why I am trying to find a few flybacks of known performance to make some (hopefully) well designed and
reasonably spec'ed power supplies.

Cheers.

[Findm-Keepm]

Originally Posted by Alan Sailer

Miniman,



Don't worry that I will be using up too many flybacks. I only need a few good units. The world seems to have
mostly lost the ability to make good high voltage AC coils so I have to find suitable vintage coils.

Cheers.

And with the dearth of good flybacks for pre-1967 sets, you may find it hard to find one cheap. A good Fly 276, 277 or 308 is hard to find.

I'm like others in my recommendation - for a few microamps of current, look at cheap Black and White flybacks from the tube era, perhaps something for a 19 or 21" set, sure to be rated at enough current for a plasma globe. Without the capacitance of the CRT, they do put out a bit more of HV...we made a stationary 2" arc at a friends house one evening (drive was from an HR Diemen flyback tester ((EDIT: like this one: http://www.ebay.com/itm/HR-STVDST-01...EAAOSw2xRYlU~H ))) and the flyback was from a 19" Sanyo tube B/W set. The fly ate itself, presumably because we didn't load it like the yoke and CRT would normally. Arced to the core, and smoked the paper at the core.