TV flyback transformer "pedal"?

[patricks]

Hi all,
I've got hold of a chassis, valves, and components from a 1964 valve television recently, intending to make a theremin out of it.
The flyback transformer/line transformer is in there too, what are your thoughts on using it to make something like the Plasma Drive pedal that's made by Gamechanger audio?
I thought about using it to make a plasma speaker too, but I doubt it'd produce enough volume to be much more than a fun device

[GibsonGM]

Not familiar with designs using the flyback transformer, Patricks...but if messing around with one, I think I'd be VERY, VERY, VERY careful, and wouldn't want it near my pedal chain...

[patricks]

That's a really good point about the pedal chain.

I built a plasma globe with one once, it worked really well. The design used a regular incandescent bulb.
It had the potential to be pretty dangerous, though, I ran it from a home made 3 amp power supply and could feel the arc tickle my finger through the glass when I touched it 

[amptramp]

A flyback transformer is designed to provide the 15,000 volt supply (or 25,000 volt for colour) for the anode of the cathode ray tube.  That doesn't mean the turns ratio is the 15,000 volts over the B+ supply because similarly, the ignition coil on a car may generate 25,000 volts from a 12 volt supply but the turns ratio may be no more than 100:1.  Sudden shutoff of current is what makes a flyback transformer or an ignition coil generate voltages well above the supply x turns ratio.  Basically an inductor tries to keep the current through it constant and will generate high voltage if the current is shut off.

If you want a vacuum tube theremin, this article (and the website) will give you what you need:

https://theremin.us/Schultz/Schultztheremin.html

You might want to look at the DuKane Ionovac tweeter as an example of a 25 watt tweeter with excellent performance since there is no speaker cone.  There is an article about it here on page 134:

https://www.worldradiohistory.com/Archive-Radio-TV-Experimenter/Radio-TV-Experimenter-1958-551.pdf#search=%22dukane%20ionovac%22

[R.G.]

Then there are flame speakers. There was a "talking candle" setup from early hifi days where a big signal was impressed across electrodes  in a (hopefully quiet on its own) flame. The electricity modulated the flame, produced audible stuff. Unfortunately, bass response was in proportion to the size of the flame. Need BIG flames for bass.

[patricks]

A flyback transformer is designed to provide the 15,000 volt supply (or 25,000 volt for colour) for the anode of the cathode ray tube.  That doesn't mean the turns ratio is the 15,000 volts over the B+ supply because similarly, the ignition coil on a car may generate 25,000 volts from a 12 volt supply but the turns ratio may be no more than 100:1.  Sudden shutoff of current is what makes a flyback transformer or an ignition coil generate voltages well above the supply x turns ratio.  Basically an inductor tries to keep the current through it constant and will generate high voltage if the current is shut off.

If you want a vacuum tube theremin, this article (and the website) will give you what you need:

https://theremin.us/Schultz/Schultztheremin.html

You might want to look at the DuKane Ionovac tweeter as an example of a 25 watt tweeter with excellent performance since there is no speaker cone.  There is an article about it here on page 134:

https://www.worldradiohistory.com/Archive-Radio-TV-Experimenter/Radio-TV-Experimenter-1958-551.pdf#search=%22dukane%20ionovac%22

Brilliant, thanks for the pointers!
That theremin design looks quite a bit simpler than the one I'd saved previously:
https://www.radiomuseum.org/r/hgpalmer_trg3p_104_tv_1006_rg.html
I had chosen this schematic because it doesn't require winding coils, but the coils in the schematic you posted seem pretty simple.

I like the idea of the ionovac tweeter, as well, that's intriguing. I'll digest the article and post up questions, if that's okay.

Then there are flame speakers. There was a "talking candle" setup from early hifi days where a big signal was impressed across electrodes  in a (hopefully quiet on its own) flame. The electricity modulated the flame, produced audible stuff. Unfortunately, bass response was in proportion to the size of the flame. Need BIG flames for bass.

This is soooo tempting! Bass response is necessary, of course, so I will need moar flames! 

[PRR]

look at the DuKane Ionovac tweeter

I don't know (I've seen one but heard none) that later investgators found the Ionovac output was mostly distortion.

Somebody continued this line of work with tanks of helium (hydrogen?) in the listening room fed by kilowatt amps.

[mac]

I used a car ignition coil to drive a neon-bulb-as-a-clipping-diode:

some IC distortion --> LM386 --> LT700 --> ignition coil --> some kilo ohms --> neon bulb --> resistor network & volume pot to drop voltage --> amp

With a 18v PS the LT700 could be not needed...

Another project you may try is an electrostatic speaker.
https://en.wikipedia.org/wiki/Electrostatic_loudspeaker

mac