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Plasma Speakers

I'd like to build some plasma arc speakers. After all, what could better than combining audio and high voltage?

Most designs I've seen involve using corona to produce sound. It seems to me that this has the disadvantages of either needing a RF ground or interfering with other electronic devices and of wasting a lot of energy in ultrasonic current variation. And I want to do things differently in any case. :-)

What I was thinking I would do: Make a especially well smoothed rectifier circuit, which goes through a H-bridge of power BJTs, something like

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maybe. The audio input is switched between the bases of the power transistors through small transistors. This H-bridge feeds either a tightly coupled half-wave double-resonant solid state tesla coil or an autotransformer cascade. The autotransformer cascade would be made something like a tesla coil secondary, with the wire reversing direction at each stage and with high voltage wires going up and down the thing, and with a capacitor on the inputs to give soft switching. The small transistors switching the base current of the larger transistors would be controlled by a filament. The high voltage high frequency output of the secondaries would then be rectified by strings of diodes, something like
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maybe. This rectified current then goes through a small inductor (to filter out the resonant frequency component) and the arc that's doing the transducing.

IGBTs are usually used for this sort of thing, of course, but for an audio application I figured I'd want the good transconductance of the BJTs.

It would probably be something like 60kv across it, ie +/- 30kv. More than that and I'd get pretty sick of soldering diodes.

Any obvious flaws I'm missing here? What's worrying me now is nonlinearity from the bridge output to the current across the arc.

Reply to
bhauth
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As an aside to the above ideas, try Googling Ionofane and you'll get hits for home made speakers. Likewise, Solid State Tesla Coils (SSTC) are increasingly showing up at Teslathons with audio modulation. A few designs driving flybacks can also be found on the net too. I've built one, nice tinny sound, a bit quiet though. Cheers. VW.

Reply to
Vidor Wolfe

So I hear.

Any hints / unexpected problems you fixed?

I'm going for 400-800 watts - should be a little less quiet.

Reply to
bhauth

I had an Ionofane Ionic treble speaker about 30 years ago. As I remember it had a couple of major problems. It was very dependant on the weather and produce its best sounds on dry days. With humidity it was lower in volume and higher in hiss level and nonlinearity. That background noise was always present and after a while became the main reason why I sold it. I replaced it with a Quad Electrostatic speaker which gave a much cleaner and noise free sound.

L> I'd like to build some plasma arc speakers. After all, what could

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Reply to
WDino

I'm not using pulse width modulation, I'm using the BJT transconductance. Atmospheric condition dependency of corona is one of the reasons I want a DC arc design.

Reply to
bhauth

Reply to
Mike Berger

Huh. I'd-a thought that combustion instability would dominate at frequencies on the order of 10k Hz.

Reply to
bhauth

Reply to
Mike Berger

Well, if you Google "Richie Burnett" you'll get his excellent site with details on SSTCs and audio modulation. His last coil at the Nottingham Teslathon earlier this year, was in the kilowatt range and very loud. Quite listenable if you like to "see music" coming from an 18" flame. Mine have been purely done to see if it can be done and show my kids "magic." About 50 - 100 watts. Cheers. VW.

Reply to
Vidor Wolfe

I figure that would depend largely on fuel-oxidizer mixing. Which is turbulent.

Reply to
bhauth

Alright, I've solved everything myself. Nevermind. ^^

Reply to
bhauth

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