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George Green 1st March 2007 02:55 PM

Good morning HiFis, may I present my plasma loudspeakers here to you? For the amateur handicraftsman somewhat progressed the reproduction might prepare hardly problems. The beginner should only read it. Rel. simple circuit, not expensively, without smell, loud, beautifully. Living room-suited, sense-extending. Not more dangerously than a hair dryer.

Made in Germany.

Dire Straits

Without input

Enough for Living-Rooms

Never heard better.

Best regards

atarashi 1st March 2007 03:04 PM



Grumpy_Git 1st March 2007 03:06 PM

Congratulations George,

Do you have any design drawings, it seems a little different from the usual Plasma design.


George Green 1st March 2007 09:12 PM

Hello Friends,
this circuit shows the main-part of this thing.
The tube is a PL519, also works others with more then 15 Watts.
The PL519 is easy to get an has a power of 35 Watts, for a short time I think it is possible to get up to 100Watts or more.
Then the tube begins to glow, thus I limit the time for the possible overloading to approx. 5 seconds.
But with this work I am not yet completely finished. It functions already like also the automatic ignition, but I would not like to show incomplete or wrong plans. Therefore only in each case excerpts of the work at which I straight are or which is correctly finished.
If someone should nevertheless be interested in it, to that not yet finished things, I can show gladly the incomplete plans with explanations.
The tweeters to work at me nearly 18 hours on day without problems

This picture shows the entrance wiring up to the opto coupler. This is responsible for the galvanic separation.
The separation frequency amounts to approx. 7000 cycles per second

But relying you asks not completely on these values, but it functions in such a way.

This circuit steers roars at the screen grid on

the inverse feedback of the screen grid is not yet drawn in to the basis of Q1, that is no longer well audibly, which must is measured, I rigs straight only.

Alles zu seiner Zeit.

Best regards,

Rob Dingen 4th March 2007 10:56 AM


Nice looking.
Does it start by itself or do you have to help it?


Audio_idiot 5th March 2007 12:23 AM

Great job! Keep em coming!

I have a pair of PL519 lying somewhere in the junk box too, I'll probly clone your work here if you don't mind.


Audio_idiot 5th March 2007 09:37 AM

Hi George,

I have great interest in Plasma tweeter but because I'm "electronically challanged" and low SPL of These tweeters, I restrain myself from building one.

Your spark look a lot longer and fatter then other tweeters which I'd found in the net. Soo SEXY!!! Love it!!! Could you guide me along the way to build one?

Questions on the oscilator.

For clarification,
1) The top coil is 21-turn, internal dia. 1.4-cm of coil, total 5-cm total coil length, wire size is dia.1.2mm (i.e. coil spacing is ~1mm),

2) The bottom coil is 3-turn, but is it the same gauge wire (1.2-mm dia.)? what is the coil dimension?

3) can't figure out the "hot" section, Would you kindly show me the Mat'l/size you use for the spark tips? A sketch would be most appriciated.

Other questions,

Are all the values critical? especially the RF choke filter?

Are you having 2 sparks? It looks like it in the "dire strait" clips, it that how you achieve 110db sound level?



George Green 5th March 2007 10:00 AM

Hello of friends,
here place I mean automatic ignition forwards. One ignites with a high voltage spark from an old HV-Transf. of the S/W-TV comes. If the SG-river is high enough ignites a thyristor, against an unintentional ignition with high achievement comes still another photodiode direction flame, i.e. if the flame is there, the ignition is switched off. To the spark one does not see because the flame burns immediately. Flat follows wenn´s is finished.
This picture is more than six Months ago, but still it works.
@Audio_idiot, this work is here that You do this.
There are no Problems,
you must be able to work on only one spark plug or look for help for this.

................ Straight ones a while ago I played someone “Time” from Pink Floyd, such a face expression must I photograph, become me an automatic camera for it to insert, the people sit finally always on the same armchair, mine, give surely best photos. Many greetings, George

that is the for the time being next to last and still incomplete connection diagram. One ignites me a spark from (still) a HV-Transf. from B/W equipment. The spark from a photo flash appartus is enough because of the necessary Distance to the point, do not ignite however can he also. That can be done automatically, only this corner is not yet finished, but functions very well and already years long. In former times I have a “antenna” into close of the coil had, so 3cm long, afterwards a diode and a that has the Thy over a transistor headed for and the spark was measures there, now I by the resistance of 10R at the collector from the BUT the voltage drop and switch thereby the ignition. A photodiode at the end of a glass fiber of approx. 5cm length determines whether the flame burns. I stated however that by the kind of the feedback like I have her conditions somewhat changing now in favor of the achievement and over-regulation firmness. Therefore this circuit is only provisional and should therefore not yet absolute in SMD technology to be implemented. Three resistances of the SG (3/6)of the PL to the basis from the BF still are with me by one Trim potentiometer said by 1M replaced, as, finished is the circuit not yet. But like that as it, with the trim potentiometer runs it is and the half night all day long now there. And stink does also nothing. The G2 tension amounts to about 115 V, better said for instance 35mA river flows. 310 V of anode voltage directly over a throttle on the anode. I do not use any Transf. for the anode voltage. But the opto coupler and the two condensers at the anode and at the lattice ensure for security, therefore one should pay attention in these places to best quality, is not not expensive. But over security I may not give obligatory pieces of advice, anyhow not over those straight construction units used by me. If on a condenser “VDE” paint on so is still for a long time no warranty for the fact that in the case of two-skin burns not nevertheless. In evenly these places one should insert condensers like it also the radio amateurs use, the more HV-the safe side. With me 2kV is enough today and already ever ago until. Thus I did not have ever an estimate or a short circuited. The housing is complete made of metal and shielded and is grounded, green yellow. The power switch is to ignite a triac in zero crossover, up to now still does it without. Please understands that I for the connection diagram no warranty to give can, but I have still a few marks checked up. The resistance before the opto coupler has approx. 1,2k adjust at the best one with a trimmer to a quiescent current of for instance 9-10mA. The backplate electrode is not completely important, without runs anything. And the distance the point of the Keramikplate, only if comes that is correct property correctly! The condenser is not easily built only the spark plug divides is like that without. Those you need however for it or you invent something else, an old safety device tut´s also. Is as close only the large and I wants ran as possible to the plate.

This ist a Google-translation, I hope that it is correct.
Best Regards,

Netlist 5th March 2007 10:07 AM

Wonderful project and I'm sure your English is far better than translations by Google.
Please try to use your own words.:)


George Green 5th March 2007 12:24 PM

Hugo thanks! Hello Ken, 110db? 117,6 last week had. A problem is for it to be over solved there! The upper coil is 19 turn, diameter is not critically, 1.4 centimeter of 2.5 cm if enough place, silver 1.2 mm. 5 cm lengthens. under reel is for decimetric waves filters. works also without. Point of spark is tungsten of 3,2 millimeters on piece of iron welded, backplate electrode silver because of oxidation. little critical parameters, only ignition with high voltage and condenser for feedback should be made in such a way like here. And naturally the acoustic baffle, the reflector, that is a slot emitter! from a tile with a spark plug in it. RF choke filter? do you mean the 100ยต 1A? without nothing goes. Greeting, George

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