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Old 30th November 2007, 10:24 PM   #91
Carlp is offline Carlp  United States
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Hmmm. So there's no noise from the arc itself or from heated gases around the arc, etc.? Seems hard to believe to me. Wish I could hear one of these.
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Old 1st December 2007, 08:42 PM   #92
OzMikeH is offline OzMikeH  Australia
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the buzzing you hear from "normal" arcs is because the frequency is only 50Hz or 60Hz.

this arc's carrier frequency is 27000000 Hz.
It is Amplitude Modulated at the audio frequency.

the clever thing is that it can arc into thin air because the 27 000 000 Hz signal can radiate into the air instead of to a grounded conductor.

If your power supply has poor filtering you will hear some faint buzzing.
Almost every stage of these things have enough voltage to kill you. you must respect it.
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Old 2nd December 2007, 08:49 AM   #93
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This arc is not to hear, like a wax candle, very quiet.

OzMikeH wrote: If your power supply has poor filtering you will hear some faint buzzing.
That is correct.

This is the schematic of the power supply.
Who does not know something with the fingers should omit.

Click the image to open in full size.


So I run both tweeters.
The power switch is a small Japan-Typ with 3A.
So again to the statement: It is not a question of the tube first heat and then the anode voltage switching, which is nonsense anyway, but only a matter of a simple and small switch can be used without the contacts remain stuck.
When one 250 µ F flow directly involved as a short sometimes more than 20A, you can even turn off the automatic backup.

So laufen bei mir beide Tweeter.
Der Netzschalter ist ein kleiner Japan-Typ mit 3A.
Also nochmal zur Erklärung: Es geht nicht darum, die Röhre zuerst zu heizen und dann die Anodenspannung zu schalten, was sowieso Unsinn ist, sondern nur darum, einen einfachen und kleinen Schalter benutzen zu können ohne dass die Kontakte kleben bleiben.
Wenn man 250µF direkt einschaltet fließen da kurzzeitig schon mal mehr als 20A, da kann sogar der Sicherungsautomat abschalten.



The relay circuit is designed for soft start.
The 58 R Resistor is for the rapid discharge of 1000 µ provided to the circuit after disconnection immediately ready
The operating voltage is not consistent with the mass-housing. Similarly, the 0-V connecting the NF-operating voltage not with the cabinet Ground

And it looks from the inside, on the left side there is the NF and the filter
The two 100 µ F capacitors are in the RF part because there is no more space was

Click the image to open in full size.

I work only with the sheet angle grinders and welding, so nothing is very straight and just
It is not the problem of an electric arc to produce, or a plasma flame, the device is so loud by the construction of the reflektor

Best Wishes,
George
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Old 2nd December 2007, 05:26 PM   #94
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HF

Click the image to open in full size.
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Old 30th December 2007, 10:45 AM   #95
OzMikeH is offline OzMikeH  Australia
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Some tests with my friend's plasma tweeter. The electrode is tungsten. The driver stage of this one is all vacuum tube. output circuit is similar to yours with a capacitor added to stop the 700Vdc from going through the output coil.

We tried a quick corner reflector from MDF, the heat from the plasma is incredible, the corner reflector helped the volume.

The sound got louder when it was arcing to the carbon (the white sparks)

I wonder how it would sound with a tube for the electrode with a small gas flame like a cigarette lighter. It should make starting easier.
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Old 30th December 2007, 10:52 AM   #96
OzMikeH is offline OzMikeH  Australia
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So we added another electrode for the ground and a very dodgy horn from the gardening department. The pot helped to stop the wind from blowing the plasma away.

With a constant tone from the signal generator this was uncomfortably loud to be near. We were only putting 125mA at 700V through the tube. As it is here it was much Louder than it needed to be for a tweeter at normal listening volume.

You can see the output coil is very large, it doesn't get hot at all. It needs to be shortened, it is running at 21MHz here.
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Old 19th January 2008, 10:49 PM   #97
Dalus is offline Dalus  Netherlands
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Found some interesting links

http://www.youtube.com/watch?v=7xnLqSGtkOk
http://users.skynet.be/BillsPage/PLL...TeslaPage.html
http://4hv.org/e107_plugins/forum/fo...opic.php?16969
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Old 18th February 2008, 07:29 AM   #98
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Exclamation Plasma ranking

Dear George;

Excellent work. Would you mind describing the sound of your plasma tweeters. How do they compare to electrostatic, ribbons, compression drivers etc... What are the pros & cons in its sound?

Thank-you
BN
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Old 18th February 2008, 08:27 AM   #99
OzMikeH is offline OzMikeH  Australia
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If you get the electronics right it is better than ANY ribbon or compression driver.
No diaphragm of any sort can come close. The electromagnetic field is directly moving the air... Mms is virtually zero.

Cons: doesn't go loud easily, complex build, emits ozone, electrodes burn away. Very poor efficiency.

Commercial plasma tweeters are all horn loaded. The air in the room needs to be quite still, a draught that would flutter a candle could blow this out so you need to restart it.
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Old 18th February 2008, 08:35 AM   #100
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Default removal of ozone...

Anybody knows how to remove the ozone without having a blower connected? Absorption by somekind of chemical substance maybe?

Regards,

Jesper
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