Plasmatweeter

[Marco audio]

Actual schematic :

Moderation note... see post #362 regarding safety issues with this circuit:
Safety concerns

 

[Lampie519]

No transformer? If not you can not use a voltage doubler!

 

[Marco audio]

Why?
Ionovac use a Schenkel voltage doubler without transformer.
Perhaps the full wave voltage doubler doesn't work without transformer, but why ?

 

[Lampie519]

Look again! Your ground is the same as your power line neutral and that is causing the fuse to blow. In the other schematic there is additional capacitor to prevent this ground issue. Anyway it is bad practice to do it like this! So please use a transformer and you will live longer!

 

[Marco audio]

C9? ...and C10 ?

 

[Lampie519]

No, C14

 

[Marco audio]

Lampie 519,thanks a lot.
I must realy learn again and again.
Regards

 

[Lampie519]

Using a transformer is highly recommendet!!!!

 

[Marco audio]

Hello Lampie 519.
I re-builded my speakers.
I added 12 Ohm 20 w resistor In front off my voltage doubler.
Power supply works well.
Unloaded ,voltage is 676V and 338v on middle point.
I connected my frame speakers to neutral.
I tryed them:
I must use a screw driver to start the system.
I got a weak arc but it doesn't work.
Coils are :
15,5uH for L1(24 turns d=45 mm l=53mm)
10 uH for L2(17 turns d=37mm h=21mm)

 

[Marco audio]

 

[Lampie519]

Hello Marco, i guess you created some capacitance because of wiring, you will need to check if the oscillator works! Plus if you have no audio the screen driver doesn’t work. Is there enough current flow through the tube?

 

[Marco audio]

Thanks Lampie 519.
I will check all.
But i'm In doubt with my 807 tube pinout too, can you check please ?
In fact my question is what's hapen if Kathod and Screen are inverted?

 

[Lampie519]

I never tried reversing the screen and cathode, my guess it that not much will happen. The cathode will draw all current.

 

[bentoronto]

Good stuff. Thanks.

If you like ESLs, you gotta say a prayer before bed for the development of plasma speakers.

BUT.... there's a desperate need for an ozone tester suitable for DIYaudio experimenters. Ozone can be quite dangerous and a means of knowing when there's too much in the room is a critical need.

Anybody????

B.

 

[Lampie519]

Ozone is very reactive and will dissolve very fast. Just make sure you are not too close to the source and keep the room ventilated. Having a small source in a ventilated room is not very dangerous. A big source like a full range speaker should not be used without measures.

 

[Marco audio]

Thanks Lampie 519.
Ben Toronto :A making?A schematic ? an idea why my unit doesn't work ?
If you are interested about plasma speaker why don't you try it? (A unit with the cheap gu50 @ 27 MHz with a voltage quadrupler for example...).
How many time and how many people have said the same things:
"Ozone is dangerous.
Ground your plasma speaker.
Use a transformer."
It doesn't bring much...

 

[Lampie519]

Hi Marco, you don’t need very high voltage for a plasma speaker as the power coil will sweep up the voltage if it is in resonance. So 300v should be fine. The screen voltage is maybe too low in your case. Do you use a driver stage here?

 

[Marco audio]

Lampie , i'm just starting a new try.Tube is heating.
Screen is directly conected on middle point of the voltage doubler,so it got enought voltage.
In my case ,i have two coil In front of the tube: L1 and another one In front of my 0,1uf pulse capacitor.I wirered a 3,9R 10w resistor instead.

 

[Lampie519]

Where is the audio input connected?

 

[Marco audio]

For the moment no audio input connected.
Screen is supplied only with 300v.
As you said i think i have a capacitance trouble:
When i put the screwdriver to adjust the variable capacitor i see a very little arc.I want to replace the hexagonal screw why a nylon one.