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The circuit - from here Thank you Dr. Kilovolt. I have made some changes to the circuit (mainly add filters and add a GDT driver).
For the flyback - I've tested a total of 6, and it turned out that an old bulgarian AC flyback - sounded best. Power consumption - around 120W, the spark can be extended to around 3.5sm and it easily starts at 2.5sm. At lower frequencyes the spark increases up to 5 - 5.5sm but it sufferes from sound quallity ... badly.
Aboud the sound - I am trully amazed how well that thing sounds ... it sounds better than my laptop ( just weaker and it can't do the low freq range ... well)
Yep - the pics were taken with flash, but in reallyty the arc isn't too different than that - it is yelow (what you see on the pic) with just a thin, barely visible, purple spark in the flame. The two tips of the tungsten electrodes are glowin in a very beautifull purple color (as it can be seen from the pics).
Registered Member #1497
Joined: Thu May 22 2008, 05:24AM
Location: Toronto, Ontario, Canada
Posts: 801
I've always wondered if the distortion whenever plasma speakers or audio modulated TC's attempt to play low frequency (sounds like sputtering) could be removed by using a lowpass filter so only mid-high plays and overall sound quality improves?
Registered Member #902
Joined: Sun Jul 15 2007, 08:17PM
Location: North Texas
Posts: 1040
in that schematic, is the resistor below the 2.2K one (in the top image) a variable resistor connected like shown??? or is that an error? I plan to put one of these together... with some modifications ^_0
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Dr. H, nice speaker, cool to see someone build the circuit and it actually working
DaJJHman wrote ...
in that schematic, is the resistor below the 2.2K one (in the top image) a variable resistor connected like shown??? or is that an error? I plan to put one of these together... with some modifications ^_0
It is a standard "trimmer". They usually (well, almost always ) have 3 legs, it really does not matter if you leave the 3rd leg floating or not, but for some reason I was in a strange mood and drew it the way I did (this is how it was drawn in old books in our country)
The obvious improvement is the use of gate drivers. I don't see any other modifications which could help.
I've always wondered if the distortion whenever plasma speakers or audio modulated TC's attempt to play low frequency (sounds like sputtering) could be removed by using a lowpass filter so only mid-high plays and overall sound quality improves?
That is what I am also doing - a very basic first order high pas filter to get ride of the "low" freqs. About the values ... don't ask me - it was a tryal and error - and in the end I have a bunch of caps and resistors on the downside of the board
Dr. Kilovolt -> The obvious improvement is the use of gate drivers. I don't see any other modifications which could help.
Well that is what I also observed - without the drive chips, I coudn't go higher than 30-40khz - the fets were heating badly (the gate laveform was anything but good ) ... sooo adding the UCC now I am happily runing at 110khz and the fets are not heating at all, when no sound is played - ohh and that higher freq really makes a difference in the sound
Registered Member #902
Joined: Sun Jul 15 2007, 08:17PM
Location: North Texas
Posts: 1040
Dr. Kilovolt wrote ...
Dr. H, nice speaker, cool to see someone build the circuit and it actually working
DaJJHman wrote ...
in that schematic, is the resistor below the 2.2K one (in the top image) a variable resistor connected like shown??? or is that an error? I plan to put one of these together... with some modifications ^_0
It is a standard "trimmer". They usually (well, almost always ) have 3 legs, it really does not matter if you leave the 3rd leg floating or not, but for some reason I was in a strange mood and drew it the way I did (this is how it was drawn in old books in our country)
The obvious improvement is the use of gate drivers. I don't see any other modifications which could help.
yeah I know what they are, it is just that the image in the schematic looked kinda weird and I thought it might have been something else... anyways, the mods I have planned are not of a serious design nature, but rather of a, how should I put this without giving everything away, selection of one component and using it to it's full potential?
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Dr. H. wrote ...
Well that is what I also observed - without the drive chips, I coudn't go higher than 30-40khz - the fets were heating badly (the gate laveform was anything but good ) ... sooo adding the UCC now I am happily runing at 110khz and the fets are not heating at all, when no sound is played - ohh and that higher freq really makes a difference in the sound
Hmm, thats strange, it ran fine for me without the gate drivers just the gate waveform was a bit slow (but still good and resembled a square wave). Did you have the clamping diodes on the output?
Hmm, thats strange, it ran fine for me without the gate drivers just the gate waveform was a bit slow (but still good and resembled a square wave). Did you have the clamping diodes on the output?
Yep - I've putted them (underneath the board if you are wondering where they are ). Hey - this might be due to the IC I've used - there are many different manufacturers, and where I live and what the quallyty of parts is here - I wouldn't be surprised if it was made in some chinasee basement
Soo no problem if it doesn't work fine for me
But I reccomend drive chips - they will make the waveform much cleaner.
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Plasma speaker - flyback
). 