| plasma tweeter - Click HERE for Original Thread |
| Tekko |
Anyone heard of the "plasma" tweeter that is supposed to be the best kind of tweeter you can have ?
If so, what is your opinions ?
Myself i must say it is really good, i actually tossed one together out of scrap i had laying around, and the sound is really good.
Heres some pics and videos of my test unit:
Click here
Maybe i should mention that my digicam has real poor audio pickup, 8khz sampling. |
|
|
| Tenson |
| wow... what sort of frequency range are you getting from it? Also do you have any designs for such a tweeter? |
|
|
| Tekko |
I dunno but around a few 100Hz up to over 20KHz, the thing runs on around 10-30MHz.
I just searched google pictures for "plasma tweeter";) |
|
|
| Tenson |
Yeah I found this - http://www.hardcoreaudio.de/
It has nice details but I can't read German! It looks like he may sell the PCB and parts? |
|
|
| Rodeodave |
Hi,
I don't think that he sells PCBs or parts, and there's nothing about it in the text either.
But you don't need a PCB, it's not too many parts. Just avoid any sharp edges (dealing with HF) and wire p2p. I once wanted to build one of them plasmatweeters, but it became one of my unfinished projects...maybe this summer I'll find the time to finish it...
The parts are all off the shelf (hopefully the right expression), the only special thing is the body of the inductor, it should be made of some kind of electrically isolating material that can take some heat...I built one out of clay (!) that I wrapped around a film can (you know, back in the days people used 35mm film instead of CCDs) with a clay-thicknes of ca. 4mm. Clay's cheap and can be "processed" in a stove :hot:
The other (smaller) inductor is said to be a tricky choice, but I don't have any experiences yet.
And the tube will get really hot.
Check out http://www.plasmatweeter.de/ He's got a nice design too and that foreign-language thing. And links. |
|
|
| Tekko |
I wound my coild on used up solder spools, and yet they seem to cope with the heat, i only managed to melt it near the plasma electrode as it was quite near .
Its the plasmatweeter.de unit i have built. |
|
|
| Marik |
| As a coil form for my plasmas I was using straight shaped glass candle holders, drilling a couple little holes with diamond bits. No overheating problems, whatsoever. |
|
|
| lndm |
I have built a plasma tweeter and have to say it is very revealing, led me to realise that more deficiencies in my treble reproduction were due to electronics than I realised.
The plasma didn't have an 'edge' or a resonance, it was flat and immediate but not artificial in the slightest.
Biggest problem was the power. I tried horns but they interfered with the plasma, grounding the oscillation. I understand that some have done it. I had to start mine with a screwdriver and couldnt reach the electrode with a fine horn on it.
I used a 30W plate dissipation device and a 600V B+. I tried 6 poles of upper midrange rolloff but could only achieve moderate SPL's.
I believe some have used mosfets as the oscillator with massive power dissipation.
PS the trick to efficiency is to give enough space between the windings (adjust the interwinding capacitance) so that the coil is high Q (maybe a dozen coils with a 1/4" between worked for me). |
|
|
| georgehifi |
One of the best sounds I have ever heard was a Pair of double stacked Quads 57's, a pair of 36ins Hartleys crossed over at 100hz mounted in the brick wall behind the Quads using the next room as the box box, and a pair of Ionic Plasma Tweeters by Magnat (German) crossed over to the Quads at 10khz, the front end was a Stax Electrostatic cartridge that need to be tuned in with a cro that took about 1/2hr and it stayed in tune for about 15mins, then had to be tuned again. Now that's a system. All this was back in 1976. and i have not heard anything that even comes close in the last 30years.
Cheers George |
|
|
| bear |
Please beware that in most countries there are rules governing emission of Radio Frequency interference and power levels!
Plasma tweeters emit RF.
In the USA all commercial plasma tweeters are set on a frequency set aside for unlicensed low power operation (in the 27mHz band, iirc).
You need to put a GROUNDED CAGE around your plasma itself, and also put the driving circuit inside a grounded box. Otherwise you stand to interfere with other broadcast and communications services.
his becomes increasingly important as you start to build with higher power/larger tubes.
Fwiw, some are also concerned about the production of Ozone by the plasma, and by shortwave UV light from the plasma.
_-_-bear :Pawprint: |
|
|
| rcavictim |
If one can assume policy by the actions of the regulators themselves then I see no evidence that the emission of huge amounts of radio communications killing EMI over a wide frequency range on a nearly globalwide basis is unlawful anymore. I give the accepted deployment of BPL (Broadband over Power Line) as my example.
B A S T a R D S !!!!!!!! :smash: |
|
|
| Tekko |
| This one is not 27MHz, more like 1-5MHz if even that. |
|
|
| lndm |
| Just FYI, the coil inductance and interwinding capacitance determine this frequency. BTW I used 2MHz in my experiments, my flame was almost 1/2" at its best. |
|
|
| Tekko |
I just tiossed mine together in a hour and i have no clue what freq it uses.
It doese not disturb radio/tv tho. |
|
|
| Tekko |
Now the PT is running again. I got two PL519 so now it works like a charm, only that it also hums loudly.
The hum reduces if i touch the audio input.
Anyone got an idea on a solution ? |
|
|
| lndm |
Could this be a simple AF problem? Ground deficiency etc. I don't remember significant hum, but I sure think it will ruin your headroom.
Have you put a high pass filter in yet? |
|
|
| Tekko |
I tried replacing the moduklator tube modulating the oscillator screen grid with an tubeamp audio output transformer in reverse and presto most hum gone.:)
Tho i need to find some magnoval sockets for the big tubes. |
|
|
| Tekko |
Now the tweeter is dramatically improved.
It sounds really nice and plays happily together with a woofer.:):) |
|
|
| klm1 |
Try Antique Electronic Supply, they have ceramic tubes cheap:here
only .50 ea! |
|
|
| Tekko |
What i need is sockets for the PL519 tubes and 35mm ceramic formers for the resonance coils.
I cant buy from USA anymore, i have made promise the one im living with. Also that link doesent work. |
|
|
| Tekko |
R.I.P Plasma Tweeter :(
The resonance coil had melted the former and deformed so it had started to overload the tube, i have made like 4 attemts on a new coil and none works.
Now the tube only goes orange no matter what coil i do, so therefore i declare the tweeter DEAD :bawling: :( |
|
|
| bear |
| quote: | Originally posted by rcavictim
If one can assume policy by the actions of the regulators themselves then I see no evidence that the emission of huge amounts of radio communications killing EMI over a wide frequency range on a nearly globalwide basis is unlawful anymore. I give the accepted deployment of BPL (Broadband over Power Line) as my example.
B A S T a R D S !!!!!!!! :smash: |
No doubt that BPL is Butte Stupid....
However that does not relieve DIYer of responsibility for not interfering with existing services or for creating RFI.
1-5 Mhz is used by AM broadcast, Amateur Radio and Foreign Broadcast. Emitting more than 100mW is strictly speaking (certainly in USA & Canada) is illegal. Euro rules are more strict.
And, it is bad practice to build things that knowingly emit RFI - plus it will get back into your system, and act like a parasitic would.
So DON'T DO THAT!! |
|
|
| Rodeodave |
| quote: | Originally posted by Tekko
R.I.P Plasma Tweeter :(
Now the tube only goes orange no matter what coil i do, so therefore i declare the tweeter DEAD :bawling: :( |
Grid voltage too high?
I made my resonance coil out of clay that I wound around a film can. |
|
|
| Tekko |
The resonance coil and ran hot and melted the platic former and deformed, this detuned the circuit and started to overload the tube.
I did four attemts to make a new coil, all failed, tube went orange with all of them and ended with injury.
I have no probs at all with interference, i have ran the thing for a month with no complaints.
These things run in the 27MHz area which in sweden is an ameture band, you can send there as mutch as you want even without a license. |
|
|
| lndm |
| quote: | Originally posted by Rodeodave
I made my resonance coil out of clay that I wound around a film can. |
Interesting, this ought to be the way to go.
I built a horn out of plaster. In my case the plaster killed the resonance. Unsure whether it was an electrical or magnetic issue.| quote: | Originally posted by Tekko
I did four attemts to make a new coil, all failed, tube went orange with all of them |
Could it be that tube? I temporarily had a 6550 working once.
I also used a cardboard tube as a former. It would get warm but wouldn't deform. (of course it is a small but manageable fire hazard.) |
|
|
| Tekko |
Yes it could be the tube.
When a tube is overloaded the cathodes emmitive layer boils off and sticks to the control grid, making the tubes life even harder as the grid gets less effective. This is an evil circle, so when i in a dark room discovered that the tube had started to glow very faint red it was probobly already too late, so my latter attemts on new coils set in the final shoot.
Tho its most likely the coils i used, they do not match the schematic by any measure, the resonance coil is too small and the RF coils has way to less turns, it should be 100µH, calculations reveals its around 20-25µH.
And when making they new coil attemts i slipped with the pair or pliers and hit my nose about 1.5-2cm from my right eye, god spared my eye but not the tweeter. |
|
|
| lndm |
Sorry to hear about your nose. I suspect the actual inductance is less important than the Q of the circuit. After all, the lower inductance with a correspondingly lower capacitance should produce an ideal coil that works at a higher frequency.
I hear that this can be done with mosfets. Just for the oscillator that is. |
|
|
| Tekko |
| I know but i ain´t got any gate drivers. |
|
|
| bear |
Even on 27 Mhz. there is a power radiation limit.
Ground and shield, it is good practice.
And if it is an amateur band and not a "Citizens Band" over there, you need a license. Technically you need a license here in the USA on CB too...
The criterion is not a lack of complaints, fwiw.
_-_-bear |
|
|
| Lord Winter |
If u want succes follow the basic rules of RF power circuitry:
- HV ceramic capacitors for decoupling
- transmitting type tubes
- ceramic coil former (low dielectric losses)
- silver plated wire (low "skin" losses)
- RF shield, because you dont want your neighbors to kill you,
and 30~50 watts of RF power quickly starts to "boil" your head
(I'm serious about this ... personal experience)
------------------------
What we see now is like a dim image in a mirror. |
|
|
| lndm |
I remember last time I played with a 1200MHz transciever I was holding the output whilst transmitting (trying to match antennas). My hand felt like what I imagine being in a microwave oven feels like. I guess the RF probably spread throughout my body.
It took a few seconds to notice, then I felt like I may have sustained some strange kind of damage. What is your opinion as to that damage? |
|
|
| Brian Beck |
According to conventional wisdom, you probably sustained mostly a thermal load, in other words a slight increase in temperature, especially in your outer body layers, but probably short of an obvious burn. What did it feel like? There is some unproven suspicion that EM fields can also disturb transfer of ions (Ca, Na, Mg, K, etc) across cell membranes, but this not largely accepted. There is a related and raging debate on the safety of chronic cell phone transmissions close to the head. However, in your case, you probably suffered no significant long-term damage from your single experience.
Years ago, when I was a young RF engineer, several of my older colleagues had developed cataracts. They felt that this was due to exposure to high power microwaves that had heated their corneas. They likened it to heating raw clear egg “whites” until they turn white, due to denaturing of the constituent proteins. Again, unproven, but the number of cataract cases in that company among older engineers and technicians hardly seemed like a coincidence to me. I am very cautious around EM fields. |
|
|
| lndm |
| quote: | Originally posted by Brian Beck
What did it feel like? |
You know the way mains feels, that you can feel the frequency and know it's AC? It felt like AC, only at a much higher frequency, which is odd as I don't presume I could sense such a high frequency.
It started as a strange nervy warmth radiating from one point and into my fingertips. This was combined with a feeling of slight tension reaching through my hand and wrist. |
|
|
| johnthedoctor |
| I can't find a ceramic former but most of the old hybrid TVs used a long wirewound resistor with various tapping points. Similar od to the ceramic former so maybe it's suitable once the wires are stripped off? |
|
|
| agrobler |
I wonder if EM like your brain and rest of nervous system use can be affected by RF... I mean it's all just energy... If you hold a RF remote next to your head, it "reaches" further - same if you hold it next to car antenna... obviously. If you stand close to FM / AM Radio, of older type - it also gets interference, sometimes it gets better if you move closer... makes tuning a bear :D Maybe my brainwaves are just a tad out there, like the post...
So the nervous tension you got from the transmitter, may be a case of resonating nerves... more likely it is because your nervous systems also use a.o. anions to cross synapses... so the tension might be a short slow down of neurotransmitters...
But then again I also feel the cellphone ear buzzing/glowing/slight headache thing... So I might be considered an odd one. |
|
|
| lndm |
| The transciever offers 10W into the ideal load. I had a direct electrical connection. I don't know what this added up to in my case but I seem to have gone into very mild shock for a short time IIRC but I am not sure whether this was a direct result, or just the thought of what I felt. I did feel a little groggy for a time afterward. |
|
|
| Lord Winter |
Please guys don't wander off too far.
I believe all of us wants to build a working plasma tweeter!
During the experiments with my friend Ivan we found two serious issues:
1) Load matching: we used PL519 as oscillator, 600 V for B+,
120~140 V for g2, 15 turns on a 35 mm coil former.This is a
working setup but not ideal, perhaps the number of turns
had to be increased...
2)Modulation quality: altough we used heavy high-pass filtering
on audio signal, the unit is easily overloaded with mid
frequencies and starts to
distort, thus compromising dinamic range.this is perhaps caused
by inherent non-linearity of PL519's screen grid.In commercial
AM transmitters anode line modulation is used, i believe that
this is more linear.
As long as i dont get my babyes, i want to hear a few good advices regarding this modulation issue. |
|
|
| lndm |
I found the same problem. I rigged up a sixth order passive xover at 2kHz and still could not get the drive. Maybe the valve was the issue (I may have been overdriving the screen). Try driving the screen (if this is how you are doing it), from a cathode follower. IIRC this helped a bit.
How far spaced are your turns? I found this to be critical, and 15 turns for me worked best on a 35mm former at a total length of 7-10cm IIRC. |
|
|
| Lord Winter |
We used xover at 5 kHz! And an EL84 cathode follower too!
Also, we tried an inverted output trannie but this doesn't help anyway.
Evenly spaced turns indeed matter much... |
|
|
| lndm |
Just like Tekko and myself, you seem to have found this point a stumbling block. I figured I needed more power. I looked at Mosfets and considered pages from people looking to produce plasma midranges.
To be honest, the thought of sitting mere metres from a source of MW with enough power to traverse a city, was unnerving. Unfortunately, I decided to move on.
If someone were to find a way though, and could get good SPL's at a reasonably low xover point, safely and reliably (autostarting for eg), I might be inspired to take it up again. |
|
|
| Lord Winter |
Mosfet?
Perhaps no.
Even if you succeed, a handful of blown mosfets will be the by-product.Fast,powerful,reliable devices tend to be expensive!
A single transient kickback can kill a monster FET, but this is not the case with tubes.Once i tried with mosfet, and immediately failed ( bitter experience).Generally speaking tubes can withstand overload conditions for long time, so they are particularly siuted for this kind of operation.The bigger, the better!
However don't be worried about HF radiation, good shielding always helps! |
|
|
| lndm |
I have no idea what device I could use. I only know how to use a pentode. Could we use cascoded triodes to simulate a tetrode? We could then use 211's or something like that. The cost will rise though, and I would rather not use a useful and rare device like that as the oscillator.
Could we invent a bigulator, and blow up a 6sn7 to 1:20 scale :cool: |
|
|
| Lord Winter |
There is a myriad of suitable devices 807,813, russian equivalents
GU-13,GK-71,GU-81M etc... |
|
|
| lndm |
I have too much on to go promising to do this right now, but I am open to the possibility of a future project.
I do have another idea. One thing I was working on earlier was a horn. I don't feel like doing the math right now but it wouldn't surprise me if going from full space radiation to horn loaded would give us greater than 18dB.
I do like the concept of the ultimate point source radiator, but you know, practicality and all. I can't see why a nice tractrix wouldn't sound good. Even though I wonder just how effective it will be as there is no mass involved except for the air itself.
I suppose the horn may act just as a waveguide. Even concentrating the sound would be helpful.
I did cast a horn from plaster, as I think I mentioned and it killed the flame. I stumbled on the idea to use egg timers to create the horn throat.
My wife suggested she knew where to get them and promptly returned with a couple of rotating mechanical timers :D
I picked up some glass tube types. I wanted to cut them in half at the narrowest point, remove the rounded end from one half and poke it over the electrode. I promptly broke them trying to cut them.
Then I decided to cut them using the plasma flame :hot: , great idea.
Anyway, I think the horn is a worthwhile idea. I did manage to get moderate SPL's this way, and may have been able to tweak something half decent if I'd continued. |
|
|
| bear |
Another point of research is the Hill Plasmatronic speaker.
Driven by 4 x 572B, iirc.
There may be threads in the archive here too...
Oh, ceramic insulators? Easy. Ur local farm supply will have them as electric fence insulators. Many hardware stores will have them too. Ur electric company is a possibility. As is almost any pottery shop, or person who does pottery.
But, if ur efficiency is right you should be able to use air coils held by styrene plastic no problem - thats a typical "Airdux" RF coil construction, used in commercial and ham radio rigs. Rf chokes are a different construction - check a ham radio book! ;)
_-_-bear :Pawprint: |
|
|
| Nixie |
| No kidding. Hill's design beats all the other ones by virtue of using a glow discharge rather than a corona or arc, as all the other ones do. My modifications to do away with the helium tank are described in several existing threads. |
|
|
| bobo1on1 |
One thing I'm wondering is, how do you get rid of the ozone, other than venting?
I remember seeing a plasma tweeter in a magazine a couple of years ago that somehow used an electric field to get rid of it?
Pherhaps if a sort of a foil like enclosure is built around the flame to contain any gasses that are emitted by the flame.
Then there is only the problem of the foil melting because of the heat. |
|
|
| Nixie |
Grid plated with catalyst.
My solution is to remove away most of it outside, very low airflow is sufficient. By varying temperature you can minimize ozone produced anyway. |
|
|
| bobo1on1 |
I just rememberd it could have been UV as well.
A catalyst is also a good option, as long as it doesn't burn because of the heat.
I've also read somewhere that a plasma tweeter produces some kinds of nitrogen oxide that cause the smell. |
|
|
| Nixie |
Yes, UV can be a problem.
The catalyst won't burn if you space it enough from the discharge. And yes, NO2 is produced (which reacts with water and oxygen in the lungs to make nitric acid, and in sufficient amounts cause pulmonary edema), but the catalyst deals with that too. Cars usually use platinum/rhodium to reduce it to N2 and O2. |
|
|
| bear |
| quote: | Originally posted by Nixie
No kidding. Hill's design beats all the other ones by virtue of using a glow discharge rather than a corona or arc, as all the other ones do. My modifications to do away with the helium tank are described in several existing threads. |
Could you post the link?
I searched ur posts and did not notice it. I am curious about your method(s)...
Or email me privately...
_-_-bear :Pawprint: |
|
|
| Nixie |
I used to be known as Prune.
Hill's patent is US4,219,705. My updates are based on microhollow discharges as electron sources for the main discharge instead of simple cathodes, which removes cathode fall instabilities and creates a stable air plasma; thus, you don't need to refill helium tanks as in Hill's design. See "Direct Current Glow Discharges in Atmospheric Air" (IEEE Transactions on Plasma Science, Vol. 30, No. 1, February 2002) and "Formation of Large-volume, High-pressure Plasmas in Microhollow Cathode Discharges" (Applied Physics Letters, Vol. 82, No. 19, 12 May 2003).
See this thread starting with post #12.
Unfortunately, jayphil's page is offline so you can't see the waterfall plot and other measurements he did on his Plasmatronics, but believe me they were excellent, even when he lowered the crossover from 1 kHz to 700 Hz. I'm aiming for 500 Hz, but have 50-100% increase in power dissipation to get that. |
|
|
| bobo1on1 |
| quote: | Originally posted by Nixie
Yes, UV can be a problem.
The catalyst won't burn if you space it enough from the discharge. And yes, NO2 is produced (which reacts with water and oxygen in the lungs to make nitric acid, and in sufficient amounts cause pulmonary edema), but the catalyst deals with that too. Cars usually use platinum/rhodium to reduce it to N2 and O2. |
So could I buy a catalyst from a scrapyard and use that?
How would it be used? |
|
|
| Nixie |
| No. There's no way to convert the geometry of the ceramic honeycomb to something you can use. Also, car converters contain both reducing and oxidizing catalysts, in series; you don't need the latter. You need a mesh and have it plated with platinum and rhodium, then space from the heat of the discharge it so it stays in its effective temperature window. |
|
|
| bobo1on1 |
| Sounds really expensive. |
|
|
| Nixie |
| Not really. You'd use a tiny fraction of the amount of plating that is in a car's catalytic converter -- I couldn't imagine needing more than $30 worth of the precious metals. As for the plating, you can likely do it yourself. Platinum for example dissolves by electrolysis in HCl (muriatic acid from the hardware store) without the need of aqua regia -- I've plated tungsten electrodes with chloroplatinic acid made this way. Not sure about the rhodium, but it's probably similar. |
|
|
| bobo1on1 |
You can also buy platinum coated connectors, pherhaps a platinum coated metal strip from a scart connector will do.
They look sort of brass like.
Is there any need for rhodium when using platinum?
There are also rhodium coated connectors. |
|
|
| Nixie |
| quote: | Originally posted by bobo1on1
Is there any need for rhodium when using platinum? |
Yes. The reducing catalyst is platinum/rhodium, whereas the oxidizing one is platinum/palladium. |
|
|
| bobo1on1 |
| How should it be constructed? One piece of metal plated with a platinum/rhodium alloy or one piece of metal plated with platinum and another piece of metal plated with rhodium. |
|
|
| Nixie |
| It's plated with both metals. You should ask at a chemistry forum, I haven't built it yet -- probably the last part of the project. |
|
|
| Bernhard |
:D :D :D
 |
|
|
| Nixie |
Horn-loaded corona discharge... UGH
Horns ALWAYS add coloration and are a cheap way to extend the bottom of the frequency response.
Corona discharge is inferior to glow discharge, but much easier to get stable. |
|
|
| mgb |
@bernard,
I have seen some pictures of your plasma tweeters. Do you have some more information regarding your speakers? I know you have solved the ozon problem with the high temp in your speaker. You use some kind of horn. What schematic do you use and what does your flame thrower look like? |
|
|
| bear |
| quote: | Originally posted by Nixie
Horn-loaded corona discharge... UGH
Horns ALWAYS add coloration and are a cheap way to extend the bottom of the frequency response.
Corona discharge is inferior to glow discharge, but much easier to get stable. |
Ummm... no. Horns do not ALWAYS add coloration. Much depends on two big factors: the inherent distortion of the driver and the HOM (higher order modes) for a given horn + driver combination!
One can make a horn with frighteningly low distortion and nil coloration. It's just that most examples that are found do not fit that bill. The addition of "coloration" is not an inherent quality of all horns by any stretch of the imagination.
_-_-bear :Pawprint: |
|
|
| hilbren |
I did some research and I want to build one.
one question what is the differents in driving the flame with a fet in stead of a tube.
I don't understand why you can't get the same (good) results with a fet? |
|
|
| hilbren |
| yeah this is probably the first hit of google if your searching for plasma tweeters. very usefull! |
|
|
| lndm |
Yes it was, as a matter of fact, but I posted it for a reason. When I was building these tweeters, I was thinking along the same lines of using fets. I was following a project at some uni where the students were designing one from scratch. It wasn't finished.
Today whilst searching, I couldn't find the project I was following before, but I found this one, and it appears to be more complete than the other. Maybe it is the same one.
I didn't follow up with that project, so I can't help you further :( |
|
|
| Bernhard |
| It does not look like plug and play. |
|
|
| hilbren |
| well it is actualy ;) |
|
|
| hilbren |
Should have used the edit button... i know
But i had a question in my mind and i had to ask it; can the coil be replaced by a transmisionline.
It should have a few atvantages like no influences to other magnetic fields ect... |
|
|
| lndm |
| The coil is the resonance device at the heart of a plasma tweeter. Yes, electromagnetic radiation is a drama with these tweeters (as the flourescent tubes will show :D) |
|
|
| Nixie |
| That's why, once again, I recommend the audio-modulated DC discharge. |
|
|
| a333bt |
Hi,
my test plasma tweeter is working, but after few minutes tube PL519 get red. Maximum size of flame was 6mm. Sound is very pleasant.
I built this one:
http://www.hardcoreaudio.de/plasmatweeter.htm
Maybe someone can help how to optimize circuit.
I know that flame dont like metal near.
regards, Bostjan |
|
|
| lndm |
FWIW, I had the occasional red plate which IIRC was related to the coil. I experimented with various windings with various results. Your flame does look good. I feel you could extend it maybe 2-3 times in length and present a better load to the output device.
Your windings are very close. This creates a high interwinding capacitance and the resonance Q is less than optimum. You may have better results if you leave a 3-5mm gap between each winding. I would keep the same number of turns.
Nixie, that's a pretty impressive block of work you've done :). Where could I find the latest info on it? |
|
|
| a333bt |
Hi Indm,
thank you for reply.
I will try today 3-5mm gap between each winding and make report.
Ceramic base i got as sample of one ceramic factory here in Slovenia.
I attach one foto more, if someone would interested to build.
This is just test setup. I plan to build maybe with alu horn.
regards, Bostjan |
|
|
| a333bt |
Hi,
yesterday i tried with your sugestion of Tesla coil.
Distance between windings was 5mm.
Flame gets 2x bigger and efficiency is also better. javascript:smilie(';)')
wink
Music is now louder than before.
But still tube is getting red after 2 minutes.
Is it related this to the tesla coil?
regards, Bostjan;) |
|
|
| a333bt |
| here is tube getting red:bawling: |
|
|
| lndm |
Hi a333bt,
Glad to hear about the flame :). Sorry that I can't remember more about the red plates. |
|
|
| Lord Winter |
Hi Bostjan !
Its good to see someone from the neighborhood !
Dont worry about those red plates, just increase the number of windings, it will help. Myself and Ivan had a lot of experimenting with turns number, we believe that 15 turns are far from ideal in this setup (EL/PL 519 , 600 Volts).
We even tried Litz wire from an old radio, but ended up with NO flame and RED plate, consider this a dead end.
BTW, did anyone use bigger tube for the oscillator ? |
|
|
| a333bt |
Hi Lord Winter,
nice to hear also.
thanks for info.
How many windings you suggest?
Bigger tube - you think about 813 tube?
regards, Bostjan |
|
|
| Lord Winter |
Hi Bostjan !
Try doubling the number, or perhaps more, but the spacing should remain the same. A thicker, silver plated wire is a must for maximum efficiency.
The 813 would be a nice candidate for an overkill plasma tweeter, but it needs 1,5kV++ for full effect. I even considered GU-81, but that would be a really hazardous toy to play with.
Recently I bought a pair of OS51 tubes (Pa=45W) that should give considerably more power than PL519, when running from 900V B+. Right now my hands are full, so I will post the results later... |
|
|
| a333bt |
Hi Lord Winter,
thank you again.
Wire should be same 0.9mm?
I have some pure silver wire 1mm.
I am very interested of your progress with big tubes for plasma tweeter.
It would be nice to see some photos.
One question:
did anyone tried plasma tweeter with ignition coils? Like here:
http://www.barlowlabs.upgradecolumb...ition%20coil%22
regards, Bostjan |
|
|
| Lord Winter |
Hi there !
The wire does not have to be solid silver, that's a waste, just silver enameled wire("skin losses"). At higher frequencies only the outermost layer of wire is conducting, therefore we need greater surface. Thin, enameled copper ribbon would be ideal, but that is almost impossible to wind on a coil former.
I bought the materials in Budapest, Hungary.
A company called "HAM bazaar" is selling surplus military and radio-amateur stuff at really competitive prices (OS51 for less than 10 EUR, 40x90 mm ceramic coil former for 0,4 EUR ...) |
|
|
| Lord Winter |
| And here goes the coil former: |
|
|
| Lord Winter |
| And the geometry of the tube: |
|
|
| a333bt |
Lord Winter this is very nice tubes and ceramic.
I made litlle search for tubes, but i didnt find it.javascript:smilie(':smash:')
smash
Yesterday i tried with double windings and working much better.
bigger flame and tube is not getting redjavascript:smilie(':)')
smile
But i got other problems. It makes computer to confuser, cd player is not working properly, when is plasma tweeter working.
I guess i have now to make metal case and ground it.
I am very interested for your progress with plasma tweeter.
best regards, Bostjan |
|
|
| Lord Winter |
Well done Bostjan !!!
You will never find almost any data regarding the OS51, but actually it is an exact copy of PE 1/100 - datasheet available.
RF shielding is mandatory !
A year ago me and Ivan made a "test run" with our plasma. I made a mistake by leaning closer to the coil (about 40cm). After a half minute I realized that the sound is changing a bit, it became less "harsh". A few moments passed and suddenly my vision began to blur, I felt dizzy and almost vomited. Needless to say, we shut down the plasma very fast.
It took about half hour to return to normal state, still feeling some headache, so be cautious with this toy !
We used a perforated metal cage from an old TV.
However I know a simple cure for this problem, it might help.
All you need is to put a "harmonic supressor" between the anode and the coil. Just take an old 50-220 Ohm / 2-3W resistor and wind a few turns of 1mm copper wire on it (6-10 turns will do). Solder the wire ends on the resistor leads and youre done !
I cannot guarantee the succes, but it will help to minimize the interference in the lower TV band. |
|
|
| Nixie |
It's likely not the RF (which has never been proven to have an effect on biological tissue, unless you have sufficient power to actually heat it), but the ozone and nitrogen dioxide.
Of course, why bother with RF and tesla coils? Just use DC. |
|
|
| a333bt |
| quote: | Originally posted by Nixie
It's likely not the RF (which has never been proven to have an effect on biological tissue, unless you have sufficient power to actually heat it), but the ozone and nitrogen dioxide.
Of course, why bother with RF and tesla coils? Just use DC. |
Hi Nixie,
what do you mean Just use DC? Well i opened for other idea.
to use ignition coils?
Yes i believe that plasma tweeter is quite danger.
I had plan to put in well RF protected case with alu horn. Ozone is disapearing with heat.
regards, Bostjan |
|
|
| Nixie |
| I mean, a plain linear power supply to create high voltage DC for the discharge, then modulate it with audio. For example, I took a 2 kVA industrial control transformer I got on eBay for $30, and rewound the secondaries for 2500 VAC. Rectified and with a CLCRC filtering, I get 2850 VDC with ripple on the fraction of millivolt. |
|
|
| a333bt |
| quote: | Originally posted by Nixie
I mean, a plain linear power supply to create high voltage DC for the discharge, then modulate it with audio. For example, I took a 2 kVA industrial control transformer I got on eBay for $30, and rewound the secondaries for 2500 VAC. Rectified and with a CLCRC filtering, I get 2850 VDC with ripple on the fraction of millivolt. |
Do you have schematic for that?
regards, Bostjan |
|
|
| Lord Winter |
You guys cant be serious !
The basic advantage of the oscillator-tesla coil design is to have a very STABLE discharge at LOW power levels.
The DC arc tends to be rather problematic:
- great variations of current consumption, depending on electrode distance, ion and humidity levels of air.
- one of the electrodes will start to wear off quickly, you will have to readjust the distance from time to time = constatnt babysitting
- the actual device will consume enormous amount of energy
- modulation can be an issue at these power levels
I advise you to reconsider the whole idea, however its worth trying.
A year ago I made small but powerful solid-state tesla coil for a friend. We experimented and learned a lot about high voltage AC discharges. Our small "scientific" team abused almost anything we could lay our hands on, from wood to plexiglass, including CDs (its rather spectacular) and live cockroaches(indicates that my friend is clearly insane).
My point is, that its worth to experiment and gain practical knowledge, no matter how crazy/pointless subject you're working on. |
|
|
| Nixie |
| quote: | Originally posted by Lord Winter
You guys cant be serious ! |
There are so many things wrong with your post, I don't know where to start.
| quote: | | The DC arc tends to be rather problematic: |
Who's talking about an arc? Arc is indeed ****, but so is the corona discharge of a tesla coil. Does the image below look like an arc to you?
| quote: | | The basic advantage of the oscillator-tesla coil design is to have a very STABLE discharge at LOW power levels. |
Low power levels is a bad thing. The plasma is more linear if its average temperature is very high compared to the audio frequency modulation. Mathematical derivation of this result is given in Hill's patent on plasma speakers, US #4,219,705. Of course, I've only referenced this like 50 times throughout the forums here. He also talks about why corona discharge is not as good as a glow discharge. You only had to go back to post #53 in this thread. But hey, clearly you're not the type of person to actually bother to read a thread before crapping in it!
| quote: | - great variations of current consumption, depending on electrode distance, ion and humidity levels of air.
- one of the electrodes will start to wear off quickly, you will have to readjust the distance from time to time = constatnt babysitting
- the actual device will consume enormous amount of energy
- modulation can be an issue at these power levels |
Blah blah blah... you wasted your time listing problems with something no one here is discussing. Let's see what other strawmen you'll find to attack next!
| quote: | | I advise you to reconsider the whole idea, however its worth trying. |
I advise you to consider the measurements shown below for the 500 Hz and above frequency range, and show me one tesla coil corona discharge that can reproduce anything this good with a crossover this low, at reasonable SPL.
Before you post next time, I suggest you study a good text discussing the various types of discharges through the whole range: dark, corona, subnormal glow, normal glow, abnormal glow, arc, thermal arc. I've posted at least the I-V curves for these multiple times throughout the forums.
[Note:] Images courtesy of Jay Philippbar. |
|
|
| hilbren |
| WOW that are some very nice plots! the step response is practically the same as it would be in theory! |
|
|
| Lord Winter |
Okay Nixie, don't get it too serious.
My intent was to help Bostjan setting up his project, for the benefit of others, too.
Unfortunately, most of us cannot afford the equipment you're working with. Sorry, I'm just trying to be practical.
Your reaction was over-emphasized.:mad: |
|
|
| Nixie |
| Afford? LOL. An appropriate power supply can be built for below two hundred dollars with used parts from eBay. |
|
|
| Bernhard |
Nixie, do you have a link to your posts about glow discharge ?
I searched the forum , but could not find too much.
Do you use gas or metal catalysts ? |
|
|
| Nixie |
I used to have another nick here ;P
I'll post more tomorrow; too tired now. |
|
|
|
|
|
