Good advices for a newbie (threading tools lathe)

[rendoman]

Hi! new update!
This plasma is similar to Sasha Grey, it sucks current like a princess!
The final part of circuit is not running well, got a nice flame but it drinks too much bourbon, tubes and coils run too hot imho, have to make test, for sure I want to avoid burning tubes.
Flame is hot, really hot! I can smell a little ozone only with nose up to flame, not so alarming. Flame is silent, completely no sound from spark! Got some noise from 2 transformer of power supply, not a big problem, the single unit will be a toroid, maybe from poland, covered with resin.
Still not have auto fire, i hope i will tune the circuit. I have to improve fuel consumption and interactions between coils. Maybe frequency is really too high... I'll do some test!
Really impressive interactions with objects near, without metal shield around flame coil the metal edge of the wooden table gives spark to my hand! Without shield if you touch the edge the flame lower size!
I never thought that the cage was the first part to be designed! I discover new things every day! Have to think the shape, and how to create a good and nice one!

[rendoman]

Hi! I begin to understand why there are few plasma tweeter and they cost so much... developping the circuit is really hard!
I tried different coils, resistors, capacitors but the tune isn't easy and it's not trouble only working on circuit, it's a complex set. I built some new coils with lathe for test. It's really impressive that very little changes can make huge difference or destroy the tube. In the 3rd picture under 10 sec up to overdrive can turn the final tube bright red. I buyed some testing equipment for doing measurement, a frequency counter and a lcr meter, for sure they can help, hope they get here soon from China! I'm searching in this days for a good oscilloscope with probes.

Have to make some steel gage all around frame and coils, fix in different positions coils for easy substitution. Unfortunately I'll have to modify many parts from original idea ( and I don't want to sacrifice early 316 inox )

In the meantime I carry on for easter with pear and chocolate cake and some good belgian White

[PJs]

Thanks Stefano and Happy Easter! This isn't a simple matter to work out for sure. You don't see them much except for very high end applications because of the costs involved to develop it to a frequency range for the application with out harmonics. But there are a few like yourself still working to dial them in. I'm still unclear what that range is for you also. Full range 20-20k or what? After all of this I still don't know if you designed this circuit or found it somewhere(?), plus we started out with making very cool cones on the lathe.

I found a couple of links for you. Most of the stuff out there now uses IC's not tubes.

This one seems closer to what you are trying to accomplish but uses a brass horn.

and straight out of the plasma...simple computer power supply and a couple of coils, caps and note his comments about the electrodes. Simple but very good sound but can't see if he is driving from an MP3 or what.

And here is a white paper from U of I. Note how he is modulating the flyback with a PWM chip (pg. 5+) and the differences between a full wave vs half wave rectifier circuits and their harmonics.

~PJ

[C-Bag]

WOW, that's crazy! Now I see what you are looking for. I appreciate that the guy messed with the plasma and made it very convincing the plasma was making the sound not some other speakers. It's hard to tell with the camera mic's and my crappy little speaker on my iPad exactly what it sounds like, but it's amazing a flame is reproducing music.

Indeed!

[PJs]

It's about sound pressure waves created by the modulated plasma. A shortened story from the Peabody and way-back machine...back in high school a buddy and I talked across light using one of the first photo diodes a (Fairchild Semi) and a lab spectrum tube for a science/physics project. Basically we modulated the neon type transformer for the helium tube with an amp and microphone and connected an array of the diodes stuck in a single hole rubber stopper ( still cheap and cheerful to this day ) to an old wire recorder to demodulate the signal from the diodes to a head phone. Seems like that was around 67' yet the principles are the same because the helium is basically in a plasma/ionized state but enclosed in the tube so we couldn't hear it from the tube.

And now we have fiber optics across the country and world for that matter doing the same thing essentially but with some serious bandwidth and sophisticated encoding/decoding going on. We're gonna need some bigger bags of popcorn over the next few years I think! ~PJ

[C-Bag]

"Peabody and the way back machine" LOL! I wonder how many that means anything to?

Once again I'm blown away with the tech you've been part of Wiz. Mighty deep bench around here when folks come out of the lurk.

Referring back to your linked vid, did it seem the plasma was directional? It seemed he was demo'ing that when he was standing up and moving around. If so, why would you need a wave guide, other than maybe focusing the sound and maybe keeping things away from the plasma? It was also real hard to judge how loud it really got. It would seem it draws a lot less amps than Stefano's rig, no?

So many questions and so little knowledge on my part. But it is extremely interesting! Gotta pop another bag

[rendoman]

Hi all and happy Easter!
If I can express my humble opinion, on the net there are many circuit with "strange" solutions and components, in few words, many circuit not running or performance not so good.

Thanks for the links! I wrote to conscious flash, he gave me some advice, but he said that his plasma with gu50 resonate at very low freq (1mhz +/-), it's clear because he used a very tall Hv coil. He said also it was a "stand alone project" not for hifi use. I want to replicate his low freq coil just for experiment, to see if the circuit runs (with autofire).

I think that big flame with flyback tranformer is good only for show, not for audio. For sure "tesla people" make this because it's funny and cheap, but it's not good.. I tried flyback years ago, they are not made for keeping current at high freq, and with low freq we can't talk about hi end use. I destroyed 3 or 4 flyback, and audio was really poor with noisy flame.

I did some research on solid state, mosfet type plasma, but for high freq troubles everywhere and very poor efficiency.

The base site for diy plasma tweeter is this, of Ullrich Haumann
Ulrich Haumann's DIY PLASMA TWEETER

It's a very good starting point, with info on all commercial type and diy schematic (hybrid and full tubes). I spoke with Ullrich and he said that the efficiency was really, really low, even with the "turbo" tube version.
My schematic uses the same concepts as that of Haumann, there is the last tube that is a class C oscillator tuned with few parts and cathode to gnd, driven by a modulator with a series resistors with potentiometer that modifies the voltage in g2 of final tube. The first "little" part is a normal audio amplifier with triode+pentode.
I only wanted to use different tubes, pcl82 (triode/pentode specific for audio) and el84 as modulator, then cheap and strong Gu50, but the big basic parts of circuit are the same. Haumann was right, 27mhz is a right tube for oscillator, it helps keeping flame silent , efficient and good sounding.

I havn't the truth in my pocket, and I know that before speaking I should do a trial run, but Il you see the schematic i can tell you something:

- with 600v B+ and 350v on modulator , nothing happens
- with 600v on both modulator and oscillator something happens
- adjust g2 to 60-90v for use, at the moment i can't keep the voltage so low (or the current so low like Conscious flash ) the circuit starts at a minimum of 130v till 300, i'm completely over range.
- maybe the problem is something in frame-cables- optimisation, but with 100\200 uH coils, nothing happens, my coils are bigger non slightly...



For sure my circuit is not tuned well, but i see too many strange things in different schematics, and either some friends that experienced plasma tw building said the same.

if you've come this far, you can feel that many builders stopped developing circuit as soon as first start, and don't replicate for stereo. For sure this oscillator circuit is 5 parts, but it's really hard to tune.

Cbag you're right, my circuit is drawing lot of current! it's good that the flame even at full power is completely silent, but the grid of gu50 is a bit red and that's not good. I post my facebook video of the flame, with no sound ( i'm focusing on oscillator parts for now ) you can see the ammeter is nearly closed to 190ma, but if you see the color and the shape of the corona discharge is completely different. Conscious flesh seems to have a longer flame, more narrow and not so stable (see angle) with less current.

i talked also with a owner of a commercial Corona, and he said that in audio use, flame is 5-6mm, really tiny compared with mine... but i want to improve performances of entire circuit

The choice of horn comes to the need to use quartz or pyrex cell to degradate ozone. For sure 360° sound can be a great experience, but for closed rooms it's better avoid ozone, and the cell can help a lot. Horn for sure helps keeping flame low, it's at least +10db without touching flame size, that can really help with high efficency system

https://www.facebook.com/stefano.ran...8729516698000/

I hope I have not bored you with this technical info
what do you think at the light of the new information?

[rendoman]

sorry i forgot a thing
My goal is reach 1000\1500hz to 20khz , If i can run the flame at lower frequency is better, I aim to keep "tweeter" range with no noise and wonderful sound

[PJs]

Happy Easter C-Bag! Yes it is directional to a degree. I believe the sound comes out of the plasma radially and probably loudest at the peak of the flame for a 2 electrode system. As he moved to the left and away the level did decrease as I think the sound is least, in the plane of the electrodes. As for the wave guide I would say that is what helps focus and tune the frequency range. The higher the voltage (more pressure) the louder it can be with out one. If you look at some of this guys videos on a modulated Tesla coil you can tell by the length of the spark he is cranking out some serious voltage as well as sound pressure.

The one in the video above is using a 2 electrode system...much easier to start and not as high a voltage, although I would guess by the length he was pushing 25-30kv.

The big trick is to be able to create a corona/spark from a single electrode centered toward a cone. If you look at the second link above about half way down the page you will see what I mean.

He says; "The closed glass discharge chamber confines the discharge increasing efficiency of the speaker and reduces the production of the ozone . The discharge chamber is connected to the brass horn which improves the reproduction of the lower frequencies." The picture below this statement shows the tube, electrode and an exciter coil around the glass to get it going and plugged into the horn.

I only saw one of these back when rocks were formed and there wasn't a cone on it and was 2 electrodes...not safe for normal humans is the other reason they never made it to the public realms and the RF will play havoc around the hood. I believe the frequency response is pretty phenomenal from what I remember as well as the quality. The Tesla versions are real popular in with the Techno crowds and a lot more Staccato.

S'all I know...more popcorn and ozone please. ~PJ

[C-Bag]

Thanks Stefano. You are on another plane of knowledge from me with electronics. I'm sure the Wiz will be along soon and understand all. Interesting that the Quartz/Pyrex and horn are part of a means to keep ozone down. Like to boost the efficiency? Or as a catalyst?

I was hoping that you were not going for such a huge flame as it seems dangerous if nothing else that much heat in a horn would sure mess up your nice polish job in a hurry a big tube amp already puts out a lot of heat, having two plasma torches going on would be hell during the summer! Also you are going for a single flame, not double like in the vid PJ's/ Wiz posted.

Interesting my old Heil's operate at the exact same frequency you are wanting the plasma for. I salute you for your diligence. Thanks for the update and stay safe.