Fantastic continued documentation once again!
I noticed in your previous videos that you switched over to the simple multiple gap design (as mentioned in Teslas lecture "
Experiments with Alternate Currents of High Potential and High Frequency").
I was curious what your thoughts were on the gains & drawbacks of this design are when compared to the controllable timing of the rotary spark gap.
Interesting question! I have used a stepper motor controlled rotary spark gap before so to have very precise control over the timing. That of course also requires some other modifications in the HV source, but this precise control was at that point my main focus. The result was that I could generate short pulses at a rate up to about 30 Hz, using up to 3000 Watt.
Now, I would like to operate in a more continuous mode and with more power. 30 BPS is way too low to accomplish this. Also the voltage in the primary circuit is up to 44KV (from 11-22KV earlier) Now it is difficult (but possible) to design a high speed spark gap for 44KV, yet to do it right you will need to adjust the timing of the spark gap to the frequency of your source (50 Hz) and that makes it very complicated.
-- here is an excellent source for more info on that subject --
A static spark gap is by far the easiest solution in this case. And the multiple gap design makes the extinguishing easier.
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Ahh, yes, I remember the thoroughness of that Richie Burnett guy. Good refresher on this subject. Im happy to hear that the multiple sparkgap is the more appropriate choice for CW operation. Its just so darn simple looking. Is there a reason why you wouldn't submerge that in oil as opposed to blowing air across it? I like the idea of a faster, cooler & quieter quench.
I picked up a copy of Tesla's Lecture before the New York Academy of Sciences (April 6, 1897) and was being inspired about his progress with the table top high frequency oscillators and got stuck at his description to what I think he is calling the ballast inductor. He calls it the 'charging coil' to "help raise the pressure to any value desired for charging the condenser."
This lecture was before his learnings at Colorado Springs with his fires, so perhaps its a premature description.
I love the simplicity of his table top oscillators and was hoping to take the learnings in his writings and your learnings here to produce an desktop of my own for experimenting and practicing with tuning. But with some of the new considerations from Mr. Burnett, i'm scratching my head a bit on how to precisely (and simply) think about the ballast / charging coil.
Looks like Tesla doesn't use a step up transformer in his boxes here. :o
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I very much like the oil submerged spark gaps too, but the problem is that the oil needs to be in constant motion otherwise the sparks will burn the oil and cause carbon channels to form. This means that you'll have to build a relatively complicated contraption such as you'll find in Tesla's many patents.
The charging coil is a very simple way to get excessively high voltages. When done correctly, it creates a resonant charging circuit with the capacitor, that resonates at the same frequency as your AC source. I didn't (consciously) use it, but in earlier circuits I used a ballast to limit the current. Inadvertently the ballast I used formed a resonant circuit with my primary capacitors at near 50 Hz. I was expecting 11KV but I killed my ceramic capacitors rated for 40 KV. That was an expensive lesson that I still regret as those ceramic caps were really fantastic in their performance.
If you'd like more details let me know and I'll do a separate post on that.
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oooh, good point, I never really came across anyones documentation on the carbonizing of oil. Im curious what would be the minimum requirement for this to not be a problem. I had some thoughts earlier on mixing Tesla's flat disc viscosity turbine with the rotary spark gap to create some motion in the oil, but then I lost some heart with the complexities of controlling a motor and all its moving parts alongside the complexities of timing and whatnot. Really can't beat the simplicity of a multi spark-gap!
Upon your note of the resonant charging circuit and seeing how simplistic Tesla's circuit evolution descriptions were, I am very interested in hearing more about your expensive lessons on resonant charging! I would love to do away with heavy iron in these desktop designs. Another trademark testament to the importance of understanding "tuning"!
I caused some good curiosity with my Grandpa this Thanksgiving when showing him my illustration work on Teslas 1981 lecture (that you and I have talked about earlier this year), and he asked me if I could build him a high frequency oscillator for his office. I would love to send him something that doesn't require 20lbs of iron and oil for powerful and beautiful operation :D as for my office as well. Yes!
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I'll do a post on resonant charging then, later.
Perhaps for your Grandpa's oscillator it could save a lot of iron if you start out with a high frequency transformer such as is often used with halogen lighting. What they do is, the first create an AC of about 40 KHz and then they use a small step-down transformer to get 12V. This 40 KHz AC will make resonant charging a lot easier (read: less iron required, compact design)
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oh my gosh:
http://www.loneoceans.com/labs/flyback/
How surpassingly simple! :s I love the doing away with the 12v monster DC supply. Now this is what I am talking about!
Makes resonant charging easier? Im ready for the next installment! :)
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You found LoneOceans! Look at his QCW... I tried to contact him, but he does not respond :(
But... erhm... yeah, a flyback circuit is very easy, as is a Slayer Exciter Coil (SEC). Look it up if you are looking for a simple HV source.
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Yea I built my fair share of those sec designs.. but when compared to a 12v 40khz source off of a 120vac supply cuts down on alot of junk to package.
But im also having a desire to stick to the original desktop ideas that were perfected at maximizing the action at the terminals. This probably also includes the need for a good spark-gap for the quickest transients to reproduce the illuminating parallel wire experiments (transistors may not be as quick for efficiency sake).
The hallogen transformer + a flyback circuit sounds like it can compact the Blast part of this design. Leaving the spark-gap up for exploration still.
I remember your QCW plasma forming 'swords' topic... I also would like to hear another installment on that again :p
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