A Kapanadze generator replication - Febuary 2013

[TinselKoala]

@Lakes: Thanks! That one is a time exposure, 15 seconds iirc, showing the corona from a simple corona motor made from a coathanger wire and an acorn nut for the center pivot.

@Farmhand:
Thanks for your interest, I hope my experiences might be helpful to you.

I use two cameras: the videos are taken with a Panasonic SDR-H40PC in full-auto mode and the stills are taken with a Canon 400D/Xti using the stock 18-55 mm lens in manual focus mode.

The stills in the slideshow above are frame-grabs from the Panasonic's video, full auto. It's dark night, the ambient light is from an LED flashlight aimed at the reflective roof of my observa-yurt and the rest of the light comes from the spark gap and the corona discharges.

The other stills from the Canon are either 1/15 sec, f/6.3, or long 15 or 30 seconds. ISO1600. I also used the LED flashlight for some fill lighting during the spark shots but almost all of the illumination comes from the primary spark gap and the corona itself.

I used a steady tripod and a remote shutter switch, and lately I've been shooting in multiple-shot mode, taking 10 or 12 frames in quick succession, 3 or 4 frames per second.

Processing includes cropping, noise reduction, contrast and saturation adjustment, sharpening slightly and resampling to smaller pixel count sizes using gimp.

The slide show was made from stills grabbed from a video, and assembled with YouTube's slideshow editor.

The videos are processed with OpenShot and WinFF.

Here is an older video showing TinselKoil 1, a completely solid-state Tesla Coil, no spark gap or tank capacitor bank, lighting an incandescent bulb with one wire, the other side of the bulb just connected to a bit of suspended aluminum foil as an "earth antenna". I've since modded this coil with a different resonator, lower aspect ratio (TinselKoil 2), but unfortunately I don't have it here at my present location to play with.

http://www.youtube.com/watch?v=7BMRJoqdy6E

So this showing the high voltage high frequency output "radiant", enabling the capacitative coupled, one-wire transmission of power, and the high-current output capability, making the filament glow brightly from Joule heating. This filament is actually broken, this bulb won't light from the AC mains!!

The driving electronics are very similar to some of the schemes I've seen detailed here. A 494 is used to generate the main clock pulses, which are split and inverted by some 2n7000 mini-mosfets; these signals are then fed to a current amplifier stage made of an H-bridge of complementary bipolar transistors; the outputs of this current amp drives two trifilar toroidal phase transformers, which then drive the power section H-bridge made from mosfets, which are switching rectified and filtered line current at about 170 VDC into the coil's primary. This one runs at around 830 kHz.... blanks out AM reception !!

I think if you have a lot of wire in your primary, lots of turns, you will actually interfere with the free ringing of the secondary, by mutual inductance effects. I think this is one reason that most Tesla-type coil arrangements are rather loosely coupled between primary and secondary. Another reason is to avoid arcing between the secondary and the upper turns of the primary, since a properly working coil will already have a great deal of voltage at the height of the primary upper turns.


ETA: A note on construction of these high-voltage air-core resonators: do NOT terminate or route your coil end wires inside the tube! If you do, even by making little holes just to secure the wire ends, you will be creating a relatively low-resistance pathway inside the coil form and the coil may spark preferentially inside and along the inner surface of the coil form. Also avoid using black PVC or black rubber parts, I think it's colored with carbon soot or something and is more conductive (at HV) than you would like.
How do I know these things? Miles of wasted wire and hours/days of wasted time, that's how.

Here's one corona psark I photographed last night. 1/15 sec, f/6.4, iso1600, the coil has a pointed breakout point magnetically attached to the doorknob on top of the toroid. Distance from top of the psark to the bottom breakout point is about 18-20 inches.

[Farmhand]

Thanks for the tips TinselKoala, I'm getting better with the camera, I use a tripod and the 2 second shutter delay so the camera has time to stop moving.
First I focus and click the shutter then turn on the coil. The photo below is 1/10 of a second, f 3.5 and ISO 1600. I think there is something to learn in looking at the effects
on film because a lot is missed by eye. The pretty stuff is a nice side effect of the research. The small coils i'm using to light the bulbs were never meant for HV or much current
I made them for 12 volt experiments, I am going to make another coil for HV but it'll be on a varnished wooden frame I hope.



Cheers

[zcsaba77]

Yes, 30 kV or perhaps a bit more when I up the input to the driver. You'll note that I have the flyback transformer totally immersed in oil for insulation and cooling.

That is not "cold fire"... far from it. There is so much power in that plasma that it actually burns the nitrogen in the air to nitrogen dioxide. Even a small JL will burn enough nitrogen to make a significant amount of NO2. This is one big advantage from using the ZVS driver: it is very efficient at transferring power into the load.

The plasma runs up the ladder because it is hot; convection currents in the surrounding air carry it upwards until the gap is so great that the plasma breaks up and stops the current.... then the voltage causes the arc to re-strike at the narrowest gap of the electrode set.

Hi Tinsel

Thank for information, but if you dont let escape plasma spark by example jar, will the plasma spark stay in the jar? and in vacuum spark is longer or shorter?

rgrds zcsaba77

[TinselKoala]

@Farmhand:
Nice shot of the spark, it seems that there are common features in these displays. Last night I saw a video of some small sparks, under 3 inches, but close-up... and they looked just like big sparks, with the lights off and no scale reference I couldn't tell much difference. The sparks are fractal structures, like watershed patterns of rivers but in 3 and 4 dimensions instead of 2, draining the "watershed" of space down into the source -- the Earth ground.

@zcsaba77:
Sure, you can contain the flyback plasma or spark in a sealed container. In fact, the arc burns nitrogen in the air down into nitrogen dioxide, NO2, which is a toxic yellowish gas that reacts with water to form nitric acid, so it's not good to be breathing this in any great quantity.
Vacuum.... there are vacuums, laboratory vacuums, and true hard vacuums. But there's really no such thing as a "real vacuum" that contains no ionizable gas molecules. Dry air at standard one atmosphere pressure can sustain 30 kV/cm between large spheres before breaking down. Point electrodes lower that considerably.... call it 10 kV/cm for "ordinary" small discharge electrodes. But when you start lowering the pressure the breakdown voltage goes down. This means longer sparks with decreasing pressure, up to a point. At some low pressure, easily obtainable with small vac pumps like air-conditioning service pumps or single-stage lab vac pumps, air becomes so conductive that you can't even build up enough voltage to "spark" at all -- the whole chamber with your low pressure air in it glows purple and shorts out your HV. To get down to the point where your "vacuum" is no longer conductive takes a much stronger vacuum pump, like a turbo or oil-diffusion pump, and is beyond my reach here in my home lab.

If you want to see some incredibly long, true sparks from HV current or static machines, try a chamber filled with Argon at 1 atm pressure. Other gases also make interesting displays with HV..... I came across this last night on YouTube:

http://www.youtube.com/watch?v=3sYjGk2VqCA

[guruji]

Guys are you saying that the secret that TK says is the SG?