Tesla coil Build comparison. (Proof of ability)

[Farmhand]

As far as Topload materials and construction goes, I was thinking of using some "ribbed" aluminium ducting or some copper tubes arranged on a wooden bracket to form a virtual large capacitor from smaller bits. My thinking is the ribbed ducting will not hold charge so well. Making larger top loads is a bit of a pain. I know I can tune around it, but I want to increase the size and capacity by a bit more than double what it is now and be able to change out the topload and switch the primary cap bank capacity, then a quick tune and run at a different frequency.  I want the Maximum  primary capacitance to be about 40 nF. And if charged to 7500 volts 800 times a second that would be about 1.1 joules x the break rate of up to over 800. So Maximum input should be in the range of around - 880 to 1200 Watts. I hope.

I do have more topload rings the same as the one on it but when added on top of each other the capacitance secured is not so great, I don't think. Anyway, BBQ is a ways off yet.

Cheers

[TinselKoala]

The topload on the TinselKoil 2 is two big "baby moon" hubcaps taped together with aluminum duct tape. It is very smooth, being bright chrome plated, and it's steel so it's easy to stick a breakout point to it with a magnet. I got a dozen or so of the Chinese baby moons from Active Surplus in Toronto for a couple of dollars each. I also use them on my big Van De Graaff machines as toploads and bases. They work great! A set of four, put together into two flattened spheres and stacked, would come very close to your desired 40 pF capacitance, I think.

Four for 68 dollars from JCWhitney:
http://www.jcwhitney.com/baby-moon-hub-caps/p2031512.jcwx?filterid=u0j1

[Farmhand]

Hi Tinsel, Yes I like those hub caps they look real nice. I'm sorry did I say 40 pF toplaod ? I meant 40 nF primary capacitance, maybe I'm confused. 40 pF top load might just correspond to 40 nF primary capacitance with my transformer. I think you get what I mean anyway though, I could stack two top loads and have a primary bank that can be changed from say 20 nF to 40 nF with a switch, then I could operate at one lower frequency with the two top flat spheres and 40 nF primary capacitance or whatever it takes and then remove one top sphere and switch to 20 nF in quick time and with a bit of a tune it could then operate at the higher frequency. If I could get 600 Khz or 400 Khz or something like that with a simple change it would be cool. I can also adjust the resonant charging coil inductance.

That makes the baby moon hub caps look really appealing over and above the aluminium ducting, which would be "electrically" smooth as you say, but not adjustable without more trouble.

I fear that if I up the power input too much my diodes will give out. If I heat sink the diodes with some simple wrap sinks might that help I wonder ?

And what is your opinion on a ground plane just under the platform the coil sits on ? I did have an aluminium sheet just under the platform and it was connected to ground but I removed it, not sure if it made much difference except maybe to tuning, if the grounded plane was too close could it drain power from my primary coil ? I was about 20 mm below the primary with 12 mm of plywood between. I can draw a simple sketch to show it if my description is not clear. I thought it was a bit close and increased input but decreased performance.

Cheers

[TinselKoala]

Look! A ONE MILLION VOLT Tesla coil! !!!! (sic)

http://www.youtube.com/watch?v=-qKl_JhNVWM

[Neo-X]

Hellow 2 all.. I have a question, is it possible to make 100,000 sparks in 1 second?