Hi Jeg, Tinsel, I tried using an AC circuit with series caps and parallel spark gaps which kinda worked with an inverter type supply but
not so well, it did also work from the grid but caused problems.
So I decided that for a plug in the wall setup I needed the HV rectified and a DC charging circuit with lots of inductance to limit the current,
I made the HV supply like in the picture and use a rotary gap of a shorting bar design at about 500 BPS is good, but higher rates can put more power through.
I used two anti parallel MOT's and the charging inductance is a MOT secondary ( over 20 Henry's) but it does work with 4.7 Henry's as well (with the primary shorted).
The spark gap doesn't fire to ground it fires to the negative floating supply which i think is important for keeping noise off the lines.
I have filters and such on the input side, the HV supply transformers are grounded to the Tesla coil ground stake not the house ground.
I've blown one series set of caps in the cap bank, there are over thirty caps in the HV cap bank. I think that was caused by a mistake of my own.
http://i227.photobucket.com/albums/dd168/Toey1/DualMOTPrimaryCircuit12.jpgAlso Tinsel I was wondering what your opinion is of the three coil Tesla coil designs, as in with the fairly close coupled primary-secondary and the loose coupled secondary - extra coil ?
Like the transformer in the attached picture. In the second picture I put a long aluminium tube on top of the secondary so it hung out over the front to get the sparks to ground there.
Maybe it might be possible to load the secondary of such a transformer or pair of them while still maintaining some resonance either by directly loading the powerd transformer or by loading the secondary of an induced transformer, like in the third picture.
Here's a short clip showing the light from the output coil of an induced transformer, do you notice the very slow rhythmic sound almost like the frequency is building slowly then
suddenly changing back. Any idea's what might cause that ?
http://www.youtube.com/watch?v=ZVx1FzLFFXcI figured this was as good a thread as any to talk about Tesla coils without, imposing on other threads.
Cheers
P.S. I did a rough turn count the secondary has 38 turns and the extra coil has about 165 turns but i keep loosing count due to going cross eyed.
Not many turns wire is 1 mm, I'm considering winding a coil 115 mm diameter from 0.7 mm wire so that it's frequency matches the setup as it is now then use it for an
extra coil sometimes for more voltage, I'll need to use more primary capacitance then and maybe go to 2 primary turns to keep it low enough. I can go to about 40 nF of primary caps rated to 20 kV without too much trouble.
The black wire behind the sparking coil in the third picture is hanging in free air at some distance behind, it's just a wire through the purple coil to ground, for safety, the coil is to keep the vibrations
of the discharges to ground fairly low frequency, also to reduce extra HF ground noise. Trying to damp any discharges to ground is all.
..