DC Resonance Charging Advice Sought

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Dave Kyle by way of Terry Fritz <teslalist-at-qwest-dot-net>" <dave-at-kyleusa-dot-com>

Several months ago after being inspired by Steve Conner's very impressive DC
coil http://www.scopeboy-dot-com/tesla/index.html I started my own DC coil
project. I was drawn to the very elegant power control permitted by DC
resonance charging. Richie Burnett's site offers an excellent explanation
and provided the designs rules that I have followed
http://www.richieburnett.co.uk/dcreschg.html#resonant. Of course for the
ultimate expression of DC resonance charging one only needs to look at Greg
Leyh's incredible Electrum http://www.lod-dot-org/index.html.

I have now completed and tested to 8KVDC (without load) the DC power supply
which can be seen here:
http://home.austin.rr-dot-com/dkyle/images/temp/dc_tesla_ps.jpg. For scale the
base disk is two feet across. You will note the very large black power
transformer, full wave rectifier and de-Qing circuit, smoothing capacitors
with safety bleeders and grey charging inductor.

Specifications are as follows:
4.700KVAC 775VA transformer (6.65KVDC rectified)
7uf -at- 10KVDC of smoothing capacitors
20Henry -at- 15KVDC inductor

Under construction:
.02uf -at- 20KVDC cap
0 to 500bps RSG
4 inch x 25 inch secondary with 1400 turns of #26 gauge wire
6x24 inch toroid
15 turn primary (tuned at 11 turns)

Advice needed on the following:

1.) I have yet to resolve the system grounding. Is it advisable to ground
the center point of the main transformer for safety (like an NST)? Or would
it be better to simply ground the negative side of the DC power supply? Or
let it all float and just ground the secondary?

2.) I am assuming this transformer is not shunted (current limited) but
short of dismantling it how can I tell? DC resonance charging is self
current limiting so that will not be an issue but I would like pull current
slightly higher than the transformer's rating.

3.) Assuming the transformer is not shunted would there be any benefit to
adding PFC caps?

4.) I have noticed in some of the very few DC coils documented on the net
that a clamp diode and air inductor are sometimes added to the charging
circuit presumably to protect the supply and caps from over voltage and
transients. Can anyone comment on the need for this?

Dave

=========================================
Dave Kyle
Austin, TX USA
Email: dave-at-kyleusa-dot-com