SSTC Question from a newbie.

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

Original poster: "Mike Panetta by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ahuitzot-at-mindspring-dot-com>

I am intersted in making a tesla coil, and I want my first to be an
SSTC.  Let me start with some background on myself, and what kind of
things I have done related to tesla, so you can tell me (hopefully) how
sucessfull I will be, and if its a good idea for me to start with an
SSTC.

I have some prior experience with high voltage in the form of messing
with flyback xfmers from tv's as a kid, and more recently flyback type
xfmers that I salvaged from a 180KV high voltage PSU that I got on a
dumpster diving "expadition".  I have designed several different
circuits myself to drive these xfmers, from the simple circuit of just a
flyback transistor from a TV and a 555, to the (slightly more complex)
circuit of 3 IGBT's drivin by a 555 with some tuning circuitry and all
powered by 12V PSU.  On the old TV flyback circuits I got some nice blue
arcs (as I remember it was awhile ago), and I even modulated the arc
with audio once by modulting the frequency output of the 555 driving the
circuit.  On the later circuits (the ones using the xfmers from the
180KV PSU) I have got some real nice hot arc's with some of the
intresting side effects described on some of the SSTC pages I have read
(nearby metal objects seem to get a "charge" on them, etc...).  I have
never been able to get more then a 1" arc (very hot at that!) from these
xfmers though. I have always wanted to build a tesla coil, ever since my
first spark I generated from an old TV flyback as a kid, I have just
never known where to start.  I think I would be happy with 6-12"
sparks/arcs at first!  I would really love to build a small tesla coil
to play with just to start.  Maybe I would move up to something larger
as I learn more.

So now that I have introduced myself a bit, I have a few questions.

1. I really think I could get alot  more then 1" arcs out of the xfmers
I pulled from the 180KV PSU.  I think they were meant to be used in a
push-pull type driver circuit, given the way the circuit board they were
on was wired, and I think they were meant to drive a voltage multiplyer
circuit, which would explain why the insulation on them breaks down so
easily.  My main question is, how can I improve the insulation on these
suckers so that I could atleast get a 2" hot arc out of them without
them arcing back onto themselves (thats the main problem I have now,
they arc back to the base of the secondary, and to the farrite core).  I
have tried clear nail polish with little success (It got me to 1"
atleast), and I have thought about submerging them in silicone oil, but
I cannot find any.  Do any of you guys have any suggestions?  I have
like 6-12 of these things (I cant remember how many I kept) just laying
around, and I would really love to start using them in something! 
Possibly even an SSTC driver coil for a bottom driven config.

2. On the SSTC schematics I have seen so far, everyone uses a xfmer gate
drive.  Is there any reason noone has used a gate driver chip to direct
drive the gates?  If the output current is not enough for the frequency
(the IR parts I was thinking about only go up to half an amp I think),
there are schematics that show how to multiply the output current up to
6A.  If isolation is a problem (I cant believe that the wire people are
using on these xfmers can withstand any voltage, maybe 600V at max...)
then maybe using one of these gate drive chips with some form of optical
isolation would be in order.  Maybe fiberoptic cable?

3.  Do any of these circuits work at voltages as low as 12V up to say a
max of 48V?  I would like to run the thing off a lower input voltage
while I am first learning.  Would running at a lower voltage (even if it
means higher current, say up to 100A) be possible for an SSTC?  Remember
I would be happy with arcs as short as 6" for my first coil, and 12"
would be awsome!  (I am easy to please arent I? ;)

4. (This question may show just how little I know about tesla coils ;) I
was wondering if it may be advantagious to place the SSTC primary inside
the secondary instead of outside.  Does this make sense?  Why would it
not work?  If it worked what drawbacks (if any) would it have over
placing the primary on the outside?  If the primary would work on the
inside of the secondary, would it be possible to fill a portion of the
secondary cavity with some sort of insulating oil to prevent flashovers
between the primary and secondary due to the close proximity placing the
primary inside the secondary may cause? Would it be possible to use a
conventional flat primary (external of course) with an SSTC driver? 
What would the pros/cons of this configuration be?


I think thats enough questions for now.  I am sure I can come up with
more ;)  

Thanks,
Mike