Re: HV MMCs was Re: Magnifier conversion

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

Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>

Hi Jim,

If Ross, Glassman, Craggs and Meek...  think it is a good idea, it probably 
is ;-))  So that is what I will do.  Something like this:

http://hot-streamer-dot-com/temp/NewMag/0416-01.gif

Four caps per turn and I can easily tap it up from the bottom.  I don't 
think i will need a low corona ring, but no big deal if...  I have G-10 and 
all coming in tomorrow.  Probably be open frame but I will make it so I can 
put a tube over it if it needs for handling.  I just ordered up a nice 
selection of orbs to have around from Waterscapes.  I will just cut a hole 
in a six inch one for the top terminal.

I am going to add two 0.100uF Geek poly MMC caps for 200nF at the very 
bottom of the string and make it like a high voltage capacitive divider AC 
probe.  That will give a ~~1:1000 voltage divider so I can scope the top 
voltage.  Might not be a "perfect" HV probe, but it is very easy to do here.

If it is 3.5 inches in diameter, 19 inches long, 25 turns...  We can maybe 
guess at an inductance of 9.3uH (wheeler's).  that gives a resonance of 
4.5MHz.  I "should" be ok ;-)   A "counter winding" to cancel the 
inductance is a cool idea!  But should not be needed.  We'll see.  Be fun 
just to try if the voltage across it was not to great.?

Many thanks for your most useful thoughts on this capacitor design!!  I 
just got the caps and resistors so time to start work on it :-))

Dan wrote:

>The problem with resistive dummy loads is that they never really represent
>load conditions which will really
>be used in practice.  For example, if you were designing a power supply for
>use with tesla coiling, or any other
>type pulsed load condition, a resistive load would be an extremely poor
>choice.

Yes!!

I can't begin to explain all the complexities of getting such a load to 
look "just resistive" under high frequency AC conditions!!  We have talked 
of a high voltage AC probe (150kV, 10MHz) on Paul's TSSP list.  The design 
of such a beast is horrific!!  (we decided the Jennings style of shielded 
HV probes is the best method but with oil not vacuum) In this case, the 
resisitive loads are for DC or maybe 60Hz only.  I will add a scope probe 
output to my cap but there are no great claims to accuracy due to the 
intrinsic capacitance of the structure and the inductances Jim 
mentions.  The scope thing is just sort of a "toy".  It might be useful to 
Paul's work if the physical structure can be fit to his models, but just a 
toy right now.

Cheers,

         Terry