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Re: cap specs or non-specs
>>From bigr-at-teleport-dot-comFri Jun 21 12:19:30 1996
>Date: Thu, 20 Jun 1996 23:22:47 -0700
>From: bigr-at-teleport-dot-com
>To: tesla list <tesla-at-pupman-dot-com>
>Subject: cap specs or non-specs
>Since 80% of email I've received from this group has been about
>capacitor specifications, I thought I'd weigh in on the discussion-
>even though in my own setup- a solid-state driver: the only resonant
>caps are in the oscillator circuit (a mylar 4700pf unit, and not
>really resonating: a relaxation osc) and the parasitic series resonant
>C from the coil to ground.
>What I was getting at in my previous post is that it appears that
>there really is no specification at all in regard to these commercial
>caps that are rated to work with an AC transformer of X volts-rms.
>Although the manufacture specifies that the cap will work with X
>volts, it really doesn't mean anything since, as I showed, and others
>confirmed, under some conditions the real voltage across the cap can
>be many times the rms transformer voltage. (and confirmed again by
>the real world explosion of a very expensive cap)
>I imagine that the situation results from a defense contractor selling
>to hobbytists. In my experience in the semiconductor industry, in
>most cases the cost of testing and characterization of a mil device
>was many times the actual value of a similar commercial device.
>To many of you I imagine I am just stating the obvious; but to a
>person inexperienced in the world of component vapor specs, maybe you
>might save several hundred dollars that you could pay toward rent- or
>some other trivial expenditure. :) :)
>I have worked as both a product engineer and a test engineer, so I am
>proposing that this group form its own specification for caps. This
>can't be that difficult, and might extend the state-of-the-art. Who
>knows, the next "black budget" gov. project might reference telsa
>group cap specs for some exotic cap application.
>Finally, I am wondering about home built caps. Tesla used bottles
>filled with salt water (no- not the cheapo seamed bottles of today,
>but real blown ones made out of decent quality glass- would probably
>be impossible to obtain except by custom manuf. by some glass blower)
>Using modern materials, maybe I am reinventing the wheel again, but
>what about polypropylene film caps using dieletric sandwitched between
>some thin brass or other metal and compression adjusted like in the
>small trimmer caps. It seems like an oil impregnated version of this
>would be ideal and cheap for amateur to build. Poly sheeting is avail
>in many thicknesses from hardware stores.
>Best Regards. Rob.
Rob,
I think your idea that The Group establish a set of realistic technical
specifications, and perhaps an appropriately robust recommended test procedure
(my addition) is a worthy one and deserves thought and comments from
the most experienced amongst us.
Creating such a 'new' pushing the corner of the envelope
specification may however be a double edged sword which we might find pop
out of Pandora's Box! Any technological country which figures out how to
make really big Tesla Coil survivable capacitors could conceivably
win the SDI cold war. If it were not a nation friendly to my own, I
would be worried, for I appreciate the large scale potential of some
of Tesla's large scale ideas if actually implemented in large scale working hardware.
The other side of this sword becomes equally great if the nation is ours and we
live to see government surplus polypropylene and silicon oil pulse
capacitors rated at a million volts start showing up on government
surplus bid sheets!
Your idea of a flat, stacked poly sheet capacitor is of course not
new, but the idea of squeezing it with adjustable pressure from a big
screw in the middle under oil is certainly new to me, and an interesting concept.
Interestingly enough, it is also in concept, a technique known widely
to work well and thusly reinforced in common knowledge. In fact, the concept
of being screwed by an external force for external benefit is fundamental to our
understanding of our terrestrial universe.
I think an adjustable Tesla capacitor via screw derived compression force
under oil is an idea equally deserving of Group feedback.
Rob, I am not making light of your ideas, I do think they deserve
serious thought. Wadda'yall think?
Happy coiling, unlimited electricity, basic food and requisite sleep, rwstephens