RE- Cap setup suggestion

From: 	Robert Michaels[SMTP:robert.michaels-at-online.sme-dot-org]
Sent: 	Friday, June 20, 1997 2:38 AM
To: 	tesla-at-pupman-dot-com
Subject: 	RE-  Cap setup suggestion

T>From:  Brandon Doughan[SMTP:fiveht-at-well-dot-com]
T>Hey you HV freaks-

T> I was lucky enough to get ahold of 20 or so doorknob caps rated
T>at 30KV and 3600 pF (.0036MFD).  I'm wondering about a few things:

T>multiplier device].  On one end of the cap pairs (I've scrapped the
T>rubber off a few) there is a resistor.  I don't know the value.  My
T>question is, if I use several pair in a coil powered by a 15KV NST, how
T>will these resistors affect my capacitance?  It would be nice to keep

        The resistors won't affect capacitance a twit.  They may
        affect damn-near everything else:

                What is the resistance value of the resistors?

                How are they wired to the capacitors - series,
                parallel, multiple?

T>the added insulation of the rubber (and not have to scrap all of it
T>off!), but if the resistance is negatively affecting my coil output, as I
T>suspect, then I'm gonna have to do it.

       Don't scrape then, dissolve it  (that's the  = solution = )

T> Second question-  I know you want to have your caps rated 3
T>times your primary voltage, but I want to get away with just have my 30KV
T>caps with my 15 KV NST.  Anyone have experience with doorknob cap
T>failure?  Think I can do it?

        On voltage -- you might squeak by.

        On the use of doorknob capacitors --  to the extent they are
        useable at all in Tesla coils, they are useable intermittently
        = at best =.

                Doorknob capacitors are for dc service, not ac --
                and certainly not high-frequency ac -- and certainly
                not high-frequency Tesla ac.

        Use them on a very low duty cycle (say 10 - 15 %) and they
        may serve well enough for you to get your feet wet in Tesla
        coiling.  That's what's important.

                You can spend the required $500 - $600 (US) on
                a proper capacitor later.  Or make your own --
                Dr. Tesla did.

T> Last question-  I cracked one of these caps open and found that T>it
consists of just two plates each no more than 3 sq. ins. and about an
T>inch of that strange ceramic dielectric.  How do these get .0036MFD??
T>This must be because of the K value of that stuff.  This amazes me.

        It's that strange ceramic dielectric, barium titanate in
        all likelihood.  Amazing, isn't it.

T>Thanks for your help_  Brandon

T>PS-  Visit the High Voltage Camp at Burningman '97!

        All right, all right!  You've got all of our collective
        attention now:   What is it?

                                          High-voltage camper, in --
                                          Detroit, USA

                                          Robert Michaels