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Re: Another doorknob cap question
Tesla List wrote:
>
> Original Poster: "A W" <fateagk-at-home-dot-com>
>
> Thanks for showing me that the other doorknob caps would be impractical
> to use. Now I have found a new set of doorknob caps. You all are
> probably saying, "Give up on the doorknobs!" Well, I found these: 0.004
> MF 20 KV doorknob capacitors. Is there any series/parallel configuration
> to use on these so they would work with a 15/30 NST. If I understand
> correctly. series drops capacitance but increases voltage rating, but
> does parallel increase capacitance but keep voltage rating the same? I
> am only familiar with wiring speakers in series and parallel, not
> capacitors. If you boo-hoo this idea, I will probably go with saltwater
> caps. These doorknob caps just seem to be a less messy/bulky way of
> doing things if I could find a combination that works! Anyway, thanks in
> advance for your help.
>
> Andrew
You are correct, hooking two equal capacitors in series cuts the
capacitance in half and doubles the voltage rating. Hooking two of such
series strings in parallel would give you the original capacitance with
twice the voltage rating. You haven't said whether you already have
those capacitors, or what they would cost if you bought them. If I
already had them or could get them cheap enough I'd give them a try and
see what happened. I ran a couple of 0.004 ufd, 15 kV doorknow filter
capacitors here, working with a 12 kV, 60 ma transformer. They worked
quite well, surely better than salt water capacitors woule, and finally
failed when I let the thing run for several minutes so the capacitors
got too hot to touch. I am using something similar now, except rated at
20 kV, and haven't blown one yet. Keep my run times to about 30
seconds, which is all the neighbors radios and TV's can stand at one
time.
Give it a try. What do you have to lose?
Ed