Re: Doorknob caps...

Hi Chris,

Your cap has got to be an electrolytic.  That is the only thing you are
likely to find with that much capacity, in that voltage, in that small
size.  They are DC only caps.  Two caps of equal voltage and condition
could be wired minus to minus and subjected to around 100 volts AC
(across the plus terminals) with a capacity of ~235 uf.  (this may not
work too well on electrolytic caps that have been sitting around for a
long time).  Connect an electrolytic to AC and they either vent or

Doorknobs are usually larger in diameter than length (hence the name). 
The ones suitable for high currents, will have threaded studs or tapped
holes at the centers.

Some really old TVs did have small, low capacity (uuf range) high
voltage, doorknob style, caps that can be used in small TC circuits. 
The ones I remember were about an inch diameter, inch long, and had 6-32
studs or tapped holes.

Hang onto the flyback.  The open core style (without everything potted
in a lump of epoxy) make very good 10 to 30 KV, 20 KHZ, generators with
a couple of transistors driving them.  There are circuits on many of the
HV pages.  The HV can be rectified and/or voltage doubled for all kinds
of inteeresting HV electrostatic experiments.  The AC output can give
you small brush discharges (1/4" to 2") or turn an ordinary light bulb
into a plasma globe.

take care
bob misiura

Tesla List wrote:
> Original Poster: "chris morgan" <crmorgan-at-hotmail-dot-com>
> I took apart an old Zenith the other day and the only thing close to HV
> caps I could find was 2 caps rated at 470uF and 200V (dosn't say AC or
> DC)Are these doorknob caps?  If not, what should I be looking for?
> These look like rolled caps, and mesure 1" diameter by 1 1/2" high.
> Also, what can I do w/ the flyback transformer?
> Chris, via the inter-thingy
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