Re: Success with PP Multi-Mini Cap


I too can attest to the value of this construction technique.
Although I don't do much coil work, I have constant need for
high voltage caps of various sizes and ratings. Boy, these
things are expensive off the shelf, eh? So, I too was drawn
to this kind of design. I picked up a few hundred units
of .2 microfarad and .01 microfarad, rated 1000 and 3000 volts
respectively. Imagine my surprise when I hooked a sample
up to a high voltage DC supply and tried to destroy it. The
3kv unit took 10kv without failure. So it doesn't surprise me
that your unit can hack the coil; don't let the AC rating
deter you as it's a continous wave rating, not the case for
TC work.

Bleeder resistors? I use them, but then I also use mine
way over rated value. They do keep the voltage even
when charging slowly, you can't rely on the leakage resistance
to be even across the stack. Relying on the capacity
is only fair if the charging rate is quite fast (or AC), perhaps
it is in your application?


At 10:54 PM 3/27/99 -0700, you wrote:
>Original Poster: Gary Lau  27-Mar-1999 2035 <lau-at-hdecad.ENET.dec-dot-com> 
>Dear List:
>As I mentioned a few days ago, I have had some encouraging results with a
>new tank capacitor made from a series/parallel array of small .015uF
>1.6KVDC polypropylene commercial caps.  Briefly, I used series strings of
>sixteen of the caps for an effective DC voltage rating of 25.6KV, with a
>15KV-RMS/60mA NST power supply.
>Last night I logged over 15 near-continuous minutes of operation, so I
>wanted to declare some measure of success.  I have documented the
>capacitor on my web page at:
>I also scanned some of the data sheets from the Wima catalog that
>describe how to determine the maximum voltages one may apply to these
>caps.  Just like a bumblebee, this thing shouldn't fly, but it does!
>Performance of the new cap seems to be identical to that of my Fair Radio
>Sales cap, as well as my failed extended-foil rolled poly cap.  Only this
>one doesn't get hot, only very slightly, barely detectably warm.
>Regards, Gary Lau
>Waltham, MA USA