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RE: Toploads that bite

Adam: I would agree that the MMC be enclosed but perhaps slightly vented to
encourage circulation if warm.
The question: How to determine the correct value of a bleeder R. Base it on
the total voltage of the MMC? And if so, to achieve what current?

Reason I ask now is that I've just received my 14x3   .047mF/1600 from D&M.
and MMC construction starts very soon.

Ted

Subject: Re: Toploads that bite


Original Poster: "Adam" <adamsmith-at-mediaone-dot-net> 

> Ralph Zekelman wrote:
> 
> Viola: a safety bleed that I can simply slip over the MMC terms
> when  I am playing with the wiring.

I thought it was musical instrument.

> Since the primary capacitor is connected across the secondary
> of the HV transformer,  doesn't it always have a discharge path thru
> the transformer secondary?

If you've got 100% good solid connections, and if the transformer secondary
is intact (no secondary burnout or open circuits), then yes, the capacitor
would discharge quickly through the transformer secondary. I've always let
my primary caps just discharge through the transformer (and in my case
through chokes, resistors and the primary coil itself), and they've never
had any charge left on them...

However, it is always better to err on the side of safety, and not make
these assumptions! Any safety features you can add to your coil that do not
significantly degrade performance are certainly worthwhile. I'm considering
adding bleeders across my main caps.

Lastly, special consideration should be given if you're using a non-enclosed
MMC, where you coil potentially come into contact with individual component
capacitors. Some of the caps may retain charge after a run, for various
reasons including but not limited to: bad solder connections, blown caps,
etc. I would enclose the MMC in an insulative case, exposing only the end
terminals to the outside world, and put a bleeder resistor across them
permanently (in addition to the resistors across each constituent cap).  I
really see no reason to leave an MMC open-frame.

Adam
adamsmith-at-mediaone-dot-net
http://people.ne.mediaone-dot-net/adamsmith/tesla/index.html