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Re: Another MMC cap candidate (UK)

This post has raised a few questions in my mind...

I am about to make a MMC for my 4" coil with 3 x 15/30 NSTs. Here in
Australia these same caps listed below (from farnell) cost $1.45 each (up to
25), and being a 16 year old i am hardly "in the money". Would i be
presenting too much stress on these caps to run them in a string of 10
(1500v ea) for total of 15Kv DC rating from 15Kv (AC) NSTs? Also, If
something went wrong, would i be likely only to blow one cap, one string, or
the whole lot?? I'll be using 4 strings of 10. Also do i still require a
safety gap?
One other question (pardon my lack of knowlege) what does MOV stand for?

thanks for your time
    Regards.
    Michael.


----- Original Message -----
From: Tesla List <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, June 22, 1999 8:57 AM
Subject: Another MMC cap candidate (UK)


> Original Poster: Alan Sharp <AlanSharp-at-compuserve-dot-com>

> Greetings all,
>
> I just tried out a string of the 0.047uF 1500V DC caps
> in parellel with my existing 0.067uF cap.
> The transformer is 8KV DC, 250mA
> The coil frequency is 200kHZ.
>
> I started with 8 in series no problem, went down to
> 6 and ran for over a minute with no apparent heating.
> I then tried 5 but I stopped the run when I thought I
> saw a flash from one of the caps - no apparent damage though.
>
> The caps are film and foil polypropylene, axial construction.
> pulse rated at 2000 V/uS.
> Made by LCR, available from Farnell (code 106-372)
> 5+ 46p (70cents) 25+ 40p, 100+ 35p, 500+ 32p
>
> I'm also using 10M equalising resistors, rated for 2500VAC (.5W)
> metal glazed. 10+ 16p, 300+ 11p,
> Farnell code (341-850)
>
> I'm probably going to use 8 in series for safety, and build 2, 8 by 8 caps
>
> I'll put off purchasing these in case any one has ideas on
> how to get them cheaper.
>
> I've got some large single sided copper clad board, is it a good idea to
> build the cap on a PCB, I can have a one inch gap for each capacitor,
> and give an inch and a half width of copper for the buses at each end.
>
> I'ld also give it a couple of coats of varnish to discourage ionisation
> on the edges of the copper tracks.
>
> Alan Sharp (UK)
>