RE: MMC advice

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz> 

Hi Chris,

On 2 Oct 2003, at 6:45, Tesla list wrote:

 > Original poster: "Mudford, Chris" <chris.mudford-at-agresearch.co.nz>
 >
 > Thanks everyone for the replies re MMC.  It appears to be an area which
 > continues to provoke differences in opinion.  So, to stoke the fire
 > again.  If you are looking at a 2 series MOT with voltage doubler that
 > is producing 13000 V peak (pulsed DC) can I use the capacitor DC rating
 > or is there a hidden complication somewhere?

It is a case of horses for courses. If you want to spend as little
money as possible, then build a cap with marginal ratings but expect
trouble somewhere along the line. If you're like me, build it with
conservative ratings and forget about it.

 > Also, as I will be building a new MMC utilising my WIMA 68 nF, 1600 VDC,
 > 650 VAC with 9 per string and 4 strings for 30 nF (1.9 x resonance) is
 > there a problem with producing a circuit board to mount them as they
 > only have short leads (~5mm)?

All my MMCs are built on PC boards. Sweet as.

 > The above MMC should also be suitable for the above MOT power supply re
 > voltage, but, what level of capacitance would I be looking at?  Of
 > course I could make 2 MMC's such as when I decide to go to a MOT supply
 > (probably if my NST gives up) I can run the 2 in parallel.

Expts to determine the best capacitance for a particular coil _prior
to building the final cap_ is where the cheap option is useful. Like
a single string run single shot or in very short bursts with the coil
more-or-less in tune.

Malcolm