Re: Warning Desasterous MMC failures, Rotton caps from Mouser.

["Mike Novak" <acmnovak-at-xxxxxxxxxxxxx> (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

Garry,
How far apart are your caps? With strings of 15 each, the individual caps
shouldn't see more than 1kV each. So, unless they are spaced <2mm, they
should not arc to each other... However, as far as the bleeders go, I think
John M.'s design for MMCs is best. Use 1/4" thick plexi or lexan and put the
bleeders beneath the caps.  I use those hosfelt snubbers which I mounted
that way with a spacing of 1/4" and it works flawlessly. Soldering these was
almost too easy. I used small dabs of 100% silicone caulk to hold each cap
in place, then I bent their leads down and tied all the bleeders in. After
that, it took about 5 mins per string to solder.
It seems to me $85 is a heck of alot to pay for 6.6nF. Maybe you should use
these:
http://www.illcap-dot-com/FilmRadialDetails.asp?FilmQuery_Action=Find('PARTNUMBE
RID','10771')&FilmQuery_Position=FIL%3ASERIESID+%3D+%2734%27ORD%3AABS%3A43KE
Y%3A10771PAR%3A
I bought these in my bulk buy earlier this summer. They cost 1.45 each, they
have a dv/dt of 4200, and they have a hefty expoxy potted package. Others
who bought these got a dramatic increase in streamer length when switching
from saltwater caps to these. However, the minimum order is 25 caps as I
recall, so you'll end up paying about $35-40 for a box. You could get two
strings of 5.5nF -at- 24kVDC for half of what you paid for those crap mouser
caps. I suggest you write mouser a nasty letter and move on. Heck, you could
even sell the other string of caps if you don't want them.
Just don't give up after a setback such as this. Please reconsider your
removal request, we're in this togather remember.
Hope that helped,

-Mike

mailto:acmnovak-at-msn-dot-com




> Original poster: "Garry F." <garryfre-at-pacbell-dot-net>
>
> I purchased some 2kv polypropelene .033 uF caps for an MMC of three
strings of
> 15 caps for a total cost for the caps of $85 and they stink to high
heaven!!
> The caps were substituted by rolled tube type caps of equivalent
properties but
> these caps differ greatly from the usual caps in that the shell is a white
> gladwrap thin plastic that allows arching between the caps unless the caps
are
> separated by some sort of insulation.
>
> When I plugged in the MMC, a cap blows every three seconds a cap would
blow,
> Now I no longer have enough caps to repair the MMC and I would have to
order a
> minimum of 50 more caps from Mouser.
>
> I want to warn people not to use tube type caps unless you isolate each
and
> every cap from the accompanying bleeder resisters and caps next to them.
>
> I am unwilling to waste any more money on trying to make this tesla coil
work
> for a reasonably good run. I have a cap Terry Fritz sent and it works fine
> except it does get hot fast.
>
> This final last frustrating and discouraging loss and disgusting failure
of a
> cap marks the end of my hobby as a tesla coiler.
>
> I request removal from the tesla list effective December 1st.
>
> Thanks for all the good advice, but I have had quite enough torture trying
to
> get something that lasts and I have to call and end to this spending money
like
> I was bill gates only to get such rotton results.
>
> Thanks especially to Terry Fritz. Happy coiling and may you walk in the
light.
>
>
>
>