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Re:Re: Caps Question:

Thanks Terry!  It sounds as if you have tried the doorknob caps and
traded them in so to speak for the mmc's.  What would be your principle
reason for using the mmc's?  Better spark?  More Spark?  Why did you stop
using the doorknobs?  It sounds like you are on to something that I have
yet to get a grasp on, even with my previously bad experience with the
mmc's.  Maybe I used the wrong types of caps and expected too much from
them.  Will your mmc's take a sustained run?  There is not much more time
to Halloween, and I need something good for a new fourth coil I am
building. I need two good coils running simultaneously and cannot find
any more 'good,cheap' doorknobs to fit my budget. I would need a minimum
of 30 more ganged in series for my 4th coil.   That is why I wonder if I
could use my existing 40kv doorknobs singly, so I could split up my
supply of them.  They are 'new' caps and cost $25  each.  I have 30 of
them.   Do you think that maybe that is why they cost so little and have
no coherent A.C./D.C. markings?   Possibly seconds or fallouts?    They
do work very well in series, but I am scared to try them singly unless I
can somehow find if they are 40kv A.C. rated.  Although I may never
really know.       Al

On Tue, 05 Sep 2000 17:49:30 -0600 "Tesla list" <tesla-at-pupman-dot-com>
> Original poster: Terry Fritz <twftesla-at-uswest-dot-net>
> At 03:09 AM 9/6/00 -0400, you wrote:
> >Hi Terry!  Is this the proper way to get into the website when I 
> have a ?
> >about coiling?  If not please tell me how and I will rewrite this
> >mailing.  
> Yep, this is it!
> >If it is correct, then, is there anyone on the list that could
> >tell me if my doorknob caps would be rated for A.C or D.C. if there 
> is no
> >mention of it on the cap?  The people I got them from did not know 
> the
> >voltage type.  They are .004mf at 40kv.  So, is there any unwritten 
> rule
> >that will tell one what type of volts the device is rated for when 
> there
> >is no info on the cap? Reason I am asking is because I would like 
> to use
> >the 40kv caps as singles on my coil rather than doubling them up in
> >series the way I have them now, but I don't want to fry them by 
> learning
> >the hard way that I did when I used a gang of hockey pucks which 
> were
> >15kv rated and stamped as D.C. volts on the shell.  It gets very
> >expensive in a hurry when these caps fail.  
> If they are new, you can tell be the price.  AC high Q door knobs 
> are
> really expensive.  Like $100+ each...  It is odd they are not marked 
>  I
> have a bunch of 30KV 1.72nF TDK caps that are about 1.5 inches in 
> diameter
> and 3/4+ inch thick.  If they look of very high quality and have 
> heave
> terminals they may indeed be nice high-Q types.  If anything on them 
> looks
> like rolled paper, they are definitely low-Q.
> >I had the 15kv D.C. caps
> >doubled up in series for a 30kv D.C. rating on my two 15kv -at- 60ma. 
> neons
> >and the caps still fried fairly quickly.  So should I just leave 
> the good
> >40kv caps doubled up as I have them now just to play it safe, 
> because
> >they appear to be indestructible when doubled. Has anyone else had
> >experience with this kind of setup?    I know that M.M.C. cap banks 
> seem
> >to be the rage, but my luck with them was no good when I used them 
> for a
> >sustained 15 minute run.  Have any of you coilers had better luck 
> than me
> >with M.M.C. caps on extremely long runs?  Because those little 
> M.M.C.
> >scutters get real expensive too when the banks fry.  I have never 
> had
> >just one go bad, nosiree, they would short or open up in grand 
> fashion
> >and drove me nuts troubleshooting the banks looking for the 
> culprits.   I
> >would like to try the M.M.C.'s again but would like to hear from 
> others
> >first. Is there a really prime M.M.C. cap available that would go 
> for
> >say, at least possibly more than an hour with no damage that I 
> could use
> >on my yet to be built fourth coil?   Thank you,  Al.
> MMCs will easily work but you have to use polypropylene pulse rated 
> caps
> and only run about 3 amps RMS through each string.  If they get 
> fairly
> warm, the current through them is too high and they will melt 
> internally.
> If you try MMCs again we can help with the details. 
> >
> >So many questions! So little time! 
> >
> Cheers,
> 	Terry