Re: The MMC debate continues . . . . . .

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: otmaskin5@xxxxxxx 

I have only been into coiling for a little over a year & have gotten 
shocked 2 different times from unplugged coils.  Once from one of the 
caps in the MMC on a small coil - I didn't have bleeder resistors in 
that case.  That shock wasn't too bad, just a little unsettling that 
it happened.

The other time I was doing some work on the Terry filter on my larger 
coil & got a much stronger shock.  That one shook me up a bit.  I'm 
not sure if the discharge was from the caps on the Terry filter or 
from the MMC which discharged through the Terry filter.

I now have bleeders on the MMC for my larger coil.  Which leads me to 
a question...do people typically use bleeders on Terry filter 
caps?  If so what values is the recommended value?

Thanks, Dennis Hopkinton MA


-----Original Message-----
From: tesla@xxxxxxxxxx
To: tesla@xxxxxxxxxx
Sent: Sat, 17 Feb 2007 12:34 AM
Subject: The MMC debate continues . . . . . .

Original poster: "resonance" <resonance@xxxxxxxxxxxx>


I have played with AC powered TCs for nearly 45 years now and I have 
never ever had a shock from a small, medium, or large TC that runs on 
AC. I recall Ed Wingate has issued warnings where he has had bad 
experiences with dual cap "equi-drive" systems, but I have not used 
this type of drive so really can't comment on it.

Some of the VTTCs use rectification and Terry's Piranha MOT coil uses 
rectification with the MMCs so you would certainly always use 
bleeders on this design.

Terry F. has also reported some storaged charges on MMC caps so I 
certainly don't want to discourage anyone from using the bleeders, 
but I have never found any charge on some of the smaller MMC style 
commercial coils we produce. Both Matt and I have never received a 
shock from an AC MMC coil nor have any of my approximately 60 
customers of MMC small coils. Many of these units are used in science 
museums 7 days per week and sometimes up to three performances per 
day. The operators and techs put the coil away and usually clean them 
at least once per day and so far, no reported shocks from cap 
storage. These are all strictly NST and AC powered coils.

Best to error on the side of caution if you have any doubts.

I would suggest using a small ground probe with an NE-2 neon bult to 
"test" the caps and check them after use in your particular coil 
design. If after dozens of operations, and no stored charge found, I 
think it would be safe to discontinue such tests.

Be safe!

Dr. Resonance

>Dr. R- as I recall you told me once that you don't use bleeders 
on >MMC banks and they aren't necessary. Have you changed your view 
or >does this just apply to VTTC coils?




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