Re: first coil issues (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Thu, 16 Aug 2007 20:15:06 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: first coil issues (fwd)

Hi Drake,
The proximity between coils is 1" and fine if your at or below the 
bottom winding on the secondary. A wee bit high on coupling when even, 
so if your there, look out for racing sparks or pri to sec arcing (or 
even orange glowing spots in that vicinity).

A 1/4" copper tubing would do just fine for this coil. I personally like 
a 1.5" spacing with this coil size between inner turn primary and secondary.

The MMC, well, it sounds like you simply have some proximity arcs 
occurring (my read on it). Increase proximity. Oil will help, but isn't 
necessary. I keep my MMC's spaced by about 1/2". I think you can figure 
out what you need to do for that cap to stop the arcing. It's really in 
your hands and if it's proximity arcing, then just increase the 
proximity. Oil is ok, but unnessary unless you just don't want to change 
it all again. I can certainly understand that feeling. I started my 
first MMC in the worst possible configuration. Even blew a cap due to my 
naive considerations. I eventually mounted them on a 8" pvc cylinder 
which naturally spaced them out and has actually been very convenient 
over the few years since I've built it.

http://www.classictesla.com/photos/mmc/mmc.html

A 12/90 NST can get some decent sparks. You simply need to clean up the 
loose ends.

Take care,
Bart


Tesla list wrote:

>---------- Forwarded message ----------
>Date: Wed, 15 Aug 2007 20:07:17 -0500
>From: Drake Schutt <drake89@xxxxxxxxx>
>To: Tesla list <tesla@xxxxxxxxxx>
>Subject: first coil issues
>
>Hi All,
>I've been tinkering with my coil off and on for the past few days and just
>when i thought i had everything set, i'm having more troubles.  The first
>issue was the vaccum motor broke off its mounts, then the spark gap
>electrodes broke off and now my MMC is broken.  I mounted it on i think 1/8"
>thick plexiglass which i can now tell you cracks very easily.  I desoldered
>the caps and tried configuring them on a cutting board from walmart.  The
>leads were too short to thread through the board so they are literally
>soldered together (rather haphazardly) in strings sort of like this:
>
>
>====|
>====|
>====|
>
>the strings all terminate in about the same spot and i'm using some bare Cu
>(maybe 6 awg) grounding wire a nice fella at home depot gave me for free.
>The trouble now is when I turn the varic up to about 60V the MMC bank starts
>sparking noisily.  I cannot spot anywhere where the caps have failed or
>carbon tracking on the PE mounting board.  I tried insulating the "bus bars"
>with some PE tubing which helped a bit.  I am thinking about putting them in
>a container filled with oil to keep it from shorting out.  What do you think
>would be a good short term solution as I am sort of nearing a deadline with
>a project for school.
>
>Also- I was using I/O gauge wire in my tank circuit but it was just too hard
>to work with.  I'm now using #6 stranded wire.  Can I go smaller?
>
>What would be a good primary tap (1/4 Cu tubing)? as the one i'm using now
>was sort of lashed together
>
>Thanks a million
>drake schutt
>
>p.s.- dave do you remember it ever being sooo hot here?  I can hardly stand
>just going outside.  I sort of feel guilty for watering my grounding rod
>during a drought ^_^
>
>pps-  coil specs:
>
>xfrmr- 12kv/90ma
>cap- 0.028uf@32kv
>primary- 1/4 cu tubing, 8.5in ID, 21in OD
>secondary- 6.5" OD-  30" of #22
>top load- 6"x24" ducting/pizza pan/Al tape (slightly dented, w/6" copper
>breakout point)
>
>
>
>
>
>  
>