Re:Re: M.M.C.

["Al Hassick" <uncadoc-at-juno-dot-com> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Hi Terry.  I have never used any math to design any of my coils.  I just
used trial and error and a common sense approach.  So I have no idea what
frequency my coil operates at.  I just like to experiment, this is the
fun part!  The spark gap I currently run is a R.Q. type.  It has 8 of the
3/4" copper pipe couplings bolted into a 4" abs pipe coupling.  The gaps
were spaced at .030 each with a automotive feeler gage.  That gives seven
actual gaps, and they cover an area of roughly 2/3 of the interior of the
abs coupling.  It is quenched by a 4" 120 volt muffin box fan epoxied to
one end of the abs coupling farthest away from the working gap which is
mounted flush with the other end of the coupling.  Now, as far as the
value of the caps,  I really am not sure about that,  this is why I am
enquiring about them,  I want something to do a sustained 60 minute run
on my 8" coil without them melting down.  The coil is 18ga. iso
fluorethane insulated or something like that prime solid motor wire,
there is 7 and 1/2 pounds of this wire wound on the coil which is a
cardboard concrete tube, cut down to a finished height of 25".  The wire
covers the entire surface of the 25" form completely from end to end.  I
just wound the wire until it ran out and then cut off the remainder of
the tube, which started out as a 36" cutoff from the concrete form.  The
tank uses two unpotted modified neons with two shunt plates removed from
each tranny 1/2 section, they are allanson 60ma 15kv neons.  The tank is
wired with 18ga. stranded silicon 40kv wire, it has two 3" ferrite donuts
wound with 14ga. stranded thhn wire on the entry and exit of the spark
gap.  The tranny outputs go through two 1" pvc tubes 12" long wound end
to end with one layer of 23ga. scc solid wire for protection.  Both
tranny outputs also go directly into a single beer bottle cap wired to
each paralled high volt output and then to the dedicated Tesla ground to
which the bottom of the secondary is also attached. That is my protection
circuit for the tank. The primary is flat wound 14 turns with 3/8" refrig
tube, spaced about 5/16 to 3/8 inch between each loop. So what type of
indestructable mmc would you recommed for this coil?  I have no certain
idea about the caps I want, since coilers seem to use a variety of them, 
this is what I want to know.   I just want the best possible arrangement
of caps/resistors to mount on my solid sheet of nomex board.  Which I
will cut and drill to suit the caps/resistors I use.  Thank you.  Al.

On Wed, 06 Sep 2000 13:28:58 -0600 "Tesla list" <tesla-at-pupman-dot-com>
writes:
> Original poster: Terry Fritz <twftesla-at-uswest-dot-net>
> 
> Hi Al,
> 
> 	I need to know some details:
> 
> What frequency does you coil run at?  Poly caps heat more at higher
> frequencies so they have to be sized to the frequency if one is 
> trying to
> be really careful.
> 
> What type of gap do you have.  The RMS current is directly 
> propartional to
> the firing rate.  I assume the firing voltage is about 21kV.
> 
> If you know the values of cap you want that helps ;-))
> 
> There is a simple BASIC DOS program below that can do the 
> calculations for
> you too:
> 
> http://users.better-dot-org/tfritz/site/programs/MMCCALC2.ZIP
> 
> The numbers change a bit depending on the exact type, value, and
> manufacturer of cap you use.  I use ones from DigiKey which I know 
> well,
> but there are all kinds of great caps. 
> 
> Check the links in these posts out and let me know the data about 
> your coil
> and we can work the numbers.  If the voltage peak is within the DC 
> rating
> and the RMS current does not heat them more than 5C, they will last
> thousands of hours...
> 
> At 11:40 AM 9/6/00 -0400, you wrote:
> >Hi Terry and all.  Terry, what kind of polypropylene caps would you
> >recommend for a coil using two paralleled 15kv-at-60ma modified neons 
> that
> >could sustain a minimum of a 60 minute run?  They draw 16 amps at 
> full
> >output but limited by 4500w 240v water tank elements.   At full 
> blast
> >with no resistive load they will pop a 20 amp breaker after about 
> 10 to
> >15 minutes, I guess from the heating effect on the 20a. line.  So I 
> run
> >them on a separate 30a. 10 ga. 120v. line to get sustained runs.    
> 
> >Thank you  Al.
> >
> 
>