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RE: [TCML] Spark gap assembly, acrylic?? and toroid size



Lexan is the trade name for polycarbonate.  Plexiglas is the trade name for acrylic, and is more likely to crack.  These are two very different materials.

While I agree that neither is a good first choice for an RSG disk, one must consider the specifics of the particular gap.  If it is with just a low power NST, and if the rotating electrodes are large enough to keep their temperature rise in the area of the disk to a modest level, then a Lexan disk may be OK (acrylic is just too brittle).  But when building an RSG, a substantial amount of common (and uncommon) sense is needed, and is probably not the best choice for a newbie.

For low (maybe medium?) power, I really recommend the propeller gap RSG configuration, as it eliminates the disk entirely.

Regards, Gary Lau
MA, USA



> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of DC Cox
> Sent: Thursday, July 17, 2008 1:55 AM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] Spark gap assembly, acrylic?? and toroid size
>
> Don't use Lexan (acrylic) for a RSG.  It may soften and your rotating
> electrodes may strike your stationary electrodes, exploding in sharp shards.
>
> Not a very good idea.
>
> Dr. Resonance
>
>
>
>
>
> On Wed, Jul 16, 2008 at 3:51 PM, John Matok <jmatoknoon@xxxxxxxxx> wrote:
>
> > Scot,
> >
> > You said that Lexan is good for low temperature applications, but is it
> > suitable to use in a spark gap?  On the website that I provided, the plans
> > said to use Lexan.  How hot can the Lexan get if it's not in direct contact
> > with the copper?  How hot do spark gaps get in general?
> >
> > Nicholas Goble
> >
> >
> > On Wed, Jul 16, 2008 at 7:56 AM, bunnykiller <bunnikillr@xxxxxxx> wrote:
> >
> > > Hey John...
> > >
> > > I havent built the spark gap as shown with the aluminum holders but I did
> > > build the one without the aluminum... I had it running on a coil that was
> > > powered by 4 15/30 NST's in paralell and it worked quite well. Eventually
> > > tho, I had to clean the surfaces of the tubes due to oxidation etc. I
> > found
> > > that adding a small fan to the unit increased its quenching too... see
> > link
> > > below for pictures
> > >
> > > http://members.cox.net/bunnikillr/sprk.htm
> > >
> > > As far as plastics, obtain a cutting board ( white plastic 1/4"+
> > thickness)
> > > from places like Wal Mart etc. Usually they are made of HDPE
> > > ( Hi-Density-Poly-Eurathane).
> > > acrylic,polycarbonate,lexan,plexiglass are ok for low temp applications
> > but
> > > can be either brittle or "gummy" when machined ( altho Lexan is great at
> > low
> > > speeds and cuts nice)  normally clear in color
> > > Perfboard isnt really a plastic its more of a laminate/epoxy combo
> > > MMC's are good on either HDPE, perfboard or G-10
> > > Sparkgaps work best with G-10 due to the heat produced
> > > Primary coil, once again HDPE
> > >
> > > Toriod size "normally" is about the same over dia = to length of
> > secondary
> > > and smaller dia =to a bit less than secondary dia.
> > > example, you have a 20X4.5    toroid would be good at  18-20 X 3-4
> > >
> > > a second primary on a different power supply... ummm I would say no.  a
> > bi
> > > level primary on a single supply would work... someone on the list has
> > done
> > > so but I dont remember who did it... I dont know if it increased output
> > tho,
> > > seems to me it wouldnt..
> > >
> > > A magnifier is a "2 coil system", it has a very tight coupling coeficient
> > > on the 1st primary/secondary coil which drives a second secondary and
> > > toroid. Special design considerations must be made to get this type of
> > > system to work properly. Antonio has some great literature on this type
> > of
> > > coil...
> > >
> > > Scot D
> > >
> > >
> > >
> > _______________________________________________
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> > Tesla@xxxxxxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
> >
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