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

["Lau, Gary" <Gary.Lau@xxxxxx>]

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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> >
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