[TCML] TC Newbie

[Lau, Gary]

According to my sources, dielectric constant of PET is 4.0, while polypropylene (PP) is 2.25.  So from that perspective, PET is superior.

But the more significant measure of merit for a capacitor dielectric (and often overlooked by newbies) is dissipation factor - how lossy it will be.  At 1 MHz, PP is 0.5, while PET is 20.  Higher numbers are bad here.  The Azom.com table you cite for PET indicates a very low dissipation factor at 1Khz, but no mention of 1MHz.  Being in the Mylar family, this is not surprising.

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: tesla-bounces at pupman.com [mailto:tesla-bounces at pupman.com] On
> Behalf Of Dave Halliday
> Sent: Monday, December 08, 2008 2:00 AM
> To: 'Tesla Coil Mailing List'
> Subject: RE: [TCML] TC Newbie
>
> Probably meant PET or Polyethylene terephthalate - soda pop bottles.
>
> http://en.wikipedia.org/wiki/Polyethylene_terephthalate
>
> Has a dielectric constant of 3.0 - not good...
>
> http://www.azom.com/details.asp?ArticleID=2047
>
> Dave
>
> > -----Original Message-----
> > From: tesla-bounces at pupman.com
> > [mailto:tesla-bounces at pupman.com] On Behalf Of David Rieben
> > Sent: Sunday, December 07, 2008 5:41 AM
> > To: Tesla Coil Mailing List
> > Subject: Re: [TCML] TC Newbie
> >
> > Hi Gary, all,
> >
> > I'm afraid that I don't recognize the acronym "PETA"
> > in reference to plactic. The only thing that I can think
> > of for this one is "(p)eople for the (e)thical (t)reatment
> > of (a)nimals" ;^) I know "PE" is polyethylene and HDPE
> > is high density polyethylene but I just can't figure out
> > what the "TA" means. Someone please enlighten me :^?
> >
> > David
> >
> >
> > ----- Original Message -----
> > From: "Lau, Gary" <Gary.Lau at hp.com>
> > To: "Tesla Coil Mailing List" <tesla at pupman.com>
> > Sent: Saturday, December 06, 2008 11:25 AM
> > Subject: RE: [TCML] TC Newbie
> >
> >
> > PETA is a very lossy dielectric.  But even beyond that, I
> > think that plastic
> > bottles are not a good choice for bottle caps.  Any time
> > there is corona,
> > visible or not, that will rapidly degrade and melt a plastic
> > dielectric and
> > result in a puncture, and that is true regardless of whether
> > or not the
> > plastic is a lossy dielectric.  Glass is much more resistant
> > to corona than
> > plastic, so glass bottle caps can survive even with corona.
> > Corona is the
> > reason that commercial plastic dielectric HV caps are
> > constructed as many
> > lower voltage units in series - so that the voltage across
> > each section will
> > be below the "corona inception voltage".
> >
> > Regards, Gary Lau
> > MA, USA
> >
> > > -----Original Message-----
> > > From: tesla-bounces at pupman.com [mailto:tesla-bounces at pupman.com] On
> > > Behalf Of Jim Mora
> > > Sent: Saturday, December 06, 2008 1:25 AM
> > > To: 'Tesla Coil Mailing List'
> > > Subject: RE: [TCML] TC Newbie
> > >
> > > Hello,
> > >
> > > I wonder if 1 or 2 liter PETE coke (or whatever) clear
> > plastic bottles
> > > could
> > > be used. PETE has a very high dielectric strength and
> > puncture resistance
> > > and is thin enough to really raise the capacitance and
> > lower the weight a
> > > bit. Maybe PE bottles which are thicker though.
> > >
> > > Jim Mora
> >
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