Re: A4 Poly-Pockets for Capacitor?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "rheidlebaugh by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rheidlebaugh-at-zialink-dot-com>

Jolyon: I suggest you NOT try that idea. The poly pockets are much to thin.
I use 12 layers of 4mil thick poly for my NST 15/60. Your choice of coil is
higher in voltage than my NST.I have more power, but less voltage. You will
be working with 30 to 36 Kv.
   Robert  H

> From: "Tesla list" <tesla-at-pupman-dot-com>
> Date: Tue, 13 Aug 2002 07:43:04 -0600
> To: tesla-at-pupman-dot-com
> Subject: A4 Poly-Pockets for Capacitor?
> Resent-From: tesla-at-pupman-dot-com
> Resent-Date: Tue, 13 Aug 2002 07:57:42 -0600
> 
> Original poster: "Jolyon Vater Cox by way of Terry Fritz
<twftesla-at-qwest-dot-net>"
> <jolyon-at-vatercox.freeserve.co.uk>
> 
> I am thinking of making a primary capacitor using A4-size poly-pockets (these
> are thin plastic sheet pouches used to keep documents in -usually with a row
> of
> holes down one side for the spring-binder)for the dielectric and aluminium
> foil
> for the capacitor plates.
> 
> My anticipated method involves zig-zagging each foil between every two
> poly-pockets at rightangles to the other foil.
> 
> I have measured the capacitance of a single poly pocket capacitor this is
> circa
> 1.5 nanofarads  with the dielectric sandwiched between two plates I am
> doubtful
> about the dielectric strength however -perhaps several
> capacitor "units" will have to be stacked in series to increase the voltage
> rating.
> 
> The capacitor is to be DC-charged by a rectified ignition-coil setup (driven
> by
> 555 via electronic ignition) powered from 13.8VDC supply.
> A value of 20 nanofarads would be desirable as I have found this is necessary
> to produce 6 inch sparks with my TC- so far I have been using 2 litre
> pop-bottle SWC's and these fail often- for this reason I switch on the power
> for the minimum time I need to observe the effect and turn off again -the
> purple corona that seethes around the outside of the bottles does not take
> long
> to find a weak spot!
> 
> Pop-bottles are polyethylene terepthalate (PET) -what is the probable
> breakdown
> potential for this and what is it likely to be for a polypocket- only I
> underestand ignition coil produces voltage in region of 20-40KV.
> 
> The capacitance per bottle is 3-4nF against 1.5 nF for a polypocket- what
> about
> cutting open a bottle and laying the PET flat and interweaving with foil as
> described?
> 
> Does anyone know if the "poly pocket/zigzagged-foil-at rightangles" method of
> capacitor construction has ever been used for a primary cap or is it a novel
> idea? has anyone used similar "stationery" materials such as transparencies
> for
> capacitors -if so, what are the best types?
> 
> Or is it difficult and just a recipe for failure?
> 
> I am also considering building an MMC and I understand the capacitors are
> expensive -however would this this be better value for money?
> 
> 
> 
> 
> 
> 
>