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Re: Caps.



Tesla List wrote:
> 
> Original Poster: "Charles Arruda" <carruda-at-channelseek-dot-com>
> 
> Has anyone tried to make a cap with a really nice powdered dielectric
> (High K) like Barium Titanate? BaTi has an K factor of about 1,200
> compared to other materials that are around 6-12. Would it load down the
> system or take to long to charge up with that much capacity?  What would
> be a clever way to make one with ordinary materials?
> 
> You could stack a few metal plates in a plastic container and fill the
> gap between them with the dielectric powder?  This would produce great
> storage capacity in a relatively small space - you could also remove/add
> dielectric and adjust the spacing between the plates (or remove plates)
> to produce a capacitor of just about any value and capable of very high
> potentials (with a good physical separation between the plates).

  Bad idea. The k you mention is for bulk material; powder will be
somewhere between the bulk value and air (unless you evacuate your
cap). You'd have to sinter the powder back to a solid before use.

  Even then, it's slightly piezoelectric. Not good.

  I also recall BaTi has a relatively low puncture voltage (can't
remember the source, though). Fine for ordinary circuit use, but HV?
No way.

  Mark L. Fergerson