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Re: Caps.
-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Wednesday, March 22, 2000 10:37 PM
Subject: Re: Caps.
>Original Poster: "Mark Fergerson" <mfergerson1-at-home-dot-com>
>
>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?
I have ranted about it every so often. I looked up some ceramic companies
and found I could by the raw BaTO3 powder for around $20/50 grams (IIRC) or
I could by a few Kg's of BaCO3 and TiO2 and try to fire the frit. I'm not a
ceramics artisan, have no desire to become one, have read that oxygen during
the firing process affects the character of the ceramic- dielectric
constant, hysteresis, losses, et.
Now even if you use commercial peizo caps, you still have ultrasonic
considerations. The piezo ceramic stores all that energy as stress, and your
cap can end up looking like a massive inductor at reasonance! That's right,
the quartz crystal in your wristwatch has an effective inductance and
thousand of Henries, IIRC! Thats because energy as stress turns into
vibrational momentum (effective inductance). So you must design your
capacitor with acoustics, mechanics, in mind.
Having said all that, if you can do it you will have one heck of a cap!!!
;-)
>> You could stack a few metal plates in a plastic container and fill the
>> gap between them with the dielectric powder?
Fracture a piezo disk with over-voltage and watch all the pretty blue corona
and smell the ozone...
> 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.
There is some web site that shows a Marx generator with piezo caps. Of
course, thats intermittant pulse operation.
Scott