Re: The manufacture of capacitors
Tesla List wrote:
> >From rwall-at-ix-dot-netcom-dot-com Tue Dec 10 21:48:01 1996
> Date: Tue, 10 Dec 1996 15:58:37 -0800
> From: Richard Wayne Wall <rwall-at-ix-dot-netcom-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: The manufacture of capacitors
> You wrote:
> >Re: Oil dielectric capacitors
> > Why not go the whole way and eliminate the solid dielectric
> >material between the plates? I have an article in an old (circa
> >1921) QST describing an 0.01 mfd, 30 kV capacitor using only oil
> >as the dielectric. Quite a construction job to get the plates
> >flat enough to avoid excessive average spacing, but genuinelyh
> >genuinely indestructable!!!!!! By the way, this one worked at
> >the "special" wavelength of 350 meters, or about 857 kHz, so the
> >inductance must have been pretty small.
> > Why doesn't some get ambitious? Or, more likely, will
> >someone who HAS been ambitious describe his results.
> >Ed Phillips
> I've put some big cheap hamfest air variables in plastic cases and have
> done just this by adding oil. Voila! An oil variable cap. The
> capacitance increases at a ratio of about oil k over air k (1). But
> not as much as you might think. The larger air caps can often be
> disassembled and reassembled with smaller washer spacers so the oil gap
> can be made smaller. But, a point of deminishing return appears as oil
> break down voltage is somewhere around 5 kV. I thought of using SF6,
> but its not worth the time and expense.
> If you make a fixed oil cap you may consider several sections in
> series. Also, the oil has to be boiled or otherwise desicated and the
> cap has to be sealed against moisture.
> Getting the right design and getting rid of all the poly, air bubbles,
> vacuum etc., would a boon to home cap builders. We certainly know how
> to build salt water caps, so why not switch it around and use a liquid
> dielectric rather than solid and metal plates rather than salt water
> Let us know how it works out if you build one.
I can't believe the flurry of interest in this old method!!!! Hey guys,
I have made several of these and own a commercial sprague unit! You
think it is a waste of time and bucks to build the big rolled poly
caps?!!! You ain't seen real waste yet!! Build one of these and you
Save a lot of time and trouble. Go to the dump and find the largest
disgarded electrostatic percipitatior or "smoke eater". Dismantle to the
percipitator plate group. Buy a 50 gallow trash barrel. Splash in 150
pounds of Diala AX oil and enjoy your .007ufd 10kv cap with your 100 watt
micro tesla coil power by a 5KV 30 ma neon transformer!!
Good luck with this one guys!
By the way, the oil dunked air variables is a great idea and works
incredibly well for fine tweeking of smallish systems. I have made one
and Lou Balint of PA uses huge units in 7 gallon pails to fine tune
magnifier transmission lines!! I would never advise the use of oil units
for main caps though. (unless you have the money, time, and the space)
Richard Hull, TCBOR