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RE: Home made capacitors rule..sort of



Original poster: "John H. Couture" <couturejh-at-mgte-dot-com> 


Philip -

I have Wavetek DM27XT and Beckman DM25L multimeters that test capacitance.
They are rated +/- 2% and I have found them within 1% when I tested them
with General Radio capacity standards. They both measure down to 1 pf
capacitance, however, below 100 pf the accuracy is very poor. I should add
that even bridge testers do no better. I use resonance tests with frequency
counters for these low capacities.

John Couture

-----------------------------------

---Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Sunday, December 07, 2003 1:12 PM
To: tesla-at-pupman-dot-com
Subject: Re: Home made capacitors rule..sort of


Original poster: "Philip Brinkman" <peeceebee-at-mindspring-dot-com>

      After looking at many of the capacitor designs out there, I feel the
home made stacked plate design is the easiest, cheapest, and strongest
design out there. I don't understand why so many people say the MMC design
is easier... soldering together 20 or so caps, assembling the base board,
resistors, wires, etc.and spending all that money does not seem easy to me.
     I built a "notebook capacitor" using extra heavy duty plastic notbook
sheet protectors (5 mils thick) and aluminum foil sheets. Each page was
filled with mineal oil, an extra page between each plate gives 4 layers (20
mils) of high quality plastic insulation, I say high quality because these
sheet protectors are much stronger, with fewer defects than plastic
sheeting from the hardware store, and far better quality than "zip lock"
bags I've used in the past.
     I bet the assembly of this capacitor was faster than many MMC's out
there.... total cost about $25.
    If a cell, or several cells fails, it is easily removed and replaced with
a new cell (my new design has not failed yet). Cells can be added if
needed. My design has 24 plates, running a 15000 volt 30 ma NST at full
power. I get arcs to ground now over 2 feet, corona about 1 foot. Still
fine tuning the beast...
     I guess the biggest weak point of home made capacitors is never knowing
the exact capacitance. Does any one know if there is a EASY way to measure
the capacitance of one of these? Will a hand held multimeter with
capacitance meter on it work?