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how can I build a high voltage capacitor? Answered


How high ?

Double sided PCB material works pretty well to a couple of kV

Keep reading, its nearer 32kV, if you use 1/16 FR4.

what does pcb stand for isnt it prototyping circuit board?

PRINTED circuit board - but in this case, unetched PCB, excelp Its helpful to etch a 10mm border around the edges, to prevent flashover.

An excellent suggestion keep arc length long for the high voltage copper plates.
FR4 has a Dielectric strength of 20 kV/mm
o.063 FR4 is about 17.1pF per sq inch brake down 32KV.
o.032 FR4 is about 33.7pF per sq inch brake down 16KV.

FR4 is the manufacturers name for the fiberglass .

thanks i didn't know you really are a pro

Do you have access to any ionic conducting liquid such as boric acid or sodium borate? If not you won't be able to build a high voltage cap. A quick look at the Wikipedia article about electrolytic capacitors will tell you what they are made of. 

Google "Leyden jar. You'll get many ideas from the result.