How to build your own Butterfly Capacitor.
The best material for the front and the back is CLEAR PVC 3 or 5 mm thick as alternative you can use GREY PVC or 2 sheets pcboard together with the copper removed .
The best material for the washers, nuts (M6) and threaded rod (M6) is brass or stainless steel,( NON MAGNETIC MATERIALS for the losses).
For the spacing of the vanes you can use 2 washers M6= ( 6Kv) or a nut M6 =( 12 Kv) if you use aluminum plate 1 mm thick.
If you use a nut then the best thing to do is remove the thread by drilling withØ 6.2 mm.
The effective area for the vanes is 11.7 cm² and with the formula
for 2 washers = (0.0885 x 11.7 cm²)/ 0.1 cm = 10.35 pF for 1 air gap.
for 1 nut = (0.0885 x 11.7 cm²)/0.2 cm = 5.17 pF for 1 air gap
Example:
If you you make a capacitor with 2 washers as spacing and you make
5 rotor vanes and 6 stator vanes then you have 10 air gaps.
10.35 pF x 10 = 103 pF + 10 pF stray capacitance = 113 pF / 2 = 56 pF
The final result is a capacitor with a value from 5 - 56 pF.
Last Update 03 December 1999. ON4CEQ Van Herck, Tony QTH: Anwerp( JO21FF ) BELGIUM.
