[TCML] Capacitor dielectric examples and Tesla coil equations
mrapol at verizon.net
mrapol at verizon.net
Wed Dec 2 14:45:10 MST 2009
I can't comment on how lossy the Chinese polystyrene caps are, but I burned
up 4 of them in quick succession. They simply burned through at some point
inside, often with a puff of soot. I run small tabletop coils too, not big
ones. The caps were rated at 20kV apiece at 4 nF.
Paul
----- Original Message -----
From: "Paul Brodie" <pbbrodie at bellsouth.net>
To: "Tesla Coil Mailing List" <tesla at pupman.com>
Sent: Wednesday, December 02, 2009 3:58 PM
Subject: Re: [TCML] Capacitor dielectric examples and Tesla coil equations
A recent comment on this list said that the polystyrene caps made in China
that are sold on eBay almost all of the time should be avoided for MMC use
because they are lossy and will heat up and fail. IIRC, this comment was
made by someone who I believe is a very highly regarded TC builder and long
time contributor to the TCML.
I'm not trying to start an argument but I would like to know which is
correct. Is polystyrene lossy or not?
Paul
Think Positive
----- Original Message -----
From: futuret at aol.com
To: tesla at pupman.com
Sent: Tuesday, December 01, 2009 20:02
Subject: Re: [TCML] Capacitor dielectric examples and Tesla coil equations
Those who may not be familiar with capacitor dielectric materials should
be
aware that many of the materials listed are lossy, and not well suited for
Tesla coil use. The best common dielectrics for low loss in TC use are:
Polypropylene, Polyethylene, Polystyrene, Ruby Mica, some ceramics,
and perhaps a few other materials.
Cheers,
John
-------------------
-----Original Message-----
From: Brian Hall <brianh4242 at hotmail.com>
To: tesla at pupman.com
Sent: Tue, Dec 1, 2009 7:37 pm
Subject: [TCML] Capacitor dielectric examples and Tesla coil equations
<snip>
=======================================================================
INFORMATION FOR BUILDING CAPACITORS:
Comments
|
Puncture Voltage |
Material Dielectric strength per Mil |
"K" (0.001 inch) |
| | |
-----------------------------------------------------------------------
Miscellaneous
-------------
Vacuum 1.0
Paper, bond 3.0 200
Paper, Royal Grey 3.0 200
Paper, telephone, treated 2.5 - 4 200 - 250 *
Paper, Parafin Coated 2 -3.5
Paper, Kraft 2.2
Oil, Castor 4.67
Oil, Mineral, Squibb 2.7 200
Oil, Mineral 2.2
Oil, Transformer 2.1 - 2.5 75 *
Rubber 3.0
Rubber, Hard 3.0 160 - 500 *
Rubber, Vulcanized 3.2 - 3.9 1
Fibre 5.0 - 7.5 150 - 180
Fibre, Red 5.0
Mica 4.5 - 8.0 3800 - 5600
Mica, Ruby 5.4 3800 - 5600
Quartz 3.8 - 5.0 1000
Quartz (Fused) 4.2 150 - 200 *
Shellac 2.5 - 4.0 200 - 400
Spar Varnish 4.8 - 5.5
Steatite, low loss 5.8 150 - 315
Steatites (Magnesium silicate,etc) 5.5 - 7.5 200 - 300
Cambric (Varnished) 4.0 2
Alsimag 196 5.7
Gutta Percha 4.0 3
Amber 3.0 - 7.0 4
Resin 2.48 - 2.57
Enamel 5.1 450
Mycalex 7.4 250
Silicone RTV 3.6 550
Wood 2.0 - 5.2
Wax (Parafin) 2.1 - 2.5 250 - 450 *
Beeswax 2.9 - 3.0
Slate 7.0 5
Barium titanate(25 C) 1200
Bariam titanate 6000
Titanium dioxide 125
Cellulose acetate 3.3 - 3.9 250 - 600
Casein, Moulded 6.4 6
Polytetraflourethylene 2.0 A
Aluminum oxide 8.7
Tantalum pentoxide 22
Glass
-----
Glass 4.8 - 10 300
Plate Glass 6.8 - 8.4
Pyrex Glass 4.8 - 10 335
Window Glass 7.6 - 7.8 200 - 250
Ceramics
--------
Cordierite ceramics 5.0 - 5.5 100
Magnesium titanate ceramic 12 - 18 150
Porcelain 5.1 - 7.5 40 - 280
Titanium dioxide ceramic 70 - 90 100
Titanium-zirconium dioxide ceramic 40 - 60 150
Plastics
--------
Bakelite 4.4 - 5.8 300
Bakelite, Mica filled 4.7 325 - 375
Epoxy Circuit Board 5.2 700
Formica 4.6 - 4.9 450 7
Nylon (lowest values of 3 types) 3.2 407
PVC (rigid type) 2.95 725
Plexiglass 2.8 450 - 990
Polyethylene 2.2 - 2.3 450 - 1200
Polycarbonate (Lexan) 2.96 400
Polyethylene Terphthalate (Mylar) 3.0 - 3.1 7500
Polystyrene 2.5 - 2.6 500 - 700
Teflon 2.1 1000 - 2000
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