[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [TCML] Capacitor dielectric examples and Tesla coil equations



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@xxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
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@xxxxxxx
 To: tesla@xxxxxxxxxx
 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@xxxxxxxxxxx>
 To: tesla@xxxxxxxxxx
 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





 _______________________________________________
 Tesla mailing list
 Tesla@xxxxxxxxxx
 http://www.pupman.com/mailman/listinfo/tesla
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla