Re: Re - spec for my coil - comments please

In a message dated 12/8/98 10:53:11 PM Pacific Standard Time, tesla-at-pupman-dot-com

<< Original Poster: guy wilson <wilson-at-vossnet.de> 
 Dear All
 I have tried to give a full spec of the coil which I plan to build. This
 will be
 my first coil. I have 3 caps which were in an electrostatic air cleaner and
 rather small (about 1,5 inch diameter and 2,5 inches long). I also have a
 at the moment tripping the circuit breaker here when I switch on the variac
 with no load on it.
 I would welcome any comments on the suitability of any part of the system
 and what
 I might expect to get out of this design.
 The calculated values are from Ed Sondermanns program as "improved" by
 Corey Ruch
 and from R Scott Coppersmith's "Wintesla" - many thanks.
 They must be Absolutely Potty
 Guy Wilson
 Design Parameters - Guy's (first) Tesla Coil
 Line Filter , Line side of Variac     10A Siems commercial EMI Filter
 Fuse                                  15A, slow blow
 Variac                                5(10A) - need help with surge
 supression -
 trip switch
 Transformer                           Oil Burner 10kV 20mA
 Kickback Choke                        2 x 50 turns on 2 inch (50mm)
 diameter pe
 Safety gap                           three ball bearings,middle movable and
 Safety caps                           pass -i don't have any suitable now
 Primary inner diameter              2,0 inch (50,8 mm)
 Wire Diameter                       0,079 inch (2,0 mm)
 Wire spacing                       0,2 inch (5 mm)
 Total turns                        9, tapped at ca. 5,6 for res. Frequency of
 Inductance                            0,016mH, 0,006mH at 5,65 turn tap
 Caps                                 3 x 0,022uF film caps in series, rated
 DC (and fingers crossed) Should give around 0,07uF - matched to transformer
 Spark Gap                        RQ type or flat hard copper pipe, six gaps
 of ca.
 1mm (0,04                             inch)
 Coil Form   Plastic pipe 2 inch OD x 20 inch long
 Winding length   14 inches
 Wire gauge    33 (0,18mm) - a bit thin, but it's what I've got
 Turns per inch   ca. 133
 Wire length    ca. 950 ft    (quarter wavelength would be 1046 feet)
 H/D Aspect Ratio  7,00
 Inductance   22,16mH
 Medhurst K   1,00 (does this mean something?)
 Self C    5,08pf
 Top Load   Toroid, alu duct, 4 inch D x 14 inch outer diameter
 Top Load C   15,6 pf
 Res Freq. With top load  235khz
 I also have the following transformers which could be used with the system -
 6600v -at- 30mA neon, centre tapped
 8000v -at- 34mA OBI,no centre tap
 10.000v -at- 20mA series to give 40mA
 7500v -at- >100mA Neon (Rated is 75mA, shorted with shunts removed gives 120mA)


It looks like you have put a lot of thought into this design.  The first
advice I might give you is that small diameter, tall coils (candlestick
looking) really don't perform very well.  I would suggest more like 3.0"
diameter for the secondary with a winding length of maybe 13".  I have a coil
just like this wound with #28 wire for a 13.1" winding length.  I would also
suggest making the primary with about 14 turns so you have some flexibility
for the future and the inside diameter about 4.5".

Have fun,  Ed Sonderman