Re: please help

To: "'Tesla List'" <tesla-at-poodle.pupman-dot-com>
Subject: Re: please help
From: Tesla List <tesla-at-stic-dot-net>
Date: Sat, 1 Nov 1997 00:30:02 -0600
Approved: tesla-at-stic-dot-net

From: 	Esondrmn-at-aol-dot-com[SMTP:Esondrmn-at-aol-dot-com]
Sent: 	Friday, October 31, 1997 6:49 AM
To: 	tesla-at-pupman-dot-com
Subject: 	Re: please help

In a message dated 97-10-30 19:57:38 EST, you write:

<< 
 My mame is Chris and I have recently started my first coil. My time is
 running short to complete this project. I have received help from this cool
 on a list. He told me my capacitance was way to small. If any body knows
 where I could find caps to fit my coil. The only resource that I have found
 to carry the voltage that I need has too small of a capacitance. Any help is
 appreciated. Here are my specs.
 
 12kv neon at 30mA
 
 was going to use 3 .0047uF doornob caps at 6kv a piece in series.
 
 2 spark gaps using binding posts and hevy wire
 
 a adjustable primary with 14 windings of 8 gauge grounding wire wrapped
 around 4 dowel rods with 1/2" spacing in-between wires.
 
 My secondary is a 14 7/8 by 3 1/2 pvc wrapped with 28 gauge magnet wire with
 an inch left at both ends.
 
 I have decided to make a Toroid from duct elbows. 
 
 
 But he said I needed 10x the capacitance. I need some caps fast and
 hopefully resaonable. 
 
 Please help!!!!!!! 
 Thanks Chris
  >>
Chris,

I did some calculations on your coil.  The secondary should be about 20.5 mh.
 It's resonant frequency should be 431 khz unloaded and 272 khz with a 10 pf
toroid on top.  If your primary is 5.0" in dia, it's inductance should be
about 11.6 uh, if it is 6.0" in dia, it should be about 16 uh.  This will
require a capacitor between .03 mfd and .02 mfd, depending on the diameter of
the primary.

You would be better off with a flat pancake primary.  Same wire and same
spacing between windings with 5.0" I.D. would produce 60 uh.  This would
require a .007 mfd cap to tune at about 12 turns on the primary.

This is the first time I have directly compared the iductance produced by a
solenoid type primary v.s. a flat pancake primary.  In this case the flat
pancake style would use 580" of wire v.s. 219" of wire for the solenoid.  The
flat primary discused here produces 5 times as much inductance even
considering it utilizes about 2.6 times as much wire.

Ed Sonderman