Rotary Spark Gap Design

To: tesla-at-pupman-dot-com
Subject: Rotary Spark Gap Design
From: Rodney Davies <rodney-at-johnxt7.anu.edu.au>
Date: Tue, 14 May 1996 02:33:10 +1000 (EST)
[NOTE: The gif file will be sent to those on the image sub-list.  If you are on 
       the list and do not get the image, let me know.
       -- Chip ]
Hi Guys,

I've attached a gif file (Sparkgp2.gif) schematic of my rotating spark 
gap assembly.

The original design was taken from Bill Wysock's 
3.5MV Super Model 9 Tesla Coil.
We have this coil in our National Science and Technology Centre 
(Questacon), Canberra Australia.

Very impressive too!

Specs: 
------
Power Supply - 20KV -at- 12.5KVA
	       Current and Voltage Limited by variacs of some kind.

2 x 0.1uF Caps in series = 0.2uF -at- 50KVDC each.

Rotating Spark Gap (see GIF file)

Primary - 5 turns 1/2" copper pipe, archimedes flat spiral
	  Outside Diameter - roughly 28" - 29"
          Inside Diameter - 2" larger than secondary, ie, 1" spacing 
	  		    between primary and secondary.

Secondary - 800 Turns of 3mm (appears plastic insulated)
	    Diameter - roughly 15"- 18"

30" x 10" professionally made Alluminium toroid

Frequency - 80Khz

Output - 3.5MV (at full power)

Spark Lengths - roughly on average 6-10 feet.


The template on the coil and power supply says -

Tesla Technologies
Monrovia California

The UHV Division of Proffesional Sound Systems. 
(I don't know if it exists, or under a different name)


This coil is inside a cage, yet my friend works at the organization, and 
were allowed inside for a closer look, therefore the measurements are 
mostly from observational point of view, as I forgot my tape measure that 
day, yet the error would be +/- 1" on dimensions except toroid.

Unfortunately, no matter how much we begged, they wouldn't let us be 
inside the cage during operation - standing at least 5 metres away behind 
a fixture. The decibel reading in the cage is around 100dB.

BTW, we're crazy HV guru's and love the thrill of standing close to 
coils, but we're still living, and haven't been struck....yet! :-)

Hope the design can help others, and that Bill doesn't mind...
Hi Bill! :-)

Comments welcome...

Rod

Rodney%Johnxt7-at-Student.anu.edu.au