No Subject

Now on to materials and methods...

For a cheap terminal capacitance - you can buy a length of flexible 
aluminum dryer pipe from a local hardware or department store for 
about $6 and form it into a wonderful toroid.  You can tape it together 
with metal tape, and Richard had one wrapped in aluminum foil to 
smooth it out (I think he used spray glue to hold the foil on, but I'm not 
sure).  It seems that if you can pump enough power into the system to 
drive it, the larger the output terminal, the better your results will be (tip 
from Hull's "Guide to the CSN").  For larger systems, the flexible pipe is 
also available in larger diameters, although you will probably have to 
search around to find it.

Another interesting idea from the Teslathon is to use a neon lamp as an 
indicator to see how many discharges you're getting from your spark 
gap per half-cycle of house current.  At it's simplest, solder a 4" or 5" 
wire onto one terminal of a neon lamp.  While your coil is running in a 
darkened room, simply spin the lamp around in a circle by the end of 
the wire. Each time your spark gap fires, it will cause the lamp to light 
in a strobe effect.  If you're getting multiple breakdowns, you should 
see some closely spaced lamp flashes, then a dark space, then a few 
more lamp flashes, etc...  If you're only getting a single discharge, 
you'll see a circle of evenly spaced single flashes.  You can even get 
real fancy like Richard Hull did and solder one terminal of the Ne lamp 
to the outside edge of a 6" diameter circle cut from a single sided PC 
board.  He then mounted the PC board on the shaft of a small battery 
powered motor and built a plastic case to hold everything.  When he 
pushed the switch in the handle, the PC board spun around at a fairly 
constant rate and looked just great!  It's really neat...you can use this 
50 cent device (and that's only if you don't have a Ne lamp) to check 
you gap on everything from your tiny little 50 W coil up to your multiple 
kilowatt magnifier system.

Finally, my first excursion into mail order.  I just bought a bunch of 
circular mica insulators (used to mount large stud diodes) at a hamfest 
that would be perfect to make quenched gaps.  They're 1.375" across 
with a .6875" hole in the middle, and they're thick enough that they 
would probably have to be split a few times to be used (one gap design 
I found calls for .01" thick mica insulators).  If anyone is interested in 
buying some at a nominal cost (25 for $1.00 plus postage), email me 
and we can work something out.  I can also include a couple of designs 
for a quenched gap if you want.  Note: you would probably need access 
to a lathe to turn the electrodes since I can't think of anything that could 
be used off the shelf.  Since I don't have access to a lathe, if anybody 
would like to trade some machine shop time for mica insulators, just let 
me know.  If you're interested and we can come to an equitable 
agreement, I'd be more than happy to pay for the materials and the 
shipping of the finished electrodes.  I'm not sure about the power 
handling capabilities of a quenched gap made with these insulators... 
but the actual sparking surface of the electrodes would be on the order 
of .75 square inches, and if anybody has any thoughts on the matter, 
please speak up. 

Steven Roys (sroys-at-radiology.ab.umd.edu)