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A 4" garage -- GNATS's first meeting

Greetings all,

Last Sunday Dave Burman, Dave Baehr, and I got together in my garage for 
the first meeting of GNATS (Greater Niwot Area Tesla Society).  

The purpose of the meeting was to fire up coils of course.  
I have recently completed my rotary gap and was anxious to test it.  
After a few power cabinet glitches we got electricity to all the 
components and were ready to fire up my 4" coil.  

I fired up the rotary at about 700 breaks per second (12 contacts, 
running at a fixed speed of about 3500 rpm).  As I turned up the power, 
the sound was significantly different from the static gap that I had 
used.  As the static gap starts to fire, it starts out as a popping sound 
and increases in frequency as the voltage is increased.  With the rotary 
gap, the frequency is constant (700 hz?) and increases in volume with the 
increased voltage.  The sound is a robotic growling whine.  As the 
voltage was turned up, the sparks grew longer and longer.  It was 
wonderful.  I didn't measure the length, but I estimate 4' sparks were 
flying for sure.  The sparks were striking the garage door and anything 
with metal that was near.  

Acting on the advice from Dave Burman I had unplugged the garage door 
opener before hand.  (More on this later).

After firing up my 4" coil, we fired up Dave Burman's 6" coil.  I didn't 
turn up the power too much before the thing was constantly sparking to 
something grounded -- garage door, opener, my coil sitting nearby, etc.

It was apparent that my garage is not big enough for a 6" coil, but is 
big enough for a 4" one.  That led us to devise a new garage size rating 
system:  the maximum diameter of coil that can work in a garage.  Thus, I 
have a 4" garage.  Perhaps we can put a vaulted ceiling in it to get up 
to 6".

After running Dave's coil, we plugged in the garage door opener and it 
didn't work which was distressing.  However, Dave mentioned that his 
garage door opener had the same problem and it was the wall switch that 
was bad, and not the opener at all.  It turns out that I had the same 
problem.  To solve it he disconnected one of the wires on the switch and 
just touches it to the contact where the wire was screwed down.  Weird 
circuitry in that little switch.

Despite my size restrictions, I'm chomping at the bit to start on the new 
6" coil.

A word or two about the rotary gap -- I used 1/4-20 brass acorn nuts for 
the moving electrodes and 1/8" tungsten rods for the stationary ones.  I 
did notice a little erosion on the tips of the rods, but nothing 
excessive.  The holders for the rods are turned from aluminum rod about 
1.5" diameter.  They have a 1/8" hole down the center and are threaded at 
one end with a 1-8 thread.  This allows me to only expose about 1/8" of 
the tungsten rod and provides a large radiating surface to keep them 
cool.

We took pictures which I'll post oncd they get back.  I'm also going to 
post pictures of the rotary gap, once I get them scanned. (The scanner at 
work is flakey, but one of our list members offered to scan them for me, 
so we'll see.)

All in all, a great afternoon of coiling.  All I can say is "goodbye 
neons"

Chip

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
 Chip Atkinson 
 http://bhs.broo.k12.wv.us/homepage/chip/info.htm
 --- Everyone is someone else's weirdo. ---
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