Re: Rotary Gap Electrodes - A first-hand experience

To: tesla-at-pupman-dot-com
Subject: Re: Rotary Gap Electrodes - A first-hand experience
From: Richard Hull <hullr-at-whitlock-dot-com>
Date: Thu, 24 Oct 1996 10:36:46 -0700
Tesla List wrote:
> 
> >From bturner-at-apc-dot-netWed Oct 23 21:20:39 1996
> Date: Wed, 23 Oct 1996 01:27:25 -0700
> From: open_minded <bturner-at-apc-dot-net>
> To: tesla-at-poodle.pupman-dot-com
> Subject: Rotary Gap Electrodes - A first-hand experience
> 
> Hi all...
> 
>   Well, I had a very successful, and eye-opening experience tonight. Lit
> up my larger coil system with the new, 3600 RPM sync. motor. The coil
> sure came to life...I had frantic, white, energetic discharges waving
> into the air. Physically measured strikes came out to 67" to a metal
> ladder near the coil. (Hey, whatever works.) Not shabby for a secondary
> with only 22" worth of windings.
> 
>   One interesting thing though - I sure vaporized the tips off the
> stationary electrodes in my rotary gap! Whoooeeeee. I had 1/8" tungsten
> rods fixed into brass holders. At full poop, the stationary rods
> achieved a nice, brilliant yellow after about 20-30 seconds. The rotating
> electrodes (same stuff) stayed nice and cool.
> 
>   Pre-ionization was quite evident as the discharges initially started
> out very long, then after about 5-7 seconds, shrank back as the electrode
> tips got exceedingly hot. At least I think it was pre-ionization. After
> the gap cooled for a few seconds, it would again light up with long
> discharges that again would shrink back a bit as the tips heated up.
> Anybody experience this phenomenon? (BTW - this same coil *didn't* have
> this behavior with it's old 1800-RPM gap with other electrodes, so I am
> rather sure that everything else hasn't changed.)
> 
>   Looks like a quick retro-fit is in order here. I will replace the 1/8"
> rod in the stationary holders with 1/4", and cut some rather massive
> and heavily finned brass heatsinks. Hopefully, this will help to keep
> the (fixed) electrode temperature down below the 'nasty' point.
> 
>   Aside from dwell times and such, one must be careful to match the
> electrode size and shape to the operating power levels! Either that, or
> I will need to figure out a way to liquid-cool them....!!!!
> 
> - Brent


Brent,

Good work!  That's three times the secondary length in spark and that 
must be considered "plus-ultra performance".  This is about what the best 
two coiler systems, on average, achieve.  Though I have seen others and 
have myself taped out to 4 times the length with a two coiler (Nemesis). 
 That is really close to the limit possible though with real high power 
systems (5-15KVA).  You are to be commended for achieving this level of 
performance.  I consider the 3X mark with two coils systems as placing 
you in the "winners circle".

Richard Hull, TCBOR