Re: Variacs and stationary gap TCs

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "J. B. Weazle McCreath" <weazle-at-hurontel.on.ca> 


At 07:45 AM 09/01/04 -0700, you wrote:

 >Original poster: Thomas <tom-at-pwrcom-dot-com.au>
 >
 >I was wondering how useful a variac would be to control the power to a
 >stationary gap TC.
 >
 >As the firing voltage is set by the gap distance, would a variac be any
 >use at all (other than for increasing the voltage, a la autotransformer
 >style)?
 >

Yes indeed.  I'm using a static gap on my PDT powered coil, and I use a
variac to ramp the power up and down over a rather large range without
any problems.  I have a smaller variac on the vaccuum cleaner compressor
which provides the air blast to the gap, and by adjusting that I can set
the airflow to match any given power setting.  I have a toroidal current
transformer on my secondary ground, connected to an R.F. voltmeter which
gives me a nice indication of when the optimum setting for the airflow
is achieved...max indication = max streamer length.

 >
 >My tank cap is resonant with the NST, so would the resonant rise let the
 >gap fire over a small range near the upper end of the variac setting?
 >

I'm not sure about that, but I hope you've got properly adjusted safety
gaps and a "Terry Filter" to protect your NST!

 >Tom.


73, Weazle, VE3EAR/VE3WZL

Details of my "Hyperbaric Gap" and Tesla coil are at:
http://www.hurontel.on.ca/~weazle