Re: Double Throw Spark Gap (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Sun, 14 Oct 2007 10:23:36 EDT
From: FutureT@xxxxxxx
To: tesla@xxxxxxxxxx
Subject: Re: Double Throw Spark Gap (fwd)

This burst TC operation seems similar to a project I built in the  past which
I called a DC Disruptive Compound Storage Staccato Tesla Coil.   This
project is written up in the Oct 1996 TCBA Newletter (Volume 15,  #4).
The project is also shown on my VHS video tapes # 16, 17, and  18. 
 
This system stored energy in a DC filter capacitor.  This energy  in
turn was fed through a large choke to a rotary switching spark  gap.
This gap rotated at a slow rate, and was in series with the normal
fast turning rotary gap in the tank circuit.  The tank cap also  stored
energy of course.
 
The sparks from the toroid emitted in bursts at the rate of about
3 per second and was noticeably pulsed from a visual and aural
point of view.  Each burst consisted of about 24 bangs.  The  sparks
were about 56" long.  Input power was about 460 watts.
 
The sparks seemed to appear extra bright probably because of how
the human eye reacts to such pulsed spark streamers.
 
The rotary switch was made from a sheave pulley from which arc
sections were cut away.  This gave the correct amount of  "on-time"
vs. "off-time".  This pulley was driven at a rate of 1/6th rps.   I tried
running the switch faster, but this made the sparks dimmer.  The
timing was such that 48 bangs should have occurred  during each  burst,
but the voltage dropped below the spark gap firing threshold, so only
about 24 bangs actually occurred during each burst.  
 
For best results there should be a proper balance among; input  current
limiting, filter cap value, output choke inductance, "on/off" times and  
ratio,
and break-rate of the standard rotary gap.
 
Observe suitable safety precautions since this is a DC coil.  
 
John



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