Re: Double Throw Spark Gap (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Sun, 14 Oct 2007 11:19:00 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Double Throw Spark Gap (fwd)

Interesting John. As I was looking through the specs of both Chris and 
Steve, one thing stood out; A slower rotation of the disc would be 
beneficial in the charging circuit (as would increased rotational 
diameter and increased number of rotating electrodes). I was looking at 
steady charging and not associating a precharge storage cap in the 
process. This will no doubt allow the cap to be charged by the energy 
stored in Cs and the fact that there is minor charging occurring during 
that time.

In Chris's case, I calculated 12 bangs of the gap before the storage cap 
would need to be charged again. In the same respect, to run a higher 
rotational speed or simply increase charge time, the stationary 
"charging" electrodes could be maximized to allow vastly increased 
mechanical dwell and really help the recharge situation as well as the 
number of bangs before quench.

I mentioned in this thread somewhere how different the main gap is from 
a normal RSG. Normally, we set electrodes close and let timing control 
the bangs. Here, that may not be the best thing to do as it might start 
conduction earlier than wanted. However, the static gap on the front end 
will not only help the quench but will also allow a narrow gap width on 
the main gap (ensuring timing between charge and main gap firing is 
separated as desired) and allow voltage control in the main gap. This 
gap will be controlled by both timing and voltage.

Take care,
Bart

Tesla list wrote:
> ---------- 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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