Re: Double Throw Spark Gap (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Thu, 11 Oct 2007 20:26:35 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Double Throw Spark Gap (fwd)

Hi Steve,

I didn't understand your statement regarding charging, but then my brain 
turned on. What your saying is that as the disc is spinning, the 
charging gap will perform several passes of each rotating electrode 
until the bang voltage is achieved, at which point the main gap fires. 
So, a high bps will decrease charge time and should also act as a power 
delivery adjustment (you get out what you put in). I don't see how your 
fully charging the 50nF cap to 2xVDC in 235us however. This should take 
nearly 14ms with your power supply (14/250) unless your firing at a 
lower voltage of about 17KVDC? Still plenty of voltage to do some decent 
sparks! Chris is using a 12/30 which is 10x less power than your system.

Have you measured DCV at the cap? The reason I ask is I wonder about 
that measurement where 28KVDC is charging in pulses vs. the actual 
"settled" charge on the cap. This might be very difficult to measure. 
You would probably read the charging voltage and not the actual charged 
voltage. This same problem occurs with classic AC charging measurements 
as well. 235uF is just too quick in my head for the full voltage.

BTW, I enjoyed your setup and PPT file! Excellent work! Your coils look 
great and your charging inductor, motor, and cap bank are tidy and 
clean. The cabinet also was a work of art. A nice coil to be very proud 
of! Thanks for sending it. BTW, I don't have PowerPoint but I did have 
the viewer, so all was good. You made a believer out of me!

Take care,
Bart

Tesla list wrote:
> ---------- Forwarded message ----------
> Date: Tue, 9 Oct 2007 12:43:41 -0600
> From: S&JY <youngs@xxxxxxxxx>
> To: 'Tesla list' <tesla@xxxxxxxxxx>
> Subject: RE: Double Throw Spark Gap (fwd)
>
> Adam & all,
>
> I can't speak for everyone, but yes, the circuit works fine.  I have used it
> for several years.  
>
> It absolutely doesn't need to charge the tank cap in the same time it is
> discharged with the main bang.  If you calculate dwell time, assuming about
> a quarter inch gap presentation length at the highest break rate you will
> use, you will see that there is plenty of time to charge the cap with a
> charging reactor.  With my 12 electrode RSG, at max of 370 breaks per
> second, the time to charge the MMC is about 235 microseconds. I use a 112 mH
> reactor to charge a 50 nF tank cap. The inductance of the charging reactor
> needs to be high enough to limit the peak current to something the de-Qing
> diode string can handle.  My peak current is about 8 amps.  I use 40 3 amp
> (steady state) 1N5408s in series with a DC supply of up to 14 KV (28 KV as
> doubled by the charging reactor) and have never had a diode failure. 
>
> --Steve Y.  
>
> -----Original Message-----
> From: Tesla list [mailto:tesla@xxxxxxxxxx] 
> Sent: Tuesday, October 09, 2007 6:49 AM
> To: tesla@xxxxxxxxxx
> Subject: Double Throw Spark Gap (fwd)
>
>
> ---------- Forwarded message ----------
> Date: Tue, 9 Oct 2007 03:46:42 -0700 (PDT)
> From: Yurtle Turtle <yurtle_t@xxxxxxxxx>
> To: tesla@xxxxxxxxxx
> Subject: Double Throw Spark Gap
>
> I haven't really been following this thread, so
> forgive me if this comment has already been addressed.
>
>
> Regarding the following circuit:
>
> http://tangent.cluenet.org/~chules/hv/tesla/dtsg.html
>
> Does everyone think the cap can charge adequately in
> the same amount of time it can discharge? Without
> doing the math, I gotta believe that if one set of
> flying electrodes zooms around at several hundred rpm,
> the presentation time for the charging portion will be
> too short to fully charge the cap. After all, most rsg
> coils are charging the whole time they aren't
> presenting (well not exactly). I guess you gotta know
> the dwell time and the size of the pig feeding this.
>
> Adam
>
>
>        
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