RE: CHris - Quenching Theory Question (fwd)

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Original poster: List moderator <mod1@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Sat, 19 May 2007 17:01:59 -0600
From: S&JY <youngs@xxxxxxxxx>
To: 'Tesla list' <tesla@xxxxxxxxxx>
Subject: RE:  CHris - Quenching Theory Question

Chris,

Regarding your scheme below:  I have been using such a scheme successfully
for years, and it works great!  I recommend you use a charging reactor with
a deQing diode string to charge your primary cap.  This drastically reduces
the peak charging current and also gives the benefit of charging your
primary cap to roughly twice the DC supply voltage and eliminating charging
spark gap erosion (the spark is much, much smaller than that of the
discharge gap).  Once the charging gap fires, the voltage drop across it is
not enough to be concerned about.  

My setup actually charges the primary cap in series with the primary.  The
thought was that the charging cycle might contribute a small amount of
energy coupled into the secondary to compliment the main discharge cycle.

The benefits are great:  No need for ballasting, break rate can go down to 1
bang every few seconds if you wish without the power arcing you would have
with a normal DC powered single gap ARSG setup, you have independent control
of break rate and power (assuming you have a variac for your DC supply.),
and the power supply is disconnected from the resonant primary circuit when
the gap discharges.  Another advantage is that the charging reactor can be
much smaller - mine is five handmade 23 mH aircore inductors in series to
withstand the voltage. 

I am able to produce seven foot streamers using a 6-MOT supply drawing about
1.9 KVA from two regular house 20 amp outlets.

I have described my setup a few times previously on the list, but as far as
I can tell, noone else has tried it.  Please do let us know how yours
performs.

--Steve Y.
-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx] 
Sent: Friday, May 18, 2007 7:32 PM
To: tesla@xxxxxxxxxx
Subject: RE: Quenching Theory Question (fwd)

Original poster: List moderator <mod1@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Fri, 18 May 2007 21:04:36 -0400
From: "Breneman, Chris" <brenemanc@xxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: RE: Quenching Theory Question (fwd)

This information was really helpful also, but really what I'm getting at
is somewhat more specific, relating to capacitor charging through a gap.  
Here's the overall picture: I was thinking of building a DC coil, and was
looking up various ways to do so.  The two ways that I found were to use a
charging reactor (which would have to be large and have to support a high
voltage) or to use a charging resistor (dissipating significant power).  
>From what I can see, these are necessary to prevent shorting out the power
supply (presumably containing parallel capacitors) when the gap fires.  I
thought that there might be a better way to do this than these methods, by
physically breaking the connection with the power supply when the gap
fired.  The only way I could think of doing this was to use a modified
ARSG, with three contacts.  One contact would be connected to one lead of
the tank capacitor, and it would always be within gap firing distance of
the rotor, which would alternate sparks between two different sets of
contacts, one set attached to the power supply and one set attached to the
primary.  The other power supply lead, tank cap lead, and primary lead
would be connected together. In addition to solving the shorted power
supply problem in DC coils, this design would also have an advantage over
traditional gap AC coils, because there would be no loss due to the power
supply being shorted at peak voltage when the gap fired.  This would be
particularly advantageous for power supplies employing voltage doublers
because the capacitors in the doubler wouldn't completely discharge.  It
would also be an improvement over DC coils with a charging reactor because
the break rate could be varied continuously without changing the charging
reactor.  I have actually ordered parts to build such a gap, and have been
working on several equations to describe gap operation. I can't think of
any problems with this design, except for the issue with the capacitor
charging through a spark gap.  This is where my question was going.  
Because the DC power supply would have a capacitor in parallel with the
power supply of a significantly higher capacitance than the tank
capacitor, when the gap fired to charge the tank capacitor, the initial
current would be high.  My concern is that the tank capacitor might not
charge to the same voltage as it normally would with a charging resistor
or reactor.  So, what are the issues with charging the tank capacitor
through a gap? Also, as soon as the parts for this gap arrive, I'll
construct it, test it, and let you all know how it works.  I'm just very
curious about the aforementioned issues with charging a tank capacitor
through a gap.  I've derived several equations regarding the functionality
of the gap, bang size, power throughput, etc., but none of them take into
account the capacitor charging through the gap.

Thanks a lot, Chris