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Re: Then what's the topload FOR?



Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

Chris,

The topload adds capacitance, lowers the secondary's resonant frequency,
and its radius of curvature prevents premature breakout. As the
secondary "rings up", energy is transferred from the primary circuit to
the secondary, and the amplitude of the voltage oscillations at the
topload increase, eventually exceeding the breakdown voltage around the
terminal. Once breakout occurs and the spark begins to propagate, events
happen very quickly - so quickly that the relatively low frequency
oscillations in the secondary "look" much like high voltage DC. This is
because the actual current spikes associated with spark propagation are
of the order of 10's of nanoseconds while operating frequency of the
coil may have a period of the order of 10,000 nanoseconds (1000X
greater). 

However, if you increase the time scale so that you're looking at a much
larger interval (i.e., a large number of cycles of oscillation at the
coil's operating frequency), then the topload voltage excursions are
indeed purely Radio Frequency AC, centered about 0 average volts like
any other transformer.   

Best regards,

-- Bert --
-- 
Bert Hickman
Stoneridge Engineering
Email:    bert.hickman-at-aquila-dot-net
Web Site: http://www.teslamania-dot-com

Tesla list wrote:
> 
> Original poster: "Christopher Boden by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <chrisboden-at-hotmail-dot-com>
> 
> Been following the AC-DC thread...got to thinking.....
> 
> Ok....by definition a Tesla Coil is an air-cored radio frequency RESONANT
> TRANSFORMER...right? good
> 
> Now, Resonant and Transformer both seem to indicate an AC thing to me, I
> have yet to see a DC Transformer (though I could REALLY use a few), or
> anything that resonates only one way never crossing a zero point.
> 
> Ok....then, what's the toplaod do?
> 
> A Topload forms one side of a large air capacitor, cool, now, when the
> capacitor discharges (i.e. a streamer) it does this either into the air, or
> into a grounded object, the instantanious discharge would be DC because
> we're dischargeing a capacitor.
> 
> But it's an AC system!???
> 
> Ok, now if the topload stores energy until it overcomes the breakdown of the
> air and the maximum charge density allowed for the given curvature of the
> toroid the it has to be storing that energy during several cycles of the
> ringdown.
> 
> So...we're trying to charge a DC storage device from an AC supply...wouldn't
> this just result in a net charge of 0V? Think about it....
> 
> Each bang in the tank circuit is of opposite polarity to the next. And Once
> the bang occures there is a fast ringdown into the primary coil of a damped
> AC waveform....everything is AC...each Bang is reversed, each cycle of the
> ringdown reverses....how the hell do we get a spark at all?
> 
> In theory, at least in my own warped and twisted head meat, we shouldn't
> have more than a few hundred volts, if that, ever seen in a topload.
> 
> I know I'm wrong (obviously) I just want to know why.
> 
> Christopher "Duck" Boden Geek#1
> President / C.E.O. / Alpha Geek
> The Geek Group
> www.thegeekgroup-dot-org
> Because the Geek shall inherit the Earth!
> 
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