Re: NST implemented Cockroft-Walton Multiplier

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

At 11:19 AM 5/1/2003 -0600, you wrote:
>Original poster: "Mccauley, Daniel H by way of Terry Fritz 
><teslalist-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com>
>
>
>Regarding my Cockroft-Walton multiplier which I plan for a CW type tesla
>coil and marx generator circuit:
>
> >From the responses, there were some concerns regarding the use of a standard
>NST connected to a C-W multiplier because of its
>center-tapped ground terminal.
>
>What is the best way to implement an NST into a C-W multiplier.  I think KEN
>mentioned to have two C-W multiplier arrays on either side of the
>center-tapped ground, but I think this would lead to a configuration that
>has a floating output.  I would ideally want to have my marx generator
>referenced to earth-ground.

Nope you won't get floating ground, but you DO get half the output voltage.
This is a standard technique, and has the advantage that the ripple is much 
less (twice the pump frequency)



>Also, what types of values were you guys typically use for capacitors for
>your big cap charging circuits.
>I'm currently looking at some TDK 1000pF, 40kV capacitors, and based on my
>charge current, I'll still get about 400-500V
>ripple at the marx generator capacitors during charging.  I could reduce
>charge current, but that would increase charge time which may or may not be
>desirable.


You won't get any ripple at the output, because the marx capacitance acts 
as a huge filter.  Think of the CW stack, in this situation, as a charge 
pump that pumps packets of charge up the stack. When the output voltage is 
low (i.e. marx has low charge), the upper stages of the CW don't do much.. 
as the output voltage rises, the upper stages start to help move the charge 
up the stack.