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Re: [TCML] Crock Croft Walton Voltage Multiplier
Hi,
of course Cockrroft and Walton are the famous Nobel winners for using this
device:
http://en.wikipedia.org/wiki/Cockcroft%E2%80%93Walton_generator
but why should it not be mentiond, that it was invented long time before by
:
http://en.wikipedia.org/wiki/Heinrich_Greinacher ... the Greinacher
cascade
...just a Q, this is no AC vs. DC war! ;-) ... and I'm not too much of a
patriot.
Bert: I enjoy happily your explanations to the device: super!
Regards, Kurt
-----Ursprüngliche Nachricht-----
From: Bert Hickman
Sent: Thursday, May 03, 2012 5:39 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] Crock Croft Walton Voltage Multiplier
Just about any HV capacitors will work, including Power Factor
Correction (PFC) caps. However, PFC caps contain internal bleeder
resistors that will reduce the overall output of your CW multiplier.
The rated DC voltage of the stage capacitors must be at least as high as
the peak HV input voltage, and the HV rectifiers must be at least 2X the
peak HV input voltage. Add 20% - 50% to this to provide a degree of
design margin. Use fast recovery rectifiers if you'll be driving from a
high frequency source (see below). You can stack a series of identical
lower voltage rectifiers to create higher voltage rectifiers.
Although a CW multiplier can be used for "hair raising" experiments,
this is really NOT recommended unless you know EXACTLY what you are
doing... especially if you're storing significant energy in your CW
stage capacitors. This trick is done by connecting a series chain of
high voltage resistors (Gigaohm(s)) between the CW output and your
volunteer to severely limit maximum current to no more than 10's of
microamperes. If your volunteer suddenly decides to step off the
insulated platform, or if the platform flashes over, the HV resistor
chain MUST safely withstand the full voltage of your CW without breaking
down. Your volunteer's life may very well depend on YOUR engineering and
construction skills.
Give serious consideration to the total amount of energy stored within
the stage capacitors before arbitrarily selecting large valued stage
capacitors. Consider powering your CW from a high frequency (20 - 25
kHz) HV source. This will allow you to reduce the stage capacitance and
total CW energy. Also, remember that short-circuiting the HV output will
likely destroy some (or all) of your rectifiers.
Some good design information for half-wave and full-wave CW designs can
be found here:
http://blazelabs.com/e-exp15.asp
http://home.earthlink.net/~jimlux/hv/cw1.htm
Good luck and play safely,
Bert
--
Bert Hickman
Stoneridge Engineering
http://www.capturedlightning.com
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Neon Tesla wrote:
Im not sure if this is of topic but;
I wan't to build a voltage multiplier but I have seen very little on the
practical construction of large units, my 3 main questions of construction
are, firstly what type of capacitors would work, would high voltage
distribution PFC's be suitable? Secondly what are the values that should
be used for the Capacitors and Diodes in relation to the power source,
should the parts be over rated? And last I've seen Crock Croft Walton
multipliers used in the same way as a Van De Graff in hair raising stunts,
should or could this safely be attempted?
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