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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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