Hi Thomas,The voltage rating of each diode must be _at least_ 2 times the peak output voltage of the HV supply. For the 10 kVrms SMPS supplies mentioned in the original thread, if the supply outputs a (mostly) sinusoidal waveform, 2 x Vpk would be about 3 x Vrms (rounding 28 kV upwards to 30 kV). However, I'd suggest using a rectifier (diode chain) rated for a reverse voltage of at least 3.5 - 4 x Vrms (or 35 - 40 kV) to provide healthy system margin and robustness.
In a standard cascade C-W multiplier (using equal-value capacitors/stage), each capacitor must be rated for _at least_ the peak voltage of the HV supply (or 15 kV for a 10 kVrms sinusoidal source). I'd suggest using capacitors rated for at least 2 x Vrms (20 kV) to provide good margins and robustness. BTW, note that there are some other multiplier circuit variants (such as Greinacher multipliers) that apply progressively higher voltages across the DC stage caps.
Some additional sites you may find useful:
Theory and component rating:
http://www.eettaiwan.com/ARTICLES/2001JUN/2001JUN14_AMD_AN2009.PDF
http://hep.uchicago.edu/~rosner/p226/proj09/voltmult.pdf
Java-based C-W calculator:
http://www.cosmicrays.org/muon-cockroft-walton-calculation.php
Bert
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jhowson4@xxxxxxxxxxx wrote:
Hey guys i have one of those solid state neon transformers as well, and i too was looking for something useful to do with it. voltage multiplier seems like a good idea. especially since i have a ton of 2kv .5A diodes and 2kv .01uf ceramic caps laying around. the transformer is rated for 6kv 30ma I know this is not a tesla coil question so respond to my e-mail at jhowson4@xxxxxxxxxxx How do you determine the voltage ratings for the diodes and the capacitors needed in the multiplier circuit? I have looked on the internet for an answer and have yet to find a clear one. Will the stuff i have work. thanks in advance , Jay Howson Hi Thomas,The high frequency (20+ kHz) output is ideal for driving a Cockroft-Walton (C-W) Voltage Multiplier, since smaller HV capacitorscan be used in each stage. The following web page provides useful C-W design info for both half and full wave C-W multipliers: http://www.blazelabs.com/e-exp15.asp Bert
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