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I've got a virtual isolation transformer by connecting two 12V transformers at the secondaries, so the input to my circuit is an isolated 120VAC (US).

I'm creating a 2 level Greinacher style voltage multiplier, so a voltage quadrupler, roughly. Based on my simulations, about 1uF for the caps ought to get me up to a bit under 440V (anywhere in the 400V arena is fine).

Does it matter what kind of caps I use? Will a 500V rating be sufficient?

Edit: It just occurred to me that the 4 caps that are part of the multiplyer never see more than about 220V or so across them. The only cap that would see the full 440V or so would be the filter cap, as only one other cap, in the first level of the multiplier, references ground. The others reference the previous stage which is ~220V less.

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You are totally correct on the voltage front, polarized should be fine, i wasn't looking at the diagram correctly. That being said when using polarized capacitors a 50% safety margin is recommended because they tend to fail in very spectacular ways, both aluminum and tantalum. Please be careful.

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  • \$\begingroup\$ Why no polarized caps? I've seen a number of schematics for Greinacher multipliers that specify them and the voltage on one side is always going to be the same or higher than the other. \$\endgroup\$ – Pete Aug 30 '15 at 23:46
  • \$\begingroup\$ Thanks for your help. I don't have a 50% margin on one of the filter caps. It's a 500V electrolytic at just under 400V. It's inside a metal chassis, so if it blows, it shouldn't hurt anyone... I'm just using this for making a leakage detector so I can test a bunch of vintage caps I got. The voltage quadrupler works as my simulations suggested it would. Thanks again. \$\endgroup\$ – Pete Sep 13 '15 at 14:56

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