Hey, I saw a schematic floating around for a "two phase" Cockcroft-Walton voltage multiplier. I was wondering if this would essentially work the same with a 3 wire (2 lives, 1 neutral) 240v supply. I had a couple concerns about it so I figured I would post it here to get some information about any issues it might have. I was specifically wondering if C3 can be polarized or not and if the output can go across a load into neutral safely.

 

This is not a safe thing to do. Use a step-up transformer.

 

This is not a safe thing to do. Use a step-up transformer.

I understand that in practice this is a very sketchy thing to do but I am mainly just curious about any potential (circuit breaking) flaws with it.

 

You will have two problems. When you try to double the voltage you cut the current by more than half. Capacitors at that voltage will leak like sieve. Remember the immutable rule of DC-DC conversion schemes which is:

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Power out will ALWAYS be less than power in. Sometimes it will be much less.​

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This is one of those rules that you cannot get over, under, around, or through, regardless of how hard you try or how earnest your quest. This particular bit of physics does not care a whit about your needs and wants. I have a simulation I can share if you are interested. It has a 1: 3 transformer and two doubling stages which in an ideal world would produce 36VDC. Sadly it only makes it 31.9 so you can see the losses. So it can change 3 volts into 31.9 Volts which is only 88% efficient in voltage. the problem with drawing a load from the CW generator is that it will discharge the capacitors and kill the multiplication factor.