The AM Forum

There's a need to sextuple a voltage coming from a "100 Watt, 120V modified square wave inverter". Coming out from the inverter is the wave, about 280V peak to peak. There is no center tap.

0.) full wave multiplier as shown is preferred because the stress is alike on all the diodes and caps.

1.) there is no real shortage of current from the inverter. Diodes are 1KV@6A (overkill but at hand)

2.) The goal is to charge a 39uF cap to about 810V in about 2 seconds.

3.) It would be best to use small physical sizes of multiplier caps, to reduce the overall volume of this item. Electrolytics are fine because they are the smallest per uF.

4.) there is no need for good regulation under load, only to charge the 39uF capacitor.

The question is: what values of capacitor would I need to charge the HV cap to the full amount in the time allotted?

It seems like there should be a way to figure this out.
The voltage should work its way up, limited by the amount of charge that can be moved each cycle.
The maximum time to charge it would be imposed by the multiplier stages' capacitor sizes. All the same.

If the caps are each 6uF and are in series there, then is it like a 1uF cap and the result is that 1uF worth of coulombs will be deposited into the 39uF cap each power supply half cycle?

Then, is that 39 power supply half cycles to charge the 39uF cap? It feels like something is missing.


The reason that the "stack of capacitors" of the inverter can't be used as the 39uF cap is because electrolytics will have too much inductance for the eventual load, take too long to discharge. The discharge current and time has to be controlled, therefore the separate 39uF cap to be charged.

all sorted out! 800V in 4 seconds will have to do because of the battery size vs. internal resistance. Learned: LTSpice would be better if it could use more than one processor core.