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Ultra High Gain, low current voltage multiplier - Cap leakage tester

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dazz1:
Hi

I want to flog an old dead horse with a new whip.  I want to design a modern version of a capacitor leakage tester/ reformer.
I have surveyed the available designs and not found quite what I am looking for.

I want:
Arduino Nano based because it is cheap and can directly drive 5V logic (and it's cheap),
16ch x 3 line LCD display interfaced to the Nano (also cheap and easy) for display output
Rotary encoder/push switch for user input (simple and cheap),
adjustable from 15VDC to at least 500V output voltage
current limited from 0mA up to 5mA output
inductors yes, transformers no.
no Cockcroft–Walton voltage multipliers because the stage gain is too low (need too many stages)
easy to make (no custom diy parts/coils, off-pcb-parts etc)
physically small size.
Input voltage supply something between 12VDC and 48VDC from a standard mains power SMPS.  This will be a bench test equipment, never battery powered.

My questions focus on the problem of HVDC generation.  The traditional methods are still an option, but I would like to take advantage of the  extensive R&D on voltage multipliers for solar to mains DC.  There are a number of new candidates.  My favourite candidate to date is found here:
https://www.nature.com/articles/s41598-023-42638-5 

It offers high gain and low component stress (cheaper parts, more reliable).  The major disadvantage is the complexity of driving the MOSFET gates plus an oscillator etc, offset by the use of small off-the-shelf inductors. The use of small inductors and more parts will still allow for small form factor.

I have not studied the circuit in sufficient detail to figure out if/how another stage could be added to further increase the voltage gain.

My question is: is there a better and modern alternative voltage multiplier??
The answer does not include "fly-back", "transformer", "Cockcroft-Walton"  etc.  They are the old dead horses.

moffy:
You can do it with a single boost inductor, you only want 2.5W out, at a switching frequency of say 100kHz that is 25uJ energy per cycle at 5ma.

Someone:

--- Quote from: dazz1 on October 03, 2023, 08:31:56 am ---My question is: is there a better and modern alternative voltage multiplier??
The answer does not include "fly-back", "transformer", "Cockcroft-Walton"  etc.  They are the old dead horses.
--- End quote ---
Parts get better so traditional approaches get easier/better/cheaper.
https://www.eevblog.com/forum/projects/555-timer-boost-converter-(and-buck-converter)-switching-power-regulator/

Marco:

--- Quote from: moffy on October 03, 2023, 08:57:53 am ---You can do it with a single boost inductor, you only want 2.5W out, at a switching frequency of say 100kHz that is 25uJ energy per cycle at 5ma.

--- End quote ---
Indeed, when efficiency doesn't matter "component stress" doesn't matter and extreme duty cycles don't matter ... who cares if you're burning most of the power in the MOSFET. As long as a little gets to the capacitor, you can reach your desired output voltage.

JohanH:
I have this small boost converter (not the exact link, but seems to be the same): https://www.ebay.com/itm/224509164439

It goes higher than 450V when adjusted, but the output cap is 450V, so it would have to be changed. It looks like a simple circuit, but the 8-pin chip has only some Chinese characters on it, so I don't know what it says.

BTW, this converter is so cheaply built. The output diode is just glued to the heat sink/casing with legs almost touching the wall. The screw holding two HY1707 Mosfets is barely tightened and the metal clip could fall and touch other components. Requires some modifications to be safer.

Edit: As said below, the chip is marked with the name of the company and it could possibly be MC34063 or similar.

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