I am wondering if I could modify a MT3608 boost module by winding a custom inductor / transformer for it, to generate a kV range voltage (at sub mA current).
I'm thinking of replacing the 22uH inductor with a transformer with a similar primary inductance and turns ratio of about 10:1 for a step up voltage of a few hundred volts. Page 14 of https://www.mouser.co.uk/datasheet/2/609/lt1304-1504180.pdf (LT1304) shows the kind of scheme I want to attempt, the top circuit with the Cockcroft-Walton multiplier on the output (my application is for a photomultiplier tube for a scintillation counter). I doubt I can legally copy that image here but essentially its just a standard boost converter with a flyback transformer instead of a inductor.
I only need a few hundred microamps output.
The MT3608 runs at around 1.3MHz which is higher than I have experience with.
Would trying some ferrite rod material be a decent start? Or should I be looking at a bobbin, very small E core, etc. I've got plenty of old magnetics around here, but most of them are much larger than what I imagine I would need - the smallest probably half an inch to an inch cubed. Would it be a problem to use a much larger core than is needed? I realise I need an air gap, but since I am not trying to get high power through a minimally sized ferrite, can I just use a bit of ferrite rod for instance?
