A question about alternative power supply for hp41 series

[Artur - Brasil]

Hi,

These days I was playing with my 41 connected to a wall power supply that I have made but, it's really anoying can't move to other rooms with it.
So, I'm studying construct one step-up internal power supply, that could transform a single 1.5V cell (AA) in 6V, using discrete components, as I don't know if I'll find such ultra small step-up ICs by here.
I have been studying the old charges and internal circuits of some even older HP calculators that used such circuits to generate other voltages from some power supply.
Any ideas?