********first’1′-************–
u canot find a 5 volt battery
insted u can use a 7805 regulator ic and
9v battery as input
it will give you 5volt suppluy
*******second*********
u will never find axact 750K resistor
so you can use “preset”(small potentiometer)
or
use 680K and 68K resistors in series.
i prefer you to study the the book
“practical electronics for inventors”
you can find it free pdf online