This shows the negative supply. The +12 comes to a 7812 3 terminal reg and then to 2 7660 inverters.
I used 10 mfd tantalum caps for filtering. the 7660's are operated in parallel to be certain of having
adequate current capacity. the 7660's are pretty solid on their output without additional regulation.
Just visible at the left is a 470 mfd electrolytic cap which is filtering the negative 12 volts.