CowJam:
Another question: Ground sharing.Do I share the ground for the 180v and 5v circuits?
Yes. Ground must be shared between all circuits, just be sure never to share VCC. I suppose you could, theoretically, make separate circuits with optoisolators, but for what we are doing that makes no sense. I have had no problems sharing ground between all of my circuits, just keep the high voltage separate from low voltage through transistors, driver circuits, whatever.
Edit:oops, didn't see there was another page. Glad you figured it out. As you can see from my schematic (I think I posted that here) I'm just driving a bunch of MPSA42s from a shift register.