How do you get 200+ volts from a AA battery? By using a disposable camera's flash unit. And what do you do with 200+ volts once you have it? Drive a nixie tube, of course!
I have removed the large capacitor that stored the charge to run the flash - this is where the high voltage was present. I then removed all the remaining 'flash' components, leaving just the high voltage charge circuit. The board layout allowed me to cut the end off, leaving just a small secton 2cm x 2.8cm.
Now, all that's left is to build myself a battery powered clock!
