The proposed 3V to 110V 0r 220V circuit listed below is actually a DC to DC converter having a ordinary 3-0-3V VAC center tapped power transformer rigged in a blocking-oscillator configuration.
The circuit is not really quite efficient, nevertheless will certainly generate the intended high voltage workable with any desired low power application needs.
The input battery voltage is boosted many folds through the transformer. Typically the circuit may take in around 40 milliamps and should function approximately 200 hours on a couple of 'D' alkaline battery packs. Higher current may be acquired simply by lowering the 4.7K bias resistor and for higher voltages you simply need to increase the input voltage to 4.5V or 6V.
The diagram for the discussed 3V to 110V/220V converter circuit can be seen below: