replacing home appliances' internal 120v to 220v
There's one trick I know which works for some very simple, resistive load only appliances with high thermal mass. One can use diodes to cut the power in half, making some 120V devices happily accept 240V. For example, I had this 120V toaster which worked quite well in Europe:







simulate this circuit &ndash; Schematic created using CircuitLab

There are many gotchas with this approach, and it's probably doomed if your device has anything else than resistors (motors, electrical timers, LCDs and so on). I wouldn't recommend it if you don't have the full picture of how your device works.