My guess is 1. Because that technology is used absolutely everywhere, eg in cars, and 2. Because it's quite easy: take a transformer, replace the lower-voltage

My guess is 1. Because that technology is used absolutely everywhere, eg in cars, and 2. Because it's quite easy: take a transformer, replace the lower-voltage side with a few turns of a _really_ thick wire, connect the other side to mains and make lots of amps flow for a few seconds through two pieces of sheet metal pushed together.