With a transformer, they work thanks to two inductances, i have studied them though i don't remembre very well. So you are getting more volts in the output than you have in the input but with a current limitation. For example if you have 3 volts and you want 6 volt you can get them but as far as the wattage has to be the same (in real life you would get less wattage in the output) you will have half the current in the output than you had in the input. Also these transformers works with AC so you need to transform your DC in AC using a MAX253 and an oscilator. So you need an oscilator, a max253 and a transformer. That's it.